Obesity does not impact incidence of ventilator-associated pneumonia

Obesity does not appear to be associated with an increased incidence of ventilator-associated pneumonia among adults receiving invasive mechanical ventilation and vasopressor support, according to results published in Chest.

“Although mortality attributable to ventilator-associated pneumonia is a matter for debate, this infection is associated with increased duration of mechanical ventilation, length of ICU stay and cost,” Saad Nseir, MD, PhD, professor of critical care at University Hospital of Lille in France, and colleagues wrote. “Better understanding of pathophysiology and risk factors for ventilator-associated pneumonia could be helpful to improve its prevention and treatment.”

Nseir and colleagues performed a post hoc analysis of 2,325 adults from NUTRIREA2, an open-label, randomized controlled trial, who received invasive mechanical ventilation and vasopressor support for shock and parenteral or enteral nutrition in 44 French ICUs. Obesity was defined as a BMI of at least 30 kg/m² at ICU admission. Only first ventilator-associated pneumonia episodes were obtained.

The primary outcome was incidence of ventilator-associated pneumonia. Secondary outcomes included incidence of early-onset ventilator-associated pneumonia, duration of mechanical ventilation, ICU length of stay, 90-day mortality rates and incidence of abundant microaspiration of gastric contents or oropharyngeal secretions.

In the cohort, 699 patients (30%; mean age, 67.8 years; 63.7% men) had obesity.

There were 224 first ventilator-associated pneumonia episodes, with 60 episodes occurring in those with obesity and 164 occurring in those with normal weight. At 28 days, the incidence of ventilator-associated pneumonia was 8.6% among patients with obesity and 10.1% among those with normal weight (HR = 0.85; 95% CI, 0.63-1.14; P = .26). The incidence of ventilator-associated pneumonia remained nonsignificant between both groups after adjustment for variables (HR = 0.89; 95% CI, 0.66-1.2; P = .46).

Researchers observed no significant difference in duration of mechanical ventilation and length of ICU stay between the groups. Ninety-day mortality was lower among patients with obesity compared with those with normal weight (39.3% vs. 44.7%; P = .02).

In addition, there was no significant difference in the rate of abundant microaspiration of gastric contents or oropharyngeal secretions in a subgroup of 123 patients with pepsin and alpha-amylase measurements.

“Our results suggest that obesity is not associated with increased risk for ventilator-associated pneumonia,” the researchers wrote.