Length of stay, duration of mechanical ventilation, mortality, and acute kidney injury in acute respiratory failure requiring endotracheal intubation.

BACKGROUND: Critically ill patients often present on admission or develop acute respiratory failure requiring intubation and application of positive pressure ventilation during their hospital stay. AIM: To investigate and identify the epidemiological data, parameters associated with respiratory settings or the mechanics, and values related to arterial blood gases (ABGs) that are associated with outcomes in critically ill patients. METHODS: A retrospective analysis of 131 patients [mean age, 67.3 years; mean acute physiology and chronic health evaluation (APACHE) score, 21.4] with acute respiratory failure requiring invasive mechanical ventilation was performed. The parameters that were statistically analyzed included demographic data, the presence of comorbidities, the presence of coronavirus disease 19 (COVID-19), the respiratory rate (RR), peak airway pressure (Ppeak), minute ventilation (MV), positive end-expiratory pressure, and the values related to ABGs. In order to facilitate the statistical analysis, patients were evaluated and compared in groups: Survivors (n = 41) vs non-survivors (n = 90) and patients without acute kidney injury (AKI) (n = 60) vs patients with AKI (n = 71). Four endpoints were studied: Mortality, length of stay, duration of mechanical ventilation, and AKI. Group comparisons were performed using the following statistical tests: The χ 2 test with Yates' correction, Fisher's exact test, the Mann-Whitney U test, and Spearman's rank correlation analysis. Binary logistic regression analysis conducted after the univariate statistical tests facilitated the investigation of the independent predictors of mortality and AKI. A two-sided P value of less than 0.05 was considered the threshold of statistical significance. RESULTS: Non-survivors presented statistically significant differences in terms of being older in age, the presence of comorbidities, elevated APACHE score, medical (vs surgical) reasons for admission, presence of COVID-19, lower pH at ABGs, lower values of the oxygenation ratio (arterial oxygen partial pressure to the fraction of inspired oxygen) and arterial oxygen partial pressure, and elevated values of Ppeak, positive end-expiratory pressure, RR, arterial carbon dioxide partial pressure, and MV. The factors identified as independent predictors of mortality were the presence of comorbidities, APACHE score, COVID-19 status, arterial carbon dioxide partial pressure, Ppeak, RR, and MV. COVID-19 presence and elevated values of RR and Ppeak were positively correlated with the other three endpoints (length of stay, the duration of mechanical ventilation in survivors, and the occurrence of AKI in the entire study population) that were studied. The other parameters exhibited a variable (either positive/negative, or no) correlation to the four endpoints under investigation. CONCLUSION: Among all investigated outcome measures, COVID-19, Ppeak, and RR were strongly associated with all the endpoints studied, suggesting that proper interventions involving the modifiable respiratory parameters Ppeak and RR could improve the overall outcome in these patients. A novel finding of this study was the relationship between RR and AKI, which is worthy of further investigation. Future studies may explore the clinical interpretation of these findings to improve outcomes in critically ill patients with acute respiratory failure.