Invasive Mechanical Ventilation in Severe CAP Increased Mortality Risk

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There was an independent association between mortality and the combination of invasive MV, septic shock, increased blood serum potassium, and worse hypoxemia.
There was an independent association between mortality and the combination of invasive MV, septic shock, increased blood serum potassium, and worse hypoxemia.

Patients admitted to hospitals with severe community-acquired pneumonia (CAP) who subsequently required invasive mechanical ventilation (MV) had a higher mortality risk compared with individuals who did not require invasive MV, according to a study published by PLoS One.

Researchers recruited 3719 individuals diagnosed with CAP in Barcelona, Spain, and conducted a prospective observational study during the course of 12 years to determine the outcomes associated with invasive MV in this patient population. The purpose of this study was to identify a patient population within those with severe CAP with an observed high mortality rate to guide research trials toward interventions and treatments to reduce the mortality rate. 

Of the recruited individuals, 664 (18%) met criteria for severe CAP and 198 (30%) had septic shock. Regarding ventilation, 154 (23%) received invasive MV and 510 (77%) did not. However, of those individuals who did not receive invasive MV, 94 (18%) did receive noninvasive ventilation during their hospitalization.

Overall, the 30-day mortality rate was 22%, and intensive care unit (ICU) admission rate was 55%. Study results demonstrated a higher 30-day mortality rate and longer ICU stay in individuals treated with invasive MV (33%) compared with those not treated with invasive MV (18%).

Of note, individuals admitted to the ICU who were not intubated and not placed on invasive MV had a significantly lower 30-day mortality rate (adjusted odds ratio [OR], 0.77, 95% CI, 0.36-1.62; P =.49). Individuals placed on invasive MV and had septic shock had the highest mortality rate, whereas multivariate analysis found the combination of invasive MV, septic shock, severe hypoxemia, and high levels of blood serum potassium resulted in a higher 30-day mortality (area under the receiver operating characteristic, 0.78; 95% CI, 0.70-0.86).

The number of individuals predicted by Acute Physiology and Chronic Health Evaluation II (APACHE II) criteria to have a high mortality risk was lower than the actual mortality rate observed in individuals who received invasive MV. Mortality risk was found to be lower than predicted by the APACHE-II in those who did not undergo invasive MV (33.0% vs 26.0% and 18.0% vs 23.5%, respectively). Of individuals whose CAP was scored on either major or minor criteria according to Infectious Diseases Society of America/American Thoracic Society 2007 guidelines for severe CAP, those individuals with ≥1 major criteria had a higher mortality rate than those individuals with minor criteria (86%, 29% vs 59%, 16%, P <.001).

Researchers came to 2 major conclusions based on this study. First, individuals who received invasive MV had a higher 30-day mortality rate compared with those who did not. Second, there was an independent association between mortality and the combination of invasive MV, septic shock, increased blood serum potassium, and worse hypoxemia

The finding that patients with severe CAP who receive invasive MV have a significantly higher mortality risk than those who do not receive invasive MV should help guide more research regarding new interventions for patients with severe CAP who require invasive MV. Clinicians should also be encouraged to monitor for signs of sepsis and intervene early because of the significant association of sepsis with a higher mortality risk.  

Reference

Ferrer M, Travierso C, Cilloniz C, et al. Severe community-acquired pneumonia: characteristics and prognostic factors in ventilated and non-ventilated patients [published online January 25, 2018]. PLoS One. doi:10.1371/journal.pone.0191721

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