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Spatenkova V, Mlcek M, Mejstrik A, Cisar L, Kuriscak E. Standard versus individualised positive end-expiratory pressure (PEEP) compared by electrical impedance tomography in neurocritical care: a pilot prospective single centre study. Intensive Care Med Exp 2024; 12:67. [PMID: 39103646 DOI: 10.1186/s40635-024-00654-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 07/24/2024] [Indexed: 08/07/2024] Open
Abstract
BACKGROUND Individualised bedside adjustment of mechanical ventilation is a standard strategy in acute coma neurocritical care patients. This involves customising positive end-expiratory pressure (PEEP), which could improve ventilation homogeneity and arterial oxygenation. This study aimed to determine whether PEEP titrated by electrical impedance tomography (EIT) results in different lung ventilation homogeneity when compared to standard PEEP of 5 cmH2O in mechanically ventilated patients with healthy lungs. METHODS In this prospective single-centre study, we evaluated 55 acute adult neurocritical care patients starting controlled ventilation with PEEPs close to 5 cmH2O. Next, the optimal PEEP was identified by EIT-guided decremental PEEP titration, probing PEEP levels between 9 and 2 cmH2O and finding the minimal amount of collapse and overdistension. EIT-derived parameters of ventilation homogeneity were evaluated before and after the PEEP titration and after the adjustment of PEEP to its optimal value. Non-EIT-based parameters, such as peripheral capillary Hb saturation (SpO2) and end-tidal pressure of CO2, were recorded hourly and analysed before PEEP titration and after PEEP adjustment. RESULTS The mean PEEP value before titration was 4.75 ± 0.94 cmH2O (ranging from 3 to max 8 cmH2O), 4.29 ± 1.24 cmH2O after titration and before PEEP adjustment, and 4.26 ± 1.5 cmH2O after PEEP adjustment. No statistically significant differences in ventilation homogeneity were observed due to the adjustment of PEEP found by PEEP titration. We also found non-significant changes in non-EIT-based parameters following the PEEP titration and subsequent PEEP adjustment, except for the mean arterial pressure, which dropped statistically significantly (with a mean difference of 3.2 mmHg, 95% CI 0.45 to 6.0 cmH2O, p < 0.001). CONCLUSION Adjusting PEEP to values derived from PEEP titration guided by EIT does not provide any significant changes in ventilation homogeneity as assessed by EIT to ventilated patients with healthy lungs, provided the change in PEEP does not exceed three cmH2O. Thus, a reduction in PEEP determined through PEEP titration that is not greater than 3 cmH2O from an initial value of 5 cmH2O is unlikely to affect ventilation homogeneity significantly, which could benefit mechanically ventilated neurocritical care patients.
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Affiliation(s)
- Vera Spatenkova
- Neurocenter, Neurointensive Care Unit, Regional Hospital Liberec, Husova 357/10, 460 01, Liberec, Czech Republic.
- Institute of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, 128 00, Prague, Czech Republic.
- Department of Anaesthesia and Intensive Care, Third Faculty of Medicine, Charles University, Srobarova 50, 100 34, Prague, Czech Republic.
- Faculty of Health Studies, Technical University of Liberec, Studentská 1402/2, 461 17, Liberec 1, Czech Republic.
| | - Mikulas Mlcek
- Institute of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, 128 00, Prague, Czech Republic
| | - Alan Mejstrik
- Institute of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, 128 00, Prague, Czech Republic
- 2nd Department of Medicine-Department of Cardiovascular Medicine, Charles University in Prague, U nemocnice 2, 128 08, Prague, Czech Republic
| | - Lukas Cisar
- Technical Department, Regional Hospital Liberec, Husova 357/10, 460 01, Liberec, Czech Republic
| | - Eduard Kuriscak
- Institute of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, 128 00, Prague, Czech Republic
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Frerichs I, Händel C, Becher T, Schädler D. Sex differences in chest electrical impedance tomography findings. Physiol Meas 2024; 45:075005. [PMID: 38959902 DOI: 10.1088/1361-6579/ad5ef7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 07/03/2024] [Indexed: 07/05/2024]
Abstract
Objective.Electrical impedance tomography (EIT) has been used to determine regional lung ventilation distribution in humans for decades, however, the effect of biological sex on the findings has hardly ever been examined. The aim of our study was to determine if the spatial distribution of ventilation assessed by EIT during quiet breathing was influenced by biological sex.Approach.219 adults with no known acute or chronic lung disease were examined in sitting position with the EIT electrodes placed around the lower chest (6th intercostal space). EIT data were recorded at 33 images/s during quiet breathing for 60 s. Regional tidal impedance variation was calculated in all EIT image pixels and the spatial distribution of the values was determined using the established EIT measures of centre of ventilation in ventrodorsal (CoVvd) and right-to-left direction (CoVrl), the dorsal and right fraction of ventilation, and ventilation defect score.Main results.After exclusion of one subject due to insufficient electrode contact, 218 data sets were analysed (120 men, 98 women) (age: 53 ± 18 vs 50 ± 16 yr (p= 0.2607), body mass index: 26.4 ± 4.0 vs 26.4 ± 6.6 kg m-2(p= 0.9158), mean ± SD). Highly significant differences in ventilation distribution were identified between men and women between the right and left chest sides (CoVrl: 47.0 ± 2.9 vs 48.8 ± 3.3% of chest diameter (p< 0.0001), right fraction of ventilation: 0.573 ± 0.067 vs 0.539 ± 0.071 (p= 0.0004)) and less significant in the ventrodorsal direction (CoVvd: 55.6 ± 4.2 vs 54.5 ± 3.6% of chest diameter (p= 0.0364), dorsal fraction of ventilation: 0.650 ± 0.121 vs 0.625 ± 0.104 (p= 0.1155)). Ventilation defect score higher than one was found in 42.5% of men but only in 16.6% of women.Significance.Biological sex needs to be considered when EIT findings acquired in upright subjects in a rather caudal examination plane are interpreted. Sex differences in chest anatomy and thoracoabdominal mechanics may explain the results.
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Affiliation(s)
- I Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - C Händel
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - T Becher
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - D Schädler
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
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Rahtu M, Frerichs I, Pokka T, Becher T, Peltoniemi O, Kallio M. Effect of body position on ventilation distribution in healthy newborn infants: an observational study. Arch Dis Child Fetal Neonatal Ed 2024; 109:322-327. [PMID: 38071525 DOI: 10.1136/archdischild-2023-325967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 11/15/2023] [Indexed: 04/20/2024]
Abstract
OBJECTIVES Newborn infants have unique respiratory physiology compared with older children and adults due to their lungs' structural and functional immaturity and highly compliant chest wall. To date, ventilation distribution has seldom been studied in this age group. This study aims to assess the effect of body position on ventilation distribution in spontaneously breathing healthy neonates. DESIGN Prospective observational study. SETTING Maternity wards of Oulu University Hospital. PATIENTS 20 healthy, spontaneously breathing, newborn infants. INTERVENTIONS Electrical impedance tomography data were recorded with a 32-electrode belt (Sentec AG, Landquart, Switzerland) in six different body positions in random order. Ventilation distribution was retrospectively assessed 10 minutes after each position change. MAIN OUTCOME MEASURES In each position, regional tidal impedance variation (ΔZ) and ventral-to-dorsal and right-to-left centre of ventilation were measured. RESULTS The mean global ΔZ was the largest in supine position and it was smaller in prone and lateral positions. Yet, global ΔZ did not differ in supine positions, ventilation distribution was more directed towards the non-dependent lung region in supine tilted position (p<0.001). In prone, a reduction of global ΔZ was observed (p<0.05) corresponding to an amount of 10% of global tidal variation in supine position. In both lateral positions, tidal ventilation was distributed more to the corresponding non-dependent lung region. CONCLUSIONS Prone or lateral body positioning in healthy spontaneously breathing newborns leads to a redistribution of ventilation to the non-dependent lung regions and at the same time global tidal volume is reduced as compared with supine.
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Affiliation(s)
- Marika Rahtu
- Department of Pediatrics and Adolescent Medicine and Research Unit of Clinical Medicine, Oulu University Hospital, Oulu, Finland
| | - Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein Campus Kiel, Kiel, Schleswig-Holstein, Germany
| | - Tytti Pokka
- Department of Pediatrics and Adolescent Medicine and Research Unit of Clinical Medicine, Oulu University Hospital, Oulu, Finland
- Research Service Unit, Oulu University Hospital, Oulu, Finland
| | - Tobias Becher
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein Campus Kiel, Kiel, Schleswig-Holstein, Germany
| | - Outi Peltoniemi
- Department of Pediatrics and Adolescent Medicine and Research Unit of Clinical Medicine, Oulu University Hospital, Oulu, Finland
| | - Merja Kallio
- Department of Pediatrics and Adolescent Medicine and Research Unit of Clinical Medicine, Oulu University Hospital, Oulu, Finland
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Frerichs I, Vogt B, Deuss K, Hennig V, Schädler D, Händel C. Distribution of regional lung function in upright healthy subjects determined by electrical impedance tomography in two chest examination planes. Physiol Meas 2024; 45:015001. [PMID: 38096575 DOI: 10.1088/1361-6579/ad15ac] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 12/14/2023] [Indexed: 12/20/2023]
Abstract
Objective. The variation in pulmonary gas content induced by ventilation is not uniformly distributed in the lungs. The aim of our study was to characterize the differences in spatial distribution of ventilation in two transverse sections of the chest using electrical impedance tomography (EIT).Approach. Twenty adult never-smokers, 10 women and 10 men (mean age ± SD, 31 ± 9 years), were examined in a sitting position with the EIT electrodes placed consecutively in a caudal (6th intercostal space) and a cranial (4th intercostal space) chest location. EIT data were acquired during quiet breathing, slow and forced full expiration manoeuvres. Impedance variations representing tidal volume (VT), vital capacity (VC), forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were calculated at the level of individual image pixels and their spatial distribution was determined using the following EIT measures: the centres of ventilation in ventrodorsal (CoVvd) and right-to-left direction (CoVrl), the dorsal and right fractions of ventilation, the coefficient of variation (CV) and the global inhomogeneity (GI) index.Main results. The sums of pixel ventilation-related impedance variations reproduced reliably the volumetric dissimilarities amongVT, VC, FEV1and FVC, with no significant differences noted between the two examination planes. Significant differences in ventilation distribution were found between the planes during tidal breathing and slow full expiration, mainly regarding the ventrodorsal direction, with higher values of CoVvdand dorsal fraction of ventilation in the caudal plane (p< 0.01). No significant differences in the spatial distribution of FEV1and FVC were detected between the examination planes.Significance. The spatial distribution of ventilation differed between the two examination planes only during the relaxed (quiet breathing and slow VC manoeuvre) but not during the forced ventilation. This effect is attributable to the differences in thoracoabdominal mechanics between these types of ventilation.
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Affiliation(s)
- I Frerichs
- University Medical Centre Schleswig-Holstein, Campus Kiel, Department of Anaesthesiology and Intensive Care Medicine, Kiel, Germany
| | - B Vogt
- University Medical Centre Schleswig-Holstein, Campus Kiel, Department of Anaesthesiology and Intensive Care Medicine, Kiel, Germany
| | - K Deuss
- University Medical Centre Schleswig-Holstein, Campus Kiel, Department of Anaesthesiology and Intensive Care Medicine, Kiel, Germany
| | - V Hennig
- University Medical Centre Schleswig-Holstein, Campus Kiel, Department of Anaesthesiology and Intensive Care Medicine, Kiel, Germany
| | - D Schädler
- University Medical Centre Schleswig-Holstein, Campus Kiel, Department of Anaesthesiology and Intensive Care Medicine, Kiel, Germany
| | - C Händel
- University Medical Centre Schleswig-Holstein, Campus Kiel, Department of Anaesthesiology and Intensive Care Medicine, Kiel, Germany
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Heines SJH, Becher TH, van der Horst ICC, Bergmans DCJJ. Clinical Applicability of Electrical Impedance Tomography in Patient-Tailored Ventilation: A Narrative Review. Tomography 2023; 9:1903-1932. [PMID: 37888742 PMCID: PMC10611090 DOI: 10.3390/tomography9050150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/05/2023] [Accepted: 10/16/2023] [Indexed: 10/28/2023] Open
Abstract
Electrical Impedance Tomography (EIT) is a non-invasive bedside imaging technique that provides real-time lung ventilation information on critically ill patients. EIT can potentially become a valuable tool for optimising mechanical ventilation, especially in patients with acute respiratory distress syndrome (ARDS). In addition, EIT has been shown to improve the understanding of ventilation distribution and lung aeration, which can help tailor ventilatory strategies according to patient needs. Evidence from critically ill patients shows that EIT can reduce the duration of mechanical ventilation and prevent lung injury due to overdistension or collapse. EIT can also identify the presence of lung collapse or recruitment during a recruitment manoeuvre, which may guide further therapy. Despite its potential benefits, EIT has not yet been widely used in clinical practice. This may, in part, be due to the challenges associated with its implementation, including the need for specialised equipment and trained personnel and further validation of its usefulness in clinical settings. Nevertheless, ongoing research focuses on improving mechanical ventilation and clinical outcomes in critically ill patients.
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Affiliation(s)
- Serge J. H. Heines
- Department of Intensive Care Medicine, Maastricht University Medical Centre+, 6229 HX Maastricht, The Netherlands; (I.C.C.v.d.H.); (D.C.J.J.B.)
| | - Tobias H. Becher
- Department of Anesthesiology and Intensive Care Medicine, Campus Kiel, University Medical Centre Schleswig-Holstein, 24118 Kiel, Germany;
| | - Iwan C. C. van der Horst
- Department of Intensive Care Medicine, Maastricht University Medical Centre+, 6229 HX Maastricht, The Netherlands; (I.C.C.v.d.H.); (D.C.J.J.B.)
- Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6229 HX Maastricht, The Netherlands
| | - Dennis C. J. J. Bergmans
- Department of Intensive Care Medicine, Maastricht University Medical Centre+, 6229 HX Maastricht, The Netherlands; (I.C.C.v.d.H.); (D.C.J.J.B.)
- School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, 6229 ER Maastricht, The Netherlands
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Xiao L, Yu K, Yang JJ, Liu WT, Liu L, Miao HH, Li TZ. Effect of individualized positive end-expiratory pressure based on electrical impedance tomography guidance on pulmonary ventilation distribution in patients who receive abdominal thermal perfusion chemotherapy. Front Med (Lausanne) 2023; 10:1198720. [PMID: 37731718 PMCID: PMC10507689 DOI: 10.3389/fmed.2023.1198720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 08/15/2023] [Indexed: 09/22/2023] Open
Abstract
Background Electrical impedance tomography (EIT) has been shown to be useful in guiding individual positive end-expiratory pressure titration for patients with mechanical ventilation. However, the appropriate positive end-expiratory pressure (PEEP) level and whether the individualized PEEP needs to be adjusted during long-term surgery (>6 h) were unknown. Meanwhile, the effect of individualized PEEP on the distribution of pulmonary ventilation in patients who receive abdominal thermoperfusion chemotherapy is unknown. The primary aim of this study was to observe the effect of EIT-guided PEEP on the distribution of pulmonary ventilation in patients undergoing cytoreductive surgery (CRS) combined with hot intraperitoneal chemotherapy (HIPEC). The secondary aim was to analyze their effect on postoperative pulmonary complications. Methods A total of 48 patients were recruited and randomly divided into two groups, with 24 patients in each group. For the control group (group A), PEEP was set at 5 cm H2O, while in the EIT group (group B), individual PEEP was titrated and adjusted every 2 h with EIT guidance. Ventilation distribution, respiratory/circulation parameters, and PPC incidence were compared between the two groups. Results The average individualized PEEP was 10.3 ± 1.5 cm H2O, 10.2 ± 1.6 cm H2O, 10.1 ± 1.8 cm H2O, and 9.7 ± 2.1 cm H2O at 5 min, 2 h, 4 h, and 6 h after tracheal intubation during CRS + HIPEC. Individualized PEEP was correlated with ventilation distribution in the regions of interest (ROI) 1 and ROI 3 at 4 h mechanical ventilation and ROI 1 at 6 h mechanical ventilation. The ventilation distribution under individualized PEEP was back-shifted for 6 h but moved to the control group's ventral side under PEEP 5 cm H2O. The respiratory and circulatory function indicators were both acceptable either under individualized PEEP or PEEP 5 cm H2O. The incidence of total PPCs was significantly lower under individualized PEEP (66.7%) than PEEP 5 cm H2O (37.5%) for patients with CRS + HIPEC. Conclusion The appropriate individualized PEEP was stable at approximately 10 cm H2O during 6 h for patients with CRS + HIPEC, along with better ventilation distribution and a lower total PPC incidence than the fixed PEEP of 5 cm H2O.Clinical trial registration: identifier ChiCTR1900023897.
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Affiliation(s)
- Li Xiao
- Department of Anesthesiology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Kang Yu
- Department of Anesthesiology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Jiao-Jiao Yang
- Department of Anesthesiology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Wen-Tao Liu
- Department of Anesthesiology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Lei Liu
- Department of Science and Technology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Hui-Hui Miao
- Department of Anesthesiology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Tian-Zuo Li
- Department of Anesthesiology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
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Tank H, Kennedy G, Pollock R, Hodkinson P, Sheppard-Hickey RA, Woolford J, Green NDC, Stevenson A. Cabin Pressure Altitude Effect on Acceleration Atelectasis After Agile Flight Breathing 60% Oxygen. Aerosp Med Hum Perform 2023; 94:3-10. [PMID: 36757237 DOI: 10.3357/amhp.6123.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
INTRODUCTION: A flight trial was conducted to determine whether breathing 60% oxygen during high performance flight maneuvers using contemporary pilot flight equipment induces atelectasis and to explore whether cabin altitude had any influence on the extent of atelectasis identified.METHODS: On 2 separate days, 14 male aircrew flew as passengers at High [14,500-18,000 ft (4420-5486 m)] and Low [4000-6000 ft (1219-1829 m)] cabin pressure altitude in a Hawk T Mk1 aircraft breathing 60% oxygen. Sorties comprised 16 maneuvers at +5 Gz, each sustained for 30 s. Lung volumes (spirometry), basal lung volume (electrical impedance tomography, EIT), and peripheral oxygen saturation during transition from hyperoxia to hypoxia (pulmonary shunt fraction) were measured in the cockpit immediately before (Pre) and after (Post) flight.RESULTS: Forced inspiratory vital capacity (FIVC) was significantly lower Postflight after High (-0.24 L) and Low (-0.38 L) sorties, but recovered to Preflight values by the fourth repeat (FIVC4). EIT-derived measures of FIVC decreased after High (-3.3%) and Low (-4.4%) sorties but did not recover to baseline by FIVC4. FIVC reductions were attributable to decreased inspiratory capacity. Spo₂ was lower Postflight than Preflight in High and Low sorties.DISCUSSION: Breathing 60% oxygen during flight results in a 3.8-4.9% reduction in lung volume associated with a small decrease in blood oxygenation and an estimated pulmonary shunt of up to 5.7%. EIT measures suggest persisting airway closure despite repeated FIVC maneuvers. There was no meaningful influence of cabin pressure altitude. The operational consequence of the observed changes is likely to be small.Tank H, Kennedy G, Pollock R, Hodkinson P, Sheppard-Hickey R-A, Woolford J, Green NDC, Stevenson A. Cabin pressure altitude effect on acceleration atelectasis after agile flight breathing 60% oxygen. Aerosp Med Hum Perform. 2023; 94(1):3-10.
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Borgmann S, Linz K, Braun C, Dzierzawski P, Spassov S, Wenzel C, Schumann S. Lung area estimation using functional tidal electrical impedance variation images and active contouring. Physiol Meas 2022; 43. [PMID: 35764094 DOI: 10.1088/1361-6579/ac7cc3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 06/28/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Electrical impedance tomography is a valuable tool for monitoring global and regional lung mechanics. To evaluate the recorded data, an accurate estimate of the lung area is crucial. APPROACH We present two novel methods for estimating the lung area using functional tidal images or active contouring methods. A convolutional neural network was trained to determine, whether or not the heart region was visible within tidal images. In addition, the effects of lung area mirroring were investigated. The performance of the methods and the effects of mirroring were evaluated via a score based on the impedance magnitudes in functional tidal images. MAIN RESULTS Our analyses showed that the method based on functional tidal images provided the best estimate of the lung area. Mirroring of the lung area had an impact on the accuracy of area estimation for both methods. The achieved accuracy of the neural network's classification was 94%. For images without a visible heart area, the subtraction of a heart template proved to be a pragmatic approach with good results. SIGNIFICANCE In summary, we developed a routine for estimation of the lung area combined with estimation of the heart area in electrical impedance tomography images.
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Affiliation(s)
- Silke Borgmann
- Universitatsklinikum Freiburg, Hugstetter Straße 55, Freiburg, 79106, GERMANY
| | - Kim Linz
- Universitatsklinikum Freiburg, Hugstetter Straße 55, Freiburg, 79106, GERMANY
| | - Christian Braun
- Universitatsklinikum Freiburg, Hugstetter Straße 55, Freiburg, 79106, GERMANY
| | - Patryk Dzierzawski
- Universitatsklinikum Freiburg, Hugstetter Straße 55, Freiburg, 79106, GERMANY
| | - Sashko Spassov
- Universitatsklinikum Freiburg, Hugstetter Straße 55, Freiburg, 79106, GERMANY
| | - Christin Wenzel
- Anesthesiology and Critical Care, University of Freiburg Faculty of Medicine, Hugstetter Straße 55, Freiburg, 79106, GERMANY
| | - Stefan Schumann
- Universitatsklinikum Freiburg, Hugstetter Straße 55, Freiburg, 79106, GERMANY
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Effects of PEEP on the relationship between tidal volume and total impedance change measured via electrical impedance tomography (EIT). J Clin Monit Comput 2022; 36:325-334. [PMID: 33492490 PMCID: PMC7829490 DOI: 10.1007/s10877-021-00651-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 01/06/2021] [Indexed: 01/31/2023]
Abstract
Electrical impedance tomography (EIT) is used in lung physiology monitoring. There is evidence that EIT is linearly associated with global tidal volume (VT) in clinically healthy patients where no positive end-expiratory pressure (PEEP) is applied. This linearity has not been challenged by altering lung conditions. The aim of this study was to determine the effect of PEEP on VT estimation, using EIT technology and spirometry, and observe the stability of the relationship under changing lung conditions. Twelve male castrated cattle (Steer), mean age 7.8 months (SD ± 1.7) were premedicated with xylazine followed by anaesthesia induction with ketamine and maintenance with halothane in oxygen via an endotracheal tube. An EIT belt was applied around the thorax at the level of the fifth intercostal space. Volume controlled ventilation was used. PEEP was increased in a stepwise manner from 0 to 5, 10 and 15 cmH2O. At each PEEP, the VT was increased stepwise from 5 to 10 and 15 mL kg-1. After a minute of stabilisation, total impedance change (VTEIT), using EIT and VT measured by a spirometer connected to a flow-partitioning device (VTSpiro) was recorded for the following minute before changing ventilator settings. Data was analysed using linear regression and multi variable analysis. There was a linear relationship between VTEIT and VTSpiro at all levels of PEEP with an R2 of 0.71, 0.68, 0.63 and 0.63 at 0, 5, 10 and 15 cmH2O, respectively. The variance in VTEIT was best described by peak inspiratory pressure (PIP) and PEEP (adjusted R2 0.82) while variance in VTSpiro was best described by PIP and airway deadspace (adjusted R2 0.76). The relationship between VTEIT and VTSpiro remains linear with changes in tidal volume, and stable across altered lung conditions. This may have application for monitoring and assessment in vivo.
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Frerichs I, Lasarow L, Strodthoff C, Vogt B, Zhao Z, Weiler N. Spatial Ventilation Inhomogeneity Determined by Electrical Impedance Tomography in Patients With Chronic Obstructive Lung Disease. Front Physiol 2021; 12:762791. [PMID: 34966289 PMCID: PMC8712108 DOI: 10.3389/fphys.2021.762791] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 11/16/2021] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to examine whether electrical impedance tomography (EIT) could determine the presence of ventilation inhomogeneity in patients with chronic obstructive lung disease (COPD) from measurements carried out not only during conventional forced full expiration maneuvers but also from forced inspiration maneuvers and quiet tidal breathing and whether the inhomogeneity levels were comparable among the phases and higher than in healthy subjects. EIT data were acquired in 52 patients with exacerbated COPD (11 women, 41 men, 68 ± 11 years) and 14 healthy subjects (6 women, 8 men, 38 ± 8 years). Regional lung function parameters of forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), forced inspiratory vital capacity (FIVC), forced inspiratory volume in 1 s (FIV1), and tidal volume (V T ) were determined in 912 image pixels. The spatial inhomogeneity of the pixel parameters was characterized by the coefficients of variation (CV) and the global inhomogeneity (GI) index. CV and GI values of pixel FVC, FEV1, FIVC, FIV1, and VT were significantly higher in patients than in healthy subjects (p ≤ 0.0001). The ventilation distribution was affected by the analyzed lung function parameter in patients (CV: p = 0.0024, GI: p = 0.006) but not in healthy subjects. Receiver operating characteristic curves showed that CV and GI discriminated patients from healthy subjects with an area under the curve (AUC) of 0.835 and 0.852 (FVC), 0.845 and 0.867 (FEV1), 0.903 and 0.903 (FIVC), 0.891 and 0.882 (FIV1), and 0.821 and 0.843 (VT), respectively. These findings confirm the ability of EIT to identify increased ventilation inhomogeneity in patients with COPD.
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Affiliation(s)
- Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - Livia Lasarow
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - Claas Strodthoff
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - Barbara Vogt
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.,Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Norbert Weiler
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Kiel, Germany
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Mannée DC, de Jongh F, van Helvoort H. Telemonitoring Techniques for Lung Volume Measurement: Accuracy, Artifacts and Effort. Front Digit Health 2021; 2:559483. [PMID: 34713036 PMCID: PMC8521879 DOI: 10.3389/fdgth.2020.559483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/12/2020] [Indexed: 11/13/2022] Open
Abstract
Telemonitoring becomes more important in pulmonary research. It can be used to decrease the pressure on the health care system, to lower the costs of health care and to increase quality of life of patients. Previous studies show contradictory results regarding the effectiveness of telemonitoring. According to multiple researchers, inefficiency can be a result of poor study design, low data quality and usability issues. To counteract these issues, this review proves for an in-depth explanation of four (potential) telemonitoring systems in terms of work principle, accuracy, disturbing factors and usability. The evaluated systems are portable spirometry/breath-by-breath analyzers, respiratory inductance and magnetic plethysmography and electrical impedance tomography. These insights can be used to select the optimal technique for a specific purpose in future studies.
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Affiliation(s)
| | - Frans de Jongh
- Pulmonary Department, Medisch Spectrum Twente, Enschede, Netherlands
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12
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Hochhausen N, Kapell T, Dürbaum M, Follmann A, Rossaint R, Czaplik M. Monitoring postoperative lung recovery using electrical impedance tomography in post anesthesia care unit: an observational study. J Clin Monit Comput 2021; 36:1205-1212. [PMID: 34542735 PMCID: PMC9294009 DOI: 10.1007/s10877-021-00754-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 08/29/2021] [Indexed: 11/26/2022]
Abstract
With electrical impedance tomography (EIT) recruitment and de-recruitment phenomena can be quantified and monitored at bedside. The aim was to examine the feasibility of EIT with respect to monitor atelectasis formation and resolution in the post anesthesia care unit (PACU). In this observational study, 107 postoperative patients were investigated regarding the presence and recovery of atelectasis described by the EIT-derived parameters Global Inhomogeneity Index (GI Index), tidal impedance variation (TIV), and the changes in end-expiratory lung impedance (ΔEELI). We examined whether the presence of obesity (ADP group) has an influence on pulmonary recovery compared to normal weight patients (NWP group). During the stay at PACU, measurements were taken every 15 min. GI Index, TIV, and ΔEELI were calculated for each time point. 107 patients were monitored and EIT-data of 16 patients were excluded for various reasons. EIT-data of 91 patients were analyzed off-line. Their length of stay averaged 80 min (25th and 75th quartile 52–112). The ADP group demonstrated a significantly higher GI Index at PACU arrival (p < 0.001). This finding disappeared during their stay at the PACU. Additionally, the ADP group showed a significant increase in ΔEELI between PACU arrival and discharge (p = 0.025). Furthermore, TIV showed a significantly lower value during the first 90 min of PACU stay as compared to the time period thereafter (p = 0.036). Our findings demonstrate that obesity has an influence on intraoperative atelectasis formation and de-recruitment during PACU stay. The application of EIT in spontaneously breathing PACU patients seems meaningful in monitoring pulmonary recovery.
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Affiliation(s)
- Nadine Hochhausen
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany.
| | - Torsten Kapell
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Martin Dürbaum
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Andreas Follmann
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Rolf Rossaint
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Michael Czaplik
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
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13
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Dynamic relative regional strain visualized by electrical impedance tomography in patients suffering from COVID-19. J Clin Monit Comput 2021; 36:975-985. [PMID: 34386896 PMCID: PMC8363090 DOI: 10.1007/s10877-021-00748-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 08/06/2021] [Indexed: 01/08/2023]
Abstract
Respiratory failure due to SARS-CoV-2 may progress rapidly. During the course of COVID-19, patients develop an increased respiratory drive, which may induce high mechanical strain a known risk factor for Patient Self-Inflicted Lung Injury (P-SILI). We developed a novel Electrical Impedance Tomography-based approach to visualize the Dynamic Relative Regional Strain (DRRS) in SARS-CoV-2 positive patients and compared these findings with measurements in lung healthy volunteers. DRRS was defined as the ratio of tidal impedance changes and end-expiratory lung impedance within each pixel of the lung region. DRRS values of the ten patients were considerably higher than those of the ten healthy volunteers. On repeated examination, patterns, magnitude and frequency distribution of DRRS were reproducible and in line with the clinical course of the patients. Lung ultrasound scores correlated with the number of pixels showing DRRS values above the derived threshold. Using Electrical Impedance Tomography we were able to generate, for the first time, images of DRRS which might indicate P-SILI in patients suffering from COVID-19. Trial Registration This observational study was registered 06.04.2020 in German Clinical Trials Register (DRKS00021276).
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14
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Haris K, Vogt B, Strodthoff C, Pessoa D, Cheimariotis GA, Rocha B, Petmezas G, Weiler N, Paiva RP, de Carvalho P, Maglaveras N, Frerichs I. Identification and analysis of stable breathing periods in electrical impedance tomography recordings. Physiol Meas 2021; 42. [PMID: 34098533 DOI: 10.1088/1361-6579/ac08e5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/07/2021] [Indexed: 11/11/2022]
Abstract
Objective. In this paper, an automated stable tidal breathing period (STBP) identification method based on processing electrical impedance tomography (EIT) waveforms is proposed and the possibility of detecting and identifying such periods using EIT waveforms is analyzed. In wearable chest EIT, patients breathe spontaneously, and therefore, their breathing pattern might not be stable. Since most of the EIT feature extraction methods are applied to STBPs, this renders their automatic identification of central importance.Approach. The EIT frame sequence is reconstructed from the raw EIT recordings and the raw global impedance waveform (GIW) is computed. Next, the respiratory component of the raw GIW is extracted and processed for the automatic respiratory cycle (breath) extraction and their subsequent grouping into STBPs.Main results. We suggest three criteria for the identification of STBPs, namely, the coefficient of variation of (i) breath tidal volume, (ii) breath duration and (iii) end-expiratory impedance. The total number of true STBPs identified by the proposed method was 294 out of 318 identified by the expert corresponding to accuracy over 90%. Specific activities such as speaking, eating and arm elevation are identified as sources of false positives and their discrimination is discussed.Significance. Simple and computationally efficient STBP detection and identification is a highly desirable component in the EIT processing pipeline. Our study implies that it is feasible, however, the determination of its limits is necessary in order to consider the implementation of more advanced and computationally demanding approaches such as deep learning and fusion with data from other wearable sensors such as accelerometers and microphones.
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Affiliation(s)
- K Haris
- Lab of Computing, Medical Informatics and Biomedical Imaging Technologies, Aristotle University, Thessaloniki, Greece.,Department of Informatics and Computer Engineering, University of West Attica, Greece
| | - B Vogt
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Germany
| | - C Strodthoff
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Germany
| | - D Pessoa
- University of Coimbra, Centre for Informatics and Systems of the University of Coimbra, Department of Informatics Engineering, 3030-290 Coimbra, Portugal
| | - G-A Cheimariotis
- Lab of Computing, Medical Informatics and Biomedical Imaging Technologies, Aristotle University, Thessaloniki, Greece
| | - B Rocha
- University of Coimbra, Centre for Informatics and Systems of the University of Coimbra, Department of Informatics Engineering, 3030-290 Coimbra, Portugal
| | - G Petmezas
- Lab of Computing, Medical Informatics and Biomedical Imaging Technologies, Aristotle University, Thessaloniki, Greece
| | - N Weiler
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Germany
| | - R P Paiva
- University of Coimbra, Centre for Informatics and Systems of the University of Coimbra, Department of Informatics Engineering, 3030-290 Coimbra, Portugal
| | - P de Carvalho
- University of Coimbra, Centre for Informatics and Systems of the University of Coimbra, Department of Informatics Engineering, 3030-290 Coimbra, Portugal
| | - N Maglaveras
- Lab of Computing, Medical Informatics and Biomedical Imaging Technologies, Aristotle University, Thessaloniki, Greece.,Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, United States of America
| | - I Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Germany
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15
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Jiang H, Li Q, Yu X, Zhang C, Li Y, Niu G, Tong ZH, Xi JN, Zhao Z. Ventilation improvement after pneumonia treatment evaluated with electrical impedance tomography: an observational study. Physiol Meas 2021; 42. [PMID: 33971628 DOI: 10.1088/1361-6579/abffbf] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 05/10/2021] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Due to radiation exposures, not all patients with pneumonia would receive chest x-ray or CT measurements to confirm treatment effectiveness. The aim of the study was to examine the ability of using electrical impedance tomography (EIT) to evaluate the treatment effectiveness in such patient group. METHODS A total of 35 consecutive patients with non-severe pneumonia was included in this prospective study. The patients received standard treatment according to our internal protocol. EIT measurements were performed in supine position before the treatment start and on day 6 of the treatment period. EIT-based global inhomogeneity (GI) index and center of ventilation index (CoV) were calculated. Clinical pulmonary infection score (CPIS) was obtained at both time points. RESULTS Clinically significant improvements in GI and CoV were found in patient group (ΔGI: -34%±17% and ΔCoV: -10%±11%; p<0.001). Although CPIS was also significantly improved (ΔCPIS -0.70±0.17, p<0.001), no correlations were demonstrated when it compared to ΔGI or ΔCoV. CONCLUSION EIT demonstrated individual improvement of ventilation heterogeneity after standard treatment in non-severe pneumonia, which provided different information compared to CPIS. EIT has the potential to become a routine non-invasive, non-radiative tool to assess pneumonia treatment effectiveness.
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Affiliation(s)
- Hongying Jiang
- Department of Respiratory and Critical Care Medicine, Beijing Chao-Yang Hospital, Beijing, Beijing, CHINA
| | - Qing Li
- Department of Respiratory Rehabilitation Centre, Beijing Rehabilitation Hospital of Capital Medical University, Beijing, CHINA
| | - Xin Yu
- Department of Respiratory Rehabilitation Centre, Beijing Rehabilitation Hospital of Capital Medical University, Beijing, CHINA
| | - Chenxi Zhang
- Department of Respiratory Rehabilitation Centre, Beijing Rehabilitation Hospital of Capital Medical University, Beijing, CHINA
| | - Yi Li
- Department of Respiratory Rehabilitation Centre, Beijing Rehabilitation Hospital of Capital Medical University, Beijing, CHINA
| | - Guangyu Niu
- Department of Respiratory Rehabilitation Centre, Beijing Rehabilitation Hospital of Capital Medical University, Beijing, CHINA
| | - Zhao-Hui Tong
- Department of Respiratory and Critical Care Medicine, Beijing Chao-Yang Hospital, Beijing, Beijing, CHINA
| | - Jia-Ning Xi
- Department of Respiratory Rehabilitation Centre, Beijing Rehabilitation Hospital of Capital Medical University, Beijing, CHINA
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, 710032, CHINA
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16
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Yang L, Dai M, Cao X, Möller K, Dargvainis M, Frerichs I, Becher T, Fu F, Zhao Z. Regional ventilation distribution in healthy lungs: can reference values be established for electrical impedance tomography parameters? ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:789. [PMID: 34268402 PMCID: PMC8246208 DOI: 10.21037/atm-20-7442] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/24/2021] [Indexed: 12/26/2022]
Abstract
Background Although electrical impedance tomography (EIT) is widely used for monitoring regional ventilation distribution, reference values have yet to be established for clinical use. The present study aimed to evaluate the feasibility of creating reference values for standard EIT parameters for potential clinical application. Methods A total of 75 participants with healthy lungs were included in this prospective study (male:female, 48:27; age, 34±14 years; height, 172±7 cm; weight, 73±12 kg). The subjects were examined during spontaneous breathing in the supine position. EIT measurements were performed at the level of the 4th intercostal space. Commonly used EIT-based parameters, including the center of ventilation (CoV), dorsal and most dorsal fractions of ventilation distribution (TVD and TVROI4 respectively), global inhomogeneity (GI) index, and standard deviation of regional ventilation delay index (RVDSD) were calculated. Results Following outlier detection, EIT data from 71 subjects were finally evaluated. The values of the evaluated parameters were: CoV, 48.7%±1.7%; TVD, 48.1%±5.4%; TVROI4, 7.1%±1.8%; GI, 0.49±0.04; and RVDSD, 7.0±2.0. The coefficients of variation for CoV and GI were low (0.03 and 0.07, respectively), but those for TVROI4 and RVDSD were comparatively high (0.26 and 0.28, respectively). None of the evaluated parameters showed a significant correlation with age. The GI index showed a weak but significant correlation with body mass index (R=0.29, P=0.01). The RVDSD was slightly higher in males than in females. Conclusions Our study indicated that CoV and GI were stable parameters with small coefficients of variation in participants with healthy lungs. The creation of EIT parameter reference values for setting treatment targets may be feasible.
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Affiliation(s)
- Lin Yang
- Department of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Meng Dai
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Xinsheng Cao
- Department of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Knut Möller
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Mantas Dargvainis
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre of Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre of Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Tobias Becher
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre of Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Feng Fu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.,Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
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17
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Hovnanian ALD, Costa ELV, Hoette S, Fernandes CJCS, Jardim CVP, Dias BA, Morinaga LTK, Amato MBP, Souza R. Electrical impedance tomography in pulmonary arterial hypertension. PLoS One 2021; 16:e0248214. [PMID: 33730110 PMCID: PMC7968654 DOI: 10.1371/journal.pone.0248214] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 02/22/2021] [Indexed: 02/06/2023] Open
Abstract
The characterization of pulmonary arterial hypertension (PAH) relies mainly on right heart catheterization (RHC). Electrical impedance tomography (EIT) provides a non-invasive estimation of lung perfusion that could complement the hemodynamic information from RHC. To assess the association between impedance variation of lung perfusion (ΔZQ) and hemodynamic profile, severity, and prognosis, suspected of PAH or worsening PAH patients were submitted simultaneously to RHC and EIT. Measurements of ΔZQ were obtained. Based on the results of the RHC, 35 patients composed the PAH group, and eight patients, the normopressoric (NP) group. PAH patients showed a significantly reduced ΔZQ compared to the NP group. There was a significant correlation between ΔZQ and hemodynamic parameters, particularly with stroke volume (SV) (r = 0.76; P < 0.001). At 60 months, 15 patients died (43%) and 1 received lung transplantation; at baseline they had worse hemodynamics, and reduced ΔZQ when compared to survivors. Patients with low ΔZQ (≤154.6%.Kg) presented significantly worse survival (P = 0.033). ΔZQ is associated with hemodynamic status of PAH patients, with disease severity and survival, demonstrating EIT as a promising tool for monitoring patients with pulmonary vascular disease.
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Affiliation(s)
- André L. D. Hovnanian
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
- * E-mail:
| | - Eduardo L. V. Costa
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Susana Hoette
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Caio J. C. S. Fernandes
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Carlos V. P. Jardim
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Bruno A. Dias
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Luciana T. K. Morinaga
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Marcelo B. P. Amato
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Rogério Souza
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
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18
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Lasarow L, Vogt B, Zhao Z, Balke L, Weiler N, Frerichs I. Regional lung function measures determined by electrical impedance tomography during repetitive ventilation manoeuvres in patients with COPD. Physiol Meas 2021; 42:015008. [PMID: 33434902 DOI: 10.1088/1361-6579/abdad6] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Current standards for conducting spirometry examinations recommend that the ventilation manoeuvres needed in pulmonary function testing are carried out repeatedly during sessions. Chest electrical impedance tomography (EIT) can determine the presence of ventilation heterogeneity during such manoeuvres, which increases the information content derived from such examinations. The aim of this study was to characterise regional lung function in patients with chronic obstructive pulmonary disease (COPD) during repetitive forced full ventilation manoeuvres. Regional lung function measures derived from these manoeuvres were compared with quiet tidal breathing. APPROACH Sixty hospitalised patients were examined during up to three repeated ventilation manoeuvres. Acceptable spirometry manoeuvres were performed and EIT recordings suitable for analysis obtained in 53 patients (12 women, 41 men; age: 68 ± 12 years (mean ± SD)). Pixel values of tidal volume, forced full inspiratory and expiratory volume in 1 s, and forced inspiratory and expiratory vital capacity were calculated from the EIT data. Spatial ventilation heterogeneity was assessed using the coefficient of variation, global inhomogeneity index, and centres and regional fractions of ventilation. Temporal inhomogeneity was determined by examining the pixel expiration times needed to exhale 50% and 75% of regional forced vital capacity. MAIN RESULTS All EIT-derived measures of regional lung function showed reproducible results during repetitive examinations. Parameters of spatial heterogeneity obtained from quiet tidal breathing were comparable with the measures derived from the forced manoeuvres. SIGNIFICANCE Measures of spatial and temporal ventilation heterogeneity obtained in COPD patients by EIT provide comparable findings during repeated examinations within one testing session. Quiet tidal breathing generates similar information on ventilation heterogeneity as forced manoeuvres that demand a high amount of patient effort.
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Affiliation(s)
- L Lasarow
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - B Vogt
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Z Zhao
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany.,Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, People's Republic of China
| | - L Balke
- Department of Pneumology, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - N Weiler
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - I Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
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Sophocleous L, Waldmann AD, Becher T, Kallio M, Rahtu M, Miedema M, Papadouri T, Karaoli C, Tingay DG, Van Kaam AH, Yerworth R, Bayford R, Frerichs I. Effect of sternal electrode gap and belt rotation on the robustness of pulmonary electrical impedance tomography parameters. Physiol Meas 2020; 41:035003. [DOI: 10.1088/1361-6579/ab7b42] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Lehmann M, Oehler B, Zuber J, Malzahn U, Walles T, Muellenbach RM, Roewer N, Kredel M. Redistribution of pulmonary ventilation after lung surgery detected with electrical impedance tomography. Acta Anaesthesiol Scand 2020; 64:517-525. [PMID: 31830306 DOI: 10.1111/aas.13525] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 10/09/2019] [Accepted: 11/04/2019] [Indexed: 12/25/2022]
Abstract
BACKGROUND Regional ventilation of the lung can be visualized by pulmonary electrical impedance tomography (EIT). The aim of this study was to examine the post-operative redistribution of regional ventilation after lung surgery dependent on the side of surgery and its association with forced vital capacity. METHODS In this prospective, observational cohort study 13 patients undergoing right and 13 patients undergoing left-sided open or video-thoracoscopic procedures have been investigated. Pre-operative measurements with EIT and spirometry were compared with data obtained 3 days post-operation. The center of ventilation (COV) within a 32 × 32 pixel matrix was calculated from EIT data. The transverse axis coordinate of COV, COVx (left/right), was modified to COVx' (ipsilateral/contralateral). Thus, COVx' shows a negative change if ventilation shifts contralateral independent of the side of surgery. This enabled testing with two-way ANOVA for repeated measurements (side, time). RESULTS The perioperative shift of COVx' was dependent on the side of surgery (P = .007). Ventilation shifted away from the side of surgery after the right-sided surgery (COVx'-1.97 pixel matrix points, P < .001), but not after the left-sided surgery (COVx'-0.61, P = .425). The forced vital capacity (%predicted) decreased from 94 (83-109)% (median [quartiles]; [left-sided]) and 89 (80-97)% (right-sided surgery) to 61 (59-66)% and 62 (40-72)% (P < .05), respectively. The perioperative changes in forced vital capacity (%predicted) were weakly associated with the shift of COVx'. CONCLUSION Only after right-sided lung surgery, EIT showed reduced ventilation on the side of surgery while vital capacity was markedly reduced in both groups.
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Affiliation(s)
- Martin Lehmann
- Department of Anaesthesia and Critical Care University Hospital of Würzburg Würzburg Germany
| | - Beatrice Oehler
- Wolfson Centre for Age-Related Diseases King's College London London UK
| | - Jonas Zuber
- Department of Anesthesia, General Intensive Care and Pain Management Medical University of Vienna Vienna Austria
| | - Uwe Malzahn
- Clinical Trials Center Würzburg University Hospital of Würzburg Würzburg Germany
| | - Thorsten Walles
- Department of Thoracic Surgery Magdeburg University Medicine Magdeburg Germany
| | - Ralf M. Muellenbach
- Department of Anesthesiology, Critical Care Medicine, Emergency Medicine and Pain Therapy ECMO Center Campus Kassel of the University of Southampton Kassel Germany
| | - Norbert Roewer
- Department of Anaesthesia and Critical Care University Hospital of Würzburg Würzburg Germany
| | - Markus Kredel
- Department of Anaesthesia and Critical Care University Hospital of Würzburg Würzburg Germany
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21
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Hochhausen N, Orschulik J, Follmann A, Santos SA, Dohmeier H, Leonhardt S, Rossaint R, Czaplik M. Comparison of two experimental ARDS models in pigs using electrical impedance tomography. PLoS One 2019; 14:e0225218. [PMID: 31721803 PMCID: PMC6853608 DOI: 10.1371/journal.pone.0225218] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/30/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Animal trials contribute to major achievements in medical science. The so-called lavage model is frequently used to evaluate ventilation strategies in acute respiratory distress syndrome (ARDS) using electrical impedance tomography (EIT). But, the lavage model itself might have systematic impacts on EIT parameters. Therefore, we established an additional experimental model, in which ARDS is caused by intravenously administered lipopolysaccharide (LPS). In this study, we want to examine if EIT measurements provide consistent results in both experimental models or whether the pathophysiology of the model influences the findings. Overall, we want to compare both experimental models regarding clinical parameters and EIT-derived indices, namely the global inhomogeneity (GI) index and the regional ventilation delay (RVD) index. METHODS Nineteen pigs were included in this study, allocated to the control group (CO; n = 5), lavage group (LAV; n = 7) and LPS group (LPS; n = 7). After baseline measurements and the establishment of ARDS, assessment of respiratory mechanics, hemodynamics, gas exchange and EIT recordings were performed hourly over eight hours. RESULTS In both experimental ARDS models, EIT measurements provided reliable results. But, the GI and the RVD index did not show consistent results as compared to the CO group. Initially, GI and RVD index were higher in the LAV group but not in the LPS group as compared to the CO group. This effect disappeared during the study. Furthermore, the GI index and the RVD index were higher in the LAV group compared to the LPS group in the beginning as well. This, once again, disappeared. Clinical lung injury parameters remained more stable when using LPS. CONCLUSION The two models showed quite different influences on the GI and RVD index. This implies, that the underlying pathophysiology affects EIT parameters and thus the findings. Hence, translation to EIT-guided clinical therapy in humans suffering from ARDS might be limited.
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Affiliation(s)
- Nadine Hochhausen
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Jakob Orschulik
- Philips Chair for Medical Information Technology, RWTH Aachen University, Aachen, Germany
| | - Andreas Follmann
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Susana Aguiar Santos
- Philips Chair for Medical Information Technology, RWTH Aachen University, Aachen, Germany
| | - Henriette Dohmeier
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Steffen Leonhardt
- Philips Chair for Medical Information Technology, RWTH Aachen University, Aachen, Germany
| | - Rolf Rossaint
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Michael Czaplik
- Department of Anesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
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Bauer M, Opitz A, Filser J, Jansen H, Meffert RH, Germer CT, Roewer N, Muellenbach RM, Kredel M. Perioperative redistribution of regional ventilation and pulmonary function: a prospective observational study in two cohorts of patients at risk for postoperative pulmonary complications. BMC Anesthesiol 2019; 19:132. [PMID: 31351452 PMCID: PMC6661098 DOI: 10.1186/s12871-019-0805-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 07/18/2019] [Indexed: 11/30/2022] Open
Abstract
Background Postoperative pulmonary complications (PPCs) increase morbidity and mortality of surgical patients, duration of hospital stay and costs. Postoperative atelectasis of dorsal lung regions as a common PPC has been described before, but its clinical relevance is insufficiently examined. Pulmonary electrical impedance tomography (EIT) enables the bedside visualization of regional ventilation in real-time within a transversal section of the lung. Dorsal atelectasis or effusions might cause a ventral redistribution of ventilation. We hypothesized the existence of ventral redistribution in spontaneously breathing patients during their recovery from abdominal and peripheral surgery and that vital capacity is reduced if regional ventilation shifts to ventral lung regions. Methods This prospective observational study included 69 adult patients undergoing elective surgery with an expected intermediate or high risk for PPCs. Patients undergoing abdominal and peripheral surgery were recruited to obtain groups of equal size. Patients received general anesthesia with and without additional regional anesthesia. On the preoperative, the first and the third postoperative day, EIT was performed at rest and during spirometry (forced breathing). The center of ventilation in dorso-ventral direction (COVy) was calculated. Results Both groups received intraoperative low tidal volume ventilation. Postoperative ventral redistribution of ventilation (forced breathing COVy; preoperative: 16.5 (16.0–17.3); first day: 17.8 (16.9–18.2), p < 0.004; third day: 17.4 (16.2–18.2), p = 0.020) and decreased forced vital capacity in percentage of predicted values (FVC%predicted) (median: 93, 58, 64%, respectively) persisted after abdominal surgery. In addition, dorsal to ventral shift was associated with a decrease of the FVC%predicted on the third postoperative day (r = − 0.66; p < 0.001). A redistribution of pulmonary ventilation was not observed after peripheral surgery. FVC%predicted was only decreased on the first postoperative day (median FVC%predicted on the preoperative, first and third day: 85, 81 and 88%, respectively). In ten patients occurred pulmonary complications after abdominal surgery also in two patients after peripheral surgery. Conclusions After abdominal surgery ventral redistribution of ventilation persisted up to the third postoperative day and was associated with decreased vital capacity. The peripheral surgery group showed only minor changes in vital capacity, suggesting a role of the location of surgery for postoperative redistribution of pulmonary ventilation. Trial registration This prospective observational single centre study was submitted to registration prior to patient enrollment at ClinicalTrials.gov (NCT02419196, Date of registration: December 1, 2014). Registration was finalized at April 17, 2015. Electronic supplementary material The online version of this article (10.1186/s12871-019-0805-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Maria Bauer
- Department of Anaesthesia and Critical Care, University Hospital of Würzburg, University of Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Anne Opitz
- Department of Anaesthesia and Critical Care, University Hospital of Würzburg, University of Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Jörg Filser
- Department of General, Visceral, Transplantation, Vascular and Paediatric Surgery, University Hospital of Würzburg, University of Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Hendrik Jansen
- Department of Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, University of Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Rainer H Meffert
- Department of Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, University of Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Christoph T Germer
- Department of General, Visceral, Transplantation, Vascular and Paediatric Surgery, University Hospital of Würzburg, University of Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Norbert Roewer
- Department of Anaesthesia and Critical Care, University Hospital of Würzburg, University of Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Ralf M Muellenbach
- Department of Anaesthesia and Critical Care, University Hospital of Würzburg, University of Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Markus Kredel
- Department of Anaesthesia and Critical Care, University Hospital of Würzburg, University of Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany.
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23
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Stowe S, Boyle A, Sage M, See W, Praud JP, Fortin-Pellerin É, Adler A. Comparison of bolus- and filtering-based EIT measures of lung perfusion in an animal model. Physiol Meas 2019; 40:054002. [PMID: 30965314 DOI: 10.1088/1361-6579/ab1794] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Two main functional imaging approaches have been used to measure regional lung perfusion using electrical impedance tomography (EIT): venous injection of a hypertonic saline contrast agent and imaging of its passage through the heart and lungs, and digital filtering of heart-frequency impedance changes over sequences of EIT images. This paper systematically compares filtering-based perfusion estimates and bolus injection methods to determine to which degree they are related. APPROACH EIT data was recorded on seven mechanically ventilated newborn lambs in which ventilation distribution was varied through changes in posture between prone, supine, left- and right-lateral positions. Perfusion images were calculated using frequency filtering and ensemble averaging during both ventilation and apnoea time segments for each posture to compare against contrast agent-based methods using Jaccard distance score. MAIN RESULTS Using bolus-based EIT measures of lung perfusion as the reference frequency filtering techniques performed better than ensemble averaging and both techniques performed equally well across apnoea and ventilation data segments. SIGNIFICANCE Our results indicate the potential for use of filtering-based EIT measures of heart-frequency activity as a non-invasive proxy for contrast agent injection-based measures of lung perfusion.
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Affiliation(s)
- Symon Stowe
- Systems and Computer Engineering, Carleton University, Ottawa, Canada. Author to whom any correspondence should be addressed
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24
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De la Fuente C, Weinstein A, Guzman-Venegas R, Arenas J, Cartes J, Soto M, Carpes FP. Use of accelerometers for automatic regional chest movement recognition during tidal breathing in healthy subjects. J Electromyogr Kinesiol 2019; 47:105-112. [PMID: 31158729 DOI: 10.1016/j.jelekin.2019.05.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 05/11/2019] [Accepted: 05/23/2019] [Indexed: 11/29/2022] Open
Abstract
Recognition of breathing patterns helps clinicians to understand acute and chronic adaptations during exercise and pathological conditions. Wearable technologies combined with a proper data analysis provide a low cost option to monitor chest and abdominal wall movements. Here we set out to determine the feasibility of using accelerometry and machine learning to detect chest-abdominal wall movement patterns during tidal breathing. Furthermore, we determined the accelerometer positions included in the clusters, considering principal component domains. Eleven healthy participants (age: 21 ± 0.2 y, BMI: 23.4 ± 0.7 kg/m2, FEV1: 4.1 ± 0.3 L, VO2: 4.6 ± 0.2 mL/min kg) were included in this cross-sectional study. Spirometry and ergospirometry assessments were performed with participants seated with 13 accelerometers placed over the thorax. Data collection lasted 10 min. Following signal pre-processing, principal components and clustering analyses were performed. The Euclidean distances in respect to centroids were compared between the clusters (p < 0.05), identifying two clusters (p < 0.001). The first cluster included sensors located at the right and left second rib midline, body of sternum, left fourth rib midline, right and left second thoracic vertebra midline, and fifth thoracic vertebra. The second cluster included sensors at the fourth right rib midline, right and left seventh ribs, abdomen at linea alba, and right and left tenth thoracic vertebra midline. Costal-superior and costal-abdominal patterns were also recognized. We conclude that accelerometers placed on the chest and abdominal wall permit the identification of two clusters of movements regarding respiration biomechanics.
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Affiliation(s)
- Carlos De la Fuente
- Laboratorio integrativo de biomecánica y fisiología del esfuerzo, LIBFE, Escuela de Kinesiología, Universidad de los Andes, Santiago, Chile; Carrera de Kinesiología, Departamento de Ciencias de la Salud, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile; Centro de Salud Deportivo, Clínica Santa María, Santiago, Chile; Magìster en Ciencias de la Ingenieria, School of Biomedical Engineer, Universidad de Valparaiso, Valparaíso, Chile.
| | - Alejandro Weinstein
- School of Biomedical Engineer, Universidad de Valparaiso, Valparaíso, Chile; Magìster en Ciencias de la Ingenieria, School of Biomedical Engineer, Universidad de Valparaiso, Valparaíso, Chile.
| | - Rodrigo Guzman-Venegas
- Laboratorio integrativo de biomecánica y fisiología del esfuerzo, LIBFE, Escuela de Kinesiología, Universidad de los Andes, Santiago, Chile.
| | - Juan Arenas
- Carrera de Kinesiología, Departamento de Ciencias de la Salud, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile.
| | - Jorge Cartes
- Carrera de Kinesiología, Departamento de Ciencias de la Salud, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile.
| | - Marcos Soto
- Carrera de Kinesiología, Departamento de Ciencias de la Salud, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile.
| | - Felipe P Carpes
- Applied Neuromechanics Research Group, Universidade Federal do Pampa, Campus Uruguaiana, Uruguaiana, Brazil.
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25
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Caruana LR, Barnett AG, Tronstad O, Paratz JD, Chang AT, Fraser JF. Global tidal variations, regional distribution of ventilation, and the regional onset of filling determined by electrical impedance tomography: reproducibility. Anaesth Intensive Care 2017; 45:235-243. [PMID: 28267946 DOI: 10.1177/0310057x1704500214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The reproducibility of the regional distribution of ventilation and the timing of onset of regional filling as measured by electrical impedance tomography lacks evidence. This study investigated whether electrical impedance tomography measurements in healthy males were reproducible when electrodes were replaced between measurements. Part 1: Recordings of five volunteers lying supine were made using electrical impedance tomography and a pneumotachometer. Measurements were repeated at least three hours later. Skin marking ensured accurate replacement of electrodes. No stabilisation period was allowed. Part 2: Electrical impedance tomography recordings of ten volunteers; a 15 minute stabilisation period, extra skin markings, and time-averaging were incorporated to improve the reproducibility. Reproducibility was determined using the Bland-Altman method. To judge the transferability of the limits of agreement, a Pearson correlation was used for electrical impedance tomography tidal variation and tidal volume. Tidal variation was judged to be reproducible due to the significant correlation between tidal variation and tidal volume (r2 = 0.93). The ventilation distribution was not reproducible. A stabilisation period, extra skin markings and time-averaging did not improve the outcome. The timing of regional onset of filling was reproducible and could prove clinically valuable. The reproducibility of the tidal variation indicates that non-reproducibility of the ventilation distribution was probably a biological difference and not measurement error. Other causes of variability such as electrode placement variability or lack of stabilisation when accounted for did not improve the reproducibility of the ventilation distribution.
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Affiliation(s)
- L R Caruana
- Physiotherapist, The Critical Care Research Group, The Prince Charles Hospital, The University of Queensland School of Medicine, Brisbane, Queensland
| | - A G Barnett
- Associate Professor, The Critical Care Research Group, The Prince Charles Hospital, School of Public Health & Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland
| | - O Tronstad
- Clinical Lead Physiotherapist, The Critical Care Research Group, The Prince Charles Hospital, Brisbane, Queensland
| | - J D Paratz
- Physiotherapist, The Critical Care Research Group, The Prince Charles Hospital, Burns, Trauma and Critical Research Centre, School of Medicine, University of Queensland, Brisbane, Griffith University, Southport, Queensland
| | - A T Chang
- Physiotherapist, The Critical Care Research Group, The Prince Charles Hospital, School of Health and Rehabilitation Sciences, University of Queensland, Brisbane, Queensland
| | - J F Fraser
- Director, The Critical Care Research Group, The Prince Charles Hospital, Professor, School of Health and Rehabilitation Sciences, University of Queensland, Brisbane, Queensland
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Ventilation distribution and lung recruitment with speaking valve use in tracheostomised patient weaning from mechanical ventilation in intensive care. J Crit Care 2017; 40:164-170. [PMID: 28411422 DOI: 10.1016/j.jcrc.2017.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/21/2017] [Accepted: 04/05/2017] [Indexed: 11/20/2022]
Abstract
PURPOSE Speaking valves (SV) are used infrequently in tracheostomised ICU patients due to concerns regarding their putative effect on lung recruitment. A recent study in cardio-thoracic population demonstrated increased end-expiratory lung volumes during and post SV use without examining if the increase in end-expiratory lung impedance (EELI) resulted in alveolar recruitment or potential hyperinflation in discrete loci. MATERIALS AND METHODS A secondary analysis of Electrical Impedance Tomography (EIT) data from a previous study was conducted. EELI distribution and tidal variation (TV) were assessed with a previously validated tool. A new tool was used to investigate ventilated surface area (VSA) and regional ventilation delay (RVD) as indicators of alveolar recruitment. RESULTS The increase in EELI was found to be uniform with significant increase across all lung sections (p<0.001). TV showed an initial non-significant decrease (p=0.94) with subsequent increase significantly above baseline (p<0.001). VSA and RVD showed non-significant changes during and post SV use. CONCLUSIONS These findings indicate that hyperinflation did not occur with SV use, which is supported by previously published data on respiratory parameters. These data along with obvious psychological benefits to patients are encouraging towards safe use of SVs in this critically ill cardio-thoracic patient population. TRIAL REGISTRATION Anna-Liisa Sutt, Australian New Zealand Clinical Trials Registry (ANZCTR). ACTRN ACTRN12615000589583. 4/6/2015.
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27
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Miedema M, Waldmann A, McCall KE, Böhm SH, van Kaam AH, Tingay DG. Individualized Multiplanar Electrical Impedance Tomography in Infants to Optimize Lung Monitoring. Am J Respir Crit Care Med 2017; 195:536-538. [DOI: 10.1164/rccm.201607-1370le] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Martijn Miedema
- Murdoch Children’s Research InstituteMelbourne, Australia
- Academic Medical Centre AmsterdamAmsterdam, the Netherlands
| | | | - Karen E. McCall
- Murdoch Children’s Research InstituteMelbourne, Australia
- University College DublinDublin, Ireland
| | | | | | - David G. Tingay
- Murdoch Children’s Research InstituteMelbourne, Australia
- Royal Children’s HospitalMelbourne, Australiaand
- University of MelbourneMelbourne, Australia
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28
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Schullcke B, Gong B, Krueger-Ziolek S, Tawhai M, Adler A, Mueller-Lisse U, Moeller K. Lobe based image reconstruction in Electrical Impedance Tomography. Med Phys 2017; 44:426-436. [PMID: 28121374 DOI: 10.1002/mp.12038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 09/22/2016] [Accepted: 11/25/2016] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Electrical Impedance Tomography (EIT) is an imaging modality used to generate two-dimensional cross-sectional images representing impedance change in the thorax. The impedance of lung tissue changes with change in air content of the lungs; hence, EIT can be used to examine regional lung ventilation in patients with abnormal lungs. In lung EIT, electrodes are attached around the circumference of the thorax to inject small alternating currents and measure resulting voltages. In contrast to X-ray computed tomography (CT), EIT images do not depict a thorax slice of well defined thickness, but instead visualize a lens-shaped region around the electrode plane, which results from diffuse current propagation in the thorax. Usually, this is considered a drawback, since image interpretation is impeded if 'off-plane' conductivity changes are projected onto the reconstructed two-dimensional image. In this paper we describe an approach that takes advantage of current propagation below and above the electrode plane. The approach enables estimation of the individual conductivity change in each lung lobe from boundary voltage measurements. This could be used to monitor disease progression in patients with obstructive lung diseases, such as chronic obstructive pulmonary disease (COPD) or cystic fibrosis (CF) and to obtain a more comprehensive insight into the pathophysiology of the lung. METHODS Electrode voltages resulting from different conductivities in each lung lobe were simulated utilizing a realistic 3D finite element model (FEM) of the human thorax and the lungs. Overall 200 different patterns of conductivity change were simulated. A 'lobe reconstruction' algorithm was developed, applying patient-specific anatomical information in the reconstruction process. A standard EIT image reconstruction algorithm and the proposed 'lobe reconstruction' algorithm were used to estimate conductivity change in the lobes. The agreement between simulated and reconstructed conductivity change in particular lobes were compared using Bland-Altman plots, correlation plots and linear regression. To test the applicability of the approach in a realistic scenario, EIT measurements of a patient suffering from cystic fibrosis (CF) were carried out. RESULTS Conductivity changes in each lobe generate specific patterns of voltage change. These can be used to estimate the conductivity change in lobes from measured boundary voltage. The correlation coefficient between simulated and reconstructed conductivity change in particular lobes is r > 0.89 for all lobes. Unknown position of the electrode plane leads to over- or underestimation of reconstructed conductivity change. Slight mismatches (± 5% of the forward model height) between the actual position of the electrode plane and the position used in the reconstruction model lead to regression coefficients of 0.7 to 1.3 between simulated and reconstructed conductivity change in the lobes. CONCLUSION The presented approach enhances common reconstruction methods by providing information about anatomically assignable units and thus facilitates image interpretation, since impedance change and thus ventilation of each lobe is directly determined in the reconstructions.
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Affiliation(s)
- Benjamin Schullcke
- Institute of Technical Medicine, Furtwangen University, 78045, VS-Schwenningen, Germany.,Department of Radiology, University of Munich, 80336, Munich, Germany
| | - Bo Gong
- Institute of Technical Medicine, Furtwangen University, 78045, VS-Schwenningen, Germany.,Department of Radiology, University of Munich, 80336, Munich, Germany
| | - Sabine Krueger-Ziolek
- Institute of Technical Medicine, Furtwangen University, 78045, VS-Schwenningen, Germany.,Department of Radiology, University of Munich, 80336, Munich, Germany
| | - Merryn Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, 1010, New Zealand
| | - Andy Adler
- Systems and Computer Engineering, Carlton University, Ottawa, ON, K1S 5B6, Canada
| | | | - Knut Moeller
- Institute of Technical Medicine, Furtwangen University, 78045, VS-Schwenningen, Germany
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29
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Frerichs I, Amato MBP, van Kaam AH, Tingay DG, Zhao Z, Grychtol B, Bodenstein M, Gagnon H, Böhm SH, Teschner E, Stenqvist O, Mauri T, Torsani V, Camporota L, Schibler A, Wolf GK, Gommers D, Leonhardt S, Adler A. Chest electrical impedance tomography examination, data analysis, terminology, clinical use and recommendations: consensus statement of the TRanslational EIT developmeNt stuDy group. Thorax 2016; 72:83-93. [PMID: 27596161 PMCID: PMC5329047 DOI: 10.1136/thoraxjnl-2016-208357] [Citation(s) in RCA: 494] [Impact Index Per Article: 61.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 07/12/2016] [Accepted: 07/16/2016] [Indexed: 11/04/2022]
Abstract
Electrical impedance tomography (EIT) has undergone 30 years of development. Functional chest examinations with this technology are considered clinically relevant, especially for monitoring regional lung ventilation in mechanically ventilated patients and for regional pulmonary function testing in patients with chronic lung diseases. As EIT becomes an established medical technology, it requires consensus examination, nomenclature, data analysis and interpretation schemes. Such consensus is needed to compare, understand and reproduce study findings from and among different research groups, to enable large clinical trials and, ultimately, routine clinical use. Recommendations of how EIT findings can be applied to generate diagnoses and impact clinical decision-making and therapy planning are required. This consensus paper was prepared by an international working group, collaborating on the clinical promotion of EIT called TRanslational EIT developmeNt stuDy group. It addresses the stated needs by providing (1) a new classification of core processes involved in chest EIT examinations and data analysis, (2) focus on clinical applications with structured reviews and outlooks (separately for adult and neonatal/paediatric patients), (3) a structured framework to categorise and understand the relationships among analysis approaches and their clinical roles, (4) consensus, unified terminology with clinical user-friendly definitions and explanations, (5) a review of all major work in thoracic EIT and (6) recommendations for future development (193 pages of online supplements systematically linked with the chief sections of the main document). We expect this information to be useful for clinicians and researchers working with EIT, as well as for industry producers of this technology.
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Affiliation(s)
- Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Marcelo B P Amato
- Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Anton H van Kaam
- Department of Neonatology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands
| | - David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Zhanqi Zhao
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Bartłomiej Grychtol
- Fraunhofer Project Group for Automation in Medicine and Biotechnology PAMB, Mannheim, Germany
| | - Marc Bodenstein
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Hervé Gagnon
- Department of Systems and Computer Engineering, Carleton University, Ottawa, Ontario, Canada
| | | | | | - Ola Stenqvist
- Department of Anesthesiology and Intensive Care Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Tommaso Mauri
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Vinicius Torsani
- Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Luigi Camporota
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Andreas Schibler
- Paediatric Critical Care Research Group, Mater Research University of Queensland, South Brisbane, Australia
| | - Gerhard K Wolf
- Children's Hospital Traunstein, Ludwig Maximilian's University, Munich, Germany
| | - Diederik Gommers
- Department of Adult Intensive Care, Erasmus MC, Rotterdam, The Netherlands
| | - Steffen Leonhardt
- Philips Chair for Medical Information Technology, Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Andy Adler
- Department of Systems and Computer Engineering, Carleton University, Ottawa, Ontario, Canada
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30
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Yerworth RJ, Frerichs I, Bayford R. Analysis and compensation for errors in electrical impedance tomography images and ventilation-related measures due to serial data collection. J Clin Monit Comput 2016; 31:1093-1101. [PMID: 27534624 PMCID: PMC5599443 DOI: 10.1007/s10877-016-9920-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 08/09/2016] [Indexed: 12/27/2022]
Abstract
Electrical impedance tomography (EIT) is increasingly being used as a bedside tool for monitoring regional lung ventilation. However, most clinical systems use serial data collection which, if uncorrected, results in image distortion, particularly at high breathing rates. The objective of this study was to determine the extent to which this affects derived parameters. Raw EIT data were acquired with the GOE-MF II EIT device (CareFusion, Höchberg, Germany) at a scan rate of 13 images/s during both spontaneous breathing and mechanical ventilation. Boundary data for periods of undisturbed tidal breathing were corrected for serial data collection errors using a Fourier based algorithm. Images were reconstructed for both the corrected and original data using the GREIT algorithm, and parameters describing the filling characteristics of the right and left lung derived on a breath by breath basis. Values from the original and corrected data were compared using paired t-tests. Of the 33 data sets, 23 showed significant differences in filling index for at least one region, 11 had significant differences in calculated tidal impedance change and 12 had significantly different filling fractions (p = 0.05). We conclude that serial collection errors should be corrected before image reconstruction to avoid clinically misleading results.
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Affiliation(s)
- Rebecca J Yerworth
- Medical Physics and Biomedical Engineering Department, University College London, London, WC1E 6BT, England, UK.
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Richard Bayford
- Department of Natural Sciences, Middlesex University, London, England, UK
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31
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Schullcke B, Krueger-Ziolek S, Gong B, Mueller-Lisse U, Moeller K. Simultaneous application of two independent EIT devices for real-time multi-plane imaging. Physiol Meas 2016; 37:1541-55. [DOI: 10.1088/0967-3334/37/9/1541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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32
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Krueger-Ziolek S, Schullcke B, Zhao Z, Gong B, Naehrig S, Müller-Lisse U, Moeller K. Multi-layer ventilation inhomogeneity in cystic fibrosis. Respir Physiol Neurobiol 2016; 233:25-32. [PMID: 27476932 DOI: 10.1016/j.resp.2016.07.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 07/27/2016] [Accepted: 07/28/2016] [Indexed: 11/18/2022]
Abstract
Differences in regional lung function between the 3rd and 5th intercostal space (ICS) were explored in 10 cystic fibrosis (CF) patients and compared to 10 lung-healthy controls by electrical impedance tomography (EIT). Regional ratios of impedance changes corresponding to the maximal volume of air exhaled within the first second of a forced expiration (ΔIFEV1) and the forced vital capacity (ΔIFVC) were determined. Regional airway obstruction and ventilation inhomogeneity were assessed by the frequency distribution of these ratios (ΔIFEV1/ΔIFVC) and an inhomogeneity index (GITI). The mean of the frequency distribution of ΔIFEV1/ΔIFVC and the GITI in both thorax planes were significantly different between CF patients and controls (p<0.001). CF patients exhibited a significantly lower mean of ΔIFEV1/ΔIFVC frequency distribution (p<0.05) and a significantly higher degree of ventilation inhomogeneity (p<0.01) in the 3rd ICS compared to the 5th ICS. Results indicated that EIT measurements at more cranial thorax planes may benefit the early diagnosis in CF.
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Affiliation(s)
- Sabine Krueger-Ziolek
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Straße 17, 78054 Villingen-Schwenningen, Germany; Department of Radiology, LMU University of Munich, Ziemssenstrasse 1, 80336 Munich, Germany(1).
| | - Benjamin Schullcke
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Straße 17, 78054 Villingen-Schwenningen, Germany; Department of Radiology, LMU University of Munich, Ziemssenstrasse 1, 80336 Munich, Germany(1)
| | - Zhanqi Zhao
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Straße 17, 78054 Villingen-Schwenningen, Germany
| | - Bo Gong
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Straße 17, 78054 Villingen-Schwenningen, Germany; Department of Radiology, LMU University of Munich, Ziemssenstrasse 1, 80336 Munich, Germany(1)
| | - Susanne Naehrig
- Medizinische Klinik V (Pneumology), LMU University of Munich, Ziemssenstrasse 1, 80336 Munich, Germany(1)
| | - Ullrich Müller-Lisse
- Department of Radiology, LMU University of Munich, Ziemssenstrasse 1, 80336 Munich, Germany(1)
| | - Knut Moeller
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Straße 17, 78054 Villingen-Schwenningen, Germany
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Vogt B, Zhao Z, Zabel P, Weiler N, Frerichs I. Regional lung response to bronchodilator reversibility testing determined by electrical impedance tomography in chronic obstructive pulmonary disease. Am J Physiol Lung Cell Mol Physiol 2016; 311:L8-L19. [DOI: 10.1152/ajplung.00463.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 05/17/2016] [Indexed: 01/01/2023] Open
Abstract
Patients with obstructive lung diseases commonly undergo bronchodilator reversibility testing during examination of their pulmonary function by spirometry. A positive response is defined by an increase in forced expiratory volume in 1 s (FEV1). FEV1 is a rather nonspecific criterion not allowing the regional effects of bronchodilator to be assessed. We employed the imaging technique of electrical impedance tomography (EIT) to visualize the spatial and temporal ventilation distribution in 35 patients with chronic obstructive pulmonary disease at baseline and 5, 10, and 20 min after bronchodilator inhalation. EIT scanning was performed during tidal breathing and forced full expiration maneuver in parallel with spirometry. Ventilation distribution was determined by EIT by calculating the image pixel values of FEV1, forced vital capacity (FVC), tidal volume, peak flow, and mean forced expiratory flow between 25 and 75% of FVC. The global inhomogeneity indexes of each measure and histograms of pixel FEV1/FVC values were then determined to assess the bronchodilator effect on spatial ventilation distribution. Temporal ventilation distribution was analyzed from pixel values of times needed to exhale 75 and 90% of pixel FVC. Based on spirometric FEV1, significant bronchodilator response was found in 17 patients. These patients exhibited higher postbronchodilator values of all regional EIT-derived lung function measures in contrast to nonresponders. Ventilation distribution was inhomogeneous in both groups. Significant improvements were noted for spatial distribution of pixel FEV1 and tidal volume and temporal distribution in responders. By providing regional data, EIT might increase the diagnostic and prognostic information derived from reversibility testing.
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Affiliation(s)
- Barbara Vogt
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Furtwangen University, Villingen-Schwenningen, Germany; and
| | - Peter Zabel
- Department of Pneumology, Medical Clinic, Research Center Borstel, Germany
| | - Norbert Weiler
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
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Ericsson E, Tesselaar E, Sjöberg F. Effect of Electrode Belt and Body Positions on Regional Pulmonary Ventilation- and Perfusion-Related Impedance Changes Measured by Electric Impedance Tomography. PLoS One 2016; 11:e0155913. [PMID: 27253433 PMCID: PMC4890811 DOI: 10.1371/journal.pone.0155913] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 05/08/2016] [Indexed: 11/18/2022] Open
Abstract
Ventilator-induced or ventilator-associated lung injury (VILI/VALI) is common and there is an increasing demand for a tool that can optimize ventilator settings. Electrical impedance tomography (EIT) can detect changes in impedance caused by pulmonary ventilation and perfusion, but the effect of changes in the position of the body and in the placing of the electrode belt on the impedance signal have not to our knowledge been thoroughly evaluated. We therefore studied ventilation-related and perfusion-related changes in impedance during spontaneous breathing in 10 healthy subjects in five different body positions and with the electrode belt placed at three different thoracic positions using a 32-electrode EIT system. We found differences between regions of interest that could be attributed to changes in the position of the body, and differences in impedance amplitudes when the position of the electrode belt was changed. Ventilation-related changes in impedance could therefore be related to changes in the position of both the body and the electrode belt. Perfusion-related changes in impedance were probably related to the interference of major vessels. While these findings give us some insight into the sources of variation in impedance signals as a result of changes in the positions of both the body and the electrode belt, further studies on the origin of the perfusion-related impedance signal are needed to improve EIT further as a tool for the monitoring of pulmonary ventilation and perfusion.
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Affiliation(s)
- Elin Ericsson
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Erik Tesselaar
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
- Department of Radiation Physics, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
- * E-mail:
| | - Folke Sjöberg
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
- Department of Hand and Plastic Surgery and the Burn Clinic, Linköping University, Linköping, Sweden
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Vogt B, Mendes L, Chouvarda I, Perantoni E, Kaimakamis E, Becher T, Weiler N, Tsara V, Paiva RP, Maglaveras N, Frerichs I. Influence of torso and arm positions on chest examinations by electrical impedance tomography. Physiol Meas 2016; 37:904-21. [PMID: 27200486 DOI: 10.1088/0967-3334/37/6/904] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Electrical impedance tomography (EIT) is increasingly used in patients suffering from respiratory disorders during pulmonary function testing (PFT). The EIT chest examinations often take place simultaneously to conventional PFT during which the patients involuntarily move in order to facilitate their breathing. Since the influence of torso and arm movements on EIT chest examinations is unknown, we studied this effect in 13 healthy subjects (37 ± 4 years, mean age ± SD) and 15 patients with obstructive lung diseases (72 ± 8 years) during stable tidal breathing. We carried out the examinations in an upright sitting position with both arms adducted, in a leaning forward position and in an upright sitting position with consecutive right and left arm elevations. We analysed the differences in EIT-derived regional end-expiratory impedance values, tidal impedance variations and their spatial distributions during all successive study phases. Both the torso and the arm movements had a highly significant influence on the end-expiratory impedance values in the healthy subjects (p = 0.0054 and p < 0.0001, respectively) and the patients (p < 0.0001 in both cases). The global tidal impedance variation was affected by the torso, but not the arm movements in both study groups (p = 0.0447 and p = 0.0418, respectively). The spatial heterogeneity of the tidal ventilation distribution was slightly influenced by the alteration of the torso position only in the patients (p = 0.0391). The arm movements did not impact the ventilation distribution in either study group. In summary, the forward torso movement and the arms' abduction exert significant effects on the EIT waveforms during tidal breathing. We recommend strict adherence to the upright sitting position during PFT when EIT is used.
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Affiliation(s)
- B Vogt
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany
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Donoso A, Arriagada D, Contreras D, Ulloa D, Neumann M. [Respiratory monitoring of pediatric patients in the Intensive Care Unit]. BOLETIN MEDICO DEL HOSPITAL INFANTIL DE MEXICO 2016; 73:149-165. [PMID: 29421202 DOI: 10.1016/j.bmhimx.2016.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 01/29/2016] [Accepted: 02/02/2016] [Indexed: 06/08/2023] Open
Abstract
Respiratory monitoring plays an important role in the care of children with acute respiratory failure. Therefore, its proper use and correct interpretation (recognizing which signals and variables should be prioritized) should help to a better understanding of the pathophysiology of the disease and the effects of therapeutic interventions. In addition, ventilated patient monitoring, among other determinations, allows to evaluate various parameters of respiratory mechanics, know the status of the different components of the respiratory system and guide the adjustments of ventilatory therapy. In this update, the usefulness of several techniques of respiratory monitoring including conventional respiratory monitoring and more recent methods are described. Moreover, basic concepts of mechanical ventilation, their interpretation and how the appropriate analysis of the information obtained can cause an impact on the clinical management of the patient are defined.
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Affiliation(s)
| | | | - Dina Contreras
- Hospital Clínico Metropolitano La Florida, Santiago, Chile
| | - Daniela Ulloa
- Hospital Clínico Metropolitano La Florida, Santiago, Chile
| | - Megan Neumann
- Hospital Clínico Metropolitano La Florida, Santiago, Chile
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Becher T, Vogt B, Kott M, Schädler D, Weiler N, Frerichs I. Functional Regions of Interest in Electrical Impedance Tomography: A Secondary Analysis of Two Clinical Studies. PLoS One 2016; 11:e0152267. [PMID: 27010320 PMCID: PMC4806869 DOI: 10.1371/journal.pone.0152267] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 03/13/2016] [Indexed: 11/19/2022] Open
Abstract
Introduction Patients with acute respiratory distress syndrome (ARDS) typically show a high degree of ventilation inhomogeneity, which is associated with morbidity and unfavorable outcomes. Electrical impedance tomography (EIT) is able to detect ventilation inhomogeneity, but it is unclear which method for defining the region of interest (ROI) should be used for this purpose. The aim of our study was to compare the functional region of interest (fROI) method to both the lung area estimation method (LAEM) and no ROI when analysing global parameters of ventilation inhomogeneity. We assumed that a good method for ROI determination would lead to a high discriminatory power for ventilation inhomogeneity, as defined by the area under the receiver operating characteristics curve (AUC), comparing patients suffering from ARDS and control patients without pulmonary pathologies. Methods We retrospectively analysed EIT data from 24 ARDS patients and 12 control patients without pulmonary pathology. In all patients, a standardized low-flow-pressure volume maneuver had been performed and was used for EIT image generation. We compared the AUC for global inhomogeneity (GI) index and coefficient of variation (CV) between ARDS and control patients using all EIT image pixels, the fROI method and the LAEM for ROI determination. Results When analysing all EIT image pixels, we found an acceptable AUC both for the GI index (AUC = 0.76; 95% confidence interval (CI) 0.58–0.94) and the CV (AUC = 0.74; 95% CI 0.55–0.92). With the fROI method, we found a deteriorating AUC with increasing threshold criteria. With the LAEM, we found the best AUC both for the GI index (AUC = 0.89; 95% CI 0.78–1.0) and the CV (AUC = 0.89; 95% CI 0.78–1.0) using a threshold criterion of 50% of the maximum tidal impedance change. Conclusion In the assessment of ventilation inhomogeneity with EIT, functional regions of interest obscure the difference between patients with ARDS and control patients without pulmonary pathologies. The LAEM is preferable to the fROI method when assessing ventilation inhomogeneity.
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Affiliation(s)
- Tobias Becher
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 3, Haus 12, 24105, Kiel, Germany
- * E-mail:
| | - Barbara Vogt
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 3, Haus 12, 24105, Kiel, Germany
| | - Matthias Kott
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 3, Haus 12, 24105, Kiel, Germany
| | - Dirk Schädler
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 3, Haus 12, 24105, Kiel, Germany
| | - Norbert Weiler
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 3, Haus 12, 24105, Kiel, Germany
| | - Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 3, Haus 12, 24105, Kiel, Germany
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Lupton-Smith A, Argent A, Rimensberger P, Morrow B. The effects of prone and supine positions on the regional distribution of ventilation in infants and children using electrical impedance tomography. SOUTH AFRICAN JOURNAL OF PHYSIOTHERAPY 2015; 71:237. [PMID: 30135874 PMCID: PMC6093132 DOI: 10.4102/sajp.v71i1.237] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 04/14/2015] [Indexed: 11/17/2022] Open
Abstract
Background Positioning of ill children is often used to optimise ventilation–perfusion matching, thereby improving oxygenation. Objectives To determine the effects of supine and prone positions, and different head positions, on the distribution of ventilation in healthy, spontaneously breathing infants and children between the ages of 6 months and 9 years. Methods Electrical impedance tomography measurements were recorded from participants in supine and prone positions. Head positions included the head turned to the left and right in supine and prone positions, and in the midline in the supine position. Distribution of ventilation was described using end-expiratory–end-inspiratory relative impedance change. Results A total of 56 participants (boys = 31 [55%]; girls = 25 [45%]) were studied. The dorsal lung was significantly better ventilated than the ventral lung (P < 0.001) in both body positions. The majority of participants (83%) had greater ventilation in the dorsal lung in both positions, whilst five participants (10%) demonstrated consistently better ventilation in the non-dependent lung in both positions. Head position had no effect on the distribution of ventilation. Conclusions This study demonstrates that the distribution of ventilation in healthy, spontaneously breathing infants and children in supine and prone positions is not as straightforward as previously thought, with no clear reversal of the adult pattern evident.
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Affiliation(s)
- Alison Lupton-Smith
- School of Child and Adolescent Health, University of Cape Town, South Africa
| | - Andrew Argent
- School of Child and Adolescent Health, University of Cape Town, South Africa.,Paediatric Intensive Care Unit, Red Cross War Memorial Children's Hospital, South Africa
| | - Peter Rimensberger
- Paediatric and Neonatal Intensive Care Unit, University Hospital of Geneva, Switzerland
| | - Brenda Morrow
- School of Child and Adolescent Health, University of Cape Town, South Africa.,Paediatric Intensive Care Unit, Red Cross War Memorial Children's Hospital, South Africa
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Roth CJ, Ehrl A, Becher T, Frerichs I, Schittny JC, Weiler N, Wall WA. Correlation between alveolar ventilation and electrical properties of lung parenchyma. Physiol Meas 2015; 36:1211-26. [DOI: 10.1088/0967-3334/36/6/1211] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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40
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Krueger-Ziolek S, Schullcke B, Kretschmer J, Müller-Lisse U, Möller K, Zhao Z. Positioning of electrode plane systematically influences EIT imaging. Physiol Meas 2015; 36:1109-18. [DOI: 10.1088/0967-3334/36/6/1109] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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41
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Becher T, Kott M, Schädler D, Vogt B, Meinel T, Weiler N, Frerichs I. Influence of tidal volume on ventilation inhomogeneity assessed by electrical impedance tomography during controlled mechanical ventilation. Physiol Meas 2015; 36:1137-46. [PMID: 26007294 DOI: 10.1088/0967-3334/36/6/1137] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The global inhomogeneity (GI) index is a parameter of ventilation inhomogeneity that can be calculated from images of tidal ventilation distribution obtained by electrical impedance tomography (EIT). It has been suggested that the GI index may be useful for individual adjustment of positive end-expiratory pressure (PEEP) and for guidance of ventilator therapy. The aim of the present work was to assess the influence of tidal volume (VT) on the GI index values. EIT data from 9 patients with acute respiratory distress syndrome ventilated with a low and a high VT of 5 ± 1 (mean ± SD) and 9 ± 1 ml kg(-1) predicted body weight at a high and a low level of PEEP (PEEPhigh, PEEPlow) were analyzed. PEEPhigh and PEEPlow were set 2 cmH2O above and 5 cmH2O below the lower inflection point of a quasi-static pressure volume loop, respectively. The lower inflection point was identified at 8.1 ± 1.4 (mean ± SD) cmH2O, resulting in a PEEPhigh of 10.1 ± 1.4 and a PEEPlow of 3.1 ± 1.4 cmH2O. At PEEPhigh, we found no significant trend in GI index with low VT when compared to high VT (0.49 ± 0.15 versus 0.44 ± 0.09, p = 0.13). At PEEPlow, we found a significantly higher GI index with low VT compared to high VT (0.66 ± 0.19 versus 0.59 ± 0.17, p = 0.01). When comparing the PEEP levels, we found a significantly lower GI index at PEEPhigh both for high and low VT. We conclude that high VT may lead to a lower GI index, especially at low PEEP settings. This should be taken into account when using the GI index for individual adjustment of ventilator settings.
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Affiliation(s)
- T Becher
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, 24118 Kiel, Germany
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42
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Tidal volume monitoring by electrical impedance tomography (EIT) using different regions of interest (ROI): Calibration equations. Biomed Signal Process Control 2015. [DOI: 10.1016/j.bspc.2014.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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43
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Marinho LS, Sousa NPD, Barros CABDS, Matias MS, Monteiro LT, Beraldo MDA, Costa ELV, Amato MBP, Holanda MA. Assessment of regional lung ventilation by electrical impedance tomography in a patient with unilateral bronchial stenosis and a history of tuberculosis. J Bras Pneumol 2014; 39:742-6. [PMID: 24473768 PMCID: PMC4075903 DOI: 10.1590/s1806-37132013000600013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 01/25/2013] [Indexed: 11/22/2022] Open
Abstract
Bronchial stenosis can impair regional lung ventilation by causing abnormal, asymmetric airflow limitation. Electrical impedance tomography (EIT) is an imaging technique that allows the assessment of regional lung ventilation and therefore complements the functional assessment of the lungs. We report the case of a patient with left unilateral bronchial stenosis and a history of tuberculosis, in whom regional lung ventilation was assessed by EIT. The EIT results were compared with those obtained by ventilation/perfusion radionuclide imaging. The patient was using nasal continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea syndrome. Therefore, we studied the effects of postural changes and of the use of nasal CPAP. The EIT revealed heterogeneous distribution of regional lung ventilation, the ventilation being higher in the right lung, and this distribution was influenced by postural changes and CPAP use. The EIT assessment of regional lung ventilation produced results similar to those obtained with the radionuclide imaging technique and had the advantage of providing a dynamic evaluation without radiation exposure.
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Lupton-Smith AR, Argent AC, Rimensberger PC, Morrow BM. Challenging a paradigm: positional changes in ventilation distribution are highly variable in healthy infants and children. Pediatr Pulmonol 2014; 49:764-71. [PMID: 24009188 DOI: 10.1002/ppul.22893] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 07/17/2013] [Accepted: 07/17/2013] [Indexed: 11/06/2022]
Abstract
RATIONALE Current understanding is that infants and children preferentially ventilate non-dependent lungs, a reversal of that of adults, based on studies using krypton-81m ventilation scanning. Participants in these studies had lung disease and were either sedated or ventilated. There is little understanding of the distribution of ventilation in spontaneous breathing healthy infants and children. OBJECTIVES This study aimed to determine the effects of side lying on the distribution of ventilation in healthy, spontaneously breathing infants and children between the ages of 6 months and 9 years. METHODS AND MEASUREMENTS Measurements were taken using electrical impedance tomography (EIT) in supine, left and right side lying. Distribution of ventilation was described using end-expiratory to end-inspiratory relative impedance change. RESULTS Fifty-six (31, 55% male) participants were studied. Nineteen (35%) participants consistently showed greater ventilation in the non-dependent lung, eight (15%) consistently showed greater ventilation in the dependent lung and 28 (51%) showed a varied pattern between left and right side lying. Overall, left side lying resulted in significantly better mean ventilation of the right (non-dependent) lung (P < 0.01). Distribution of ventilation in right side lying was relatively equal between left and right lungs. CONCLUSIONS This study demonstrates that the distribution of ventilation in spontaneously breathing infants and children is not as straightforward as previously described. The distribution of ventilation was variably affected by body position with no clear reversal of the adult pattern evident.
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Affiliation(s)
- Alison R Lupton-Smith
- School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa
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45
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Karsten J, Meier T, Iblher P, Schindler A, Paarmann H, Heinze H. The suitability of EIT to estimate EELV in a clinical trial compared to oxygen wash-in/wash-out technique. ACTA ACUST UNITED AC 2014; 59:59-64. [DOI: 10.1515/bmt-2012-0076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 08/30/2013] [Indexed: 11/15/2022]
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Schibler A, Pham TMT, Moray AA, Stocker C. Ventilation and cardiac related impedance changes in children undergoing corrective open heart surgery. Physiol Meas 2013; 34:1319-27. [PMID: 24021191 DOI: 10.1088/0967-3334/34/10/1319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Electrical impedance tomography (EIT) can determine ventilation and perfusion relationship. Most of the data obtained so far originates from experimental settings and in healthy subjects. The aim of this study was to demonstrate that EIT measures the perioperative changes in pulmonary blood flow after repair of a ventricular septum defect in children with haemodynamic relevant septal defects undergoing open heart surgery. In a 19 bed intensive care unit in a tertiary children's hospital ventilation and cardiac related impedance changes were measured using EIT before and after surgery in 18 spontaneously breathing patients. The EIT signals were either filtered for ventilation (ΔZV) or for cardiac (ΔZQ) related impedance changes. Impedance signals were then normalized (normΔZV, normΔZQ) for calculation of the global and regional impedance related ventilation perfusion relationship (normΔZV/normΔZQ). We observed a trend towards increased normΔZV in all lung regions, a significantly decreased normΔZQ in the global and anterior, but not the posterior lung region. The normΔZV/normΔZQ was significantly increased in the global and anterior lung region. Our study qualitatively validates our previously published modified EIT filtration technique in the clinical setting of young children with significant left-to-right shunt undergoing corrective open heart surgery, where perioperative assessment of the ventilation perfusion relation is of high clinical relevance.
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Affiliation(s)
- Andreas Schibler
- Paediatric Critical Care Research Group, Mater Children's Hospital, South Brisbane, Queensland, Australia
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47
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Topographic Distribution of Tidal Ventilation in Acute Respiratory Distress Syndrome. Crit Care Med 2013; 41:1664-73. [DOI: 10.1097/ccm.0b013e318287f6e7] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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48
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Regional ventilation in cystic fibrosis measured by electrical impedance tomography. J Cyst Fibros 2012; 11:412-8. [DOI: 10.1016/j.jcf.2012.03.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 03/24/2012] [Accepted: 03/25/2012] [Indexed: 11/20/2022]
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49
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Vogt B, Pulletz S, Elke G, Zhao Z, Zabel P, Weiler N, Frerichs I. Spatial and temporal heterogeneity of regional lung ventilation determined by electrical impedance tomography during pulmonary function testing. J Appl Physiol (1985) 2012; 113:1154-61. [PMID: 22898553 DOI: 10.1152/japplphysiol.01630.2011] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrical impedance tomography (EIT) is a functional imaging modality capable of tracing continuously regional pulmonary gas volume changes. The aim of our study was to determine if EIT was able to assess spatial and temporal heterogeneity of ventilation during pulmonary function testing in 14 young (37 ± 10 yr, mean age ± SD) and 12 elderly (71 ± 9 yr) subjects without lung disease and in 33 patients with chronic obstructive pulmonary disease (71 ± 9 yr). EIT and spirometry examinations were performed during tidal breathing and a forced vital capacity (FVC) maneuver preceded by full inspiration to total lung capacity. Regional inspiratory vital capacity (IVC); FVC; forced expiratory volume in 1 s (FEV(1)); FEV(1)/FVC; times required to expire 25%, 50%, 75%, and 90% of FVC (t(25), t(50), t(75), t(90)); and tidal volume (V(T)) were determined in 912 EIT image pixels in the chest cross section. Coefficients of variation (CV) were calculated from all pixel values of IVC, FVC, FEV(1), and V(T) to characterize the ventilation heterogeneity. The highest values were found in patients, and no differences existed between the healthy young and elderly subjects. Receiver-operating characteristics curves showed that CV of regional IVC, FVC, FEV(1), and V(T) discriminated the young and elderly subjects from the patients. Frequency distributions of pixel FEV(1)/FVC, t(25), t(50), t(75), and t(90) identified the highest ventilation heterogeneity in patients but distinguished also the healthy young from the elderly subjects. These results indicate that EIT may provide additional information during pulmonary function testing and identify pathologic and age-related spatial and temporal heterogeneity of regional lung function.
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Affiliation(s)
- Barbara Vogt
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Strasse 3, Kiel, Germany
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50
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Adler A, Amato MB, Arnold JH, Bayford R, Bodenstein M, Böhm SH, Brown BH, Frerichs I, Stenqvist O, Weiler N, Wolf GK. Whither lung EIT: Where are we, where do we want to go and what do we need to get there? Physiol Meas 2012; 33:679-94. [DOI: 10.1088/0967-3334/33/5/679] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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