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Byrne DP, Studer N, Secombe C, Cieslewicz A, Hosgood G, Raisis A, Adler A, Mosing M. Validation of three-dimensional thoracic electrical impedance tomography of horses during normal and increased tidal volumes. Physiol Meas 2024; 45:035010. [PMID: 38422515 DOI: 10.1088/1361-6579/ad2eb3] [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: 10/22/2023] [Accepted: 02/29/2024] [Indexed: 03/02/2024]
Abstract
Objective. Data from two-plane electrical impedance tomography (EIT) can be reconstructed into various slices of functional lung images, allowing for more complete visualisation and assessment of lung physiology in health and disease. The aim of this study was to confirm the ability of 3D EIT to visualise normal lung anatomy and physiology at rest and during increased ventilation (represented by rebreathing).Approach. Two-plane EIT data, using two electrode planes 20 cm apart, were collected in 20 standing sedate horses at baseline (resting) conditions, and during rebreathing. EIT data were reconstructed into 3D EIT whereby tidal impedance variation (TIV), ventilated area, and right-left and ventral-dorsal centres of ventilation (CoVRLand CoVVD, respectively) were calculated in cranial, middle and caudal slices of lung, from data collected using the two planes of electrodes.Main results. There was a significant interaction of time and slice for TIV (p< 0.0001) with TIV increasing during rebreathing in both caudal and middle slices. The ratio of right to left ventilated area was higher in the cranial slice, in comparison to the caudal slice (p= 0.0002). There were significant effects of time and slice on CoVVDwhereby the cranial slice was more ventrally distributed than the caudal slice (p< 0.0009 for the interaction).Significance. The distribution of ventilation in the three slices corresponds with topographical anatomy of the equine lung. This study confirms that 3D EIT can accurately represent lung anatomy and changes in ventilation distribution during rebreathing in standing sedate horses.
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Affiliation(s)
- David P Byrne
- School of Veterinary Medicine, Murdoch University, Murdoch, Western Australia, Australia
| | | | - Cristy Secombe
- School of Veterinary Medicine, Murdoch University, Murdoch, Western Australia, Australia
| | | | - Giselle Hosgood
- School of Veterinary Medicine, Murdoch University, Murdoch, Western Australia, Australia
| | - Anthea Raisis
- School of Veterinary Medicine, Murdoch University, Murdoch, Western Australia, Australia
| | - Andy Adler
- Department of Systems and Computer Engineering, Carleton University, Ottowa, ON, Canada
| | - Martina Mosing
- Anaesthesia and Perioperative Intensive Care, Department of Companion Animals and Horses Vetmeduni, Vienna, Austria
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Byrne DP, Keeshan B, Hosgood G, Adler A, Mosing M. Comparison of electrical impedance tomography and spirometry-based measures of airflow in healthy adult horses. Front Physiol 2023; 14:1164646. [PMID: 37476683 PMCID: PMC10354512 DOI: 10.3389/fphys.2023.1164646] [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: 02/13/2023] [Accepted: 06/26/2023] [Indexed: 07/22/2023] Open
Abstract
Electrical impedance tomography (EIT) is a non-invasive diagnostic tool for evaluating lung function. The objective of this study was to compare respiratory flow variables calculated from thoracic EIT measurements with corresponding spirometry variables. Ten healthy research horses were sedated and instrumented with spirometry via facemask and a single-plane EIT electrode belt around the thorax. Horses were exposed to sequentially increasing volumes of apparatus dead space between 1,000 and 8,500 mL, in 5-7 steps, to induce carbon dioxide rebreathing, until clinical hyperpnea or a tidal volume of 150% baseline was reached. A 2-min stabilization period followed by 2 minutes of data collection occurred at each timepoint. Peak inspiratory and expiratory flow, inspiratory and expiratory time, and expiratory nadir flow, defined as the lowest expiratory flow between the deceleration of flow of the first passive phase of expiration and the acceleration of flow of the second active phase of expiration were evaluated with EIT and spirometry. Breathing pattern was assessed based on the total impedance curve. Bland-Altman analysis was used to evaluate the agreement where perfect agreement was indicated by a ratio of EIT:spirometry of 1.0. The mean ratio (bias; expressed as a percentage difference from perfect agreement) and the 95% confidence interval of the bias are reported. There was good agreement between EIT-derived and spirometry-derived peak inspiratory [-15% (-46-32)] and expiratory [10% (-32-20)] flows and inspiratory [-6% (-25-18)] and expiratory [5% (-9-20)] times. Agreement for nadir flows was poor [-22% (-87-369)]. Sedated horses intermittently exhibited Cheyne-Stokes variant respiration, and a breath pattern with incomplete expiration in between breaths (crown-like breaths). Electrical impedance tomography can quantify airflow changes over increasing tidal volumes and changing breathing pattern when compared with spirometry in standing sedated horses.
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Affiliation(s)
- David P. Byrne
- School of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Ben Keeshan
- Department of Systems and Computer Engineering, Carleton University, Ottawa, ON, Canada
| | - Giselle Hosgood
- School of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Andy Adler
- Department of Systems and Computer Engineering, Carleton University, Ottawa, ON, Canada
| | - Martina Mosing
- Anaesthesiology and Perioperative Intensive Care, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
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Sacks M, Raidal S, Catanchin CSM, Hosgood G, Mosing M. Impact of sedation, body position change and continuous positive airway pressure on distribution of ventilation in healthy foals. Front Vet Sci 2023; 9:1075791. [PMID: 36713868 PMCID: PMC9880457 DOI: 10.3389/fvets.2022.1075791] [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: 10/20/2022] [Accepted: 12/14/2022] [Indexed: 01/15/2023] Open
Abstract
Background This study aimed to compare the distribution of ventilation measured by electrical impedance tomography (EIT), in foals under varying clinical conditions of sedation, postural changes, and continuous positive airway pressure (CPAP). To support the interpretation of EIT variables, specific spirometry data and F-shunt calculation were also assessed. Materials and methods Six healthy Thoroughbred foals were recruited for this sequential experimental study. EIT and spirometry data was recorded: (1) before and after diazepam-sedation, (2) after moving from standing to right lateral recumbency, (3) in dorsal recumbency during no CPAP (CPAP0) and increasing levels of CPAP of 4, 7, and 10 cmH2O (CPAP4, 7, 10, respectively). Ventral to dorsal (COVVD) and right to left (COVRL) center of ventilation, silent spaces, tidal impedance variation, regional ventilation distribution variables and right to left lung ventilation ratio (R:L) were extracted. Minute ventilation was calculated from tidal volume (VT) and respiratory rate. F-Shunt was calculated from results of arterial blood gas analysis. Statistical analysis was performed using linear mixed effects models (significance determined at p < 0.05). Results (1) Respiratory rate was lower after sedation (p = 0.0004). (2) In right lateral recumbency (compared to standing), the COVVD (p = 0.0012), COVRL (p = 0.0057), left centro-dorsal (p = 0.0071) and dorsal (p < 0.0001) regional ventilation were higher, while the right ventral (p = 0.0016) and dorsal (p = 0.0145) regional ventilation, and R:L (p = 0.0017) were lower. (3) Data of two foals for CPAP10 was excluded from statistical analysis due to prolonged apnea. Stepwise increase of CPAP led to increases of COVVD (p = 0.0028) and VT (p = 0.0011). A reduction of respiratory rate was detected with increasing CPAP levels (p < 0.0001). Conclusions (1) In healthy foals, diazepam administration did not alter distribution of ventilation or minute ventilation, (2) lateral recumbency results in collapse of dependent areas of the lung, and (3) the use of CPAP in dorsal recumbency at increasing pressures improves ventilation in dependent regions, suggesting improvement of ventilation-perfusion mismatch.
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Affiliation(s)
- Muriel Sacks
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, WA, Australia,*Correspondence: Muriel Sacks ✉
| | - Sharanne Raidal
- School of Animal, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Chee Sum Melanie Catanchin
- School of Animal, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Giselle Hosgood
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, WA, Australia
| | - Martina Mosing
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, WA, Australia
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Andrade FSRM, Ambrósio AM, Rodrigues RR, Faccó LL, Gonçalves LA, Garcia Filho SG, dos Santos RT, Rossetto TC, Pereira MAA, Fantoni DT. The optimal PEEP after alveolar recruitment maneuver assessed by electrical impedance tomography in healthy horses. Front Vet Sci 2022; 9:1024088. [PMID: 36570501 PMCID: PMC9780380 DOI: 10.3389/fvets.2022.1024088] [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: 08/21/2022] [Accepted: 11/09/2022] [Indexed: 12/13/2022] Open
Abstract
Background Electrical impedance tomography (EIT) has been an essential tool for assessing pulmonary ventilation in several situations, such as the alveolar recruitment maneuver (ARM) in PEEP titration to maintain the lungs open after atelectasis reversion. In the same way as in humans and dogs, in horses, this tool has been widely used to assess pulmonary aeration undergoing anesthesia, mechanical ventilation, recruitment maneuver, standing horses, or specific procedures. Objectives The present study aimed to evaluate the distribution of regional ventilation during ARM based on lung monitoring assessment by EIT, with a focus on better recruitment associated with less or no overdistention. Methods Fourteen horses of 306 ± 21 kg undergoing isoflurane anesthesia in dorsal recumbency were used. The animals were mechanically ventilated with a tidal volume of 14 ml kg-1 and a respiratory rate of 7-9. An alveolar recruitment maneuver was instituted, increasing the PEEP by five cmH2O every 5 min until 32 cmH2O and decreasing it by five cmH2O every 5 min to 7 cmH2O. At each step of PEEP, arterial blood samples were collected for blood gas analysis, EIT images, hemodynamic, and respiratory mechanics. Results Associated with the CoV-DV increase, there was a significant decrease in the DSS during the ARM and a significant increase in the NSS when PEEP was applied above 12 cmH2O compared to baseline. The ComplROI showed a significant increase in the dependent area and a significant decrease in the non-dependent area during ARM, and both were compared to their baseline values. The driving pressure decreased significantly during the ARM, and Cst, PaO2, and PaO2/FiO2 ratio increased significantly. The VD/VT decreased significantly at DEPEEP17 and DEPEEP12. There was an HR increase at INPEEP27, INPEEP 32, and DEPEEP17 (p < 0.0001; p < 0.0001; and p < 0.05, respectively), those values being above the normal reference range for the species. The SAP, MAP, DAP, CI, and DO2I significantly decreased INPEEP32 (p < 0.05). Conclusion The ARM by PEEP titration applied in the present study showed better ventilation distribution associated with better aeration in the dependent lung areas, with minimal overdistention between PEEP 17 and 12 cmH2O decreasing step. Those changes were also followed by improvements in static and regional compliance associated with increased oxygenation and pulmonary ventilation. ARM promoted a transitory decrease in arterial blood pressure and depression in CI with a concomitant drop in oxygen delivery, which should be best investigated before its routine use in clinical cases.
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Brabant O, Loroesch S, Adler A, Waldmann AD, Raisis A, Mosing M. Performance evaluation of electrode design and material for a large animal electrical impedance tomography belt. Vet Rec 2022; 191:e2184. [PMID: 36197754 DOI: 10.1002/vetr.2184] [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: 01/07/2022] [Revised: 06/14/2022] [Accepted: 08/08/2022] [Indexed: 11/06/2022]
Abstract
BACKGROUND Electrical impedance tomography (EIT) produces lung ventilation images via a thoracic electrode belt. Robust electrode design and material, providing low electrode skin contact impedance (SCI), is needed in veterinary medicine. The aim of this study was to compare three EIT electrode designs and materials. METHODS Simulations of cylindrical, rectangular and spiked electrode designs were used to evaluate electrode SCI as a function of electrode size, where skin contact was uneven. Gold-plated washers (EGW ), zinc-plated rivets (EZR ) and zinc-galvanised spikes (EZS ) were assigned randomly on two interconnected EIT belts. Gel was applied to the cranial or caudal belt and placed on 17 standing cattle. SCI was recorded at baseline and 3, 5, 7, 9 and 11 minutes later. RESULTS Simulations that involved electrodes with a greater skin contact area had lower and more uniform SCI. In cattle, SCI decreased with all electrodes over time (p < 0.01). Without gel, no difference was found between EGW and EZS , while SCI was higher for EZR (p < 0.03). With gel, SCI was lower in EGW and EZR (p < 0.026), with the SCI in EGW being the lowest (p < 0.01). LIMITATIONS Low numbers of animals and static electrode position may affect SCI. CONCLUSIONS Electrode design is important for EIT measurement, with larger electrode designs able to compensate for the use of less conductive materials. Gel is not necessary to achieve acceptable SCI in large animals.
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Affiliation(s)
- Olivia Brabant
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Sarah Loroesch
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Andy Adler
- Department of Systems and Computer Engineering, Carleton University, Ottawa, Ontario, Canada
| | - Andreas D Waldmann
- Department of Anaesthesiology and Intensive Care Medicine, Rostock University Medical Centre, Rostock, Germany
| | - Anthea Raisis
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Martina Mosing
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia
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Brabant OA, Byrne DP, Sacks M, Moreno Martinez F, Raisis AL, Araos JB, Waldmann AD, Schramel JP, Ambrosio A, Hosgood G, Braun C, Auer U, Bleul U, Herteman N, Secombe CJ, Schoster A, Soares J, Beazley S, Meira C, Adler A, Mosing M. Thoracic Electrical Impedance Tomography-The 2022 Veterinary Consensus Statement. Front Vet Sci 2022; 9:946911. [PMID: 35937293 PMCID: PMC9354895 DOI: 10.3389/fvets.2022.946911] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
Electrical impedance tomography (EIT) is a non-invasive real-time non-ionising imaging modality that has many applications. Since the first recorded use in 1978, the technology has become more widely used especially in human adult and neonatal critical care monitoring. Recently, there has been an increase in research on thoracic EIT in veterinary medicine. Real-time imaging of the thorax allows evaluation of ventilation distribution in anesthetised and conscious animals. As the technology becomes recognised in the veterinary community there is a need to standardize approaches to data collection, analysis, interpretation and nomenclature, ensuring comparison and repeatability between researchers and studies. A group of nineteen veterinarians and two biomedical engineers experienced in veterinary EIT were consulted and contributed to the preparation of this statement. The aim of this consensus is to provide an introduction to this imaging modality, to highlight clinical relevance and to include recommendations on how to effectively use thoracic EIT in veterinary species. Based on this, the consensus statement aims to address the need for a streamlined approach to veterinary thoracic EIT and includes: an introduction to the use of EIT in veterinary species, the technical background to creation of the functional images, a consensus from all contributing authors on the practical application and use of the technology, descriptions and interpretation of current available variables including appropriate statistical analysis, nomenclature recommended for consistency and future developments in thoracic EIT. The information provided in this consensus statement may benefit researchers and clinicians working within the field of veterinary thoracic EIT. We endeavor to inform future users of the benefits of this imaging modality and provide opportunities to further explore applications of this technology with regards to perfusion imaging and pathology diagnosis.
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Affiliation(s)
- Olivia A. Brabant
- School of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - David P. Byrne
- School of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Muriel Sacks
- School of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | | | - Anthea L. Raisis
- School of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Joaquin B. Araos
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| | - Andreas D. Waldmann
- Department of Anaesthesiology and Intensive Care Medicine, Rostock University Medical Centre, Rostock, Germany
| | - Johannes P. Schramel
- Department of Anaesthesiology and Perioperative Intensive Care Medicine, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Aline Ambrosio
- Department of Surgery, Faculty of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Giselle Hosgood
- School of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Christina Braun
- Department of Anaesthesiology and Perioperative Intensive Care Medicine, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Ulrike Auer
- Department of Anaesthesiology and Perioperative Intensive Care Medicine, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Ulrike Bleul
- Clinic of Reproductive Medicine, Department of Farm Animals, Vetsuisse-Faculty University Zurich, Zurich, Switzerland
| | - Nicolas Herteman
- Clinic for Equine Internal Medicine, Equine Hospital, Vetsuisse-Faculty, University of Zurich, Zurich, Switzerland
| | - Cristy J. Secombe
- School of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Angelika Schoster
- Clinic for Equine Internal Medicine, Equine Hospital, Vetsuisse-Faculty, University of Zurich, Zurich, Switzerland
| | - Joao Soares
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Shannon Beazley
- Department of Small Animal Clinical Sciences, Western College Veterinary Medicine, Saskatoon, SK, Canada
| | - Carolina Meira
- Department of Clinical Diagnostics and Services, Anaesthesiology, Vetsuisse-Faculty, University of Zurich, Zurich, Switzerland
| | - Andy Adler
- Department of Systems and Computer Engineering, Carleton University, Ottawa, ON, Canada
| | - Martina Mosing
- School of Veterinary Medicine, Murdoch University, Perth, WA, Australia
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Moreno-Martinez F, Byrne D, Raisis A, Waldmann AD, Hosgood G, Mosing M. Comparison of Effects of an Endotracheal Tube or Facemask on Breathing Pattern and Distribution of Ventilation in Anesthetized Horses. Front Vet Sci 2022; 9:895268. [PMID: 35836499 PMCID: PMC9275410 DOI: 10.3389/fvets.2022.895268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 04/25/2022] [Indexed: 11/21/2022] Open
Abstract
Equine respiratory physiology might be influenced by the presence of an endotracheal tube (ETT). This experimental, randomized cross-over study aimed to compare breathing pattern (BrP) and ventilation distribution in anesthetized horses spontaneously breathing room air via ETT or facemask (MASK). Six healthy adult horses were anesthetized with total intravenous anesthesia (TIVA; xylazine, ketamine, guaiphenesin), breathing spontaneously in right lateral recumbency, and randomly assigned to ETT or MASK for 30 min, followed by the other treatment for an additional 30 min. During a second anesthesia 1 month later, the treatment order was inversed. Electrical impedance tomography (EIT) using a thoracic electrode belt, spirometry, volumetric capnography, esophageal pressure difference (ΔPoes), venous admixture, and laryngoscopy data were recorded over 2 min every 15 min. Breaths were classified as normal or alternate (sigh or crown-like) according to the EIT impedance curve. A mixed linear model was used to test the effect of treatment on continuous outcomes. Cochran-Mantel-Haenszel analysis was used to test for associations between global BrP and treatment. Global BrP was associated with treatment (p = 0.012) with more alternate breaths during ETT. The center of ventilation right-to-left (CoVRL) showed more ventilation in the non-dependent lung during ETT (p = 0.025). The I:E ratio (p = 0.017) and ΔPoes (p < 0.001) were smaller, and peak expiratory flow (p = 0.009) and physiologic dead space (p = 0.034) were larger with ETT. The presence of an ETT alters BrP and shifts ventilation toward the non-dependent lung in spontaneously breathing horses anesthetized with TIVA.
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Affiliation(s)
| | - David Byrne
- College of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Anthea Raisis
- College of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Andreas D. Waldmann
- Department of Anaesthesiology and Intensive Care Medicine, Rostock University Medical Centre, Rostock, Germany
| | - Giselle Hosgood
- College of Veterinary Medicine, Murdoch University, Perth, WA, Australia
| | - Martina Mosing
- College of Veterinary Medicine, Murdoch University, Perth, WA, Australia
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Beazley S, Focken A, Fernandez-Parra R, Thomas K, Adler A, Duke-Novakovski T. Evaluation of lung ventilation distribution using electrical impedance tomography in standing sedated horses with capnoperitoneum. Vet Anaesth Analg 2022; 49:382-389. [DOI: 10.1016/j.vaa.2022.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 11/29/2022]
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Kozłowska N, Wierzbicka M, Jasiński T, Domino M. Advances in the Diagnosis of Equine Respiratory Diseases: A Review of Novel Imaging and Functional Techniques. Animals (Basel) 2022; 12:381. [PMID: 35158704 PMCID: PMC8833607 DOI: 10.3390/ani12030381] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/02/2022] [Accepted: 02/03/2022] [Indexed: 02/04/2023] Open
Abstract
The horse, as a flight animal with a survival strategy involving rapid escape from predators, is a natural-born athlete with enormous functional plasticity of the respiratory system. Any respiratory dysfunction can cause a decline in ventilation and gas exchange. Therefore, respiratory diseases often lead to exercise intolerance and poor performance. This is one of the most frequent problems encountered by equine internists. Routine techniques used to evaluate respiratory tract diseases include clinical examination, endoscopic examination, radiographic and ultrasonographic imaging, cytological evaluation, and bacterial culture of respiratory secretions. New diagnostic challenges and the growing development of equine medicine has led to the implementation of advanced diagnostic techniques successfully used in human medicine. Among them, the use of computed tomography (CT) and magnetic resonance (MR) imaging significantly broadened the possibilities of anatomical imaging, especially in the diagnosis of upper respiratory tract diseases. Moreover, the implementation of spirometry, electrical impedance tomography (EIT), and impulse oscillation system (IOS) sheds new light on functional diagnostics of respiratory tract diseases, especially those affecting the lower part. Therefore, this review aimed to familiarize the clinicians with the advantages and disadvantages of the advanced diagnostic techniques of the equine respiratory tract and introduce their recent clinical applications in equine medicine.
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Affiliation(s)
| | - Małgorzata Wierzbicka
- Department of Large Animal Diseases and Clinic, Institute of Veterinary Medicine, Warsaw University of Life Sciences, 02-787 Warsaw, Poland; (N.K.); (T.J.)
| | | | - Małgorzata Domino
- Department of Large Animal Diseases and Clinic, Institute of Veterinary Medicine, Warsaw University of Life Sciences, 02-787 Warsaw, Poland; (N.K.); (T.J.)
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Bleul U, Wey C, Meira C, Waldmann A, Mosing M. Assessment of Postnatal Pulmonary Adaption in Bovine Neonates Using Electric Impedance Tomography (EIT). Animals (Basel) 2021; 11:3216. [PMID: 34827949 PMCID: PMC8614262 DOI: 10.3390/ani11113216] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/04/2021] [Accepted: 11/08/2021] [Indexed: 01/06/2023] Open
Abstract
Several aspects of postnatal pulmonary adaption in the bovine neonate remain unclear, particularly the dynamics and regional ventilation of the lungs. We used electric impedance tomography (EIT) to measure changes in ventilation in the first 3 weeks of life in 20 non-sedated neonatal calves born without difficulty in sternal recumbency. Arterial blood gas variables were determined in the first 24 h after birth. Immediately after birth, dorsal parts of the lungs had 4.53% ± 2.82% nondependent silent spaces (NSS), and ventral parts had 5.23% ± 2.66% dependent silent spaces (DSS). The latter increased in the first hour, presumably because of gravity-driven ventral movement of residual amniotic fluid. The remaining lung regions had good ventilation immediately after birth, and the percentage of lung regions with high ventilation increased significantly during the study period. The centre of ventilation was always dorsal to and on the right of the theoretical centre of ventilation. The right lung was responsible for a significantly larger proportion of ventilation (63.84% ± 12.74%, p < 0.00001) compared with the left lung. In the right lung, the centrodorsal lung area was the most ventilated, whereas, in the left lung, it was the centroventral area. Tidal impedance changes, serving as a surrogate for tidal volume, increased in the first 3 weeks of life (p < 0.00001). This study shows the dynamic changes in lung ventilation in the bovine neonate according to EIT measurements. The findings form a basis for the recognition of structural and functional lung disorders in neonatal calves.
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Affiliation(s)
- Ulrich Bleul
- Department of Farm Animals, Clinic of Reproductive Medicine, Vetsuisse-Faculty University Zurich, 8057 Zurich, Switzerland;
| | - Corina Wey
- Department of Farm Animals, Clinic of Reproductive Medicine, Vetsuisse-Faculty University Zurich, 8057 Zurich, Switzerland;
| | - Carolina Meira
- Department of Clinical Diagnostics and Services, Section Anaesthesiology, Vetsuisse Faculty, University of Zurich, 8057 Zürich, Switzerland;
| | - Andreas Waldmann
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, 39071 Rostock, Germany;
| | - Martina Mosing
- Department of Veterinary Anaesthesia and Analgesia, School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Murdoch 6150, Australia;
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Herteman N, Mosing M, Waldmann AD, Gerber V, Schoster A. Exercise-induced airflow changes in horses with asthma measured by electrical impedance tomography. J Vet Intern Med 2021; 35:2500-2510. [PMID: 34505734 PMCID: PMC8478024 DOI: 10.1111/jvim.16260] [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: 10/29/2020] [Revised: 08/20/2021] [Accepted: 08/25/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Equine asthma (EA) causes airflow impairment, which increases in severity with exercise. Electrical impedance tomography (EIT) is an imaging technique that can detect airflow changes in standing healthy horses during a histamine provocation test. OBJECTIVES To explore EIT-calculated flow variables before and after exercise in healthy horses and horses with mild-to-moderate (MEA) and severe equine asthma (SEA). ANIMALS Nine healthy horses 9 horses diagnosed with MEA and 5 with SEA were prospectively included. METHODS Recordings were performed before and after 15 minutes of lunging. Absolute values from global and regional peak inspiratory (PIF, positive value) and expiratory (PEF, negative value) flows were calculated. Data were analyzed using a mixed model analysis followed by Bonferroni's multiple comparisons test to evaluate the impact of exercise and diagnosis on flow indices. RESULTS Control horses after exercise had significantly lower global PEF and PIF compared to horses with SEA (mean difference [95% confidence interval, CI]: 0.0859 arbitrary units [AU; 0.0339-0.1379], P < .001 and 0.0726 AU [0.0264-0.1188], P = .001, respectively) and horses with MEA (0.0561 AU [0.0129-0.0994], P = .007 and 0.0587 AU [0.0202-0.0973], P = .002, respectively). No other significant differences were detected. CONCLUSIONS AND CLINICAL IMPORTANCE Electrical impedance tomography derived PIF and PEF differed significantly between healthy horses and horses with SEA or MEA after exercise, but not before exercise. Differences between MEA and SEA were not observed, but the study population was small.
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Affiliation(s)
- Nicolas Herteman
- Clinic for Equine Internal Medicine, Equine Hospital, Vetsuisse Faculty, University of Zurich, Switzerland
| | - Martina Mosing
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
| | - Andreas D Waldmann
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
| | - Vinzenz Gerber
- Equine Clinic, Swiss Institute of Equine Medicine, University of Bern and Agroscope, Berne, Switzerland
| | - Angelika Schoster
- Clinic for Equine Internal Medicine, Equine Hospital, Vetsuisse Faculty, University of Zurich, Switzerland
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Sacks M, Byrne DP, Herteman N, Secombe C, Adler A, Hosgood G, Raisis AL, Mosing M. Electrical impedance tomography to measure lung ventilation distribution in healthy horses and horses with left-sided cardiac volume overload. J Vet Intern Med 2021; 35:2511-2523. [PMID: 34347908 PMCID: PMC8478054 DOI: 10.1111/jvim.16227] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 07/01/2021] [Accepted: 07/13/2021] [Indexed: 12/24/2022] Open
Abstract
Background Left‐sided cardiac volume overload (LCVO) can cause fluid accumulation in lung tissue changing the distribution of ventilation, which can be evaluated by electrical impedance tomography (EIT). Objectives To describe and compare EIT variables in horses with naturally occurring compensated and decompensated LCVO and compare them to a healthy cohort. Animals Fourteen adult horses, including university teaching horses and clinical cases (healthy: 8; LCVO: 4 compensated, 2 decompensated). Methods In this prospective cohort study, EIT was used in standing, unsedated horses and analyzed for conventional variables, ventilated right (VAR) and left (VAL) lung area, linear‐plane distribution variables (avg‐max VΔZLine, VΔZLine), global peak flows, inhomogeneity factor, and estimated tidal volume. Horses with decompensated LCVO were assessed before and after administration of furosemide. Variables for healthy and LCVO‐affected horses were compared using a Mann‐Whitney test or unpaired t‐test and observations from compensated and decompensated horses are reported. Results Compared to the healthy horses, the LCVO cohort had significantly less VAL (mean difference 3.02; 95% confidence interval .77‐5.2; P = .02), more VAR (−1.13; −2.18 to −.08; P = .04), smaller avg‐max VΔZLLine (2.54; 1.07‐4.00; P = .003) and VΔZLLine (median difference 5.40; 1.71‐9.09; P = .01). Observation of EIT alterations were reflected by clinical signs in horses with decompensated LCVO and after administration of furosemide. Conclusions and Clinical Importance EIT measurements of ventilation distribution showed less ventilation in the left lung of horses with LCVO and might be useful as an objective assessment of the ventilation effects of cardiogenic pulmonary disease in horses.
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Affiliation(s)
- Muriel Sacks
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - David P Byrne
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - Nicolas Herteman
- Equine Clinic, Department for Equine Medicine, Vetsuisse Faculty, University of Zurich, Zürich, Switzerland
| | - Cristy Secombe
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - Andy Adler
- Systems and Computer Engineering, Carleton University, Ottawa, Canada
| | - Giselle Hosgood
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - Anthea L Raisis
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - Martina Mosing
- School of Veterinary Medicine, Murdoch University, Perth, Australia
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Moreno‐Martinez F, Senior JM, Mosing M. Controlled mechanical ventilation in equine anaesthesia: Classification of ventilators and practical considerations (Part 2). EQUINE VET EDUC 2021. [DOI: 10.1111/eve.13527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- F. Moreno‐Martinez
- School of Veterinary and Life Sciences Murdoch University Perth Western Australia Australia
| | - J. M. Senior
- Department of Equine Clinical Science Institute of Veterinary Science University of Liverpool Neston UK
| | - M. Mosing
- School of Veterinary and Life Sciences Murdoch University Perth Western Australia Australia
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Secombe C, Adler A, Hosgood G, Raisis A, Mosing M. Can bronchoconstriction and bronchodilatation in horses be detected using electrical impedance tomography? J Vet Intern Med 2021; 35:2035-2044. [PMID: 33977584 PMCID: PMC8295671 DOI: 10.1111/jvim.16152] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Electrical impedance tomography (EIT) generates images of the lungs based on impedance change and was able to detect changes in airflow after histamine challenge in horses. OBJECTIVES To confirm that EIT can detect histamine-provoked changes in airflow and subsequent drug-induced bronchodilatation. Novel EIT flow variables were developed and examined for changes in airflow. METHODS Bronchoconstriction was induced using stepwise histamine bronchoprovocation in 17 healthy sedated horses. The EIT variables were recorded at baseline, after saline nebulization (control), at the histamine concentration causing bronchoconstriction (Cmax ) and 2 and 10 minutes after albuterol (salbutamol) administration. Peak global inspiratory (PIFEIT ) and peak expiratory EIT (PEFEIT ) flow, slope of the global expiratory flow-volume curve (FVslope ), steepest FVslope over all pixels in the lung field, total impedance change (surrogate for tidal volume; VTEIT ) and intercept on the expiratory FV curve normalized to VTEIT (FVintercept /VTEIT ) were indexed to baseline and analyzed for a difference from the control, at Cmax , 2 and 10 minutes after albuterol. Multiple linear regression explored the explanation of the variance of Δflow, a validated variable to evaluate bronchoconstriction using all EIT variables. RESULTS At Cmax , PIFEIT , PEFEIT , and FVslope significantly increased whereas FVintercept /VT decreased. All variables returned to baseline 10 minutes after albuterol. The VTEIT did not change. Multivariable investigation suggested 51% of Δflow variance was explained by a combination of PIFEIT and PEFEIT . CONCLUSIONS AND CLINICAL IMPORTANCE Changes in airflow during histamine challenge and subsequent albuterol administration could be detected by various EIT flow volume variables.
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Affiliation(s)
- Cristy Secombe
- School of Veterinary Medicine, Murdoch UniversityPerthAustralia
| | - Andy Adler
- Systems and Computer Engineering, Carleton UniversityOttawaCanada
| | - Giselle Hosgood
- School of Veterinary Medicine, Murdoch UniversityPerthAustralia
| | - Anthea Raisis
- School of Veterinary Medicine, Murdoch UniversityPerthAustralia
| | - Martina Mosing
- School of Veterinary Medicine, Murdoch UniversityPerthAustralia
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Raisis AL, Mosing M, Hosgood GL, Secombe CJ, Adler A, Waldmann AD. The use of electrical impedance tomography (EIT) to evaluate pulse rate in anaesthetised horses. Vet J 2021; 273:105694. [PMID: 34148609 DOI: 10.1016/j.tvjl.2021.105694] [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: 10/14/2020] [Revised: 05/04/2021] [Accepted: 05/12/2021] [Indexed: 10/21/2022]
Abstract
Electrical impedance tomography (EIT) provides clinically useful lung images; however, it would be an advantage to extract additional cardiovascular information from the data. The aim of this study was to evaluate if cardiac-related changes measured by EIT can be used to measure pulse rate (PR) under physiological as well as high and low blood pressure states in anaesthetised horses. Electrical impedance tomography data and PR from seven horses anaesthetised in dorsal recumbency were recorded over 1 min during mechanical ventilation and 1 min of apnoea. Data were collected at four measurement time points; before and during intravenous administration of nitroprusside and phenylephrine, respectively. Nine pixels, estimated to represent the heart, were chosen from the EIT image. A novel algorithm detected peaks of impedance change for these pixels over 10 s intervals. Concurrent PR measured using an invasive blood pressure trace, was recorded every 10 s. EIT- and pulse-rate data were compared using Bland-Altman assessment for multiple measurements on each horse. Overall, 288 paired datasets from six of seven horses were available for analysis. There was excellent agreement for baseline measurements, as well as during hypertension and hypotension, with a bias of -0.26 and lower and upper limit of agreement at -2.22 (95% confidence intervals [CI], -2.89 to -1.86) and 1.69 (95% CI, 1.34-2.36) beats per min, respectively. EIT can be used to evaluate PR using cardiac-related impedance changes. More work is required to determine bias that might occur in anaesthetised horses in other recumbencies or clinical situations.
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Affiliation(s)
- A L Raisis
- School of Veterinary Medicine, College of SHEE, Murdoch University, South Street, Perth, WA, Australia
| | - M Mosing
- School of Veterinary Medicine, College of SHEE, Murdoch University, South Street, Perth, WA, Australia.
| | - G L Hosgood
- School of Veterinary Medicine, College of SHEE, Murdoch University, South Street, Perth, WA, Australia
| | - C J Secombe
- School of Veterinary Medicine, College of SHEE, Murdoch University, South Street, Perth, WA, Australia
| | - A Adler
- Systems and Computer Engineering, Carleton University, Ottawa, Canada
| | - A D Waldmann
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
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Moreno‐Martinez F, Mosing M, Senior M. Controlled mechanical ventilation in equine anaesthesia: Physiological background and basic considerations (Part 1). EQUINE VET EDUC 2021. [DOI: 10.1111/eve.13476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- F. Moreno‐Martinez
- School of Veterinary and Life Sciences Murdoch University Perth Western Australia Australia
| | - M. Mosing
- School of Veterinary and Life Sciences Murdoch University Perth Western Australia Australia
| | - M. Senior
- Department of Equine Clinical Science Institute of Veterinary Science University of Liverpool Neston, Cheshire UK
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Mosing M, Waldmann AD, Sacks M, Buss P, Boesch JM, Zeiler GE, Hosgood G, Gleed RD, Miller M, Meyer LCR, Böhm SH. What hinders pulmonary gas exchange and changes distribution of ventilation in immobilized white rhinoceroses ( Ceratotherium simum) in lateral recumbency? J Appl Physiol (1985) 2020; 129:1140-1149. [PMID: 33054661 DOI: 10.1152/japplphysiol.00359.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
This study used electrical impedance tomography (EIT) measurements of regional ventilation and perfusion to elucidate the reasons for severe gas exchange impairment reported in rhinoceroses during opioid-induced immobilization. EIT values were compared with standard monitoring parameters to establish a new monitoring tool for conservational immobilization and future treatment options. Six male white rhinoceroses were immobilized using etorphine, and EIT ventilation variables, venous admixture, and dead space were measured 30, 40, and 50 min after becoming recumbent in lateral position. Pulmonary perfusion mapping using impedance-enhanced EIT was performed at the end of the study period. The measured impedance (∆Z) by EIT was compared between pulmonary regions using mixed linear models. Measurements of regional ventilation and perfusion revealed a pronounced disproportional shift of ventilation and perfusion toward the nondependent lung. Overall, the dependent lung was minimally ventilated and perfused, but remained aerated with minimal detectable lung collapse. Perfusion was found primarily around the hilum of the nondependent lung and was minimal in the periphery of the nondependent and the entire dependent lung. These shifts can explain the high amount of venous admixture and physiological dead space found in this study. Breath holding redistributed ventilation toward dependent and ventral lung areas. The findings of this study reveal important pathophysiological insights into the changes in lung ventilation and perfusion during immobilization of white rhinoceroses. These novel insights might induce a search for better therapeutic options and is establishing EIT as a promising monitoring tool for large animals in the field.NEW & NOTEWORTHY Electrical impedance tomography measurements of regional ventilation and perfusion applied to etorphine-immobilized white rhinoceroses in lateral recumbency revealed a pronounced disproportional shift of the measured ventilation and perfusion toward the nondependent lung. The dependent lung was minimally ventilated and perfused, but still aerated. Perfusion was found primarily around the hilum of the nondependent lung. These shifts can explain the gas exchange impairments found in this study. Breath holding can redistribute ventilation.
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Affiliation(s)
- Martina Mosing
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
| | - Andreas D Waldmann
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
| | - Muriel Sacks
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
| | - Peter Buss
- Veterinary Wildlife Services, South African National Parks, Kruger National Park, Skukuza, South Africa
| | - Jordyn M Boesch
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Gareth E Zeiler
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.,Centre for Veterinary Wildlife Studies and Department of Paraclinical Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Giselle Hosgood
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
| | - Robin D Gleed
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Michele Miller
- Department of Science and Technology-National Research Foundation Centre of Excellence for Biomedical TB Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Leith C R Meyer
- Centre for Veterinary Wildlife Studies and Department of Paraclinical Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Stephan H Böhm
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
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Secombe C, Waldmann AD, Hosgood G, Mosing M. Evaluation of histamine-provoked changes in airflow using electrical impedance tomography in horses. Equine Vet J 2020; 52:556-563. [PMID: 31793056 DOI: 10.1111/evj.13216] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 11/23/2019] [Indexed: 11/26/2022]
Abstract
BACKGROUND Electrical impedance tomography (EIT) generates thoracic impedance images of the lungs and has been used to assess ventilation in horses. This technique may have application in the detection of changes in airflow associated with equine asthma. OBJECTIVES The objective was to determine if histamine-induced airflow changes observed with flowmetric plethysmography (Δflow) could also be explained using global and regional respiratory gas flow signals calculated from EIT signals. STUDY DESIGN Experimental in vivo study. METHODS Six horses, sedated using detomidine were fitted with a thoracic EIT belt and flowmetric plethysmography hardware. Saline (baseline = BL) and increasing concentrations of histamine (C1-4) were nebulised into the face mask until a change in breathing pattern was clinically confirmed and Δflow increased greater or equal to 50%. After nebulisation Δflow and EIT images were recorded over 3 minutes and peak global inspiratory (InFglobal ) and expiratory (ExFglobal ) flow as well as peak regional expiratory and inspiratory flow for the dorsal and the ventral area of the right and left lungs were evaluated. Delta flow, InFglobal and ExFglobal at subsequent concentrations were indexed to baseline (yi = Ci /BL-1). Indexed and nonindexed variables were evaluated for a difference from baseline at sequential histamine doses (time). Multiple linear regression assessment of variance in delta flow was also investigated. RESULTS Consistent with histamine-provoked increases in Δflow, the global flow indices increased significantly. A significant increase in regional inspiratory flow was seen in the right and left ventral lung and dorsal right lung. Multiple regression revealed that the variance in ExFglobal , and right and left ventral expiratory flow best explained the variance in Δflow (r2 = .82). MAIN LIMITATIONS Low number of horses and horses were healthy. CONCLUSIONS Standardised changes in airflow during histamine challenge could be detected using EIT gas flow variables.
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Affiliation(s)
- Cristy Secombe
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
| | - Andreas D Waldmann
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
| | - Giselle Hosgood
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
| | - Martina Mosing
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
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Grychtol B, Schramel JP, Braun F, Riedel T, Auer U, Mosing M, Braun C, Waldmann AD, Böhm SH, Adler A. Thoracic EIT in 3D: experiences and recommendations. Physiol Meas 2019; 40:074006. [PMID: 31189141 DOI: 10.1088/1361-6579/ab291d] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE In EIT applications to the thorax, a single electrode plane has typically been used to reconstruct a transverse 2D 'slice'. However, such images can be misleading as EIT is sensitive to contrasts above and below the electrode plane, and ventilation and aeration inhomogeneities can be distributed in complex ways. Using two (or more) electrode planes, 3D EIT images may be reconstructed, but 3D reconstructions are currently little used in thoracic EIT. In this paper, we investigate an incremental pathway towards 3D EIT reconstructions, using two electrode planes to calculate improved transverse slices as an intermediate step. We recommend a specific placement of electrode planes, and further demonstrate the feasibility of multi-slice reconstruction in two species. APPROACH Simulations of the forward and reconstructed sensitivities were analysed for two electrode planes using a 'square' pattern of electrode placement as a function of two variables: the stimulation and measurement 'skip', and the electrode plane separation. Next, single- versus two-plane measurements were compared in a horse and in human volunteers. We further show the feasibility of 3D reconstructions by reconstructing multiple transverse and, unusually, frontal slices during ventilation. MAIN RESULTS Using two electrode planes leads to a reduced position error and improvement in off-plane contrast rejection. 2D reconstructions from two-plane measurements showed better separation of lungs, as compared to the single plane measurements which tend to push contrasts in the center of the image. 3D reconstructions of the same data show anatomically plausible images, inside as well as outside the volume between the two electrode planes. SIGNIFICANCE Based on the results, we recommend EIT electrode planes separated by less than half of the minimum thoracic dimension with a 'skip 4' pattern and 'square' placement to produce images with good slice selectivity.
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Affiliation(s)
- Bartłomiej Grychtol
- Fraunhofer Project Group for Automation in Medicine and Biotechnology, Mannheim, Germany. Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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Monitoring changes in distribution of pulmonary ventilation by functional electrical impedance tomography in anaesthetized ponies. Vet Anaesth Analg 2019; 46:200-208. [DOI: 10.1016/j.vaa.2018.09.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 09/05/2018] [Accepted: 09/20/2018] [Indexed: 11/18/2022]
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Hao Z, Yue S, Sun B, Wang H. Optimal distance of multi-plane sensor in three-dimensional electrical impedance tomography. Comput Assist Surg (Abingdon) 2017; 22:326-338. [DOI: 10.1080/24699322.2017.1389412] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Zhenhua Hao
- School of Electrical and Information Engineering, Tianjin University, Tianjin, China
| | - Shihong Yue
- School of Electrical and Information Engineering, Tianjin University, Tianjin, China
| | - Benyuan Sun
- School of Electrical and Information Engineering, Tianjin University, Tianjin, China
| | - Huaxiang Wang
- School of Electrical and Information Engineering, Tianjin University, Tianjin, China
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Ambrisko TD, Schramel JP, Auer U, Moens YPS. Impact of four different recumbencies on the distribution of ventilation in conscious or anaesthetized spontaneously breathing beagle dogs: An electrical impedance tomography study. PLoS One 2017; 12:e0183340. [PMID: 28922361 PMCID: PMC5603158 DOI: 10.1371/journal.pone.0183340] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 08/02/2017] [Indexed: 11/18/2022] Open
Abstract
The aim was to examine the effects of recumbency and anaesthesia on distribution of ventilation in beagle dogs using Electrical Impedance Tomography (EIT). Nine healthy beagle dogs, aging 3.7±1.7 (mean±SD) years and weighing 16.3±1.6 kg, received a series of treatments in a fixed order on a single occasion. Conscious dogs were positioned in right lateral recumbency (RLR) and equipped with 32 EIT electrodes around the thorax. Following five minutes of equilibration, two minutes of EIT recordings were made in each recumbency in the following order: RLR, dorsal (DR), left (LLR) and sternal (SR). The dogs were then positioned in RLR, premedicated (medetomidine 0.01, midazolam 0.1, butorphanol 0.1 mg kg-1 iv) and pre-oxygenated. Fifteen minutes later anaesthesia was induced with 1 mg kg-1 propofol iv and maintained with propofol infusion (0.1–0.2 mg kg-1 minute-1 iv). After induction, the animals were intubated and allowed to breathe spontaneously (FIO2 = 1). Recordings of EIT were performed again in four recumbencies similarly to conscious state. Centre of ventilation (COV) and global inhomogeneity (GI) index were calculated from the functional EIT images. Repeated-measures ANOVA and Bonferroni tests were used for statistical analysis (p < 0.05). None of the variables changed in the conscious state. During anaesthesia left-to-right COV increased from 46.8±2.8% in DR to 49.8±2.9% in SR indicating a right shift, and ventral-to-dorsal COV increased from 49.8±1.7% in DR to 51.8±1.1% in LLR indicating a dorsal shift in distribution of ventilation. Recumbency affected distribution of ventilation in anaesthetized but not in conscious dogs. This can be related to loss of respiratory muscle tone (e.g. diaphragm) and changes in thoracic shape. Changing position of thoraco-abdominal organs under the EIT belt should be considered as alternative explanation of these findings.
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Affiliation(s)
- Tamas D Ambrisko
- Anaesthesiology and Perioperative Intensive-Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
| | - Johannes P Schramel
- Anaesthesiology and Perioperative Intensive-Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
| | - Ulrike Auer
- Anaesthesiology and Perioperative Intensive-Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
| | - Yves P S Moens
- Anaesthesiology and Perioperative Intensive-Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
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Ambrisko TD, Schramel J, Hopster K, Kästner S, Moens Y. Assessment of distribution of ventilation and regional lung compliance by electrical impedance tomography in anaesthetized horses undergoing alveolar recruitment manoeuvres. Vet Anaesth Analg 2017; 44:264-272. [DOI: 10.1016/j.vaa.2016.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 01/18/2016] [Accepted: 03/04/2016] [Indexed: 10/20/2022]
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Burnheim K, Hughes KJ, Evans DL, Raidal SL. Reliability of breath by breath spirometry and relative flow-time indices for pulmonary function testing in horses. BMC Vet Res 2016; 12:268. [PMID: 27894292 PMCID: PMC5126818 DOI: 10.1186/s12917-016-0893-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 11/21/2016] [Indexed: 11/23/2022] Open
Abstract
Background Respiratory problems are common in horses, and are often diagnosed as a cause of poor athletic performance. Reliable, accurate and sensitive spirometric tests of airway function in resting horses would assist with the diagnosis of limitations to breathing and facilitate investigations of the effects of various treatments on breathing capacity. The evaluation of respiratory function in horses is challenging and suitable procedures are not widely available to equine practitioners. The determination of relative flow or flow-time measures is used in paediatric patients where compliance may limit conventional pulmonary function techniques. The aim of the current study was to characterise absolute and relative indices of respiratory function in healthy horses during eupnoea (tidal breathing) and carbon dioxide (CO2)-induced hyperpnoea (rebreathing) using a modified mask pneumotrachographic technique well suited to equine practice, and to evaluate the reliability of this technique over three consecutive days. Coefficients of variation, intra-class correlations, mean differences and 95% confidence intervals across all days of testing were established for each parameter. Results The technique provided absolute measures of respiratory function (respiratory rate, tidal volume, peak inspiratory and expiratory flows, time to peak flow) consistent with previous studies and there was no significant effect of day on any measure of respiratory function. Variability of measurements was decreased during hyperpnea caused by rebreathing CO2, but a number of relative flow-time variables demonstrated good agreement during eupnoeic respiration. Conclusions The technique was well tolerated by horses and study findings suggest the technique is suitable for evaluation of respiratory function in horses. The use of relative flow-time variables provided reproducible (consistent) results, suggesting the technique may be of use for repeated measures studies in horses during tidal breathing or rebreathing. Electronic supplementary material The online version of this article (doi:10.1186/s12917-016-0893-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- K Burnheim
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, 2650, NSW, Australia
| | - K J Hughes
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, 2650, NSW, Australia
| | - D L Evans
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, 2650, NSW, Australia
| | - S L Raidal
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, 2650, NSW, Australia.
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