Supine body position as a risk factor for nosocomial pneumonia in mechanically ventilated patients: a randomised trial

Drakulovic. Lancet 1999;354:1851-58

Clinical Question

• In patients who are mechanically ventilated does the semi-recumbent position vs. supine position reduce clinically suspected pneumonia?

Design

• Randomised controlled trial
• Computer-generated list
• Consecutive patients
• Sample size calculation: 182 patients required to show a 20% absolute risk reduction with a projected frequency in the supine group of 40%, with a false negative rate of 20% and false positive rate of 5%
• Planned interim analysis completed after 50% recruitment. This demonstrated a significant difference and the trial was stopped early
• Modified intention to treat analysis
• Non-blinded
• Univariate and multivariate analysis completed

Setting

• A respiratory ICU and a medical ICU in a tertiary university hospital in Spain
• June 1997 – May 1998

Population

• Inclusion criteria: Not stated
• Exclusion criteria: Abdominal or neurosurgical intervention within 7 days; shock refractory to vasoactive drugs or volume therapy; previous endotracheal intubation within 30 days
• 90 patients randomised
  • 47 patients randomised to control group, all completed and included in trial
  • 43 patients randomised to intervention group, 4 patients excluded (1 died during resuscitation, 3 excluded due to protocol violation [re-intubation])
• Comparing intervention vs. control groups
  • Mean age: 67 vs. 63
  • Cause of acute respiratory failure
    • COPD: 34% vs. 33%
    • Other pulmonary diseases 26% vs. 21%
  • Mean APACHE II Score: 23.8 vs. 21.3
  • Duration of mechanical ventilation (hrs): 171 vs. 145
  • Use of large bore NG tube: 87% vs. 72%
  • Enteral nutrition: 60% vs. 56%

Intervention

• Semi-recumbent (45 degrees)

Control

• Supine body position (0 degrees)

Outcome

• Primary outcome: frequency of clinically suspected pneumonia (Defined as new and persistent infiltrates on Chest x-ray most likely to be due to infection, + at least 2 of: temp >38.3; WBC <4 or >12; purulent tracheal secretions)
  • Significantly lower in semi-recumbent vs. supine: 8% vs. 34% (95% C.I. for difference 10-42, P=0.003)
• Secondary outcomes:
  • Microbiological confirmed pneumonia (defined in patient with clinically suspected pneumonia with bacterial growth above defined threshold of pathogenic microorganism in tracheobronchial aspirate, bronchoalveolar lavage, or protected specimen brush)
    • Significantly lower in semi-recumbent vs. supine: 5% vs. 23% (95% C.I. for difference 4-33, P=0.018)
    • Incidence rate of microbiologically confirmed pneumonia 7.3/1000 ventilator days in semi-recumbent vs. 28.4/1000 ventilator days in supine
  • Incidence of clinically suspected pneumonia: 10.9/1000 ventilator days in semi-recumbent vs. 41.2/1000 ventilator days in supine
  • ICU mortality – no significant difference
    • 18% in semi-recumbent vs. 28% in supine (95% C.I. -7.6 to 27.6, P=0.289)
  • Univariate logistic regression analysis demonstrated that enteral nutrition and supine body position were significantly associated with clinically suspected and microbiologically confirmed pneumonia

Authors’ Conclusions

• In mechanically ventilated patients nosocomial pneumonia is reduced with the use of a semi-recumbent position

Strengths

• Randomised controlled trial
• Clear definition for primary and secondary outcomes

Weaknesses

• Terminated early with low number of patients included
• Outcome assessors non-blinded
• Inclusion criteria not clearly defined
• Single hospital

The Bottom Line

• This small randomised trial has a number of weaknesses, but still provides convincing evidence that the risk of clinically suspected, and microbiologically confirmed pneumonia, is reduced in mechanically ventilated patients who are semi-recumbent vs. supine.

External Links

• [article] Supine body position as a risk factor for nosocomial pneumonia in mechanically ventilated patients: a randomised trial
• [further reading] PulmCCM: Ventilator bundles (VAP bundles) not evidence-based, shouldn’t be standard care
• [Further reading] Preventing Ventilator-Associated Pneumonia Does the Evidence Support the Practice?
• [Further reading] Critical Care Network in North West London: Ventilator Care Bundle

Metadata

Summary author: Dave Slessor
Summary date: 6th December 2015
Peer-review editor: Steve Mathieu