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González-Pizarro P, Acosta CM, Alcaraz García-Tejedor G, Tusman G, Ferrando C, Ricci L, Natal ML, Suarez-Sipmann F. Clinical validation of the Air-Test for the non-invasive detection of perioperative atelectasis in children. Minerva Anestesiol 2024; 90:635-643. [PMID: 39021139 DOI: 10.23736/s0375-9393.24.17933-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
BACKGROUND The incidence of anesthesia-induced atelectasis in children is high and closely related to episodes of hypoxemia. The Air-Test is a simple maneuver to detect lung collapse. By a step-reduction in FiO2 to 0.21, a fall in pulse-oximetry hemoglobin saturation <97% unmasks the presence of collapse-related shunt in healthy lungs. The aim of this study was to validate the Air-Test as a diagnostic tool to detect perioperative atelectasis in children using lung ultrasound as a reference. METHODS We first assessed the Air-Test in a retrospective cohort of 88 anesthetized children (Retrospective study) followed by a prospective study performed in 72 children (45 postconceptional weeks to 16 years old) using a similar protocol (Validation study). We analyzed the performance of the Air-Test to detect atelectasis by an operating characteristic curve (ROC) analysis, using lung ultrasound consolidation score as reference. RESULTS Preoperative SpO2 was normal in both studies (retrospective 98.7±0.6%, validation 99.0±0.9%). The Air-Test, with a SpO2 cut point <97%, resulted positive in 67 patients in the retrospective study (SpO2 93.3±2.1%) and in 59 in the validation study (SpO2 94.9±1.8%); both P<0.0001. In the validation study, the Air-Test showed a sensitivity of 0.91 (95% CI 0.85-0.92), specificity of 1.00 (95% CI 0.84-1) and an area under the curve (AUC) of 0.98 (95% CI 0.97-1.00). AUC between both studies was similar (P=0.16). CONCLUSIONS The Air-Test is a noninvasive and accurate method to detect atelectasis in healthy anesthetized children. It can be used as a screening tool to individualize patients that can benefit from lung recruitment maneuvers.
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Affiliation(s)
- Patricio González-Pizarro
- Department of Pediatric Anesthesia and Critical Care, La Paz Children's University Hospital, Madrid, Spain -
- IdiPaz Research Institute, Madrid, Spain -
| | - Cecilia M Acosta
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar de Plata, Argentina
| | | | - Gerardo Tusman
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar de Plata, Argentina
| | - Carlos Ferrando
- Department of Anesthesiology and Critical Care, Hospital Clínic of Barcelona, Barcelona, Spain
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Lila Ricci
- Department of Mathematics, Faculty of Exact Sciences, National University of Mar del Plata, Mar del Plata, Argentina
| | - Marcela L Natal
- Department of Mathematics, Faculty of Exact Sciences, National University of Mar del Plata, Mar del Plata, Argentina
| | - Fernando Suarez-Sipmann
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
- Department of Intensive Care Medicine, La Princesa University Hospital, Madrid, Spain
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
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Sipmann FS, Giralt JAS, Tusman G. Monitoring CO2 kinetics as a marker of cardiopulmonary efficiency. Curr Opin Crit Care 2024; 30:251-259. [PMID: 38690954 DOI: 10.1097/mcc.0000000000001156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
PURPOSE OF REVIEW To describe current and near future developments and applications of CO2 kinetics in clinical respiratory and cardiovascular monitoring. RECENT FINDINGS In the last years, we have witnessed a renewed interest in CO2 kinetics in relation with a better understanding of volumetric capnography and its derived parameters. This together with technological advances and improved measurement systems have expanded the monitoring potential of CO2 kinetics including breath by breath continuous end-expiratory lung volume and continuous noninvasive cardiac output. Dead space has slowly been gaining relevance in clinical monitoring and prognostic evaluation. Easy to measure dead space surrogates such as the ventilatory ratio have demonstrated a strong prognostic value in patients with acute respiratory failure. SUMMARY The kinetics of carbon dioxide describe many relevant physiological processes. The clinical introduction of new ways of assessing respiratory and circulatory efficiency based on advanced analysis of CO2 kinetics are paving the road to a long-desired goal in clinical monitoring of critically ill patients: the integration of respiratory and circulatory monitoring during mechanical ventilation.
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Affiliation(s)
- Fernando Suarez Sipmann
- Department of Intensive Care Medicine, Hospital Universitario de La Princesa, Universidad Autónoma de Madrid
- Ciber de enfermedades respiratorias, Instituto Carlos III, Madrid, Spain
| | - Juan Antonio Sanchez Giralt
- Department of Intensive Care Medicine, Hospital Universitario de La Princesa, Universidad Autónoma de Madrid
| | - Gerardo Tusman
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina
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Sanchez Giralt JA, Tusman G, Wallin M, Hallback M, Perez Lucendo A, Sanchez Galindo M, Abad Santamaria B, Paz Calzada E, Garcia Garcia P, Rodriguez Huerta D, Canabal Berlanga A, Suarez-Sipmann F. Clinical validation of a capnodynamic method for measuring end-expiratory lung volume in critically ill patients. Crit Care 2024; 28:142. [PMID: 38689313 PMCID: PMC11059761 DOI: 10.1186/s13054-024-04928-w] [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: 02/21/2024] [Accepted: 04/21/2024] [Indexed: 05/02/2024] Open
Abstract
RATIONALE End-expiratory lung volume (EELV) is reduced in mechanically ventilated patients, especially in pathologic conditions. The resulting heterogeneous distribution of ventilation increases the risk for ventilation induced lung injury. Clinical measurement of EELV however, remains difficult. OBJECTIVE Validation of a novel continuous capnodynamic method based on expired carbon dioxide (CO2) kinetics for measuring EELV in mechanically ventilated critically-ill patients. METHODS Prospective study of mechanically ventilated patients scheduled for a diagnostic computed tomography exploration. Comparisons were made between absolute and corrected EELVCO2 values, the latter accounting for the amount of CO2 dissolved in lung tissue, with the reference EELV measured by computed tomography (EELVCT). Uncorrected and corrected EELVCO2 was compared with total CT volume (density compartments between - 1000 and 0 Hounsfield units (HU) and functional CT volume, including density compartments of - 1000 to - 200HU eliminating regions of increased shunt. We used comparative statistics including correlations and measurement of accuracy and precision by the Bland Altman method. MEASUREMENTS AND MAIN RESULTS Of the 46 patients included in the final analysis, 25 had a diagnosis of ARDS (24 of which COVID-19). Both EELVCT and EELVCO2 were significantly reduced (39 and 40% respectively) when compared with theoretical values of functional residual capacity (p < 0.0001). Uncorrected EELVCO2 tended to overestimate EELVCT with a correlation r2 0.58; Bias - 285 and limits of agreement (LoA) (+ 513 to - 1083; 95% CI) ml. Agreement improved for the corrected EELVCO2 to a Bias of - 23 and LoA of (+ 763 to - 716; 95% CI) ml. The best agreement of the method was obtained by comparison of corrected EELVCO2 with functional EELVCT with a r2 of 0.59; Bias - 2.75 (+ 755 to - 761; 95% CI) ml. We did not observe major differences in the performance of the method between ARDS (most of them COVID related) and non-ARDS patients. CONCLUSION In this first validation in critically ill patients, the capnodynamic method provided good estimates of both total and functional EELV. Bias improved after correcting EELVCO2 for extra-alveolar CO2 content when compared with CT estimated volume. If confirmed in further validations EELVCO2 may become an attractive monitoring option for continuously monitor EELV in critically ill mechanically ventilated patients. TRIAL REGISTRATION clinicaltrials.gov (NCT04045262).
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Affiliation(s)
- J A Sanchez Giralt
- Department of Intensive Care, Hospital Universitario de La Princesa, Diego de León 62, 28006, Madrid, Spain
| | - G Tusman
- Department of Anesthesia, Hospital Privado de Comunidad, Mar del Plata, Argentina
| | - M Wallin
- Department of Physiology and Pharmacology (FYFA), C3, Eriksson Lars Group, Karolinska Institute, Stockholm, Sweden
| | | | - A Perez Lucendo
- Department of Intensive Care, Hospital Universitario de La Princesa, Diego de León 62, 28006, Madrid, Spain
| | - M Sanchez Galindo
- Department of Intensive Care, Hospital Universitario de La Princesa, Diego de León 62, 28006, Madrid, Spain
| | - B Abad Santamaria
- Department of Intensive Care, Hospital Universitario de La Princesa, Diego de León 62, 28006, Madrid, Spain
| | - E Paz Calzada
- Deparment of Radiology, Hospital Universitario de la Princesa, Madrid, España
| | - P Garcia Garcia
- Deparment of Radiology, Hospital Universitario de la Princesa, Madrid, España
| | - D Rodriguez Huerta
- Department of Intensive Care, Hospital Universitario de La Princesa, Diego de León 62, 28006, Madrid, Spain
| | - A Canabal Berlanga
- Department of Intensive Care, Hospital Universitario de La Princesa, Diego de León 62, 28006, Madrid, Spain
| | - Fernando Suarez-Sipmann
- Department of Intensive Care, Hospital Universitario de La Princesa, Diego de León 62, 28006, Madrid, Spain.
- CIBER Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.
- Hedenstierna Laboratory, Uppsala University, Uppsala, Sweden.
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Lundquist J, Shams N, Wallin M, Hallbäck M, Lönnqvist PA, Karlsson J. Capnodynamic end-expiratory lung volume assessment in anesthetized healthy children. Paediatr Anaesth 2024; 34:251-258. [PMID: 38055609 DOI: 10.1111/pan.14804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 10/18/2023] [Accepted: 11/21/2023] [Indexed: 12/08/2023]
Abstract
BACKGROUND Capnodynamic lung function monitoring generates variables that may be useful for pediatric perioperative ventilation. AIMS Establish normal values for end-expiratory lung volume CO2 in healthy children undergoing anesthesia and to compare these values to previously published values obtained with alternative end-expiratory lung volume methods. The secondary aim was to investigate the ability of end-expiratory lung volume CO2 to react to positive end-expiratory pressure-induced changes in end-expiratory lung volume. In addition, normal values for associated volumetric capnography lung function variables were examined. METHODS Fifteen pediatric patients with healthy lungs (median age 8 months, range 1-36 months) undergoing general anesthesia were examined before start of surgery. Tested variables were recorded at baseline positive end-expiratory pressure 3 cmH2 O, 1 and 3 min after positive end-expiratory pressure 10 cmH2 O and 3 min after returning to baseline positive end-expiratory pressure 3 cmH2 O. RESULTS Baseline end-expiratory lung volume CO2 was 32 mL kg-1 (95% CI 29-34 mL kg-1 ) which increased to 39 mL kg-1 (95% CI 35-43 mL kg-1 , p < .0001) and 37 mL kg-1 (95% CI 34-41 mL kg-1 , p = .0003) 1 and 3 min after positive end-expiratory pressure 10 cmH2 O, respectively. End-expiratory lung volume CO2 returned to baseline, 33 mL kg-1 (95% CI 29-37 mL kg-1 , p = .72) 3 min after re-establishing positive end-expiratory pressure 3 cmH2 O. Airway dead space increased from 1.1 mL kg-1 (95% CI 0.9-1.4 mL kg-1 ) to 1.4 (95% CI 1.1-1.8 mL kg-1 , p = .003) and 1.5 (95% CI 1.1-1.8 mL kg-1 , p < .0001) 1 and 3 min after positive end-expiratory pressure 10 cmH2 O, respectively, and 1.2 mL kg-1 (95% CI 0.9-1.4 mL kg-1 , p = .08) after 3 min of positive end-expiratory pressure 3 cmH2 O. Additional volumetric capnography and lung function variables showed no major changes in response to positive end-expiratory pressure variations. CONCLUSIONS Capnodynamic noninvasive and continuous end-expiratory lung volume CO2 values assessed during anesthesia in children were in close agreement with previously reported end-expiratory lung volume values generated by alternative methods. Furthermore, positive end-expiratory pressure changes resulted in physiologically expected end-expiratory lung volume CO2 responses in a timely manner, suggesting that it can be used to trend end-expiratory lung volume changes during anesthesia.
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Affiliation(s)
- Johanna Lundquist
- Pediatric perioperative medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
| | - Niki Shams
- Pediatric perioperative medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
| | - Mats Wallin
- Department of Physiology and Pharmacology (FYFA), C3, Eriksson I Lars, PA Lönnqvist group, Section of Anesthesiology and Intensive Care, Anestesi- och Intensivvårdsavdelningen, Karolinska Institute, Stockholm, Sweden
| | | | - Per-Arne Lönnqvist
- Pediatric perioperative medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
- Department of Physiology and Pharmacology (FYFA), C3, Eriksson I Lars, PA Lönnqvist group, Section of Anesthesiology and Intensive Care, Anestesi- och Intensivvårdsavdelningen, Karolinska Institute, Stockholm, Sweden
| | - Jacob Karlsson
- Pediatric perioperative medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
- Department of Physiology and Pharmacology (FYFA), C3, Eriksson I Lars, PA Lönnqvist group, Section of Anesthesiology and Intensive Care, Anestesi- och Intensivvårdsavdelningen, Karolinska Institute, Stockholm, Sweden
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Acosta CM, Poliotto S, Abrego D, Bradley D, de Esteban S, Mir F, Ricci L, Natal M, Wallin M, Hallbäck M, Sipmann FS, Tusman G. Effect of an Individualized Lung Protective Ventilation on Lung Strain and Stress in Children Undergoing Laparoscopy: An Observational Cohort Study. Anesthesiology 2024; 140:430-441. [PMID: 38064715 DOI: 10.1097/aln.0000000000004856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
BACKGROUND Exaggerated lung strain and stress could damage lungs in anesthetized children. The authors hypothesized that the association of capnoperitoneum and lung collapse in anesthetized children increases lung strain-stress. Their primary aim was to describe the impact of capnoperitoneum on lung strain-stress and the effects of an individualized protective ventilation during laparoscopic surgery in children. METHODS The authors performed an observational cohort study in healthy children aged 3 to 7 yr scheduled for laparoscopic surgery in a community hospital. All received standard protective ventilation with 5 cm H2O of positive end-expiratory pressure (PEEP). Children were evaluated before capnoperitoneum, during capnoperitoneum before and after lung recruitment and optimized PEEP (PEEP adjusted to get end-expiratory transpulmonary pressure of 0), and after capnoperitoneum with optimized PEEP. The presence of lung collapse was evaluated by lung ultrasound, positive Air-Test (oxygen saturation measured by pulse oximetry 96% or less breathing 21% O2 for 5 min), and negative end-expiratory transpulmonary pressure. Lung strain was calculated as tidal volume/end-expiratory lung volume measured by capnodynamics, and lung stress as the end-inspiratory transpulmonary pressure. RESULTS The authors studied 20 children. Before capnoperitoneum, mean lung strain was 0.20 ± 0.07 (95% CI, 0.17 to 0.23), and stress was 5.68 ± 2.83 (95% CI, 4.44 to 6.92) cm H2O. During capnoperitoneum, 18 patients presented lung collapse and strain (0.29 ± 0.13; 95% CI, 0.23 to 0.35; P < 0.001) and stress (5.92 ± 3.18; 95% CI, 4.53 to 7.31 cm H2O; P = 0.374) increased compared to before capnoperitoneum. During capnoperitoneum and optimized PEEP, children presenting lung collapse were recruited and optimized PEEP was 8.3 ± 2.2 (95% CI, 7.3 to 9.3) cm H2O. Strain returned to values before capnoperitoneum (0.20 ± 0.07; 95% CI, 0.17 to 0.22; P = 0.318), but lung stress increased (7.29 ± 2.67; 95% CI, 6.12 to 8.46 cm H2O; P = 0.020). After capnoperitoneum, strain decreased (0.18 ± 0.04; 95% CI, 0.16 to 0.20; P = 0.090), but stress remained higher (7.25 ± 3.01; 95% CI, 5.92 to 8.57 cm H2O; P = 0.024) compared to before capnoperitoneum. CONCLUSIONS Capnoperitoneum increased lung strain in healthy children undergoing laparoscopy. Lung recruitment and optimized PEEP during capnoperitoneum decreased lung strain but slightly increased lung stress. This little rise in pulmonary stress was maintained within safe, lung-protective, and clinically acceptable limits. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Cecilia M Acosta
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina
| | - Sergio Poliotto
- Department of Pediatric Surgery, Hospital Privado de Comunidad, Mar del Plata, Argentina
| | - Diego Abrego
- Department of Pediatric Surgery, Hospital Privado de Comunidad, Mar del Plata, Argentina
| | - Dolores Bradley
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina
| | - Santiago de Esteban
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina
| | - Francisco Mir
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina
| | - Lila Ricci
- Department of Mathematics, Facultad de Ciencias Exactas, Universidad Nacional de Mar del Plata, Argentina
| | - Marcela Natal
- Department of Mathematics, Facultad de Ciencias Exactas, Universidad Nacional de Mar del Plata, Argentina
| | - Mats Wallin
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden; Getinge Critical Care AB, Solna, Sweden
| | | | - Fernando Suarez Sipmann
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden; CIBERES (Network Biomedical Research Center), Madrid, Spain; Department of Critical Care, Hospital Universitario de La Princesa, Universidad Autonoma de Madrid, Madrid, Spain
| | - Gerardo Tusman
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina
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Keleher E, Iftikhar H, Schulz LF, McCanny P, Austin D, Stewart A, O'Regan W, Hallbäck M, Wallin M, Aneman A. Capnodynamic monitoring of lung volume and pulmonary blood flow during alveolar recruitment: a prospective observational study in postoperative cardiac patients. J Clin Monit Comput 2023; 37:1463-1472. [PMID: 37243954 DOI: 10.1007/s10877-023-01033-1] [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: 10/26/2022] [Accepted: 05/08/2023] [Indexed: 05/29/2023]
Abstract
Alveolar recruitment manoeuvres may mitigate ventilation and perfusion mismatch after cardiac surgery. Monitoring the efficacy of recruitment manoeuvres should provide concurrent information on pulmonary and cardiac changes. This study in postoperative cardiac patients applied capnodynamic monitoring of changes in end-expiratory lung volume and effective pulmonary blood flow. Alveolar recruitment was performed by incremental increases in positive end-expiratory pressure (PEEP) to a maximum of 15 cmH2O from a baseline of 5 cmH2O over 30 min. The change in systemic oxygen delivery index after the recruitment manoeuvre was used to identify responders (> 10% increase) with all other changes (≤ 10%) denoting non-responders. Mixed factor ANOVA using Bonferroni correction for multiple comparisons was used to denote significant changes (p < 0.05) reported as mean differences and 95% CI. Changes in end-expiratory lung volume and effective pulmonary blood flow were correlated using Pearson's regression. Twenty-seven (42%) of 64 patients were responders increasing oxygen delivery index by 172 (95% CI 61-2984) mL min-1 m-2 (p < 0.001). End-expiratory lung volume increased by 549 (95% CI 220-1116) mL (p = 0.042) in responders associated with an increase in effective pulmonary blood flow of 1140 (95% CI 435-2146) mL min-1 (p = 0.012) compared to non-responders. A positive correlation (r = 0.79, 95% CI 0.5-0.90, p < 0.001) between increased end-expiratory lung volume and effective pulmonary blood flow was only observed in responders. Changes in oxygen delivery index after lung recruitment were correlated to changes in end-expiratory lung volume (r = 0.39, 95% CI 0.16-0.59, p = 0.002) and effective pulmonary blood flow (r = 0.60, 95% CI 0.41-0.74, p < 0.001). Capnodynamic monitoring of end-expiratory lung volume and effective pulmonary blood flow early in postoperative cardiac patients identified a characteristic parallel increase in both lung volume and perfusion after the recruitment manoeuvre in patients with a significant increase in oxygen delivery.Trial registration This study was registered on ClinicalTrials.gov (NCT05082168, 18th of October 2021).
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Affiliation(s)
- E Keleher
- Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - H Iftikhar
- Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - L F Schulz
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | - P McCanny
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | - D Austin
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | - A Stewart
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | - W O'Regan
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | | | - M Wallin
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - A Aneman
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia.
- Southwestern Clinical School, University of New South Wales, Sydney, NSW, Australia.
- Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.
- Intensive Care Unit, Liverpool Hospital, Locked Bag 7103, Liverpool BC, NSW, 1871, Australia.
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Schulz L, Stewart A, O’Regan W, McCanny P, Austin D, Hallback M, Wallin M, Aneman A. Capnodynamic monitoring of lung volume and blood flow in response to increased positive end-expiratory pressure in moderate to severe COVID-19 pneumonia: an observational study. Crit Care 2022; 26:232. [PMID: 35909174 PMCID: PMC9340710 DOI: 10.1186/s13054-022-04110-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 07/20/2022] [Indexed: 11/18/2022] Open
Abstract
Background The optimal level of positive end-expiratory pressure (PEEP) during mechanical ventilation for COVID-19 pneumonia remains debated and should ideally be guided by responses in both lung volume and perfusion. Capnodynamic monitoring allows both end-expiratory lung volume (\documentclass[12pt]{minimal}
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\begin{document}$${\text{EELV}}_{{{\text{CO}}_{2} }}$$\end{document}EELVCO2) and effective pulmonary blood flow (EPBF) to be determined at the bedside with ongoing ventilation. Methods Patients with COVID-19-related moderate to severe respiratory failure underwent capnodynamic monitoring of \documentclass[12pt]{minimal}
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\begin{document}$${\text{EELV}}_{{{\text{CO}}_{2} }}$$\end{document}EELVCO2 and EPBF during a step increase in PEEP by 50% above the baseline (PEEPlow to PEEPhigh). The primary outcome was a > 20 mm Hg increase in arterial oxygen tension to inspired fraction of oxygen (P/F) ratio to define responders versus non-responders. Secondary outcomes included changes in physiological dead space and correlations with independently determined recruited lung volume and the recruitment-to-inflation ratio at an instantaneous, single breath decrease in PEEP. Mixed factor ANOVA for group mean differences and correlations by Pearson’s correlation coefficient are reported including their 95% confidence intervals. Results Of 27 patients studied, 15 responders increased the P/F ratio by 55 [24–86] mm Hg compared to 12 non-responders (p < 0.01) as PEEPlow (11 ± 2.7 cm H2O) was increased to PEEPhigh (18 ± 3.0 cm H2O). The \documentclass[12pt]{minimal}
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\begin{document}$${\text{EELV}}_{{{\text{CO}}_{2} }}$$\end{document}EELVCO2 was 461 [82–839] ml less in responders at PEEPlow (p = 0.02) but not statistically different between groups at PEEPhigh. Responders increased both \documentclass[12pt]{minimal}
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\begin{document}$${\text{EELV}}_{{{\text{CO}}_{2} }}$$\end{document}EELVCO2 and EPBF at PEEPhigh (r = 0.56 [0.18–0.83], p = 0.03). In contrast, non-responders demonstrated a negative correlation (r = − 0.65 [− 0.12 to − 0.89], p = 0.02) with increased lung volume associated with decreased pulmonary perfusion. Decreased (− 0.06 [− 0.02 to − 0.09] %, p < 0.01) dead space was observed in responders. The change in \documentclass[12pt]{minimal}
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\begin{document}$${\text{EELV}}_{{{\text{CO}}_{2} }}$$\end{document}EELVCO2 correlated with both the recruited lung volume (r = 0.85 [0.69–0.93], p < 0.01) and the recruitment-to-inflation ratio (r = 0.87 [0.74–0.94], p < 0.01). Conclusions In mechanically ventilated patients with moderate to severe COVID-19 respiratory failure, improved oxygenation in response to increased PEEP was associated with increased end-expiratory lung volume and pulmonary perfusion. The change in end-expiratory lung volume was positively correlated with the lung volume recruited and the recruitment-to-inflation ratio. This study demonstrates the feasibility of capnodynamic monitoring to assess physiological responses to PEEP at the bedside to facilitate an individualised setting of PEEP. Trial registration: NCT05082168 (18th October 2021). Supplementary Information The online version contains supplementary material available at 10.1186/s13054-022-04110-0.
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