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Saxena S, Tripathi M, Kumar V, Malviya D, Harjai M, Rai S. Study of Tidal Volume and Positive End-Expiratory Pressure on Alveolar Recruitment Using Spiro Dynamics in Mechanically Ventilated Patients. Anesth Essays Res 2020; 14:154-159. [PMID: 32843810 PMCID: PMC7428118 DOI: 10.4103/aer.aer_10_20] [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: 02/02/2020] [Revised: 02/09/2020] [Accepted: 02/21/2020] [Indexed: 11/04/2022] Open
Abstract
Background and Aims Ventilator setting in the intensive care unit patients is a topic of debate and setting of tidal volume (TV) should be patient-specific based on lung mechanics. In this study, we have evaluated to develop optimal ventilator strategies through continuous and thorough monitoring of respiratory mechanics during ongoing ventilator support to prevent alveolar collapse and alveolar injury in mechanically ventilated patients. Methods In our monocentric, randomized, observational study, we had recruited 60 patients and divided them into two groups of 30 each. In Group 1 patients, TV and positive end-expiratory pressure (PEEP) were set according to pressure-volume (P/V) curve obtained by the mechanical ventilator in a conventional manner (control group), and in Group 2, TV and PEEP were set according to P/V curve obtained by the mechanical ventilator using intratracheal catheter. PEEP and TV were set accordingly. TV, PEEP, and PaO2/FiO2 (P/F) ratio at days 1, 3, and 7, mortality within 7 days and mortality within 28 days were measured in each group and compared. Results We found a significant difference between PEEP and P/F ratio in both groups while intragroup comparison at days 1, 3, and 7. After the intergroup comparison of Group 1 and 2, we observed a significant difference of PEEP and P/F ratio between the groups at day 7 and not on day 1 or 3. Conclusion This study concludes that optimal PEEP is more accurate using an intratracheal catheter than the conventional method of deciding ventilator setting. Hence, it is recommended to use intratracheal catheter to obtain more accurate ventilator settings.
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Affiliation(s)
- Shobhit Saxena
- Department of Anesthesia and Critical Care, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
| | - Manoj Tripathi
- Department of Anesthesia and Critical Care, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
| | - Virendra Kumar
- Department of Anesthesia and Critical Care, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
| | - Deepak Malviya
- Department of Anesthesia and Critical Care, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
| | - Mamta Harjai
- Department of Anesthesia and Critical Care, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
| | - Sujeet Rai
- Department of Anesthesia and Critical Care, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
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Spaeth J, Ott M, Karzai W, Grimm A, Wirth S, Schumann S, Loop T. Double-lumen tubes and auto-PEEP during one-lung ventilation. Br J Anaesth 2016; 116:122-30. [DOI: 10.1093/bja/aev398] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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A patient-specific airway branching model for mechanically ventilated patients. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2014; 2014:645732. [PMID: 25214888 PMCID: PMC4158163 DOI: 10.1155/2014/645732] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 07/30/2014] [Accepted: 07/31/2014] [Indexed: 11/17/2022]
Abstract
BACKGROUND Respiratory mechanics models have the potential to guide mechanical ventilation. Airway branching models (ABMs) were developed from classical fluid mechanics models but do not provide accurate models of in vivo behaviour. Hence, the ABM was improved to include patient-specific parameters and better model observed behaviour (ABMps). METHODS The airway pressure drop of the ABMps was compared with the well-accepted dynostatic algorithm (DSA) in patients diagnosed with acute respiratory distress syndrome (ARDS). A scaling factor (α) was used to equate the area under the pressure curve (AUC) from the ABMps to the AUC of the DSA and was linked to patient state. RESULTS The ABMps recorded a median α value of 0.58 (IQR: 0.54-0.63; range: 0.45-0.66) for these ARDS patients. Significantly lower α values were found for individuals with chronic obstructive pulmonary disease (P < 0.001). CONCLUSION The ABMps model allows the estimation of airway pressure drop at each bronchial generation with patient-specific physiological measurements and can be generated from data measured at the bedside. The distribution of patient-specific α values indicates that the overall ABM can be readily improved to better match observed data and capture patient condition.
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Richard JC, Pouzot C, Pinzón AM, González JST, Orkisz M, Neyran B, Hoyos MH, Lavenne F, Guerin C. Reliability of the nitrogen washin-washout technique to assess end-expiratory lung volume at variable PEEP and tidal volumes. Intensive Care Med Exp 2014; 2:10. [PMID: 26266911 PMCID: PMC4512977 DOI: 10.1186/2197-425x-2-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 01/30/2014] [Indexed: 08/30/2023] Open
Abstract
Background End-expiratory lung volume measurement by the nitrogen washin-washout technique (EELVWI-WO) may help titrating positive end-expiratory pressure (PEEP) during acute respiratory distress syndrome (ARDS). Validation of this technique has been previously performed using computed tomography (EELVCT), but at mild PEEP levels, and relatively low fraction of inspired oxygen (FiO2), which may have insufficiently challenged the validity of this technique. The aims of this study were (1) to evaluate the reliability of EELVWI-WO measurements at different PEEP and VT during experimental ARDS and (2) to evaluate trending ability of EELVWI-WO to detect EELV changes over time. Methods ARDS was induced in 14 piglets by saline lavage. Optimal PEEP was selected during a decremental PEEP trial, based on best compliance, best EELVWI-WO, or a PEEP-FiO2 table. Eight VT (4 to 20 mL · kg-1) were finally applied at optimal PEEP. EELVWI-WO and EELVCT were determined after ARDS onset, at variable PEEP and VT. Results EELVWI-WO underestimated EELVCT with a non-constant linear bias, as it decreased with increasing EELV. Limits of agreement for bias were ±398 mL. Bias between methods was greater at high PEEP, and further increased when high PEEP was combined with low VT. Concordance rate of EELV changes between consecutive measurements was fair (79%). Diagnostic accuracy was good for detection of absolute EELV changes above 200 mL (AUC = 0.79). Conclusions The reliability of the WI-WO technique is critically dependent on ventilatory settings, but sufficient to accurately detect EELV change greater than 200 mL. Electronic supplementary material The online version of this article (doi:10.1186/2197-425X-2-10) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jean-Christophe Richard
- Service de Réanimation Médicale, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de la Croix Rousse, 69004, Lyon, France ,
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Khemani RG, Newth CJL. The design of future pediatric mechanical ventilation trials for acute lung injury. Am J Respir Crit Care Med 2010; 182:1465-74. [PMID: 20732987 DOI: 10.1164/rccm.201004-0606ci] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Pediatric practitioners face unique challenges when attempting to translate or adapt adult-derived evidence regarding ventilation practices for acute lung injury or acute respiratory distress syndrome into pediatric practice. Fortunately or unfortunately, there appears to be selective adoption of adult practices for pediatric mechanical ventilation, many of which pose considerable challenges or uncertainty when translated to pediatrics. These differences, combined with heterogeneous management strategies within pediatric critical care, can complicate clinical practice and make designing robust clinical trials in pediatric acute respiratory failure particularly difficult. These issues surround the lack of explicit ventilator protocols in pediatrics, either computer or paper based; differences in modes of conventional ventilation and perceived marked differences in the approach to high-frequency oscillatory ventilation; challenges with patient recruitment; the shortcomings of the definition of acute lung injury and acute respiratory distress syndrome; the more reliable yet still somewhat unpredictable relationship between lung injury severity and outcome; and the reliance on potentially biased surrogate outcome measures, such as ventilator-free days, for all pediatric trials. The purpose of this review is to highlight these challenges, discuss pertinent work that has begun to address them, and propose potential solutions or future investigations that may help facilitate comprehensive trials on pediatric mechanical ventilation and define clinical practice standards.
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Affiliation(s)
- Robinder G Khemani
- University of Southern California, Children's Hospital Los Angeles, CA 90027, USA.
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Fagerberg A, Söndergaard S, Karason S, Aneman A. Electrical impedance tomography and heterogeneity of pulmonary perfusion and ventilation in porcine acute lung injury. Acta Anaesthesiol Scand 2009; 53:1300-9. [PMID: 19719814 DOI: 10.1111/j.1399-6576.2009.02103.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The heterogeneity of pulmonary ventilation (V), perfusion (Q) and V/Q matching impairs gas exchange in an acute lung injury (ALI). This study investigated the feasibility of electrical impedance tomography (EIT) to assess the V/Q distribution and matching during an endotoxinaemic ALI in pigs. METHODS Mechanically ventilated, anaesthetised pigs (n=11, weight 30-36 kg) were studied during an infusion of endotoxin for 150 min. Impedance changes related to ventilation (Z(V)) and perfusion (Z(Q)) were monitored globally and bilaterally in four regions of interest (ROIs) of the EIT image. The distribution and ratio of Z(V) and Z(Q) were assessed. The alveolar-arterial oxygen difference, venous admixture, fractional alveolar dead space and functional residual capacity (FRC) were recorded, together with global and regional lung compliances and haemodynamic parameters. Values are mean+/-standard deviation (SD) and regression coefficients. RESULTS Endotoxinaemia increased the heterogeneity of Z(Q) but not Z(V). Lung compliance progressively decreased with a ventral redistribution of Z(V). A concomitant dorsal redistribution of Z(Q) resulted in mismatch of global (from Z(V)/Z(Q) 1.1+/-0.1 to 0.83+/-0.3) and notably dorsal (from Z(V)/Z(Q) 0.86+/-0.4 to 0.51+/-0.3) V and Q. Changes in global Z(V)/Z(Q) correlated with changes in the alveolar-arterial oxygen difference (r(2)=0.65, P<0.05), venous admixture (r(2)=0.66, P<0.05) and fractional alveolar dead space (r(2)=0.61, P<0.05). Decreased end-expiratory Z(V) correlated with decreased FRC (r(2)=0.74, P<0.05). CONCLUSIONS EIT can be used to assess the heterogeneity of regional pulmonary ventilation and perfusion and V/Q matching during endotoxinaemic ALI, identifying pivotal pathophysiological changes.
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Affiliation(s)
- A Fagerberg
- Department of Anaesthesiology and Intensive Care, Sahlgrenska University Hospital, Blå Stråket 5, Gothenburg, Sweden
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Owens RL, Stigler WS, Hess DR. Do newer monitors of exhaled gases, mechanics, and esophageal pressure add value? Clin Chest Med 2008; 29:297-312, vi-vii. [PMID: 18440438 DOI: 10.1016/j.ccm.2008.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The current understanding of lung mechanics and ventilator-induced lung injury suggests that patients who have acute respiratory distress syndrome should be ventilated in such a way as to minimize alveolar over-distension and repeated alveolar collapse. Clinical trials have used such lung protective strategies and shown a reduction in mortality; however, there is data that these "one-size fits all" strategies do not work equally well in all patients. This article reviews other methods that may prove useful in monitoring for potential lung injury: exhaled breath condensate, pressure-volume curves, and esophageal manometry. The authors explore the concepts, benefits, difficulties, and relevant clinical trials of each.
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Affiliation(s)
- Robert L Owens
- Department of Medicine, Pulmonary and Critical Care Unit, Cox 2, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
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Stenqvist O, Odenstedt H, Lundin S. Dynamic respiratory mechanics in acute lung injury/acute respiratory distress syndrome: research or clinical tool? Curr Opin Crit Care 2008; 14:87-93. [PMID: 18195632 DOI: 10.1097/mcc.0b013e3282f3a166] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Classic static measurements of lung mechanics have been used mainly for research purposes, but have not gained widespread clinical acceptance. Instead, dynamic measurements have been used, but interpretation of results has been hampered by lack of clear definitions. The review provides an overview of possible definitions and a description of methods for evaluating lung mechanics in acute lung injury/acute respiratory distress syndrome patients. RECENT FINDINGS Compliance measured using static techniques is significantly higher compared to measurements during ongoing ventilation. This indicates that lung mechanic properties depend on flow velocity during inflation and the time allowed for equilibration of viscoelastic forces. Thus, methods for evaluating lung mechanics should be clearly defined in terms of whether they are classically static, i.e. excluding resistance to flow and equilibration of viscoelastic forces, or truly dynamic, i.e. including flow resistance and unequilibrated viscoelastic forces. New techniques have emerged which make it possible to monitor lung mechanics during ongoing, therapeutic ventilation, 'functional lung mechanics', where the impact of flow resistance on tube and airway resistance has been eliminated, providing alveolar pressure/volume curves. SUMMARY Functional lung mechanics obtained during ongoing ventilator treatment have the potential to provide information for optimizing ventilator management in critically ill patients.
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Affiliation(s)
- Ola Stenqvist
- Department of Anesthesia and Intensive Care, Sahlgrenska University Hospital, Göteborg, Sweden
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Abad Gurumeta A, Calvo Vecino JM, San Norberto García L, Muñoz Avalos N, Pérez Gallardo A, Gilsanz Rodríguez F. [Monitoring airway pressure in pediatric anesthesia: an experimental model of intratracheal medication and pressure-volume loops]. ACTA ACUST UNITED AC 2008; 55:4-12. [PMID: 18333380 DOI: 10.1016/s0034-9356(08)70491-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND In the monitoring of anesthesia, airway pressure is measured in the ventilator or at the closest possible connection to the endotracheal tube. OBJECTIVE To compare the airway pressures and pressure-volume loops obtained before connection to the endotracheal tube with those obtained in the trachea. MATERIAL AND METHODS We carried out a single-blind prospective observational study on ASA 1 patients between the ages of 7 and 12 years ventilated in volume-control mode with an inspiration-to-expiration ratio of 1:2. Intratracheal and extratracheal peak and plateau pressures and pressure-volume loops were recorded. A special device was designed to monitor intratracheal pressure. Both sensors were connected to the same spirometric analysis system. The variables were measured on intubation and 5, 10, 15, 20, 30, 40, 50, and 60 minutes after intubation. The recorded pressures were compared using the t test, the Pearson product moment correlation coefficient (r), and the Spearman rank correlation coefficient (p), and regression models were fit to the data. RESULTS Seventy-one patients were enrolled. The mean (SD) pressure difference between the 2 systems was 3.5 (0.35) cm H2O (P < .01) and no differences between the endotracheal peak pressures and the plateau pressures were observed. The intratracheal areas of the pressure-volume loops were 15% lower than the extratracheal areas. The value of r for the correlation between the intratracheal peak and plateau pressures was 0.998 (P < .01). The value of r for the correlation between the intratracheal and extratracheal peak pressures was 0.981 (P < .01). Analysis of variance confirmed the linear relationship. CONCLUSIONS The difference between the intratracheal and extratracheal pressure measurements is due to the different locations at which the measurements are taken.
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Affiliation(s)
- A Abad Gurumeta
- Servicio de Anestesiología, Hospital General Universitario Gregorio Marañón, Madrid.
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10
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Calvo Vecino JM, Abad Gurumeta A, Gil Lapetra C, Muñoz Velázquez MF, Pérez Gallardo A, Gilsanz Rodríguez F. [Monitoring airway gas in pediatric anesthesia: an experimental model for endotracheal gas measurement]. ACTA ACUST UNITED AC 2008; 55:13-20. [PMID: 18333381 DOI: 10.1016/s0034-9356(08)70492-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND We designed an endotracheal probe for measuring inspired and expired gas fractions during pediatric general anesthesia. OBJECTIVE To compare the gas fractions measured by means of intratracheal and extratracheal monitoring. MATERIAL AND METHODS The study included ASA 1 patients between the ages of 7 and 12 years under inhaled anesthesia with mechanical ventilation. The following parameters were recorded inside and outside the trachea: inspired and expired oxygen, nitric oxide (N2O) and sevoflurane fractions; the expired and inspired fraction gradients; PaCO2; and end-tidal carbon dioxide (ETCO2). Measurements were taken by an airflow sensor (Pedi-Lite) in the circuit before the point of connection to the endotracheal tube and by an intratracheal probe placed between the tube and the carina. Both sensors were connected to the same monitor. Measurements were taken on intubation and 5, 10, 15, 20, 30, 40, 50, and 60 minutes thereafter. PaCO2 was recorded at the same time. The recorded values were analyzed using the t test and the Pearson product moment correlation coefficient (r), and regression models were constructed using analysis of variance. RESULTS Seventy-one patients were enrolled in the study. The mean difference (SD) ETCO2 was 5 (3) mm Hg higher according to endotracheal measurement (P < .005), and that measurement was almost identical (+/-13 mm Hg) to the PaCO2 (P < or = .5). The inspired/expired gradients of endotracheal measurement of oxygen and N2O were 3 (2) points higher (P < .05) than the gradients of extratracheal measurements. In the case of sevoflurane gradients, however, the extratracheal values were higher (mean difference, 0.6 [0.2] points, P < .05). The inspired/expired oxygen and N2O gradients became equal after 18 (3) minutes; the sevoflurane gradients became equal after 8 (2) minutes. CONCLUSIONS Intratracheal and extratracheal measurements of the inspired and expired fractions of mixed gases provide different results.
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Affiliation(s)
- J M Calvo Vecino
- Servicio de Anestesiología y Reanimación, Hospital Infantil Universitario Niño Jesús, Madrid.
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Lindgren S, Odenstedt H, Erlandsson K, Grivans C, Lundin S, Stenqvist O. Bronchoscopic suctioning may cause lung collapse: a lung model and clinical evaluation. Acta Anaesthesiol Scand 2008; 52:209-18. [PMID: 18005383 DOI: 10.1111/j.1399-6576.2007.01499.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVE To assess lung volume changes during and after bronchoscopic suctioning during volume or pressure-controlled ventilation (VCV or PCV). DESIGN Bench test and patient study. PARTICIPANTS Ventilator-treated acute lung injury (ALI) patients. SETTING University research laboratory and general adult intensive care unit of a university hospital. INTERVENTIONS Bronchoscopic suctioning with a 12 or 16 Fr bronchoscope during VCV or PCV. MEASUREMENTS AND RESULTS Suction flow at vacuum levels of -20 to -80 kPa was measured with a Timeter(trade mark) instrument. In a water-filled lung model, airway pressure, functional residual capacity (FRC) and tidal volume were measured during bronchoscopic suctioning. In 13 ICU patients, a 16 Fr bronchoscope was inserted into the left or the right main bronchus during VCV or PCV and suctioning was performed. Ventilation was monitored with electric impedance tomography (EIT) and FRC with a modified N(2) washout/in technique. Airway pressure was measured via a pressure line in the endotracheal tube. Suction flow through the 16 Fr bronchoscope was 5 l/min at a vacuum level of -20 kPa and 17 l/min at -80 kPa. Derecruitment was pronounced during suctioning and FRC decreased with -479+/-472 ml, P<0.001. CONCLUSIONS Suction flow through the bronchoscope at the vacuum levels commonly used is well above minute ventilation in most ALI patients. The ventilator was unable to deliver enough volume in either VCV or PCV to maintain FRC and tracheal pressure decreased below atmospheric pressure.
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Affiliation(s)
- S Lindgren
- Department of Anaesthesia and Intensive Care, Sahlgrenska University Hospital, SE-413 45, Gothenburg, Sweden.
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12
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Fast and Slow Compliance: Time, in Addition to Pressure and Volume, is a Key Factor for Lung Mechanics. Intensive Care Med 2007. [DOI: 10.1007/0-387-35096-9_38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Alveolar Pressure/volume Curves Reflect Regional Lung Mechanics. Intensive Care Med 2007. [DOI: 10.1007/978-0-387-49518-7_37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Lindgren S, Odenstedt H, Olegård C, Söndergaard S, Lundin S, Stenqvist O. Regional lung derecruitment after endotracheal suction during volume- or pressure-controlled ventilation: a study using electric impedance tomography. Intensive Care Med 2006; 33:172-80. [PMID: 17072587 DOI: 10.1007/s00134-006-0425-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Accepted: 09/19/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVE To assess lung volume and compliance changes during open- and closed-system suctioning using electric impedance tomography (EIT) during volume- or pressure-controlled ventilation. DESIGN AND SETTING Experimental study in a university research laboratory. SUBJECTS Nine bronchoalveolar saline-lavaged pigs. INTERVENTIONS Open and closed suctioning using a 14-F catheter in volume- or pressure-controlled ventilation at tidal volume 10 ml/kg, respiratory rate 20 breaths/min, and positive end-expiratory pressure 10 cmH2O. MEASUREMENTS AND RESULTS Lung volume was monitored by EIT and a modified N2 washout/-in technique. Airway pressure was measured via a pressure line in the endotracheal tube. In four ventral-to-dorsal regions of interest regional ventilation and compliance were calculated at baseline and 30 s and 1, 2, and 10 min after suctioning. Blood gases were followed. At disconnection functional residual capacity (FRC) decreased by 58+/-24% of baseline and by a further 22+/-10% during open suctioning. Arterial oxygen tension decreased to 59+/-14% of baseline value 1 min after open suctioning. Regional compliance deteriorated most in the dorsal parts of the lung. Restitution of lung volume and compliance was significantly slower during pressure-controlled than volume-controlled ventilation. CONCLUSIONS EIT can be used to monitor rapid lung volume changes. The two dorsal regions of the lavaged lungs are most affected by disconnection and suctioning with marked decreases in compliance. Volume-controlled ventilation can be used to rapidly restitute lung aeration and oxygenation after lung collapse induced by open suctioning.
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Affiliation(s)
- Sophie Lindgren
- Department of Anesthesia and Intensive Care, Sahlgrenska University Hospital, 41345, Gothenburg, Sweden.
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Olegård C, Söndergaard S, Houltz E, Lundin S, Stenqvist O. Estimation of Functional Residual Capacity at the Bedside Using Standard Monitoring Equipment: A Modified Nitrogen Washout/Washin Technique Requiring a Small Change of the Inspired Oxygen Fraction. Anesth Analg 2005; 101:206-12, table of contents. [PMID: 15976233 DOI: 10.1213/01.ane.0000165823.90368.55] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We developed a modified nitrogen washin/washout technique based on standard monitors using inspiratory and end-tidal gas concentration values for functional residual capacity (FRC) measurements in patients with acute respiratory failure (ARF). For validation we used an oxygen-consuming lung model ventilated with an inspiratory oxygen fraction (Fio(2)) between 0.3 and 1.0. The respiratory quotient of the lung model was varied between 0.7 and 1.0. Measurements were performed changing Fio(2) with fractions of 0.1, 0.2, and 0.3. In 28 patients with ARF, duplicate measurements were performed. In the lung model, an Fio(2) change of 0.1 resulted in a value of 103 +/- 5% of the reference FRC value of the lung model, and the precision was equally good up to an Fio(2) of 1.0 with a value of 103 +/- 7%. In the patients, duplicate measurements showed a bias of -5 mL with a 95% confidence interval [-38; 29 mL ]. A comparison of a change in Fio(2) of 0.1 with 0.3 showed a bias of -9 mL and limits of agreement of [-365; 347 mL]. This study shows good precision of FRC measurements with standard monitors using a change in Fio(2) of only 0.1. Measurements can be performed with equal precision up to an Fio(2) of 1.0.
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Affiliation(s)
- Cecilia Olegård
- Department of Anesthesiology and Intensive Care, Sahlgrenska University Hospital, S-413 45 Gothenburg, Sweden.
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Schmalisch G, Proquitté H, Schmidt M, Rüdiger M, Wauer RR. Inertance measurements by jet pulses in ventilated small lungs after perfluorochemical liquid (PFC) applications. Physiol Meas 2005; 26:239-49. [PMID: 15798299 DOI: 10.1088/0967-3334/26/3/009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Perfluorochemical liquid (PFC) liquids or aerosols are used for assisted ventilation, drug delivery, lung cancer hyperthermia and pulmonary imaging. The aim of this study was to investigate the effect of PFC liquid on the inertance (I) of the respiratory system in newborn piglets using partial liquid ventilation (PLV) with different volumes of liquid. End-inspiratory (I(in)) and end-expiratory (I(ex)) inertance were measured in 15 ventilated newborn piglets (age < 12 h, mean weight 724 +/- 93 g) by brief flow pulses before and 80 min after PLV using a PFC volume (PF5080, 3 M) of 10 ml kg(-1) (N = 5) or 30 ml kg(-1) (N = 10). I was calculated from the imaginary part of the measured respiratory input impedance by regression analysis. Straight tubes with 2-4 mm inner diameter were used to validate the equipment in vitro by comparison with the analytically calculated values. In vitro measurements showed that the measuring error of I was <5% and that the reproducibility was better than 1.5%. The correlation coefficient of the regression model to determine I was >0.988 in all piglets. During gas ventilation, I(in) and I(ex) (mean +/- SD) were 31.7 +/- 0.8 Pa l(-1) s(2) and 33.3 +/- 2.1 Pa l(-1) s(2) in the 10 ml group and 32.4 +/- 0.8 Pa l(-1) s(2) and 34.0 +/- 2.5 Pa l(-1) s(2) in the 30 ml group. However, I of the 3 mm endotracheal tube (ETT) used was already 26.4 Pa l(-1) s(2) (about 80% of measured I). During PLV, there was a minimal increase of I(in) to 33.1 +/- 2.5 Pa l(-1) s(2) in the 10 ml group and to 34.5 +/- 2.7 Pa l(-1) s(2) in the 30 ml group. In contrast, the increase of I(ex) was dramatically larger (p < 0.001) to 67.7 +/- 13.3 Pa l(-1) s(2) and to 74.8 +/- 9.3 Pa l(-1) s(2) in the 10 ml and 30 ml groups, respectively. Measurements of I by jet pulses in intubated small animals are reproducible. PFC increases the respiratory inertance, but the magnitude depends considerably on its spatial distribution which changes during the breathing cycle. Large differences between I(in) and I(ex) are an indicator for liquid in airways or the ETT.
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Affiliation(s)
- Gerd Schmalisch
- Clinic of Neonatology (Charité), Humboldt-University of Berlin, Schumannstrasse 20/21, D-10098 Berlin, Germany.
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Abraham E, Andrews P, Antonelli M, Brochard L, Brun-Buisson C, Dobb G, Fagon JY, Groeneveld J, Mancebo J, Metnitz P, Nava S, Pinsky M, Radermacher P, Ranieri M, Richard C, Tasker R, Vallet B. Year in review in Intensive Care Medicine-2003. Part 1: Respiratory failure, infection and sepsis. Intensive Care Med 2004; 30:1017-31. [PMID: 15170528 DOI: 10.1007/s00134-004-2321-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2004] [Indexed: 11/25/2022]
Affiliation(s)
- Edward Abraham
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, CO, USA
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Lindgren S, Almgren B, Högman M, Lethvall S, Houltz E, Lundin S, Stenqvist O. Effectiveness and side effects of closed and open suctioning: an experimental evaluation. Intensive Care Med 2004; 30:1630-7. [PMID: 14985963 DOI: 10.1007/s00134-003-2153-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2003] [Accepted: 12/18/2003] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To compare the effectiveness of closed system suctioning (CSS) and open system suctioning (OSS) and the side effects on gas exchange and haemodynamics, during pressure-controlled ventilation (PCV) or continuous positive airway pressure (CPAP). DESIGN Bench test and porcine lung injury model. PARTICIPANTS Twelve bronchoalveolar saline-lavaged pigs. SETTING Research laboratory in a university hospital. INTERVENTIONS In a mechanical lung, the efficacy of OSS and CSS with 12 and 14 Fr catheters were compared during volume-control ventilation, PCV, CPAP 0 or 10 cmH(2)O by weighing the suction system before and after aspirating gel in a transparent trachea. Side effects were evaluated in the animals with the same ventilator settings during suctioning of 5, 10 or 20 s duration. MEASUREMENTS AND RESULTS Suctioning with 12 and 14 Fr catheters was significantly more efficient with OSS (1.9+/-0.1, 2.8+/-0.9 g) and with CSS during CPAP 0 cmH(2)O (1.8+/-0.2, 4.2+/-0.5 g) as compared to CSS during PCV (0.2+/-0.2, 0.8+/-0.3 g) or CPAP 10 cmH(2)O (0.0+/-0.1, 0.7+/-0.4 g), p<0.01 (means +/- SD). OSS and CSS at CPAP 0 cmH(2)O resulted in a marked decrease in SpO(2), mixed venous oxygen saturation and tracheal pressure, p<0.001, but the side effects were considerably fewer during CSS with PCV and CPAP 10 cmH(2)O, p<0.05. CONCLUSIONS Irrespective of catheter size, OSS and CSS during CPAP 0 cmH(2)O were markedly more effective than CSS during PCV and CPAP 10 cmH(2)O but had worse side effects. However, the side effects lasted less than 5 min in this animal model. Suctioning should be performed effectively when absolutely indicated and the side effects handled adequately.
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Affiliation(s)
- Sophie Lindgren
- Department of Anaesthesia and Intensive Care, Sahlgrenska University Hospital, 413 45 Gothenburg, Sweden.
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Affiliation(s)
- O Stenqvist
- Department of Anaesthesiology and Intensive Care, Sahlgrenska University Hospital, Göteborg, Sweden.
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