Association between serum osmolality and the risk of ventilator-associated pneumonia in patients undergoing prolonged mechanical ventilation: a retrospective cohort study from MIMIC-IV database

Background

The study aimed to investigate the relationship between serum osmolality with the risk of ventilator-associated pneumonia (VAP) and in-hospital mortality in patients with prolonged mechanical ventilation (PMV).

Method

This study was a retrospective cohort study with data derived from the Medical Information Mart for Intensive Care database. Patients were categorized into two groups based on a serum osmolality cutoff of 295 mmol/L, with the reference group having values below 295 mmol/L. The primary outcome variable was the occurrence of VAP. The secondary outcome was in-hospital mortality. Logistic and Cox regression models assessed the effects of serum osmolality on VAP risk and in-hospital mortality, respectively, with sensitivity analysis conducted post-propensity score matching (PSM).

Results

The study included a total of 6749 patients a median follow-up duration along with the first and third quartiles of 9.23 (5.96, 15.95) days. Among the included patients, 574 cases of VAP occurred, and 1143 patients died in the hospital. The analysis revealed that compared to the reference group with serum osmolality <295 mmol/L, serum osmolality ≥295 mmol/L was associated with a higher risk of VAP occurrence [odds ratio (OR): 1.36, 95 % confidence interval (CI): 1.11–1.67] and a higher risk of in-hospital mortality [hazard ratio (HR): 1.22, 95 %CI: 1.06–1.40] (all P < 0.05). The analysis results after PSM matching were still significant (all P < 0.05).

Conclusions

Serum osmolality at the initiation of ventilation significantly correlated with the risks of VAP occurrence and in-hospital mortality in patients on PMV. This study highlights the importance of maintaining serum osmolality for patients undergoing PMV.