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?


  • 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


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


  • 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%


  • Semi-recumbent (45 degrees)


  • Supine body position (0 degrees)
All patients routinely subjected to:
  • Sterile endotracheal suctioning
  • No change of mechanical ventilation tubing systems
  • Stress ulcer prophylaxis with sucralfate in patients who tolerated enteral nutrition, and IV ranitidine or omperazole in patients receiving TPN
  • Enteral nutrition
    • Starting rate 33.3ml/hr
    • Gastric aspiration performed every 4 hours
    • Target feed 30-35 kcal/kg/day
Study completed when any of the following criteria met:
  • 1st weaning trial
  • Extubation
  • Permanent change in body position for >45 minutes
  • Death


  • 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
supine vs semirecubment

Authors’ Conclusions

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


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


  • 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


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

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