Probiotics for Prevention of Ventilator-Associated Pneumonia (VAP)
Do probiotics prevent ventilator-associated pneumonia (VAP)? There’s a good biologic rationale: administering friendly commensal bacteria like Lactobacillus into the GI tract could suppress the emergence of more virulent gut bacteria like Pseudomonas, Klebsiella and Citrobacter, which travel up the esophagus and sneak around endotracheal tube cuffs during mechanical ventilation to cause VAP. A 2010 meta-analysis of 5 randomized trials concluded that yes, probiotics prevented ventilator-associated pneumonia with a pooled odds ratio of ~0.60, without improving mortality.
Since that meta-analysis, 4 more randomized trials have been published including 631 patients. After performing their own meta-analysis including these more recent trials, with an n of 1,142, Wan-Jie Gu, Chun-Yin Wei, and Rui-Xing Yin of Guangxi Medical University (China) conclude that in fact, probiotics provide no protection overall against ventilator-associated pneumonia, and do not reduce mortality. They publish their results in the October 2012 Chest.
They did not include 2 of the trials from the 2010 meta-analysis, they say because those trials lacked a consistent definition of VAP cases. However, they say that inclusion of those 2 trials wouldn’t have changed the result. The odds ratio was 0.82 for ventilator associated pneumonia while receiving probiotics, with a 95% CI of 0.55-1.24 (p = .35).
Most of the positive studies reported extremely high VAP rates (~50-80%), calling into question their applicability, since most centers report dramatically lower VAP incidence.
Trauma patients were one group that did seem to benefit from probiotics as prevention for ventilator associated pneumonia, with more than one study in this population suggesting a benefit.
Probiotics as prevention for VAP and health-care associated pneumonia never really caught on. Evidence suggests that probiotics do prevent antibiotic associated diarrhea, and probiotics’ potential role in C. difficile treatment and prevention is being debated. The study and use of probiotics have been hampered by lack of standardization of the species and doses used.
For the interested reader, PulmCCM.org has previously reviewed many other prevention techniques for ventilator associated pneumonia, including VAP bundles, subglottic suctioning, automatic cuff pressure maintenance, early tracheostomy, aerosolized antibiotics for VAP, and gut decontamination for VAP.
The reported incidence of VAP is rapidly declining, probably both through increased adherence with prevention strategies, and (if you’re cynical) a rising tendency to define respiratory infections in the ICU as ventilator-associated tracheobronchitis — which, as a non-”never event,” will continue to be reimbursed by third party payers — rather than as ventilator associated pneumonia.
Wan-Jie Gu, Chun-Yin Wei, and Rui-Xing Yi. Lack of Efficacy of Probiotics in Preventing Ventilator-Associated Pneumonia:A Systematic Review and Meta-analysis of Randomized Controlled Trials. Chest 2012; 142: 859-868.