Protective mechanical ventilation in patients with risk factors for ARDS: prospective cohort study.

OBJECTIVE: To evaluate the association that protective mechanical ventilation (MV), based on VT and maximum distending pressure (MDP), has with mortality in patients at risk for ARDS. METHODS: This was a prospective cohort study conducted in an ICU and including 116 patients on MV who had at least one risk factor for the development of ARDS. Ventilatory parameters were collected twice a day for seven days, and patients were divided into two groups (protective MV and nonprotective MV) based on the MDP (difference between maximum airway pressure and PEEP) or VT. The outcome measures were 28-day mortality, ICU mortality, and in-hospital mortality. The risk factors associated with the adoption of nonprotective MV were also assessed. RESULTS: Nonprotective MV based on VT and MDP was applied in 49 (42.2%) and 38 (32.8%) of the patients, respectively. Multivariate Cox regression showed that protective MV based on MDP was associated with lower in-hospital mortality (hazard ratio = 0.37; 95% CI: 0.19-0.73) and lower ICU mortality (hazard ratio = 0.40; 95% CI: 0.19-0.85), after adjustment for age, Simplified Acute Physiology Score 3, and vasopressor use, as well as the baseline values for PaO2/FiO2 ratio, PEEP, pH, and PaCO2. These associations were not observed when nonprotective MV was based on the VT. CONCLUSIONS: The MDP seems to be a useful tool, better than VT, for adjusting MV in patients at risk for ARDS.

Protective mechanical ventilation in patients with risk factors for ARDS: prospective cohort study / Ventilação mecânica protetora em pacientes com fator de risco para SDRA: estudo de coorte prospectiva

ABSTRACT Objective: To evaluate the association that protective mechanical ventilation (MV), based on VT and maximum distending pressure (MDP), has with mortality in patients at risk for ARDS. Methods: This was a prospective cohort study conducted in an ICU and including 116 patients on MV who had at least one risk factor for the development of ARDS. Ventilatory parameters were collected twice a day for seven days, and patients were divided into two groups (protective MV and nonprotective MV) based on the MDP (difference between maximum airway pressure and PEEP) or VT. The outcome measures were 28-day mortality, ICU mortality, and in-hospital mortality. The risk factors associated with the adoption of nonprotective MV were also assessed. Results: Nonprotective MV based on VT and MDP was applied in 49 (42.2%) and 38 (32.8%) of the patients, respectively. Multivariate Cox regression showed that protective MV based on MDP was associated with lower in-hospital mortality (hazard ratio = 0.37; 95% CI: 0.19-0.73) and lower ICU mortality (hazard ratio = 0.40; 95% CI: 0.19-0.85), after adjustment for age, Simplified Acute Physiology Score 3, and vasopressor use, as well as the baseline values for PaO2/FiO2 ratio, PEEP, pH, and PaCO2. These associations were not observed when nonprotective MV was based on the VT. Conclusions: The MDP seems to be a useful tool, better than VT, for adjusting MV in patients at risk for ARDS.

RESUMO Objetivo: Avaliar a associação da ventilação mecânica (VM) protetora, com base no VT e na pressão de distensão máxima (PDM), com a mortalidade em pacientes com fator de risco para SDRA. Métodos: Este estudo de coorte prospectivo foi conduzido em uma UTI e incluiu 116 pacientes em VM que apresentavam pelo menos um fator de risco para o desenvolvimento de SDRA. Os parâmetros ventilatórios foram coletados duas vezes ao dia durante sete dias, e os pacientes foram divididos em dois grupos (VM protetora e VM não protetora) com base na PDM (diferença entre pressão máxima de vias aéreas e PEEP) ou no VT. Os desfechos foram mortalidade em 28 dias, mortalidade na UTI e mortalidade hospitalar. Os fatores de risco associados com a adoção da VM não protetora também foram avaliados. Resultados: A VM não protetora com base no VT e na PDM ocorreu em 49 (42,2%) e em 38 (32,8%) dos pacientes, respectivamente. A regressão multivariada de Cox mostrou que a VM protetora com base na PDM associou-se a menor mortalidade hospitalar (hazard ratio = 0,37; IC95%: 0,19-0,73) e em UTI (hazard ratio = 0,40; IC95%, 0,19-0,85), após ajuste para idade, Simplified Acute Physiology Score 3, uso de vasopressor e valores basais de PaO2/FiO2, PEEP, pH e PaCO2. Essas associações não foram observadas quando a VM não protetora foi baseada no VT. Conclusões: A PDM parece ser uma ferramenta útil, melhor do que o VT, para o ajuste da VM em pacientes sob risco para SDRA.

Ventilação mecânica protetora: revisão de ensaios clínicos randomizados / Protective mechanical ventilation: revision of randomized clinical trials

Introdução: A ventilação mecânica pode ser uma estratégia salvadora de vidas em pacientes com insuficiência respiratória. Porém, ela é potencialmente perigosa e pode causar a chamada lesão pulmonar induzida pela ventilação mecânica (VILI). Esta revisão objetivou analisar os resultados de ensaios clínicos randomizados (ECR) que avaliaram o impacto de ajustes ventilatórios sobre a mortalidade. Material e Métodos: Nós Buscou-se, na base PubMed ECR, artigos publicados entre 1980 e 2019, usando os seguintes termos MeSH: "respiratory distress syndrome, adult" and "respiration, artificial". Selecionou-se os ECR que compararam diferentes parâmetros ventilatórios e que tiveram a mortalidade como desfecho. Resultados: Em pacientes com síndrome do desconforto respiratório agudo (SDRA), demonstrou-se que a limitações do volume corrente, da pressão de platô e da pressão de distensão reduzem a mortalidade. Na SDRA grave, o uso de pressão expiratória final positiva (PEEP) mais alta e a posição prona também reduzem a mortalidade. Entre pacientes sem SDRA, ainda é incerto se alguma dessas estratégias associa-se a melhor sobrevida. Conclusão: Em pacientes com SDRA, deve-se estar atento para o ajuste da ventilação mecânica, pois parâmetros protetores podem aumentar a sobrevida.

Introduction: Mechanical ventilation can be a life-saving strategy in patients with respiratory failure. However, it is potentially dangerous and can induce a so-called ventilator-induced lung injury (VILI). This revision aimed to analyze the results of randomized clinical trials (RCT) that evaluated the impact of ventilatory settings on mortality. Material and Methods: We search in PubMed for RCT, published from 1980 to 2019, using the following MeSH terms: "respiratory distress syndrome, adult" and "respiration, artificial". We selected the RCT that compared different ventilatory settings and had mortality as an outcome. Results: In patients with acute respiratory distress syndrome (ARDS), it has been demonstrated that limiting tidal volume, plateau pressure, and driving pressure reduced mortality. In severe ARDS, the use of higher PEEP and prone position also reduced mortality. Among non-ARDS patients, it is still uncertain if any strategy is associated with better survival rates. Conclusion: In ARDS patients, one has to be aware of setting the ventilatory parameters because protective settings can improve survival.