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Le Pape S, Joly F, Arrivé F, Frat JP, Rodriguez M, Joos M, Marchasson L, Wairy M, Thille AW, Coudroy R. Factors associated with decreased compliance after on-site extracorporeal membrane oxygenation cannulation for acute respiratory distress syndrome: A retrospective, observational cohort study. JOURNAL OF INTENSIVE MEDICINE 2024; 4:194-201. [PMID: 38681786 PMCID: PMC11043634 DOI: 10.1016/j.jointm.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 09/11/2023] [Accepted: 09/26/2023] [Indexed: 05/01/2024]
Abstract
Background Extracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome (ARDS) is systematically associated with decreased respiratory system compliance (CRS). It remains unclear whether transportation to the referral ECMO center, changes in ventilatory mode or settings to achieve ultra-protective ventilation, or the natural evolution of ARDS drives this change in respiratory mechanics. Herein, we assessed the precise moment when CRS decreases after ECMO cannulation and identified factors associated with decreased CRS. Methods To rule out the effect of transportation and the different modes of ventilation on CRS, we conducted a retrospective, single-center, observational cohort study from January 2013 to May 2020, on 22 patients with severe ARDS requiring on-site ECMO and ventilated in pressure-controlled mode to achieve ultra-protective ventilation. CRS was assessed at different time points ranging from 12 h before ECMO cannulation to 72 h after ECMO cannulation. The primary outcome was the relative change in CRS between 3 h before and 3 h after ECMO cannulation. The secondary outcomes included variables associated with the relative changes in CRS within the first 3 h after ECMO cannulation and the relative changes in CRS at each time point. Results CRS decreased within the first 3 h after ECMO cannulation (-28.3%, 95% confidence interval [CI]: -38.8 to -17.9, P<0.001), while the decrease was mild before and after these first 3 h after ECMO cannulation. To achieve ultra-protective ventilation, respiratory rate decreased in the mean by -13 breaths/min (95% CI: -15 to -11) and driving pressure by -8.3 cmH2O (95% CI: -11.2 to -5.3), resulting in decreased tidal volume by -3.3 mL/kg of predicted body weight (95% CI: -3.9 to -2.6) as compared to before ECMO cannulation (P <0.001 for all). Plateau pressure reduction, driving pressure reduction, and tidal volume reduction were significantly associated with decreased CRS after ECMO cannulation, whereas neither respiratory rate, positive end-expiratory pressure, inspired fraction of oxygen, fluid balance, nor mean airway pressure was associated with decreased CRS. Conclusions Decreased driving pressure resulting in lower tidal volume to achieve ultra-protective ventilation after ECMO cannulation was associated with a marked decrease in CRS in ARDS patients with on-site ECMO cannulation.
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Affiliation(s)
- Sylvain Le Pape
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
| | - Florent Joly
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
| | - François Arrivé
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
| | - Jean-Pierre Frat
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
- INSERM Centre d'Investigation Clinique 1402, IS-ALIVE Research Group, Université de Poitiers, Poitiers, France
| | - Maeva Rodriguez
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
| | - Maïa Joos
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
| | - Laura Marchasson
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
| | - Mathilde Wairy
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
| | - Arnaud W. Thille
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
- INSERM Centre d'Investigation Clinique 1402, IS-ALIVE Research Group, Université de Poitiers, Poitiers, France
| | - Rémi Coudroy
- Centre Hospitalier Universitaire de Poitiers, Service de Médecine Intensive Réanimation, Poitiers, France
- INSERM Centre d'Investigation Clinique 1402, IS-ALIVE Research Group, Université de Poitiers, Poitiers, France
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Jiang L, Chen H, Xie J, Liu L, Yang Y. Prognostic value of time-varying dead space estimates in mechanically ventilated patients with acute respiratory distress syndrome. JOURNAL OF INTENSIVE MEDICINE 2024; 4:187-193. [PMID: 38681797 PMCID: PMC11043632 DOI: 10.1016/j.jointm.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 08/09/2023] [Accepted: 08/10/2023] [Indexed: 05/01/2024]
Abstract
Background The dead space fraction (VD/VT) has proven to be a powerful predictor of higher mortality in acute respiratory distress syndrome (ARDS). However, its measurement relies on expired carbon dioxide, limiting its widespread application in clinical practice. Several estimates employing routine variables have been found to be reliable substitutes for direct measurement of VD/VT. In this study, we evaluated the prognostic value of these dead space estimates obtained in the first 7 days following the initiation of ventilation. Methods This retrospective observational study was conducted using data from the Chinese database in intensive care (CDIC). Eligible participants were adult ARDS patients receiving invasive mechanical ventilation while in the intensive care unit between 1st January 2014 and 31st March 2021. We collected data during the first 7 days of ventilation to calculate various dead space estimates, including ventilatory ratio (VR), corrected minute ventilation (V ˙ Ecorr ), VD/VT (Harris-Benedict), VD/VT (Siddiki estimate), and VD/VT (Penn State estimate) longitudinally. A time-dependent Cox model was used to handle these time-varying estimates. Results A total of 392 patients (median age 66 [interquartile range: 55-77] years, median SOFA score 9 [interquartile range: 7-12]) were finally included in our analysis, among whom 132 (33.7%) patients died within 28 days of admission. VR (hazard ratio [HR]=1.04 per 0.1 increase, 95% confidence interval [CI]: 1.01 to 1.06; P=0.013), V ˙ Ecorr (HR=1.08 per 1 increase, 95% CI: 1.04 to 1.12; P < 0.001), VD/VT (Harris-Benedict) (HR=1.25 per 0.1 increase, 95% CI: 1.06 to 1.47; P=0.006), and VD/VT (Penn State estimate) (HR=1.22 per 0.1 increase, 95% CI: 1.04 to 1.44; P=0.017) remained significant after adjustment, while VD/VT (Siddiki estimate) (HR=1.10 per 0.1 increase, 95% CI: 1.00 to 1.20; P=0.058) did not. Given a large number of negative values, VD/VT (Siddiki estimate) and VD/VT (Penn State estimate) were not recommended as reliable substitutes. Long-term exposure to VR >1.3, V ˙ Ecorr >7.53, and VD/VT (Harris-Benedict) >0.59 was independently associated with an increased risk of mortality in ARDS patients. These findings were validated in the fluid and catheter treatment trial (FACTT) database. Conclusions In cases where VD/VT cannot be measured directly, early time-varying estimates of VD/VT such as VR, V ˙ Ecorr , and VD/VT (Harris-Benedict) can be considered for predicting mortality in ARDS patients, offering a rapid bedside application.
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Affiliation(s)
- Lianlian Jiang
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Hui Chen
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
- Department of Critical Care Medicine, The First Affiliated Hospital of Soochow University, Soochow University, Suzhou, Jiangsu, China
| | - Jianfeng Xie
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Ling Liu
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Yi Yang
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
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Han HJ, Lee B, Park JD. Individualized estimation of arterial carbon dioxide partial pressure using machine learning in children receiving mechanical ventilation. BMC Pediatr 2024; 24:149. [PMID: 38424493 PMCID: PMC10902995 DOI: 10.1186/s12887-024-04642-0] [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: 12/15/2023] [Accepted: 02/13/2024] [Indexed: 03/02/2024] Open
Abstract
BACKGROUND Measuring arterial partial pressure of carbon dioxide (PaCO2) is crucial for proper mechanical ventilation, but the current sampling method is invasive. End-tidal carbon dioxide (EtCO2) has been used as a surrogate, which can be measured non-invasively, but its limited accuracy is due to ventilation-perfusion mismatch. This study aimed to develop a non-invasive PaCO2 estimation model using machine learning. METHODS This retrospective observational study included pediatric patients (< 18 years) admitted to the pediatric intensive care unit of a tertiary children's hospital and received mechanical ventilation between January 2021 and June 2022. Clinical information, including mechanical ventilation parameters and laboratory test results, was used for machine learning. Linear regression, multilayer perceptron, and extreme gradient boosting were implemented. The dataset was divided into 7:3 ratios for training and testing. Model performance was assessed using the R2 value. RESULTS We analyzed total 2,427 measurements from 32 patients. The median (interquartile range) age was 16 (12-19.5) months, and 74.1% were female. The PaCO2 and EtCO2 were 63 (50-83) mmHg and 43 (35-54) mmHg, respectively. A significant discrepancy of 19 (12-31) mmHg existed between EtCO2 and the measured PaCO2. The R2 coefficient of determination for the developed models was 0.799 for the linear regression model, 0.851 for the multilayer perceptron model, and 0.877 for the extreme gradient boosting model. The correlations with PaCO2 were higher in all three models compared to EtCO2. CONCLUSIONS We developed machine learning models to non-invasively estimate PaCO2 in pediatric patients receiving mechanical ventilation, demonstrating acceptable performance. Further research is needed to improve reliability and external validation.
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Affiliation(s)
- Hye-Ji Han
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, 03080, Republic of Korea
| | - Bongjin Lee
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, 03080, Republic of Korea.
- Innovative Medical Technology Research Institute, Seoul National University Hospital, Seoul, Republic of Korea.
| | - June Dong Park
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, 03080, Republic of Korea
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Upchurch CP, Wessman BT, Roberts BW, Fuller BM. Arterial to end-tidal carbon dioxide gap and its characterization in mechanically ventilated adults in the emergency department. Am J Emerg Med 2023; 73:154-159. [PMID: 37683313 DOI: 10.1016/j.ajem.2023.08.042] [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: 05/26/2023] [Revised: 07/23/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023] Open
Abstract
PURPOSE To evaluate early measurement of the arterial to end-tidal carbon dioxide (PaCO2-PetCO2) gap, a surrogate for physiologic dead space, and its association with clinical outcomes in intubated adults in the emergency department (ED). MATERIALS AND METHODS Observational cohort study of invasively mechanically ventilated adults in an academic medical center (years 2009 to 2016). The association of the PaCO2-PetCO2 gap was evaluated with respect to clinical outcomes; the primary outcome was in-hospital mortality. RESULTS 519 patients were included. 325 (63%) patients had an elevated (>5 mmHg) PaCO2-PetCO2. Patients with an elevated PaCO2-PetCO2 were significantly older, had higher APACHE II scores, more frequently had chronic obstructive pulmonary disease (COPD), had lower arterial oxygen to fraction of inspired oxygen (P:F) ratios, and were more likely to be intubated for exacerbation of COPD or sepsis. There was no difference in mortality for patients with an elevated PaCO2-PetCO2 (25% vs 26%) in unadjusted analysis (p = 0.829) or adjusted analysis (aOR = 0.81 [95% CI: 0.53-1.26]), as compared to a non-elevated PaCO2-PetCO2. CONCLUSIONS An elevated PaCO2-PetCO2 gap is common in the post-intubation period in the ED, but not significantly associated with clinical outcomes.
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Affiliation(s)
- Cameron P Upchurch
- Department of Medicine, Division of Pulmonary and Critical Care. MSC 8052-43-14. Washington University School of Medicine. 660 S. Euclid Ave. St. Louis, MO 63110, USA.
| | - Brian T Wessman
- Department of Emergency Medicine 660 S. Euclid Ave Campus Box 8072 St. Louis, MO 63110, USA; Department of Anesthesiology, Division of Critical Care 660 S. Euclid Ave. St. Louis, MO 63110, USA
| | - Brian W Roberts
- Cooper University Hospital Department of Emergency Medicine One Cooper Plaza Camden, NJ 08103, USA
| | - Brian M Fuller
- Department of Emergency Medicine 660 S. Euclid Ave Campus Box 8072 St. Louis, MO 63110, USA; Department of Anesthesiology, Division of Critical Care 660 S. Euclid Ave. St. Louis, MO 63110, USA
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Jayasimhan D, Chieng J, Kolbe J, Sidebotham DA. Dead-Space Ventilation Indices and Mortality in Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis. Crit Care Med 2023; 51:1363-1372. [PMID: 37204257 DOI: 10.1097/ccm.0000000000005921] [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: 05/20/2023]
Abstract
OBJECTIVES Acute respiratory distress syndrome (ARDS) is associated with high ventilation-perfusion heterogeneity and dead-space ventilation. However, whether the degree of dead-space ventilation is associated with outcomes is uncertain. In this systematic review and meta-analysis, we evaluated the ability of dead-space ventilation measures to predict mortality in patients with ARDS. DATA SOURCES MEDLINE, CENTRAL, and Google Scholar from inception to November 2022. STUDY SELECTION Studies including adults with ARDS reporting a dead-space ventilation index and mortality. DATA EXTRACTION Two reviewers independently identified eligible studies and extracted data. We calculated pooled effect estimates using a random effects model for both adjusted and unadjusted results. The quality and strength of evidence were assessed using the Quality in Prognostic Studies and Grading of Recommendations, Assessment, Development, and Evaluation, respectively. DATA SYNTHESIS We included 28 studies in our review, 21 of which were included in our meta-analysis. All studies had a low risk of bias. A high pulmonary dead-space fraction was associated with increased mortality (odds ratio [OR], 3.52; 95% CI, 2.22-5.58; p < 0.001; I2 = 84%). After adjusting for other confounding variables, every 0.05 increase in pulmonary-dead space fraction was associated with an increased odds of death (OR, 1.23; 95% CI, 1.13-1.34; p < 0.001; I2 = 57%). A high ventilatory ratio was also associated with increased mortality (OR, 1.55; 95% CI, 1.33-1.80; p < 0.001; I2 = 48%). This association was independent of common confounding variables (OR, 1.33; 95% CI, 1.12-1.58; p = 0.001; I2 = 66%). CONCLUSIONS Dead-space ventilation indices were independently associated with mortality in adults with ARDS. These indices could be incorporated into clinical trials and used to identify patients who could benefit from early institution of adjunctive therapies. The cut-offs identified in this study should be prospectively validated.
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Affiliation(s)
- Dilip Jayasimhan
- Cardiothoracic and Vascular Intensive Care Unit, Te Whatu Ora Te Toka Tumai Auckland, Auckland, New Zealand
- Respiratory Services, Te Whatu Ora Te Toka Tumai Auckland, Auckland, New Zealand
| | - Jennifer Chieng
- Respiratory Services, Te Whatu Ora Te Toka Tumai Auckland, Auckland, New Zealand
| | - John Kolbe
- Respiratory Services, Te Whatu Ora Te Toka Tumai Auckland, Auckland, New Zealand
- Department of Medicine, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - David A Sidebotham
- Cardiothoracic and Vascular Intensive Care Unit, Te Whatu Ora Te Toka Tumai Auckland, Auckland, New Zealand
- Department of Medicine, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
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Yang H, Ni Y, Huang D, Liang Z. Ventilatory ratio as a predictor for extubation failure in critical ill patients based on MIMIC-IV database (from 2008 to 2019). Front Physiol 2023; 14:1137115. [PMID: 37324397 PMCID: PMC10267390 DOI: 10.3389/fphys.2023.1137115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 05/22/2023] [Indexed: 06/17/2023] Open
Abstract
Background: The predictive ability of the ventilatory ratio (VR) for extubation failure risk in critically ill patients on mechanical ventilation is unclear. This study aims to examine the predictive ability of VR for extubation failure risk. Methods: This retrospective study was based on the MIMIC-IV database. The MIMIC-IV database consists of the clinical information of patients who were admitted to the intensive care unit at the Beth Israel Deaconess Medical Center between 2008 and 2019. With extubation failure as the primary outcome and in-hospital mortality as the secondary outcome, we assessed the predictive value of VR 4 hours before extubation using a multivariate logistic regression model. Results: Of 3,569 ventilated patients who were included, the rate of extubation-failure was 12.7% and the median Sequential Organ Failure Assessment (SOFA) score was 6 before extubation. Increased VR, elevated heart rate, greater positive end-expiratory pressure, higher blood urea nitrogen level, higher platelet count, greater SOFA score, decreased pH, decreased tidal volume, presence of chronic pulmonary disease, paraplegia, and metastatic solid tumor were independent predictors for extubation failure. A threshold of 1.595 of VR was associated with prolonged intensive care unit length of stay, higher risk of mortality and extubation failure. The area under the receiver operating characteristic curve (ROC) for VR was 0.669 [0.635-0.703], which was significantly larger than the rapid shallow breathing index [0.510 (0.476-0.545)] and the partial pressure of oxygen to the fraction of inspired oxygen [0.586 (0.551-0.621)]. Conclusion: VR 4 hours before extubation was associated with extubation failure, mortality, and prolonged length of stay in the intensive care unit. VR provides good predictive performance for extubation failure (measured by ROC) than the rapid shallow breathing index. Further prospective studies are warranted to confirm these findings.
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Mollura M, Baroncelli F, Mandelli G, Tricella G, Weissman GE, Poole D, Caironi P, Celi LA, Barbieri R, Finazzi S. Physiologic dead space is independently associated with mortality and discharge of mechanically ventilated patients with COVID-19 ARDS: a retrospective study. Sci Rep 2023; 13:5719. [PMID: 37029215 PMCID: PMC10081332 DOI: 10.1038/s41598-023-31999-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 03/21/2023] [Indexed: 04/09/2023] Open
Abstract
Physiologic dead space is a well-established independent predictor of death in patients with acute respiratory distress syndrome (ARDS). Here, we explore the association between a surrogate measure of dead space (DS) and early outcomes of mechanically ventilated patients admitted to Intensive Care Unit (ICU) because of COVID-19-associated ARDS. Retrospective cohort study on data derived from Italian ICUs during the first year of the COVID-19 epidemic. A competing risk Cox proportional hazard model was applied to test for the association of DS with two competing outcomes (death or discharge from the ICU) while adjusting for confounders. The final population consisted of 401 patients from seven ICUs. A significant association of DS with both death (HR 1.204; CI 1.019-1.423; p = 0.029) and discharge (HR 0.434; CI 0.414-0.456; p [Formula: see text]) was noticed even when correcting for confounding factors (age, sex, chronic obstructive pulmonary disease, diabetes, PaO[Formula: see text]/FiO[Formula: see text], tidal volume, positive end-expiratory pressure, and systolic blood pressure). These results confirm the important association between DS and death or ICU discharge in mechanically ventilated patients with COVID-19-associated ARDS. Further work is needed to identify the optimal role of DS monitoring in this setting and to understand the physiological mechanisms underlying these associations.
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Affiliation(s)
- Maximiliano Mollura
- Department of Electronic, Information and Bioengineering, Politecnico di Milano, Milan, Lombardia, Italy.
- Department of Medical Epidemiology, Mario Negri Institute for Pharmacological Research IRCCS, 24020, Ranica, Lombardia, Italy.
| | - Francesca Baroncelli
- Department of Anesthesia and Intensive Care, San Giovanni Bosco Hospital-ASL Città di Torino, Turin, Piemonte, Italy
| | - Giulia Mandelli
- Department of Medical Epidemiology, Mario Negri Institute for Pharmacological Research IRCCS, 24020, Ranica, Lombardia, Italy
| | - Giovanni Tricella
- Department of Medical Epidemiology, Mario Negri Institute for Pharmacological Research IRCCS, 24020, Ranica, Lombardia, Italy
| | - Gary E Weissman
- Palliative and Advanced Illness Research (PAIR) Center and Pulmonary, Allergy and Critical Care Division, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Daniele Poole
- Operative Unit ofAnesthesia and Intensive Care Unit, S. Martino Hospital, Belluno, Veneto, Italy
| | - Pietro Caironi
- Department of Anesthesia and Critical Care, Azienda Ospedaliero-Universitaria S. Luigi Gonzaga, Orbassano, Piemonte, Italy
- Department of Oncology, University of Turin, Turin, Piemonte, Italy
| | - Leo Anthony Celi
- Laboratory for Computational Physiology, Massachusetts Institute of Technology, Cambridge, MA, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Riccardo Barbieri
- Department of Electronic, Information and Bioengineering, Politecnico di Milano, Milan, Lombardia, Italy
| | - Stefano Finazzi
- Department of Medical Epidemiology, Mario Negri Institute for Pharmacological Research IRCCS, 24020, Ranica, Lombardia, Italy
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Zheng M. Dead space ventilation-related indices: bedside tools to evaluate the ventilation and perfusion relationship in patients with acute respiratory distress syndrome. Crit Care 2023; 27:46. [PMID: 36732812 PMCID: PMC9894747 DOI: 10.1186/s13054-023-04338-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Cumulative evidence has demonstrated that the ventilatory ratio closely correlates with mortality in acute respiratory distress syndrome (ARDS), and a primary feature in coronavirus disease 2019 (COVID-19)-ARDS is increased dead space that has been reported recently. Thus, new attention has been given to this group of dead space ventilation-related indices, such as physiological dead space fraction, ventilatory ratio, and end-tidal-to-arterial PCO2 ratio, which, albeit distinctive, are all global indices with which to assess the relationship between ventilation and perfusion. These parameters have already been applied to positive end expiratory pressure titration, prediction of responses to the prone position and the field of extracorporeal life support for patients suffering from ARDS. Dead space ventilation-related indices remain hampered by several deflects; notwithstanding, for this catastrophic syndrome, they may facilitate better stratifications and identifications of subphenotypes, thereby providing therapy tailored to individual needs.
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Affiliation(s)
- Mingjia Zheng
- Department of Respiratory and Critical Care Medicine, Huzhou Central Hospital, Affiliated Central Hospital Huzhou University, No. 1558, Sanhuan North Road, Wuxing, Huzhou, Zhejiang, People's Republic of China.
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9
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Slobod D, Damia A, Leali M, Spinelli E, Mauri T. Pathophysiology and Clinical Meaning of Ventilation-Perfusion Mismatch in the Acute Respiratory Distress Syndrome. BIOLOGY 2022; 12:biology12010067. [PMID: 36671759 PMCID: PMC9855693 DOI: 10.3390/biology12010067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/20/2022] [Accepted: 12/27/2022] [Indexed: 01/03/2023]
Abstract
Acute respiratory distress syndrome (ARDS) remains an important clinical challenge with a mortality rate of 35-45%. It is being increasingly demonstrated that the improvement of outcomes requires a tailored, individualized approach to therapy, guided by a detailed understanding of each patient's pathophysiology. In patients with ARDS, disturbances in the physiological matching of alveolar ventilation (V) and pulmonary perfusion (Q) (V/Q mismatch) are a hallmark derangement. The perfusion of collapsed or consolidated lung units gives rise to intrapulmonary shunting and arterial hypoxemia, whereas the ventilation of non-perfused lung zones increases physiological dead-space, which potentially necessitates increased ventilation to avoid hypercapnia. Beyond its impact on gas exchange, V/Q mismatch is a predictor of adverse outcomes in patients with ARDS; more recently, its role in ventilation-induced lung injury and worsening lung edema has been described. Innovations in bedside imaging technologies such as electrical impedance tomography readily allow clinicians to determine the regional distributions of V and Q, as well as the adequacy of their matching, providing new insights into the phenotyping, prognostication, and clinical management of patients with ARDS. The purpose of this review is to discuss the pathophysiology, identification, consequences, and treatment of V/Q mismatch in the setting of ARDS, employing experimental data from clinical and preclinical studies as support.
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Affiliation(s)
- Douglas Slobod
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Department of Critical Care Medicine, McGill University, Montreal, QC H3A 3R1, Canada
| | - Anna Damia
- Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy
| | - Marco Leali
- Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy
| | - Elena Spinelli
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Tommaso Mauri
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy
- Correspondence:
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10
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Rezoagli E, Laffey JG, Bellani G. Monitoring Lung Injury Severity and Ventilation Intensity during Mechanical Ventilation. Semin Respir Crit Care Med 2022; 43:346-368. [PMID: 35896391 DOI: 10.1055/s-0042-1748917] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Acute respiratory distress syndrome (ARDS) is a severe form of respiratory failure burden by high hospital mortality. No specific pharmacologic treatment is currently available and its ventilatory management is a key strategy to allow reparative and regenerative lung tissue processes. Unfortunately, a poor management of mechanical ventilation can induce ventilation induced lung injury (VILI) caused by physical and biological forces which are at play. Different parameters have been described over the years to assess lung injury severity and facilitate optimization of mechanical ventilation. Indices of lung injury severity include variables related to gas exchange abnormalities, ventilatory setting and respiratory mechanics, ventilation intensity, and the presence of lung hyperinflation versus derecruitment. Recently, specific indexes have been proposed to quantify the stress and the strain released over time using more comprehensive algorithms of calculation such as the mechanical power, and the interaction between driving pressure (DP) and respiratory rate (RR) in the novel DP multiplied by four plus RR [(4 × DP) + RR] index. These new parameters introduce the concept of ventilation intensity as contributing factor of VILI. Ventilation intensity should be taken into account to optimize protective mechanical ventilation strategies, with the aim to reduce intensity to the lowest level required to maintain gas exchange to reduce the potential for VILI. This is further gaining relevance in the current era of phenotyping and enrichment strategies in ARDS.
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Affiliation(s)
- Emanuele Rezoagli
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.,Department of Emergency and Intensive Care, San Gerardo University Hospital, Monza, Italy
| | - John G Laffey
- School of Medicine, National University of Ireland, Galway, Ireland.,Department of Anaesthesia and Intensive Care Medicine, Galway University Hospitals, Saolta University Hospital Group, Galway, Ireland.,Lung Biology Group, Regenerative Medicine Institute (REMEDI) at CÚRAM Centre for Research in Medical Devices, National University of Ireland Galway, Galway, Ireland
| | - Giacomo Bellani
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.,Department of Emergency and Intensive Care, San Gerardo University Hospital, Monza, Italy
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11
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Morales-Quinteros L, Neto AS, Artigas A, Blanch L, Botta M, Kaufman DA, Schultz MJ, Tsonas AM, Paulus F, Bos LD. Dead space estimates may not be independently associated with 28-day mortality in COVID-19 ARDS. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2021; 25:171. [PMID: 34001222 PMCID: PMC8127435 DOI: 10.1186/s13054-021-03570-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/08/2021] [Indexed: 02/06/2023]
Abstract
BACKGROUND Estimates for dead space ventilation have been shown to be independently associated with an increased risk of mortality in the acute respiratory distress syndrome and small case series of COVID-19-related ARDS. METHODS Secondary analysis from the PRoVENT-COVID study. The PRoVENT-COVID is a national, multicenter, retrospective observational study done at 22 intensive care units in the Netherlands. Consecutive patients aged at least 18 years were eligible for participation if they had received invasive ventilation for COVID-19 at a participating ICU during the first month of the national outbreak in the Netherlands. The aim was to quantify the dynamics and determine the prognostic value of surrogate markers of wasted ventilation in patients with COVID-19-related ARDS. RESULTS A total of 927 consecutive patients admitted with COVID-19-related ARDS were included in this study. Estimations of wasted ventilation such as the estimated dead space fraction (by Harris-Benedict and direct method) and ventilatory ratio were significantly higher in non-survivors than survivors at baseline and during the following days of mechanical ventilation (p < 0.001). The end-tidal-to-arterial PCO2 ratio was lower in non-survivors than in survivors (p < 0.001). As ARDS severity increased, mortality increased with successive tertiles of dead space fraction by Harris-Benedict and by direct estimation, and with an increase in the VR. The same trend was observed with decreased levels in the tertiles for the end-tidal-to-arterial PCO2 ratio. After adjustment for a base risk model that included chronic comorbidities and ventilation- and oxygenation-parameters, none of the dead space estimates measured at the start of ventilation or the following days were significantly associated with 28-day mortality. CONCLUSIONS There is significant impairment of ventilation in the early course of COVID-19-related ARDS but quantification of this impairment does not add prognostic information when added to a baseline risk model. TRIAL REGISTRATION ISRCTN04346342. Registered 15 April 2020. Retrospectively registered.
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Affiliation(s)
- Luis Morales-Quinteros
- Intensive Care Unit, Hospital Universitari General de Catalunya, Grupo Quironsalud, Carrer Pedro i Pons, 1, 08195, Sant Cugat del Vallès, Barcelona, Spain. .,Universidad Autonoma de Barcelona, Barcelona, Spain. .,Institut D'Investigació, Innovació Parc Taulí I3PT, Sabadell, Spain.
| | - Ary Serpa Neto
- Department of Intensive Care & Laboratory of Experimental Intensive Care and Anaesthesiology (L·E·I·C·A), Amsterdam UMC Location AMC, Amsterdam, The Netherlands.,Department of Critical Care Medicine, Hospital Israelita Albert Einstein, São Paulo, Brazil.,Australian and New Zealand Intensive Care Research Centre (ANZIC-RC), Monash University, Melbourne, Australia.,Data Analytics Research and Evaluation (DARE) Centre, Austin Hospital and University of Melbourne, Melbourne, Australia
| | - Antonio Artigas
- Universidad Autonoma de Barcelona, Barcelona, Spain.,Institut D'Investigació, Innovació Parc Taulí I3PT, Sabadell, Spain.,Critical Care Center, Corporacion Sanitaria Universitaria Parc Taulí, Sabadell, Spain.,CIBER Enfermedades Respiratorias (ISCiii), Madrid, Spain
| | - Lluis Blanch
- Universidad Autonoma de Barcelona, Barcelona, Spain.,Institut D'Investigació, Innovació Parc Taulí I3PT, Sabadell, Spain.,Critical Care Center, Corporacion Sanitaria Universitaria Parc Taulí, Sabadell, Spain.,CIBER Enfermedades Respiratorias (ISCiii), Madrid, Spain
| | - Michela Botta
- Department of Intensive Care & Laboratory of Experimental Intensive Care and Anaesthesiology (L·E·I·C·A), Amsterdam UMC Location AMC, Amsterdam, The Netherlands
| | - David A Kaufman
- Division of Pulmonary, Critical Care, and Sleep Medicine, NYU School of Medicine, New York, NY, USA
| | - Marcus J Schultz
- Department of Intensive Care & Laboratory of Experimental Intensive Care and Anaesthesiology (L·E·I·C·A), Amsterdam UMC Location AMC, Amsterdam, The Netherlands.,Nuffield Department of Medicine, Oxford University, Oxford, UK.,Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Bangkok, Thailand
| | - Anissa M Tsonas
- Department of Intensive Care & Laboratory of Experimental Intensive Care and Anaesthesiology (L·E·I·C·A), Amsterdam UMC Location AMC, Amsterdam, The Netherlands
| | - Frederique Paulus
- Department of Intensive Care & Laboratory of Experimental Intensive Care and Anaesthesiology (L·E·I·C·A), Amsterdam UMC Location AMC, Amsterdam, The Netherlands
| | - Lieuwe D Bos
- Department of Intensive Care & Laboratory of Experimental Intensive Care and Anaesthesiology (L·E·I·C·A), Amsterdam UMC Location AMC, Amsterdam, The Netherlands
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12
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Functional NMDA receptors are expressed by human pulmonary artery smooth muscle cells. Sci Rep 2021; 11:8205. [PMID: 33859248 PMCID: PMC8050278 DOI: 10.1038/s41598-021-87667-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 03/29/2021] [Indexed: 11/08/2022] Open
Abstract
N-methyl-d-aspartate (NMDA) receptors are widely expressed in the central nervous system. However, their presence and function at extraneuronal sites is less well characterized. In the present study, we examined the expression of NMDA receptor subunit mRNA and protein in human pulmonary artery (HPA) by quantitative polymerase chain reaction (PCR), immunohistochemistry and immunoblotting. We demonstrate that both GluN1 and GluN2 subunit mRNAs are expressed in HPA. In addition, GluN1 and GluN2 (A–D) subunit proteins are expressed by human pulmonary artery smooth muscle cells (HPASMCs) in vitro and in vivo. These subunits localize on the surface of HPASMCs and form functional ion channels as evidenced by whole-cell patch-clamp electrophysiology and reduced phenylephrine-induced contractile responsiveness of human pulmonary artery by the NMDA receptor antagonist MK801 under hypoxic condition. HPASMCs also express high levels of serine racemase and vesicular glutamate transporter 1, suggesting a potential source of endogenous agonists for NMDA receptor activation. Our findings show HPASMCs express functional NMDA receptors in line with their effect on pulmonary vasoconstriction, and thereby suggest a novel therapeutic target for pharmacological modulations in settings associated with pulmonary vascular dysfunction.
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13
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Dianti J, Slutsky AS, Goligher EC. Validity of Empirical Estimates of the Ratio of Dead Space to Tidal Volume in ARDS. Respir Care 2021; 66:559-565. [PMID: 33082218 PMCID: PMC9993985 DOI: 10.4187/respcare.08246] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND The ratio of dead space to tidal volume (VD/VT) is a clinically relevant parameter in ARDS; it has been shown to predict mortality, and it determines the extent to which extracorporeal CO2 removal reduces tidal volume (VT) and driving pressure (ΔP). VD/VT can be estimated with volumetric capnography, but empirical formulas using demographic and physiological information have been proposed to estimate VD/VT without the need of additional equipment. It is unknown whether estimated and measured VD/VT produce similar estimates of the predicted effect of extracorporeal CO2 removal on ΔP. METHODS We performed a secondary analysis of data from a previous clinical trial including subjects with ARDS in whom VD/VT and CO2 production ([Formula: see text]) were measured with volumetric capnography. The estimated ratio of dead space to tidal volume (VD,est/VT) was calculated using standard empiric formulas. Agreement between measured and estimated values was evaluated with Bland-Altman analysis. Agreement between the predicted change in ΔP with extracorporeal CO2 removal as computed using the measured ratio of alveolar dead space to tidal volume (VDalv/VT) or estimated VDalv/VT (VDalv,est/VT) was also evaluated. RESULTS VD,est/VT was higher than measured VD/VT, and agreement between them was low (bias 0.05, limits of agreement -0.21 to 0.31). Differences between measured and estimated [Formula: see text] accounted for 57% of the error in VD,est/VT. The predicted reduction in ΔP with extracorporeal CO2 removal computed using VDalv,est/VT was in reasonable agreement with the expected reduction using VDalv/VT (bias -0.7 cm H2O, limits of agreement -1.87 to 0.47 cm H2O). In multivariable regression, measured VD/VT was associated with mortality (odds ratio 1.9, 95% CI 1.2-3.1, P = .01), but VD,est/VT was not (odds ratio 1.2, 95% CI 0.8-1.8, P = .3). CONCLUSIONS VD/VT and VD,est/VT showed low levels of agreement and cannot be used interchangeably in clinical practice. Nevertheless, the predicted decrease in ΔP due to extracorporeal CO2 removal was similar when computed from either estimated or measured VDalv/VT.
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Affiliation(s)
- Jose Dianti
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
| | - Arthur S Slutsky
- Department of Medicine, Division of Respirology, University Health Network, Toronto, Canada
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada
| | - Ewan C Goligher
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada.
- Department of Medicine, Division of Respirology, University Health Network, Toronto, Canada
- Toronto General Hospital Research Institute, Toronto, Canada
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14
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Kallet RH. Measured Versus Estimated Dead-Space Ventilation in ARDS: Does It Matter? Perhaps. Respir Care 2021; 66:703-704. [PMID: 33782141 PMCID: PMC9993990 DOI: 10.4187/respcare.08947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Richard H Kallet
- Department of Anesthesia and Perioperative Care, Respiratory Care DivisionUniversity of California, San Francisco at San Francisco General HospitalSan Francisco, California
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15
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Fusina F, Albani F, Bertelli M, Cavallo E, Crisci S, Caserta R, Nguyen M, Grazioli M, Schivalocchi V, Rosano A, Natalini G. Corrected Minute Ventilation Is Associated With Mortality in ARDS Caused by COVID-19. Respir Care 2021; 66:619-625. [PMID: 33293365 PMCID: PMC9993986 DOI: 10.4187/respcare.08314] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND The ratio of dead space to tidal volume (VD/VT) is associated with mortality in patients with ARDS. Corrected minute ventilation ([Formula: see text]) is a simple surrogate of dead space, but, despite its increasing use, its association with mortality has not been proven. The aim of our study was to assess the association between [Formula: see text] and hospital mortality. We also compared the strength of this association with that of estimated VD/VT and ventilatory ratio. METHODS We performed a retrospective study with prospectively collected data. We evaluated 187 consecutive mechanically ventilated subjects with ARDS caused by novel coronavirus disease (COVID-19). The association between [Formula: see text] and hospital mortality was assessed in multivariable logistic models. The same was done for estimated VD/VT and ventilatory ratio. RESULTS Mean ± SD [Formula: see text] was 11.8 ± 3.3 L/min in survivors and 14.5 ± 3.9 L/min in nonsurvivors (P < .001) and was independently associated with mortality (adjusted odds ratio 1.15, P = .01). The strength of association of [Formula: see text] with mortality was similar to that of VD/VT and ventilatory ratio. CONCLUSIONS [Formula: see text] was independently associated with hospital mortality in subjects with ARDS caused by COVID-19. [Formula: see text] could be used at the patient's bedside for outcome prediction and severity stratification, due to the simplicity of its calculation. These findings need to be confirmed in subjects with ARDS without viral pneumonia and when lung-protective mechanical ventilation is not rigorously applied.
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Affiliation(s)
- Federica Fusina
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy.
| | - Filippo Albani
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
| | - Michele Bertelli
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
| | - Erika Cavallo
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of The Sacred Heart, Rome, Italy
| | - Serena Crisci
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of The Sacred Heart, Rome, Italy
| | - Rosalba Caserta
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
| | - Maia Nguyen
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
| | - Michele Grazioli
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
| | - Valeria Schivalocchi
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
| | - Antonio Rosano
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
| | - Giuseppe Natalini
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
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16
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Kallet RH, Lipnick MS. End-Tidal-to-Arterial P CO2 Ratio as Signifier for Physiologic Dead-Space Ratio and Oxygenation Dysfunction in Acute Respiratory Distress Syndrome. Respir Care 2021; 66:263-268. [PMID: 32636278 PMCID: PMC9994218 DOI: 10.4187/respcare.08061] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND The ratio of end-tidal CO2 pressure to arterial partial pressure of CO2 ([Formula: see text]) was recently suggested for monitoring pulmonary gas exchange in patients with ARDS associated with COVID-19, yet no evidence was offered supporting that claim. Therefore, we evaluated whether [Formula: see text] might be relevant in assessing ARDS not associated with COVID-19. METHODS We evaluated the correspondence between [Formula: see text] and the ratio of dead space to tidal volume (VD/VT) measured in 561 subjects with ARDS from a previous study in whom [Formula: see text] data were also available. Subjects also were analyzed according to 4 ranges of [Formula: see text] representing increasing illness severity (≥ 0.80, 0.6-0.79, 0.50-0.59, and < 0.50). Correlation was assessed by either Pearson or Spearman tests, grouped comparisons were assessed using either ANOVA or Kruskal-Wallis tests and dichotomous variables assessed by Fisher Exact tests. Normally distributed data are presented as mean and standard deviation(SD) and non-normal data are presented as median and inter-quartile range (IQR). Overall mortality risk was assessed with multivariate logistic regression. Alpha was set at 0.05. RESULTS [Formula: see text] correlated strongly with VD/VT (r = -0.87 [95% CI -0.89 to -0.85], P < .001). Decreasing [Formula: see text] was associated with increased VD/VT and hospital mortality between all groups. In the univariate analysis, for every 0.01 decrease in [Formula: see text], mortality risk increased by ∼1% (odds ratio 0.009, 95% CI 0.003-0.029, P < .001) and maintained a strong independent association with mortality risk when adjusted for other variables (odds ratio 0.19, 95% CI 0.04-0.91, P = .039). [Formula: see text] < 0.50 was characterized by very high mean ± SD value for VD/VT (0.82 ± 0.05, P < .001) and high hospital mortality (70%). CONCLUSIONS Using [Formula: see text] as a surrogate for VD/VT may be a useful and practical measurement for both management and ongoing research into the nature of ARDS.
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Affiliation(s)
- Richard H Kallet
- Department of Anesthesia and Perioperative Care, Respiratory Care Division, University of California, San Francisco at San Francisco General Hospital, San Francisco, California.
| | - Michael S Lipnick
- Department of Anesthesia and Perioperative Care, Critical Care Division, University of California, San Francisco at San Francisco General Hospital, San Francisco, California
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17
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Sayed IA, Hagen S, Rajamanickam V, Anagnostopoulos PV, Eldridge M, Al-Subu A. The Use of Alveolar Dead Space Fraction to Predict Postoperative Outcomes after Pediatric Cardiac Surgery: A Retrospective Study. Pediatr Cardiol 2021; 42:1826-1833. [PMID: 34244822 PMCID: PMC8270240 DOI: 10.1007/s00246-021-02674-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 06/30/2021] [Indexed: 11/09/2022]
Abstract
Patients with congenital heart disease (CHD) that have surgical repair with cardiopulmonary bypass (CPB) reflect a unique population with multiple pulmonary and systemic factors that may contribute to increased alveolar dead space and low cardiac output syndrome. This study aimed to assess and compare changes in the alveolar dead space fraction (AVDSf) in the immediate postoperative period with outcomes in children with CHD who underwent repair on CPB. A single-center retrospective review study of critically ill children with CHD, younger than 18 years of age admitted to the Pediatric Intensive Care Unit (PICU) after undergoing surgical repair on CPB and received invasive mechanical ventilation for at least 24 h. One hundred and two patients were included in the study. Over the first 24 h, mean AVDSf was significantly higher in patients who had longer hospital length of stay (LOS) (> 21 days) p = 0.02, and longer duration of invasive mechanical ventilation (DMV) (> 170 h) p = 0.01. Cross-sectional analyses at 23-24 h revealed that AVDSf > 0.25 predicts mortality and DMV (p = 0.03 and P = 0.02 respectively); however, it did not predict prolonged hospital LOS. For every 0.1 increase in the AVDSf, the odds of mortality, DMV, and hospital LOS increased by 4.9 [95% CI = 1.45-16.60, p = 0.002], 2.06 [95% CI = 1.14-3.71, p = 0.01], and 1.43[95% CI = 0.84-2.45, p = 0.184], respectively. The area under the ROC curve at 23-24 h for AVDSf was 0.868 to predict mortality as an outcome. AVDSf > 0.25 at 23-24 h postoperatively was an independent predictor of mortality with sensitivity and specificity of 83% and 80%, respectively and was superior to other commonly used surrogates of cardiac output. In the immediate postoperative period of pediatric patients with CHD, high AVDSf is associated with longer hospital length of stay and duration of invasive mechanical ventilation. Increased AVDSf values at 23-24 h postoperatively is associated with mortality in patients with CHD exposed to CPB.
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Affiliation(s)
- Imran A. Sayed
- grid.413957.d0000 0001 0690 7621Department of Pediatrics, University of Colorado Anschutz Medical Campus, Children’s Hospital of Colorado, Colorado Springs, CO USA
| | - Scott Hagen
- grid.28803.310000 0001 0701 8607Division of Pediatric Critical Care Medicine, Department of Pediatrics, University of Wisconsin, 600 Highland Ave, Room H6/535 CSC, Madison, WI 53792 USA
| | - Victoria Rajamanickam
- grid.28803.310000 0001 0701 8607Division of Biostatistics, Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI USA
| | - Petros V. Anagnostopoulos
- grid.28803.310000 0001 0701 8607Division of Pediatric Cardiothoracic Surgery, Department of Surgery, University of Wisconsin, Madison, WI USA
| | - Marlowe Eldridge
- grid.28803.310000 0001 0701 8607Division of Pediatric Critical Care Medicine, Department of Pediatrics, University of Wisconsin, 600 Highland Ave, Room H6/535 CSC, Madison, WI 53792 USA
| | - Awni Al-Subu
- Division of Pediatric Critical Care Medicine, Department of Pediatrics, University of Wisconsin, 600 Highland Ave, Room H6/535 CSC, Madison, WI, 53792, USA.
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18
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Morales-Quinteros L, Schultz MJ, Bringué J, Calfee CS, Camprubí M, Cremer OL, Horn J, van der Poll T, Sinha P, Artigas A, Bos LD. Estimated dead space fraction and the ventilatory ratio are associated with mortality in early ARDS. Ann Intensive Care 2019; 9:128. [PMID: 31754866 PMCID: PMC6872683 DOI: 10.1186/s13613-019-0601-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 11/05/2019] [Indexed: 12/20/2022] Open
Abstract
Background Indirect indices for measuring impaired ventilation, such as the estimated dead space fraction and the ventilatory ratio, have been shown to be independently associated with an increased risk of mortality. This study aimed to compare various methods for dead space estimation and the ventilatory ratio in patients with acute respiratory distress syndrome (ARDS) and to determine their independent values for predicting death at day 30. The present study is a post hoc analysis of a prospective observational cohort study of ICUs of two tertiary care hospitals in the Netherlands. Results Individual patient data from 940 ARDS patients were analyzed. Estimated dead space fraction and the ventilatory ratio at days 1 and 2 were significantly higher among non-survivors (p < 0.01). Dead space fraction calculation using the estimate from physiological variables [VD/VT phys] and the ventilatory ratio at day 2 showed independent association with mortality at 30 days (odds ratio 1.28 [95% CI 1.02–1.61], p < 0.03 and 1.20 [95% CI, 1.01–1.40], p < 0.03, respectively); whereas, the Harris–Benedict [VD/VT HB] and Penn State [VD/VT PS] estimations were not associated with mortality. The predicted validity of the estimated dead space fraction and the ventilatory ratio improved the baseline model based on PEEP, PaO2/FiO2, driving pressure and compliance of the respiratory system at day 2 (AUROCC 0.72 vs. 0.69, p < 0.05). Conclusions Estimated methods for dead space calculation and the ventilatory ratio during the early course of ARDS are associated with mortality at day 30 and add statistically significant but limited improvement in the predictive accuracy to indices of oxygenation and respiratory system mechanics at the second day of mechanical ventilation.
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Affiliation(s)
- Luis Morales-Quinteros
- Intensive Care Unit, Hospital Universitari Sagrat Cor, Grupo Quironsalud, Carrer de Viladomat, 288, 08029, Barcelona, Spain.
| | - Marcus J Schultz
- Department of Intensive Care, Academic Medical Center, Amsterdam, The Netherlands.,Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands.,Mahidol Oxford Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Josep Bringué
- Critical Care Center, ParcTaulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, Sabadell, Spain.,CIBER Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Carolyn S Calfee
- Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, University of California, San Francisco, San Francisco, CA, USA.,Department of Anesthesia, University of California, San Francisco, San Francisco, CA, USA.,Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Marta Camprubí
- Critical Care Center, ParcTaulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, Sabadell, Spain
| | - Olaf L Cremer
- Department of Intensive Care Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Janneke Horn
- Department of Intensive Care, Academic Medical Center, Amsterdam, The Netherlands
| | - Tom van der Poll
- Center of Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Division of Infectious Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Pratik Sinha
- Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, University of California, San Francisco, San Francisco, CA, USA.,Department of Anesthesia, University of California, San Francisco, San Francisco, CA, USA
| | - Antonio Artigas
- Intensive Care Unit, Hospital Universitari Sagrat Cor, Grupo Quironsalud, Carrer de Viladomat, 288, 08029, Barcelona, Spain.,Critical Care Center, ParcTaulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, Sabadell, Spain.,CIBER Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Lieuwe D Bos
- Department of Intensive Care, Academic Medical Center, Amsterdam, The Netherlands.,Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands.,Department of Respiratory Medicine, Academic Medical Center, Amsterdam, The Netherlands
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Evaluating Delivery of Low Tidal Volume Ventilation in Six ICUs Using Electronic Health Record Data. Crit Care Med 2019; 47:56-61. [PMID: 30308549 DOI: 10.1097/ccm.0000000000003469] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVES Mechanical ventilation with low tidal volumes is recommended for all patients with acute respiratory distress syndrome and may be beneficial to other intubated patients, yet consistent implementation remains difficult to obtain. Using detailed electronic health record data, we examined patterns of tidal volume administration, the effect on clinical outcomes, and alternate metrics for evaluating low tidal volume compliance in clinical practice. DESIGN Observational cohort study. SETTING Six ICUs in a single hospital system. PATIENTS Adult patients who received invasive mechanical ventilation more than 12 hours. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Tidal volumes were analyzed across 1,905 hospitalizations. Although mean tidal volume was 6.8 mL/kg predicted body weight, 40% of patients were exposed to tidal volumes greater than 8 mL/kg predicted body weight, with 11% for more than 24 hours. At a patient level, exposure to 24 total hours of tidal volumes greater than 8 mL/kg predicted body weight was associated with increased mortality (odds ratio, 1.82; 95% CI, 1.20-2.78), whereas mean tidal volume exposure was not (odds ratio, 0.87/1 mL/kg increase; 95% CI, 0.74-1.02). Initial tidal volume settings strongly predicted exposure to volumes greater than 8 mL/kg for 24 hours; the adjusted rate was 21.5% when initial volumes were greater than 8 mL/kg predicted body weight and 7.1% when initial volumes were less than 8 mL/kg predicted body weight. Across ICUs, correlation of mean tidal volume with alternative measures of low tidal volume delivery ranged from 0.38 to 0.66. CONCLUSIONS Despite low mean tidal volume in the cohort, a significant percentage of patients were exposed to a prolonged duration of high tidal volumes which was correlated with higher mortality. Detailed ventilator records in the electronic health record provide a unique window for evaluating low tidal volume delivery and targets for improvement.
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20
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Sjoding MW, Hofer TP, Co I, McSparron JI, Iwashyna TJ. Differences between Patients in Whom Physicians Agree and Disagree about the Diagnosis of Acute Respiratory Distress Syndrome. Ann Am Thorac Soc 2019; 16:258-264. [PMID: 30321489 PMCID: PMC6376946 DOI: 10.1513/annalsats.201806-434oc] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 10/12/2018] [Indexed: 12/21/2022] Open
Abstract
RATIONALE Because the Berlin definition of acute respiratory distress syndrome (ARDS) has only moderate reliability, physicians disagree about the diagnosis of ARDS in some patients. Understanding the clinical differences between patients with agreement and disagreement about the diagnosis of ARDS may provide insight into the epidemiology and pathophysiology of this syndrome, and inform strategies to improve the reliability of ARDS diagnosis. OBJECTIVES To characterize patients with diagnostic disagreement about ARDS among critical-care-trained physicians and compare them with patients with a consensus that ARDS developed. METHODS Patients with acute hypoxemic respiratory failure (arterial oxygen tension/pressure [PaO2]/fraction of inspired oxygen [FiO2] < 300 during invasive mechanical ventilation) were independently reviewed for ARDS by multiple critical-care physicians and categorized as consensus-ARDS, disagreement about the diagnosis, or no ARDS. RESULTS Among 738 patients reviewed, 110 (15%) had consensus-ARDS, 100 (14%) had disagreement, and 528 (72%) did not have ARDS. ARDS diagnosis rates ranged from 9% to 47% across clinicians. Patients with disagreement had baseline comorbidity rates similar to those of patients with consensus-ARDS, but lower rates of ARDS risk factors and less severe measures of lung injury. Mean days of severe hypoxemia (PaO2/FiO2 < 100) were 3.2 (95% confidence interval [CI], 2.6-3.9), 2.0 (95% CI, 1.5-2.4), and 0.8 (95% CI, 0.7-0.9) among patients with consensus-ARDS, disagreement, and no ARDS, respectively. Hospital mortality was 37% (95% CI, 28-46%), 35% (95% CI, 26-44%), and 19% (95% CI, 15-22%) across groups. Simple combinations of specific ARDS risk factors and lowest PaO2/FiO2 value could effectively discriminate patients (area under the receiver operating characteristic curve = 0.90; 95% CI, 0.88-0.92). For example, 63% of patients with pneumonia, shock, and PaO2/FiO2 < 110 had consensus-ARDS, whereas 100% of patients without pneumonia or shock and PaO2/FiO2 > 180 did not have ARDS. CONCLUSIONS Disagreement about the diagnosis of ARDS is common and can be partly explained by the difficulty of dichotomizing patients along a continuous spectrum of ARDS manifestations. Considering both the presence of key ARDS risk factors and hypoxemia severity can help guide clinicians in identifying patients with diagnosis of ARDS agreed upon by a consensus of physicians.
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Affiliation(s)
- Michael W. Sjoding
- Department of Internal Medicine
- Center for Computational Medicine and Bioinformatics, and
| | - Timothy P. Hofer
- Department of Internal Medicine
- VA Center for Clinical Management Research, Ann Arbor, Michigan
| | - Ivan Co
- Department of Internal Medicine
- Department of Emergency Medicine, University of Michigan, Ann Arbor, Michigan
| | | | - Theodore J. Iwashyna
- Department of Internal Medicine
- VA Center for Clinical Management Research, Ann Arbor, Michigan
- Institute for Social Research, Ann Arbor, Michigan; and
- Section Editor, AnnalsATS
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21
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Khauli S, Abston E, Sajjad H, Bolukbas S, Lopez JMA, Saad R, Bhatt SP, Eberlein M. Incomplete fissures are associated with increased alveolar ventilation via spiracles in severe emphysema. Interact Cardiovasc Thorac Surg 2018; 25:851-855. [PMID: 29106562 DOI: 10.1093/icvts/ivx220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 06/04/2017] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES In emphysema, air can flow preferentially via collateral pathways, which can connect an entire lung when incomplete fissures are present. Spiracles are openings through the chest wall into the lung parenchyma. We previously observed increased alveolar ventilation (VA) in subjects with severe emphysema, when spiracles occurred during lung transplant operations. In this study, we set out to identify a computed tomography (CT) imaging phenotype associated with improved VA via spiracles in severe emphysema. METHODS We retrospectively reviewed 4 patients with severe emphysema who exhaled ≥75% of the inhaled tidal volume via transpleural spiracles during a lung transplant operation. We used quantitative image analysis via VIDA VISION CT software to describe emphysema severity and distribution and fissure integrity from pretransplant CT scans of the chest. We analysed partial pressure of carbon dioxide and calculated estimates of VA at baseline and during spiracle ventilation. RESULTS All 4 subjects demonstrated severe hyperinflation (total lung capacity 148 ± 24%predicted, residual volume 296 ± 79% predicted). On CT imaging, severe emphysema was present, with an average 38.7 ± 9% (range 28-50%) of lung parenchyma showing low-attenuation areas of - 950 Hounsfield units or less. Lung fissure integrity analysis demonstrated evidence of incomplete fissures (average detectable fissure integrity 67 ± 19%, range 40 ± 11-90 ± 10%). During spiracle ventilation on unchanged ventilator settings, there was a significant reduction in partial pressure of carbon dioxide (61 ± 4-35 ± 4 mmHg, P < 0.001) and increase in estimated VA (2.1 ± 0.5-3.8 ± 0.8 l/min, P < 0.001). CONCLUSIONS Incomplete lung fissures on quantitative CT analysis seem to be a key image phenotype associated with substantial improvements in VA during transpleural ventilation via spiracles in severe emphysema.
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Affiliation(s)
- Samih Khauli
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Eric Abston
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Hassan Sajjad
- Division of Pulmonary, Critical Care and Occupational Medicine, University of Iowa, Iowa City, IA, USA
| | - Servet Bolukbas
- Department of Thoracic Surgery, Helios University Hospital Wuppertal, University Witten/Herdecke, Wuppertal, Germany
| | | | - Roberto Saad
- Faculdade de Ciências Médicas da Santa Casa de São Paulo, São Paulo, Brazil
| | - Surya P Bhatt
- Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama, Birmingham, AL, USA
| | - Michael Eberlein
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA.,Division of Pulmonary, Critical Care and Occupational Medicine, University of Iowa, Iowa City, IA, USA
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22
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Li W, Pauluhn J. Phosgene-induced acute lung injury (ALI): differences from chlorine-induced ALI and attempts to translate toxicology to clinical medicine. Clin Transl Med 2017; 6:19. [PMID: 28577109 PMCID: PMC5457389 DOI: 10.1186/s40169-017-0149-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/15/2017] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Phosgene (carbonyl dichloride) gas is an indispensable chemical inter-mediate used in numerous industrial processes. There is no clear consensus as to its time- and inhaled-dose-dependent etiopathologies and associated preventive or therapeutic treatment strategies. METHODS Cardiopulmonary function was examined in rats exposed by inhalation to the alveolar irritant phosgene or to the airway irritant chlorine during and following exposure. Terminal measurements focused on hematology, protein extravasation in bronchoalveolar lavage (BAL), and increased lung weight. Noninvasive diagnostic and prognostic endpoints in exhaled breath (carbon dioxide and nitric oxide) were used to detect the clinically occult stage of pulmonary edema. RESULTS The first event observed in rats following high but sublethal acute exposure to phosgene was the stimulation of alveolar nociceptive vagal receptors. This afferent stimulation resulted in dramatic changes in cardiopulmonary functions, ventilation: perfusion imbalances, and progressive pulmonary edema and phospholipoproteinosis. Hematology revealed hemoconcentration to be an early marker of pulmonary edema and fibrin as a discriminating endpoint that was positive for the airway irritant chlorine and negative for the alveolar irritant phosgene. CONCLUSIONS The application of each gas produced typical ALI/ARDS (acute lung injury/acute respiratory distress syndrome) characteristics. Phosgene-induced ALI showed evidence of persistent apnea periods, bradycardia, and shifts of vascular fluid from the peripheral to the pulmonary circulation. Carbon dioxide in expired gas was suggestive of increased ventilation dead space and appeared to be a harbinger of progressively developing lung edema. Treatment with the iNOS inhibitor aminoguanidine aerosol by inhalation reduced the severity of phosgene-induced ALI when applied at low dose-rates. Symptomatic treatment regimens were considered inferior to causal modes of treatment.
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Affiliation(s)
- Wenli Li
- 4th Department of Toxicology, Fourth Military Medical University, No. 169 Changle West Road, Xi’an, 710032 Shaanxi Province China
| | - Juergen Pauluhn
- 4th Department of Toxicology, Fourth Military Medical University, No. 169 Changle West Road, Xi’an, 710032 Shaanxi Province China
- Covestro Deutschland AG, Global Phosgene Steering Group, K9, 565, 51365 Leverkusen, Germany
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23
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Radermacher P, Maggiore SM, Mercat A. FiftyYears ofResearch inARDS.Gas Exchange in Acute Respiratory Distress Syndrome. Am J Respir Crit Care Med 2017; 196:964-984. [DOI: 10.1164/rccm.201610-2156so] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Peter Radermacher
- Institute of Anaesthesiological Pathophysiology and Process Engineering, University Medical School, Ulm, Germany
| | - Salvatore Maurizio Maggiore
- Section of Anesthesia, Analgesia, Perioperative, and Intensive Care, Department of Medical, Oral, and Biotechnological Sciences, School of Medicine and Health Sciences, “SS. Annunziata” Hospital, “Gabriele d’Annunzio” University of Chieti-Pescara, Chieti, Italy; and
| | - Alain Mercat
- Department of Medical Intensive Care and Hyperbaric Medicine, Angers University Hospital, Angers, France
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24
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Goligher EC, Amato MBP, Slutsky AS. Applying Precision Medicine to Trial Design Using Physiology. Extracorporeal CO 2 Removal for Acute Respiratory Distress Syndrome. Am J Respir Crit Care Med 2017. [PMID: 28636403 DOI: 10.1164/rccm.201701-0248cp] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In clinical trials of therapies for acute respiratory distress syndrome (ARDS), the average treatment effect in the study population may be attenuated because individual patient responses vary widely. This inflates sample size requirements and increases the cost and difficulty of conducting successful clinical trials. One solution is to enrich the study population with patients most likely to benefit, based on predicted patient response to treatment (predictive enrichment). In this perspective, we apply the precision medicine paradigm to the emerging use of extracorporeal CO2 removal (ECCO2R) for ultraprotective ventilation in ARDS. ECCO2R enables reductions in tidal volume and driving pressure, key determinants of ventilator-induced lung injury. Using basic physiological concepts, we demonstrate that dead space and static compliance determine the effect of ECCO2R on driving pressure and mechanical power. This framework might enable prediction of individual treatment responses to ECCO2R. Enriching clinical trials by selectively enrolling patients with a significant predicted treatment response can increase treatment effect size and statistical power more efficiently than conventional enrichment strategies that restrict enrollment according to the baseline risk of death. To support this claim, we simulated the predicted effect of ECCO2R on driving pressure and mortality in a preexisting cohort of patients with ARDS. Our computations suggest that restricting enrollment to patients in whom ECCO2R allows driving pressure to be decreased by 5 cm H2O or more can reduce sample size requirement by more than 50% without increasing the total number of patients to be screened. We discuss potential implications for trial design based on this framework.
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Affiliation(s)
- Ewan C Goligher
- 1 Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada.,2 Division of Respirology, Department of Medicine, University Health Network and Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Marcelo B P Amato
- 3 Laboratório de Pneumologia LIM-09, Disciplina de Pneumologia, Heart Institute (Incor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and
| | - Arthur S Slutsky
- 1 Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada.,4 Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
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25
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Chahla M, Larson CD, Parekh KR, Reed RM, Terry P, Schmidt GA, Eberlein M. Transpleural Ventilation via Spiracles in Severe Emphysema Increases Alveolar Ventilation. Chest 2017; 149:e161-7. [PMID: 27287591 DOI: 10.1016/j.chest.2015.12.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 12/10/2015] [Accepted: 12/21/2015] [Indexed: 10/21/2022] Open
Abstract
In emphysema airway resistance can exceed collateral airflow resistance, causing air to flow preferentially through collateral pathways. In severe emphysema ventilation through openings directly through the chest wall into the parenchyma (spiracles) could bypass airway obstruction and increase alveolar ventilation via transpleural expiration. During lung transplant operations, spiracles occasionally can occur inadvertently. We observed transpleural expiration via spiracles in three subjects undergoing lung transplant for emphysema. During transpleural spiracle ventilation, inspiratory tidal volumes (TV) were unchanged; however, expiration was entirely transpleural in two patients whereas the expired TV to the ventilator circuit was reduced to 25% of the inspired TV in one. At baseline, mean PCO2 was 61 ± 5 mm Hg, which decreased to a mean PCO2 of 49 ± 5 mm Hg (P = .05) within minutes after transpleural spiracle ventilation and further decreased at 1 to 2 h (36 ± 4 mm Hg; P = .002 compared with baseline) on unchanged ventilator settings. This observation of increased alveolar ventilation supports further studies of spiracles as a possible therapy for advanced emphysema.
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Affiliation(s)
- Mayy Chahla
- Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA
| | - Christopher D Larson
- Department of Anesthesia, University of Iowa Hospitals and Clinics, Iowa City, IA
| | - Kalpaj R Parekh
- Department of Thoracic and Cardiovascular Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA
| | - Robert M Reed
- Division of Pulmonary and Critical Care Medicine, University of Maryland, Baltimore, MD
| | - Peter Terry
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Gregory A Schmidt
- Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA; Division of Pulmonary, Occupational, and Critical Care, University of Iowa Hospitals and Clinics, Iowa City, IA
| | - Michael Eberlein
- Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA; Division of Pulmonary, Occupational, and Critical Care, University of Iowa Hospitals and Clinics, Iowa City, IA.
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26
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Blanch L, López-Aguilar J, Lucangelo U. Dead space in acute respiratory distress syndrome: more than a feeling! CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2016; 20:214. [PMID: 27473750 PMCID: PMC4967311 DOI: 10.1186/s13054-016-1381-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Lluis Blanch
- Critical Care Center, Hospital de Sabadell, Corporació Sanitària Universitària ParcTaulí, Universitat Autònoma de Barcelona, c. ParcTaulí 1, 08208, Sabadell, Spain. .,CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.
| | - Josefina López-Aguilar
- Critical Care Center, Hospital de Sabadell, Corporació Sanitària Universitària ParcTaulí, Universitat Autònoma de Barcelona, c. ParcTaulí 1, 08208, Sabadell, Spain.,CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Umberto Lucangelo
- Department of Perioperative Medicine, Intensive Care and Emergency, Cattinara Hospital, Trieste University, Trieste, Italy
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27
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Zhang YJ, Gao XJ, Li ZB, Wang ZY, Feng QS, Yin CF, Lu X, Xu L. Comparison of the pulmonary dead-space fraction derived from ventilator volumetric capnography and a validated equation in the survival prediction of patients with acute respiratory distress syndrome. Chin J Traumatol 2016; 19:141-5. [PMID: 27321293 PMCID: PMC4908214 DOI: 10.1016/j.cjtee.2016.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
PURPOSE This prospective observational study aims to evaluate the accuracy of dead-space fraction derived from the ventilator volumetric capnography (volumetric CO₂) or a prediction equation to predict the survival of mechanically ventilated patients with acute respiratory distress syndrome (ARDS). METHODS Consecutive VD/VT measurements were obtained based upon a prediction equation validated by Frankenfield et al for dead-space ventilation fraction: VD/VT = 0.320 + 0.0106 (PaCO₂-ETCO₂)⁺ 0.003 (RR)⁺0.0015 (age) in adult patients who had infection-related severe pneumonia and were confirmed as having ARDS. Here PaCO₂ is the arterial partial pressure of carbon dioxide in mmHg; ETCO₂, the end- tidal carbon dioxide measurement in mmHg; RR, respiratory rate per minute; and age in years. Once the patient had intubation, positive end expiratory pressure was adjusted and after Phigh reached a steady state, VD/VT was measured and recorded as the data for the first day. VD/VT measurement was repeated on days 2, 3, 4, 5 and 6. Meanwhile we collected dead-space fraction directly from the ventilator volu- metric CO₂ and recorded it as Vd/Vt. We analyzed the changes in VD/VT and Vd/Vt over the 6-day period to determine their accuracy in predicting the survival of ARDS patients. RESULTS Overall, 46 patients with ARDS met the inclusion criteria and 24 of them died. During the first 6 days of intubation, VD/VT was significantly higher in nonsurvivors on day 4 (0.70 ± 0.01 vs 0.57 ± 0.01), day 5 (0.73 ± 0.01 vs. 0.54 ± 0.01), and day 6 (0.73 ± 0.02 vs. 0.54 ± 0.01) (all p =0.000). Vd/Vt showed no significant difference on days 1e4 but it was much higher in nonsurvivors on day 5 (0.45 ± 0.04 vs. 0.41 ± 0.06) and day 6 (0.47 ± 0.05 vs. 0.40 ± 0.03) (both p=0.008). VD/VT on the fourth day was more accurate to predict survival than Vd/Vt. The area under the receiver-operating characteristic curve for VD/VT and Vd/Vt in evaluating ARDS patients survival was day 4 (0.974 ± 0.093 vs. 0.701 ± 0.023, p = 0.0024) with the 95% confidence interval being 0.857-0.999 vs. 0.525-0.841. CONCLUSION Compared with Vd/Vt derived from ventilator volumetric CO₂, VD/VT on day 4 calculated by Frankenfield et al's equation can more accurately predict the survival of ARDS patients.
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Abstract
OBJECTIVE Elevated dead space has been consistently associated with increased mortality in adults with respiratory failure. In children, the evidence for this association is more limited. We sought to investigate the association between dead space and mortality in mechanically ventilated children. DESIGN Single-center retrospective review. SETTING Tertiary care pediatric critical care unit. PATIENTS Seven hundred twelve mechanically ventilated children with an arterial catheter. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The end-tidal alveolar dead space fraction ((PaCO2-PETCO2)/PaCO2), a dead space marker, was calculated with each arterial blood gas. The initial end-tidal alveolar dead space fraction (first arterial blood gas after intubation) (per 0.1 unit increase: odds ratio, 1.59; 95% CI, 1.40-1.81) and day 1 mean end-tidal alveolar dead space fraction (odds ratio, 1.95; 95% CI, 1.66-2.30) were associated with mortality. The relationship between both initial and day 1 mean end-tidal alveolar dead space fraction and mortality held in multivariate modeling after controlling for any of the following individually: PaO2/FIO2, oxygenation index, 24-hour maximal inotrope score, and Pediatric Risk of Mortality III (all p<0.01), although end-tidal alveolar dead space fraction was no longer significant after controlling for the combination of oxygenation index, 24-hour maximal inotrope score, and Pediatric Risk of Mortality III. In 217 children with acute hypoxemic respiratory failure, initial end-tidal alveolar dead space fraction (per 0.1 unit increase odds ratio, 1.38; 95% CI, 1.14-1.67) and day 1 mean end-tidal alveolar dead space fraction (per 0.1 unit increase odds ratio, 1.60; 95% CI, 1.27-2.0) were associated with mortality. Day 1 mean end-tidal alveolar dead space fraction remained associated with mortality after controlling individually for any of the following in multivariate models: PaO2/FIO2, oxygenation index, and 24-hour maximal inotrope score (p≤0.02), although end-tidal alveolar dead space fraction was no longer significant after controlling for the combination of oxygenation index, 24-hour maximal inotrope score, and Pediatric Risk of Mortality III. CONCLUSIONS Increased dead space is associated with higher mortality in critically ill children, although it is no longer independently associated with mortality after controlling for severity of oxygenation defect, inotrope use, and severity of illness. However, because end-tidal alveolar dead space fraction is easy to calculate at the bedside, it may be useful for risk stratification and severity-of-illness scores.
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Estimating dead-space fraction for secondary analyses of acute respiratory distress syndrome clinical trials. Crit Care Med 2015; 43:1026-35. [PMID: 25738857 DOI: 10.1097/ccm.0000000000000921] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Pulmonary dead-space fraction is one of few lung-specific independent predictors of mortality from acute respiratory distress syndrome. However, it is not measured routinely in clinical trials and thus altogether ignored in secondary analyses that shape future research directions and clinical practice. This study sought to validate an estimate of dead-space fraction for use in secondary analyses of clinical trials. DESIGN Analysis of patient-level data pooled from acute respiratory distress syndrome clinical trials. Four approaches to estimate dead-space fraction were evaluated: three required estimating metabolic rate; one estimated dead-space fraction directly. SETTING U.S. academic teaching hospitals. PATIENTS Data from 210 patients across three clinical trials were used to compare performance of estimating equations with measured dead-space fraction. A second cohort of 3,135 patients from six clinical trials without measured dead-space fraction was used to confirm whether estimates independently predicted mortality. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Dead-space fraction estimated using the unadjusted Harris-Benedict equation for energy expenditure was unbiased (mean ± SD Harris-Benedict, 0.59 ± 0.13; measured, 0.60 ± 0.12). This estimate predicted measured dead-space fraction to within ±0.10 in 70% of patients and ±0.20 in 95% of patients. Measured dead-space fraction independently predicted mortality (odds ratio, 1.36 per 0.05 increase in dead-space fraction; 95% CI, 1.10-1.68; p < 0.01). The Harris-Benedict estimate closely approximated this association with mortality in the same cohort (odds ratio, 1.55; 95% CI, 1.21-1.98; p < 0.01) and remained independently predictive of death in the larger Acute Respiratory Distress Syndrome Network cohort. Other estimates predicted measured dead-space fraction or its association with mortality less well. CONCLUSIONS Dead-space fraction should be measured in future acute respiratory distress syndrome clinical trials to facilitate incorporation into secondary analyses. For analyses where dead-space fraction was not measured, the Harris-Benedict estimate can be used to estimate dead-space fraction and adjust for its association with mortality.
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30
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Robertson HT. Dead space: the physiology of wasted ventilation. Eur Respir J 2014; 45:1704-16. [PMID: 25395032 DOI: 10.1183/09031936.00137614] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Accepted: 09/29/2014] [Indexed: 11/05/2022]
Abstract
An elevated physiological dead space, calculated from measurements of arterial CO2 and mixed expired CO2, has proven to be a useful clinical marker of prognosis both for patients with acute respiratory distress syndrome and for patients with severe heart failure. Although a frequently cited explanation for an elevated dead space measurement has been the development of alveolar regions receiving no perfusion, evidence for this mechanism is lacking in both of these disease settings. For the range of physiological abnormalities associated with an increased physiological dead space measurement, increased alveolar ventilation/perfusion ratio (V'A/Q') heterogeneity has been the most important pathophysiological mechanism. Depending on the disease condition, additional mechanisms that can contribute to an elevated physiological dead space measurement include shunt, a substantial increase in overall V'A/Q' ratio, diffusion impairment, and ventilation delivered to unperfused alveolar spaces.
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Affiliation(s)
- H Thomas Robertson
- Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, WA, USA
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31
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Lai PS, Mita C, Thompson BT. What is the clinical significance of pulmonary hypertension in acute respiratory distress syndrome? A review. Minerva Anestesiol 2014; 80:574-585. [PMID: 24193181 PMCID: PMC4036117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Elevated pulmonary arterial pressures appear to be a prominent feature of the acute respiratory distress syndrome (ARDS). Current clinical guidelines for the management of ARDS do not specifically address treatment of pulmonary hypertension or associated right ventricular dysfunction because the clinical significance of this entity remains unclear. Interpretation of elevated pulmonary arterial pressures, pulmonary vascular resistance, and transpulmonary gradient as well as signs of right ventricular dysfunction is confounded by the effects of positive pressure ventilation. There does not appear to be a consistent relationship between the diagnosis of pulmonary hypertension or right ventricular failure and mortality in patients with ARDS, but it is unclear if right ventricular failure contributes to the mortality risk per se or if the underlying cause of pulmonary hypertension, including intravascular micro and macro thrombosis, are simply markers for systemic dysregulation of coagulation and fibrinolysis that may lead to multiorgan failure in ARDS. While studies of pulmonary vasodilator therapies have not shown a mortality benefit in ARDS, such trials have targeted improved oxygenation rather than improved pulmonary hemodynamics so that the possible contribution of improved right ventricular function to better outcomes has not been directly tested in large trials. Future studies are needed to determine if treatment of pulmonary hypertension and associated right ventricular dysfunction will affect mortality in patients with ARDS.
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Affiliation(s)
- P S Lai
- Pulmonary and Critical Care Unit, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA -
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Kallet RH, Zhuo H, Liu KD, Calfee CS, Matthay MA. The association between physiologic dead-space fraction and mortality in subjects with ARDS enrolled in a prospective multi-center clinical trial. Respir Care 2013; 59:1611-8. [PMID: 24381187 DOI: 10.4187/respcare.02593] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND We tested the association between pulmonary dead-space fraction (ratio of dead space to tidal volume [V(D)/V(T)]) and mortality in subjects with ARDS (Berlin definition, P(aO2)/F(IO2) ≤ 300 mm Hg; PEEP ≥ 5 cm H2O) enrolled into a clinical trial incorporating lung-protective ventilation. METHODS We conducted a prospective, multi-center study at medical-surgical ICUs in the United States. A total of 126 ALI subjects with acute lung injury were enrolled into a phase 3 randomized, placebo-controlled study of aerosolized albuterol. V(D)/V(T) and pulmonary mechanics were measured within 4 h of enrollment and repeated daily on study days 1 and 2 in subjects requiring arterial blood gases for clinical management. RESULTS At baseline, non-survivors had a trend toward higher V(D)/V(T) compared with survivors (0.62 ± 0.11 vs 0.56 ± 0.11, respectively, P = .08). Differences in V(D)/V(T) between non-survivors and survivors became significant on study days 1 (0.64 ± 0.12 vs 0.55 ± 0.11, respectively, P = .01) and 2 (0.67 ± 0.12 vs 0.56 ± 0.11, respectively, P = .004). Likewise, the association between VD/VT and mortality was significant on study day 1 (odds ratio per 0.10 change in V(D)/V(T) [95% CI]: 6.84 [1.62-28.84] P = .01; and study day 2: 4.90 [1.28-18.73] P = .02) after adjusting for V(D)/V(T), P(aO2)/F(IO2), oxygenation index, vasopressor use, and the primary risk for ARDS. Using a Cox proportional hazard model, V(D)/V(T) was associated with a trend toward higher mortality (HR = 4.37 [CI 0.99-19.32], P = .052) that became significant when the analysis was adjusted for daily oxygenation index (HR = 1.74 [95% CI 1.12-3.35] P = .04). CONCLUSIONS Markedly elevated V(D)/V(T) (≥ 0.60) in early ARDS is associated with higher mortality. Measuring V(D)/V(T) may be useful in identifying ARDS patients at increased risk of death who are enrolled into a therapeutic trial.
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Affiliation(s)
- Richard H Kallet
- Respiratory Care Services, University of California San Francisco Department of Anesthesia at San Francisco General Hospital
| | - Hanjing Zhuo
- Cardiovascular Research Institute, University of California, San Francisco
| | - Kathleen D Liu
- Department of Nephrology, University of California, San Francisco
| | - Carolyn S Calfee
- Department of Pulmonary and Critical Care Medicine, University of California, San Francisco, San Francisco, California
| | - Michael A Matthay
- Cardiovascular Research Institute, University of California, San Francisco
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Vender RL, Betancourt MF, Lehman EB, Harrell C, Galvan D, Frankenfield DC. Prediction equation to estimate dead space to tidal volume fraction correlates with mortality in critically ill patients. J Crit Care 2013; 29:317.e1-3. [PMID: 24581935 DOI: 10.1016/j.jcrc.2013.12.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Revised: 11/14/2013] [Accepted: 12/17/2013] [Indexed: 10/25/2022]
Abstract
OBJECTIVE The measurement of dead space to tidal volume fraction (Vd/Vt) using various methodologies has been shown to be a reliable predictor of mortality in critically ill patients. In this study, we evaluated the correlation of a validated equation using clinically available information to predict calculation of Vd/Vt with clinically relevant outcome parameters in patients requiring mechanical ventilation. METHODS Calculations of Vd/Vt were obtained based upon a previously published prediction equation for dead space ventilation fraction: Vd/Vt = 0.320 + 0.0106 (Paco2--end-tidal carbon dioxide measurement) + 0.003 (respiratory rate per minute) + 0.0015 (age in years) on study days 1, 3 to 4, 6 to 9, and 14 after initiation of mechanical ventilation in adult patients who satisfied 1 of the 3 study defined diseases: (1) acute bacterial pneumonia, (2) acute respiratory distress syndrome, or (3) cystic fibrosis. RESULTS Using the final/last available time point calculation of Vd/Vt, a significant difference was observed between survivors and nonsurvivors both in relation to mean and median values (56.5% vs 71.2% and 56.0% vs 65.0%, respectively). In addition, sequential analyses of Vd/Vt calculations over time also demonstrated a statistically significant difference between survivors and nonsurvivors for days 6 to 9. CONCLUSION In this study-specific population of critically ill patients, the prediction equation of Vd/Vt using clinically available parameters correlates with mortality. In addition, we provide a simple method to estimate Vd/Vt that can be potentially applicable to all critically ill intensive care unit patients.
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Affiliation(s)
- Robert L Vender
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Penn State Milton S. Hershey Medical Center, Hershey, PA.
| | - Manuel F Betancourt
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Penn State Milton S. Hershey Medical Center, Hershey, PA
| | - Erik B Lehman
- Department of Public Health Sciences, Penn State College of Medicine, Hershey, PA
| | - Christopher Harrell
- Department of Respiratory Therapy, Penn State Milton S. Hershey Medical Center, Hershey, PA
| | - Dan Galvan
- Department of Surgery, Division of Trauma, Acute Surgery and Critical Care Surgery, Penn State Milton S. Hershey Medical Center, Hershey, PA
| | - David C Frankenfield
- Department of Clinical Nutrition, Penn State Milton S. Hershey Medical Center, Hershey, PA
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Fröhlich S, Murphy N, Boylan JF. ARDS: progress unlikely with non-biological definition. Br J Anaesth 2013; 111:696-9. [PMID: 24108727 DOI: 10.1093/bja/aet165] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- S Fröhlich
- Department of Anaesthesia and Intensive Care Medicine, St Vincent's University Hospital, Dublin, Ireland
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Sinha P, Singh S, Hardman JG, Bersten AD, Soni N. Evaluation of the physiological properties of ventilatory ratio in a computational cardiopulmonary model and its clinical application in an acute respiratory distress syndrome population. Br J Anaesth 2013; 112:96-101. [PMID: 24067330 PMCID: PMC9585654 DOI: 10.1093/bja/aet283] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Owing to complexities of measuring dead space, ventilatory failure is difficult to quantify in critical care. A simple, novel index called ventilatory ratio (VR) can quantify ventilatory efficiency at the bedside. The study objectives were to evaluate physiological properties of VR and examine its clinical applicability in acute respiratory distress syndrome (ARDS) patients. METHODS A validated computational model of cardiopulmonary physiology [Nottingham Physiology Simulator (NPS)] was used to evaluate VR ex vivo in three virtual patients with varying degrees of gas exchange defects. Arterial P(CO₂) and mixed expired P(CO₂) were obtained from the simulator while either dead space or CO₂ production was altered in isolation. VR and deadspace fraction was calculated using these values. A retrospective analysis of a previously presented prospective ARDS database was then used to evaluate the clinical utility of VR. Basic characteristics of VR and its association with mortality were examined. RESULTS The NPS showed that VR behaved in an intuitive manner as would be predicted by its physiological properties. When CO₂ production was constant, there was strong positive correlation between dead space and VR (modified Pearson's r 0.98, P<0.01). The ARDS database had a mean VR of 1.47 (standard deviation 0.58). Non-survivors had a significantly higher VR compared with survivors [1.70 vs 1.34, mean difference 0.35, 95% confidence interval (CI) 0.16-0.56, P<0.01]. VR was an independent predictor of mortality (odds ratio 3.05, CI 1.35-6.91, P<0.01). CONCLUSIONS VR is influenced by dead space and CO₂ production. In ARDS, high VR was associated with increased mortality.
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Affiliation(s)
- P Sinha
- Magill Department of Anaesthesia, Intensive Care Medicine and Pain Management Chelsea and Westminster Hospital, 369 Fulham Road, London, UK
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Sinha P, Sanders RD, Soni N, Vukoja MK, Gajic O. Acute Respiratory Distress Syndrome: The Prognostic Value of Ventilatory Ratio—A Simple Bedside Tool to Monitor Ventilatory Efficiency. Am J Respir Crit Care Med 2013; 187:1150-3. [DOI: 10.1164/rccm.201211-2037le] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Sinha P, Fauvel NJ, Singh P, Soni N. Analysis of ventilatory ratio as a novel method to monitor ventilatory adequacy at the bedside. Crit Care 2013; 17:R34. [PMID: 23445563 PMCID: PMC4057449 DOI: 10.1186/cc12541] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 02/05/2013] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION Due to complexities in its measurement, adequacy of ventilation is seldom used to categorize disease severity and guide ventilatory strategies. Ventilatory ratio (VR) is a novel index to monitor ventilatory adequacy at the bedside. VR=(VEmeasured × PaCO₂measured)/(VEpredicted × PaCO₂ideal). VEpredicted is 100 mL.Kg-1.min-1 and PaCO₂ideal is 5 kPa. Physiological analysis shows that VR is influenced by dead space (VD/VT) and CO₂ production (VCO₂). Two studies were conducted to explore the physiological properties of VR and assess its use in clinical practice. METHODS Both studies were conducted in adult mechanically ventilated ICU patients. In Study 1, volumetric capnography was used to estimate daily VD/VT and measure VCO₂ in 48 patients. Simultaneously, ventilatory ratio was calculated using arterial blood gas measurements alongside respiratory and ventilatory variables. This data was used to explore the physiological properties of VR. In Study 2, 224 ventilated patients had daily VR and other respiratory variables, baseline characteristics, and outcome recorded. The database was used to examine the prognostic value of VR. RESULTS Study 1 showed that there was significant positive correlation between VR and VD/VT (modified r = 0.71) and VCO₂ (r = 0.14). The correlation between VR and VD/VT was stronger in mandatory ventilation compared to spontaneous ventilation. Linear regression analysis showed that VD/VT had a greater influence on VR than VCO₂ (standardized regression coefficient 1/1-VD/VT: 0.78, VCO₂: 0.44). Study 2 showed that VR was significantly higher in non-survivors compared to survivors (1.55 vs. 1.32; P < 0.01). Univariate logistic regression showed that higher VR was associated with mortality (OR 2.3, P < 0.01), this remained the case after adjusting for confounding variables (OR 2.34, P = 0.04). CONCLUSIONS VR is an easy to calculate bedside index of ventilatory adequacy and appears to yield clinically useful information.
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Recombinant human soluble thrombomodulin improves mortality and respiratory dysfunction in patients with severe sepsis. J Trauma Acute Care Surg 2012; 72:1150-7. [PMID: 22673239 DOI: 10.1097/ta.0b013e3182516ab5] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Respiratory dysfunction associated with severe sepsis is a serious condition leading to poor prognosis. Activation of coagulation is a consequence of and contributor to ongoing lung injury in severe sepsis. The purpose of this study was to examine the efficacy of recombinant human soluble thrombomodulin (rhTM), a novel anticoagulant agent, for treating patients with sepsis-induced disseminated intravascular coagulation (DIC) in terms of mortality and respiratory dysfunction. METHODS This study comprised 86 consecutive patients with sepsis-induced DIC who required ventilator management. The initial 45 patients were treated without rhTM (control group), and the following 41 patients were given rhTM (0.06 mg/kg/d) for 6 days (rhTM group). Patients were followed up for 90 days after study entry. Sequential Organ Failure Assessment (SOFA) score and lung injury score were recorded until 7 days after entry. RESULTS The baseline characteristic of severity of illness was significantly higher in the rhTM group than in the control group. Nevertheless, 90-day mortality rate in the rhTM group was significantly lower than that in the control group (37% vs. 58%, p = 0.038). There was a significant difference in the serial change of SOFA score from baseline to day 7 between the two groups (p = 0.009). Both the respiratory component of the SOFA score and the lung injury score in the rhTM group were significantly lower compared with the control group (p = 0.034 and p < 0.001, respectively). CONCLUSIONS rhTM may have a significant beneficial effect on mortality and respiratory dysfunction in patients with sepsis-induced DIC. LEVEL OF EVIDENCE III, therapeutic study.
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Comparison of volumetric capnography and mixed expired gas methods to calculate physiological dead space in mechanically ventilated ICU patients. Intensive Care Med 2012; 38:1712-7. [PMID: 22893221 DOI: 10.1007/s00134-012-2670-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 07/19/2012] [Indexed: 01/21/2023]
Abstract
INTRODUCTION Physiological dead space should be a routine measurement in ventilated patients but measuring dead space using the Douglas bag (DB) method is cumbersome and requires corrections for compressed ventilator gas. These factors make this method impractical in the critical care setting. Volumetric capnography (VCAP) offers a relatively simple solution to calculating dead space. Few studies have been conducted to directly compare dead space measured by VCAP and the DB method in critically unwell adults. METHOD Prospective observational study of 48 mechanically ventilated adults ICU patients. Dead space was calculated simultaneously using VCAP (CO(2)SMO) and the Bohr-Enghoff equation. In total, 168 paired readings were taken. Single-breath CO(2) waveform areas under the curve were computed automatically by software to calculate physiological dead space. The calculated value of P(Ē(CO(2))) was also recorded from the CO(2)SMO device. Exhaust ventilator gas was collected in a 10-l mixing chamber. P(Ē(CO(2))) was measured in the chamber following correction for compressed gas. RESULTS The study demonstrated good agreement between physiological V(D)/V(T) calculated by VCAP and corrected (mean bias 0.03), and uncorrected (mean bias 0.02) Bohr-Enghoff method. There was good correlation between the two methods of measurement (VCAP vs corrected r(2) = 0.90 P < 0.001, VCAP vs uncorrected r(2) = 0.90, P < 0.001). There was good correlation between [Formula: see text] calculated by the CO(2)SMO and in the exhaust collected gas (mean bias 0.08). CONCLUSIONS VCAP shows good agreement with Douglas Bag method in measuring physiological V(D)/V(T) over a wide range of dead space fractions.
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Walkey AJ, Summer R, Ho V, Alkana P. Acute respiratory distress syndrome: epidemiology and management approaches. Clin Epidemiol 2012; 4:159-69. [PMID: 22866017 PMCID: PMC3410685 DOI: 10.2147/clep.s28800] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Acute lung injury and the more severe acute respiratory distress syndrome represent a spectrum of lung disease characterized by the sudden onset of inflammatory pulmonary edema secondary to myriad local or systemic insults. The present article provides a review of current evidence in the epidemiology and treatment of acute lung injury and acute respiratory distress syndrome, with a focus on significant knowledge gaps that may be addressed through epidemiologic methods.
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Affiliation(s)
- Allan J Walkey
- The Pulmonary Center, Boston University School of Medicine, Boston, MA, USA
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Abstract
Management of acute respiratory failure is an important component of intensive care. In this review, we analyze 21 original research articles published last year in Critical Care in the field of respiratory and critical care medicine. The articles are summarized according to the following topic categories: acute respiratory distress syndrome, mechanical ventilation, adjunctive therapies, and pneumonia.
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The association between the end tidal alveolar dead space fraction and mortality in pediatric acute hypoxemic respiratory failure. Pediatr Crit Care Med 2012; 13:11-5. [PMID: 21499169 DOI: 10.1097/pcc.0b013e3182192c42] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVE To investigate the relationship of markers of oxygenation, PaO2/FIO2 ratio, SpO2/FIO2 ratio, oxygenation index, oxygen saturation index, and dead space (end tidal alveolar dead space fraction) with mortality in children with acute hypoxemic respiratory failure. DESIGN Retrospective. SETTING Single-center tertiary care pediatric intensive care unit. PATIENTS Ninety-five mechanically ventilated children with a PaO2/FIO2 ratio <300 within 24 hrs of the initiation of mechanical ventilation. INTERVENTIONS None. MAIN RESULTS The end tidal alveolar dead space fraction, PaO2/FIO2 ratio, SpO2/FIO2 ratio, oxygenation index, and oxygen saturation index were all associated with mortality (p < .02). There was a small correlation between the end tidal alveolar dead space fraction and decreasing PaO2/FIO2 (r2 = .21) and SpO2/FIO2 ratios (r2 = .22), and increasing oxygenation index (r2= .25) and oxygen saturation index (r2 = .24). In multivariate logistic regression modeling, the end tidal alveolar dead space fraction was independently associated with mortality (p < .02). Oxygenation index, oxygen saturation index, and the end tidal alveolar dead space fraction were all acceptable discriminators of mortality with receiver operating characteristic plot area under the curves ≥ 0.7. CONCLUSIONS In pediatric acute hypoxemic respiratory failure, easily obtainable pulmonary specific markers of disease severity (SpO2/FIO2 ratio, oxygen saturation index, and the end tidal alveolar dead space fraction) may be useful for the early identification of children at high risk of death. Furthermore, the end tidal alveolar dead space fraction should be considered for risk stratification of children with acute hypoxemic respiratory failure, given that it was independently associated with mortality.
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End-tidal alveolar dead space ratio: a simple and useful parameter for intensivists. Pediatr Crit Care Med 2012; 13:92-3. [PMID: 22222643 DOI: 10.1097/pcc.0b013e318220a3dd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are distinctly modern clinical entities. Recent epidemiologic research has taken advantage of large cohorts in efforts to better describe these highly lethal syndromes with a focus on differentiation of clinically meaningful subtypes and early prediction in an effort to improve treatment and prevention. This article identifies the most significant studies and systematic reviews of recent years, defining the incidence, mortality, risk and prognostic factors, and etiologic classes of ARDS/ALI.
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Affiliation(s)
- Ross Blank
- Division of Critical Care, Department of Anesthesiology, University of Michigan Health System, 1500 East Medical Center Drive, SPC 5861, Ann Arbor, MI 48109-5861, USA.
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Fanelli V, Zhang H, Slutsky AS. Year in review 2010: Critical Care--Respirology. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2011; 15:240. [PMID: 22146748 PMCID: PMC3388674 DOI: 10.1186/cc10541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In this review, 21 original papers published last year in the respirology and critical care sections of Critical Care are classified and analyzed in the following categories: mechanical ventilation, lung recruitment maneuvers, and weaning; the role of positive end-expiratory pressure in acute lung injury models; animal models of ventilator-induced lung injury; diaphragmatic dysfunction; the role of mechanical ventilation in heart-lung interaction; and miscellanea.
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Affiliation(s)
- Vito Fanelli
- Keenan Research Centre at the Li Ka Shing Knowledge Institute of St, Michael's Hospital, Toronto, ON, Canada M5B 1W8
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Matthay MA, Kallet RH. Prognostic value of pulmonary dead space in patients with the acute respiratory distress syndrome. Crit Care 2011; 15:185. [PMID: 22067424 PMCID: PMC3334730 DOI: 10.1186/cc10346] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A study published in the previous issue of Critical Care demonstrates that measurement of the pulmonary dead-space fraction is superior to hypoxemia as an indicator of a favorable physiologic response to prone positioning in patients with severe acute respiratory distress syndrome. These results add to the growing evidence supporting the clinical and research value of measuring pulmonary dead space in patients with acute respiratory distress syndrome and using this pulmonary physiologic end-point as one indicator of a favorable response to therapy.
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Affiliation(s)
- Michael A Matthay
- Department of Medicine and Cardiovascular Research Institute at University of California, San Francisco, 505 Parnassus Avenue, M-917, San Francisco, CA 94143-0624, USA.
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Charron C, Repesse X, Bouferrache K, Bodson L, Castro S, Page B, Jardin F, Vieillard-Baron A. PaCO2 and alveolar dead space are more relevant than PaO2/FiO2 ratio in monitoring the respiratory response to prone position in ARDS patients: a physiological study. Crit Care 2011; 15:R175. [PMID: 21791044 PMCID: PMC3387618 DOI: 10.1186/cc10324] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 06/28/2011] [Accepted: 07/25/2011] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Our aims in this study were to report changes in the ratio of alveolar dead space to tidal volume (VDalv/VT) in the prone position (PP) and to test whether changes in partial pressure of arterial CO2 (PaCO2) may be more relevant than changes in the ratio of partial pressure of arterial O2 to fraction of inspired O2 (PaO2/FiO2) in defining the respiratory response to PP. We also aimed to validate a recently proposed method of estimation of the physiological dead space (VDphysiol/VT) without measurement of expired CO2. METHODS Thirteen patients with a PaO2/FiO2 ratio < 100 mmHg were included in the study. Plateau pressure (Pplat), positive end-expiratory pressure (PEEP), blood gas analysis and expiratory CO2 were recorded with patients in the supine position and after 3, 6, 9, 12 and 15 hours in the PP. Responders to PP were defined after 15 hours of PP either by an increase in PaO2/FiO2 ratio > 20 mmHg or by a decrease in PaCO2 > 2 mmHg. Estimated and measured VDphysiol/VT ratios were compared. RESULTS PP induced a decrease in Pplat, PaCO2 and VDalv/VT ratio and increases in PaO2/FiO2 ratios and compliance of the respiratory system (Crs). Maximal changes were observed after six to nine hours. Changes in VDalv/VT were correlated with changes in Crs, but not with changes in PaO2/FiO2 ratios. When the response was defined by PaO2/FiO2 ratio, no significant differences in Pplat, PaCO2 or VDalv/VT alterations between responders (n = 7) and nonresponders (n = 6) were observed. When the response was defined by PaCO2, four patients were differently classified, and responders (n = 7) had a greater decrease in VDalv/VT ratio and in Pplat and a greater increase in PaO2/FiO2 ratio and in Crs than nonresponders (n = 6). Estimated VDphysiol/VT ratios significantly underestimated measured VDphysiol/VT ratios (concordance correlation coefficient 0.19 (interquartile ranges 0.091 to 0.28)), whereas changes during PP were more reliable (concordance correlation coefficient 0.51 (0.32 to 0.66)). CONCLUSIONS PP induced a decrease in VDalv/VT ratio and an improvement in respiratory mechanics. The respiratory response to PP appeared more relevant when PaCO2 rather than the PaO2/FiO2 ratio was used. Estimated VDphysiol/VT ratios systematically underestimated measured VDphysiol/VT ratios.
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Affiliation(s)
- Cyril Charron
- Intensive Care Unit, Section Thorax-Vascular Disease-Abdomen-Metabolism, Ambroise Paré University Hospital, AP-HP, 9 Av Charles de Gaulle, F-92104 Boulogne-Billancourt Cedex, France
- Faculté de Paris Ile-de-France Ouest, Université de Versailles Saint Quentin en Yvelines, 9 boulevard d'Alembert, F-78280 Guyancourt, France
| | - Xavier Repesse
- Intensive Care Unit, Section Thorax-Vascular Disease-Abdomen-Metabolism, Ambroise Paré University Hospital, AP-HP, 9 Av Charles de Gaulle, F-92104 Boulogne-Billancourt Cedex, France
- Faculté de Paris Ile-de-France Ouest, Université de Versailles Saint Quentin en Yvelines, 9 boulevard d'Alembert, F-78280 Guyancourt, France
| | - Koceïla Bouferrache
- Intensive Care Unit, Section Thorax-Vascular Disease-Abdomen-Metabolism, Ambroise Paré University Hospital, AP-HP, 9 Av Charles de Gaulle, F-92104 Boulogne-Billancourt Cedex, France
- Faculté de Paris Ile-de-France Ouest, Université de Versailles Saint Quentin en Yvelines, 9 boulevard d'Alembert, F-78280 Guyancourt, France
| | - Laurent Bodson
- Intensive Care Unit, Section Thorax-Vascular Disease-Abdomen-Metabolism, Ambroise Paré University Hospital, AP-HP, 9 Av Charles de Gaulle, F-92104 Boulogne-Billancourt Cedex, France
- Faculté de Paris Ile-de-France Ouest, Université de Versailles Saint Quentin en Yvelines, 9 boulevard d'Alembert, F-78280 Guyancourt, France
| | - Samuel Castro
- Intensive Care Unit, Section Thorax-Vascular Disease-Abdomen-Metabolism, Ambroise Paré University Hospital, AP-HP, 9 Av Charles de Gaulle, F-92104 Boulogne-Billancourt Cedex, France
- Faculté de Paris Ile-de-France Ouest, Université de Versailles Saint Quentin en Yvelines, 9 boulevard d'Alembert, F-78280 Guyancourt, France
| | - Bernard Page
- Intensive Care Unit, Section Thorax-Vascular Disease-Abdomen-Metabolism, Ambroise Paré University Hospital, AP-HP, 9 Av Charles de Gaulle, F-92104 Boulogne-Billancourt Cedex, France
- Faculté de Paris Ile-de-France Ouest, Université de Versailles Saint Quentin en Yvelines, 9 boulevard d'Alembert, F-78280 Guyancourt, France
| | - François Jardin
- Intensive Care Unit, Section Thorax-Vascular Disease-Abdomen-Metabolism, Ambroise Paré University Hospital, AP-HP, 9 Av Charles de Gaulle, F-92104 Boulogne-Billancourt Cedex, France
- Faculté de Paris Ile-de-France Ouest, Université de Versailles Saint Quentin en Yvelines, 9 boulevard d'Alembert, F-78280 Guyancourt, France
| | - Antoine Vieillard-Baron
- Intensive Care Unit, Section Thorax-Vascular Disease-Abdomen-Metabolism, Ambroise Paré University Hospital, AP-HP, 9 Av Charles de Gaulle, F-92104 Boulogne-Billancourt Cedex, France
- Faculté de Paris Ile-de-France Ouest, Université de Versailles Saint Quentin en Yvelines, 9 boulevard d'Alembert, F-78280 Guyancourt, France
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Assessing gas exchange in acute lung injury/acute respiratory distress syndrome: diagnostic techniques and prognostic relevance. Curr Opin Crit Care 2011; 17:18-23. [PMID: 21157313 DOI: 10.1097/mcc.0b013e32834272d8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW To provide the most recent insights on the assessment of gas exchange in acute lung injury. RECENT FINDINGS Central venous blood may be used as a surrogate of arterial blood to assess carbon dioxide tension and acid-base status. In contrast arterial oxygenation cannot be estimated with confidence from venous blood. However, the use of venous blood associated with pulse oximetry may provide the SvO2 which is useful for monitoring and targeting the resuscitation therapy. Impaired CO2 clearance and increased dead space have been confirmed as useful prognostic indices of structural lung damage and mortality in acute respiratory failure. A simplified technique based on multiple inert gas technique has been described to assess ventilation-perfusion mismatch while a new analysis of pulse oximetry has been suggested to detect lung opening and closing. Finally, new insight has been provided on the relationship between lung anatomy, as detected by computed tomography, oxygenation and CO2 clearance. SUMMARY Although oxygenation assessment is of primary importance during respiratory lung injury, dead space and CO2 retention are more strictly associated with outcome. The association of central venous blood analysis and pulse oximetry may provide more information than arterial blood alone.
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Abstract
The acute respiratory distress syndrome (ARDS) is a complex disorder of heterogeneous etiologies characterized by a consistent, recognizable pattern of lung injury. Extensive epidemiologic studies and clinical intervention trials have been conducted to address the high mortality of this disorder and have provided significant insight into the complexity of studying new therapies for this condition. The existing clinical investigations in ARDS will be highlighted in this review. The limitations to current definitions, patient selection, and outcome assessment will be considered. While significant attention has been focused on the parenchymal injury that characterizes this disorder and the clinical support of gas exchange function, relatively limited focus has been directed to hemodynamic and pulmonary vascular dysfunction equally prominent in the disease. The limited available clinical information in this area will also be reviewed. The current standards for cardiopulmonary management of the condition will be outlined. Current gaps in our understanding of the clinical condition will be highlighted with the expectation that continued progress will contribute to a decline in disease mortality.
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Affiliation(s)
- Michael Donahoe
- Department of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Sinha P, Flower O, Soni N. Deadspace ventilation: a waste of breath! Intensive Care Med 2011; 37:735-46. [DOI: 10.1007/s00134-011-2194-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 02/06/2011] [Indexed: 10/18/2022]
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