[Acute respiratory failure in a medical intensive care unit. Incidence and prognosis]

Acute respiratory failure had occurred in 89 of 1594 patients in a medical intensive care unit (5.6%), 26.8% of all patients (332) on long-term mechanical ventilation. Compared with the other chronically ventilated patients those with acute respiratory failure averaged a lower age, the proportion of women was higher and the duration of ventilation longer. The death rate was significantly higher (78.7% compared with 58.3%). The important prognostic factors included the underlying disease, additional abnormal organ function, severity of pulmonary gas exchange abnormality, and advanced age. If there was septicaemia, peritonitis, liver cirrhosis with bleeding oesophageal varices or polytrauma with acute renal failure the death rate was over 80%; after hypovolaemic shock, pancreatitis or postoperative pulmonary failure it was less than 65%. Patients who had abnormal function of at most one other organ in addition and an inspiratory arterial pO2 difference below 250 mm Hg, measured 12 hours after onset of mechanical ventilation, had a relatively favourable prognosis with a death rate of 33%, while in the other groups of patients it was 86-100%.