Comparison of the Response to the Prone Position Between Pulmonary and Extrapulmonary Acute Respiratory Distress Syndrome

Intensive Care Med. 2001 Mar;27(3):477-85. doi: 10.1007/s001340000848.


Objectives: To determine whether the response to the prone position differs between acute respiratory distress syndrome (ARDS) resulting from a pulmonary cause (ARDSp) and that from an extrapulmonary cause (ARD-Sexp).

Design and setting: Prospective observational study in a medical ICU of a university-affiliated hospital.

Subjects: A consecutive series of 31 patients with ARDSp and 16 with ARDSexp within 3 days of onset of ARDS.

Intervention: Prone position for at least 2 h.

Measurements and results: In ARDSp, compared with the supine position (121 +/- 49 mmHg), PaO2/FIO2 was not increased after 0.5 h but was increased after 2 h in the prone position (158 +/- 60 mmHg). In ARDSexp, compared with the supine position (106 +/- 53 mmHg), PaO2/FIO2 was increased after 0.5 h (155 +/- 91 mmHg), but was not further changed after 2 h. Marked oxygenation response (increase in PaO2/FIO2 > 40% from baseline) after 0.5 h was 23% in ARDSp and 63% in ARDSexp, and that after 2 h was 29% and 63%, respectively. Static respiratory compliance decreased in the prone position in ARDSexp (30 +/- 11 ml/cmH2O at baseline, 27 +/- 11 after 0.5 h and 25 +/- 9 after 2 h) but not in ARDSp. Consolidation score as determined on the first chest radiography taken in the prone position decreased to a greater degree in ARDSexp (-2.4 +/- 4.1) than in ARDSp (0.3 +/- 4.1).

Conclusion: Pulmonary ARDS and extrapulmonary ARDS in their early stages respond differently to the prone position with regard to the time course of oxygenation, respiratory mechanical behaviour, and radiographic change. These findings suggest that the early pathophysiology of ARDS differs according to the type of primary insult to the lung.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Analysis of Variance
  • Blood Gas Analysis
  • Cause of Death
  • Critical Care / methods*
  • Female
  • Hemodynamics
  • Humans
  • Lung Compliance
  • Lung Diseases / complications*
  • Male
  • Middle Aged
  • Oxygen / blood
  • Positive-Pressure Respiration* / methods
  • Prone Position*
  • Prospective Studies
  • Radiography
  • Respiratory Distress Syndrome, Adult / blood
  • Respiratory Distress Syndrome, Adult / diagnostic imaging
  • Respiratory Distress Syndrome, Adult / etiology*
  • Respiratory Distress Syndrome, Adult / mortality
  • Respiratory Distress Syndrome, Adult / physiopathology
  • Respiratory Distress Syndrome, Adult / therapy*
  • Severity of Illness Index
  • Supine Position
  • Treatment Outcome


  • Oxygen