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Carvajal C, Giraldo Ramirez ND, De La Hoz Castro AD, Vidal Vargas CG, Pacheco HA, Fernández Sánchez D, González Salazar LV, Romero Otta SS, Vergara Jaimes S, Bolivar Ospina JF, Correa Céspedes J, Narvaez Orozco A, Donado JH, Cadavid CA, De La Rosa G. Association of dead space fraction to mortality in patients with COVID-19-related ARDS: A historical cohort observational study. Med Intensiva 2024:S2173-5727(24)00161-9. [PMID: 38906791 DOI: 10.1016/j.medine.2024.06.009] [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: 12/18/2023] [Revised: 04/24/2024] [Accepted: 05/17/2024] [Indexed: 06/23/2024]
Abstract
OBJECTIVE To assess the correlation of dead space fraction (VD/VT) measured through time capnography, corrected minute volume (CMV) and ventilation ratio (VR) with clinical outcomes in COVID-19 patients requiring invasive mechanical ventilation. DESIGN Observational study of a historical cohort. SETTING University hospital in Medellin, Colombia. PARTICIPANTS Patients aged 15 and above with a confirmed COVID-19 diagnosis admitted to the ICU and requiring mechanical ventilation. INTERVENTIONS Measurement of VD/VT, CMV, and VR in COVID-19 patients. MAIN VARIABLES OF INTEREST VD/VT, CMV, VR, demographic data, oxygenation indices and ventilatory parameters. RESULTS During the study period, 1047 COVID-19 patients on mechanical ventilation were analyzed, of whom 446 (42%) died. Deceased patients exhibited a higher prevalence of advanced age and obesity, elevated Charlson index, higher APACHE II and SOFA scores, as well as an increase in VD/VT ratio (0.27 in survivors and 0.31 in deceased) and minute ventilation volume on the first day of mechanical ventilation. The multivariate analysis revealed independent associations to in-hospital mortality, higher VD/VT (HR 1.24; 95%CI 1.003-1.525; p = 0.046), age (HR 1.024; 95%CI 1.014-1.034; p < 0.001), and SOFA score at onset (HR: 1.036; 95%CI: 1.001-1.07; p = 0.017). CONCLUSIONS VD/VT demonstrated an association with mortality in COVID-19 patients with ARDS on mechanical ventilation. These findings suggest that VD/VT measurement may serve as a severity marker for the disease.
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Affiliation(s)
- Carlos Carvajal
- Hospital Pablo Tobón Uribe, Medellín, Antioquia, Colombia; Departamento de Cuidado Crítico de adulto.
| | | | | | - Carlos Guillermo Vidal Vargas
- Departamento de Investigación; Estudiante de Medicina, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
| | - Hemel Antonio Pacheco
- Departamento de Investigación; Estudiante de Medicina, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
| | | | - Laura Vannesa González Salazar
- Departamento de Investigación; Estudiante de Medicina, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
| | | | - Silvia Vergara Jaimes
- Departamento de Investigación; Estudiante de Medicina, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
| | - Juan Fernando Bolivar Ospina
- Departamento de Investigación; Estudiante de Medicina, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
| | - Juliana Correa Céspedes
- Departamento de Investigación; Estudiante de Medicina, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
| | | | - Jorge Hernando Donado
- Hospital Pablo Tobón Uribe, Medellín, Antioquia, Colombia; Departamento de Investigación
| | - Carlos Alberto Cadavid
- Hospital Pablo Tobón Uribe, Medellín, Antioquia, Colombia; Departamento de Cuidado Crítico de adulto
| | - Gisela De La Rosa
- Hospital Pablo Tobón Uribe, Medellín, Antioquia, Colombia; Departamento de Cuidado Crítico de adulto
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Sousa MLA, Katira BH, Bouch S, Hsing V, Engelberts D, Amato MBP, Post M, Brochard LJ. Limiting Overdistention or Collapse When Mechanically Ventilating Injured Lungs: A Randomized Study in a Porcine Model. Am J Respir Crit Care Med 2024; 209:1441-1452. [PMID: 38354065 DOI: 10.1164/rccm.202310-1895oc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Accepted: 02/14/2024] [Indexed: 02/16/2024] Open
Abstract
Rationale: It is unknown whether preventing overdistention or collapse is more important when titrating positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS). Objectives: To compare PEEP targeting minimal overdistention or minimal collapse or using a compromise between collapse and overdistention in a randomized trial and to assess the impact on respiratory mechanics, gas exchange, inflammation, and hemodynamics. Methods: In a porcine model of ARDS, lung collapse and overdistention were estimated using electrical impedance tomography during a decremental PEEP titration. Pigs were randomized to three groups and ventilated for 12 hours: PEEP set at ⩽3% of overdistention (low overdistention), ⩽3% of collapse (low collapse), and the crossing point of collapse and overdistention. Measurements and Main Results: Thirty-six pigs (12 per group) were included. Median (interquartile range) values of PEEP were 7 (6-8), 11 (10-11), and 15 (12-16) cm H2O in the three groups (P < 0.001). With low overdistension, 6 (50%) pigs died, whereas survival was 100% in both other groups. Cause of death was hemodynamic in nature, with high transpulmonary vascular gradient and high epinephrine requirements. Compared with the other groups, pigs surviving with low overdistension had worse respiratory mechanics and gas exchange during the entire protocol. Minimal differences existed between crossing-point and low-collapse animals in physiological parameters, but postmortem alveolar density was more homogeneous in the crossing-point group. Inflammatory markers were not significantly different. Conclusions: PEEP to minimize overdistention resulted in high mortality in an animal model of ARDS. Minimizing collapse or choosing a compromise between collapse and overdistention may result in less lung injury, with potential benefits of the compromise approach.
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Affiliation(s)
- Mayson L A Sousa
- Keenan Centre for Biomedical Research, Critical Care Department, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
- Interdepartmental Division of Critical Care Medicine and
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Bhushan H Katira
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
- Pediatric Critical Care Medicine, Washington University in St. Louis, St. Louis, Missouri
| | - Sheena Bouch
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Vanessa Hsing
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Doreen Engelberts
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Marcelo B P Amato
- Divisão de Pneumologia, Faculdade de Medicina da Universidade de São Paulo, Sao Paulo, Brazil
- Instituto do Coração - InCor, Hospital das Clinicas, Faculade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and
| | - Martin Post
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Laurent J Brochard
- Keenan Centre for Biomedical Research, Critical Care Department, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
- Interdepartmental Division of Critical Care Medicine and
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Ghiani A, Paderewska J, Walcher S, Neurohr C. Mechanical power normalized to lung-thorax compliance predicts prolonged ventilation weaning failure: a prospective study. BMC Pulm Med 2021; 21:202. [PMID: 34140018 PMCID: PMC8210735 DOI: 10.1186/s12890-021-01566-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 05/21/2021] [Indexed: 01/18/2023] Open
Abstract
Background Mechanical power (MP) of artificial ventilation, the energy transferred to the respiratory system, is a chief determinant of adequate oxygenation and decarboxylation. Calculated MP, the product of applied airway pressure and minute ventilation, may serve as an estimate of respiratory muscle workload when switching to spontaneous breathing. The aim of the study was to assess MP’s discriminatory performance in predicting successful weaning from prolonged tracheostomy ventilation. Methods Prospective, observational study in 130 prolonged mechanically ventilated, tracheotomized patients in a specialized weaning center. Predictive weaning outcome ability of arterial blood gas analyses and indices derived from calculated MP at beginning and end of weaning was determined in terms of area under receiver operating characteristic curve (AUROC) and measures derived from k-fold cross-validation (likelihood ratios, diagnostic odds ratio, F1 score, and Matthews correlation coefficient [MCC]). Results Forty-four (33.8%) patients experienced weaning failure. Absolute MP showed poor discrimination in predicting outcome; whereas specific MP (MP normalized to dynamic lung-thorax compliance, LTCdyn-MP) had moderate diagnostic accuracy (MCC 0.38; AUROC 0.79, 95%CI [0.71‒0.86], p < 0.001), further improved by correction for corresponding mechanical ventilation PaCO2 (termed the power index of the respiratory system [PIrs]: MCC 0.52; AUROC 0.86 [0.79‒0.92], p < 0.001). Diagnostic performance of MP indices increased over the course of weaning, with maximum accuracy immediately before completion (LTCdyn-MP: MCC 0.49; AUROC 0.86 [0.78‒0.91], p < 0.001; PIrs: MCC 0.68; AUROC 0.92 [0.86‒0.96], p < 0.001). Conclusions MP normalized to dynamic lung-thorax compliance, a surrogate for applied power per unit of ventilated lung volume, accurately discriminated between low and high risk for weaning failure following prolonged mechanical ventilation. Supplementary Information The online version contains supplementary material available at 10.1186/s12890-021-01566-8.
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Affiliation(s)
- Alessandro Ghiani
- Department of Pulmonology and Respiratory Medicine, Schillerhoehe Lung Clinic (affiliated to the Robert-Bosch-Hospital GmbH, Stuttgart), Solitudestrasse 18, 70839, Gerlingen, Germany.
| | - Joanna Paderewska
- Department of Pulmonology and Respiratory Medicine, Schillerhoehe Lung Clinic (affiliated to the Robert-Bosch-Hospital GmbH, Stuttgart), Solitudestrasse 18, 70839, Gerlingen, Germany
| | - Swenja Walcher
- Department of Pulmonology and Respiratory Medicine, Schillerhoehe Lung Clinic (affiliated to the Robert-Bosch-Hospital GmbH, Stuttgart), Solitudestrasse 18, 70839, Gerlingen, Germany
| | - Claus Neurohr
- Department of Pulmonology and Respiratory Medicine, Schillerhoehe Lung Clinic (affiliated to the Robert-Bosch-Hospital GmbH, Stuttgart), Solitudestrasse 18, 70839, Gerlingen, Germany.,German Center for Lung Research (DZL), München, Germany
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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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Ferluga M, Lucangelo U, Blanch L. Dead space in acute respiratory distress syndrome. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:388. [PMID: 30460262 DOI: 10.21037/atm.2018.09.46] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Dead space is the portion of each tidal volume that does not take part in gas exchange and represents a good global index of the efficiency of the lung function. Dead space is not routinely measured in critical care practice, because the difficulties in in interpreting capnograms and the different methods of calculations. Different dead space indices can provide useful information in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) patients, where changes in microvasculature are the main determinants for the increase in dead space and consequently a worsening of the outcome. Lung recruitment is a dynamic process that combines recruitment manoeuvres (RMs) with positive end expiratory pressure (PEEP) and low Vt to recruit collapsed alveoli. Dead space guided recruitment allows avoiding regional overdistension or reduction in cardiac output in critical care patients with ALI or ARDS. Different patterns of ventilation affect also CO2 elimination; in fact, end-inspiratory pause prolongation reduces dead space, increasing respiratory system compliance; plateau pressure and consequently driving pressure increase accordingly. Dead space measurement is a reliable method that provides important clinical and prognostic information. Different capnographic indices can be useful to evaluate therapeutic interventions or setting mechanical ventilation.
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Affiliation(s)
- Massimo Ferluga
- Emergency and Urgency Department, Cattinara Hospital, Trieste University, Trieste, Italy
| | - Umberto Lucangelo
- Emergency and Urgency Department, Cattinara Hospital, Trieste University, Trieste, Italy
| | - Lluis Blanch
- Critical Care Department, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Universitat Autònoma de Barcelona, Sabadell, Spain
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