Severe community acquired pneumonia: a one-year analysis in a tertiary referral intensive care unit.

AIMS: To define outcomes, characteristics, microbiology and salient prognostic factors of patients admitted to our intensive care unit (ICU) with severe community acquired pneumonia, over a one year period.

METHODS: All adult patients with severe community acquired pneumonia admitted between July 1997 and July 1998 were studied. Data were extracted by retrospective chart review. Variables assessed included underlying conditions and baseline physical parameters. Evolutionary variables eg, septic shock and laboratory data including microbiology and arterial blood gas determinants were also assessed. Prognostic factors were determined by comparison of the above variables between survivors and non-survivors. The prognostic value of the British Thoracic Society discriminant 'rule one' was assessed. Results. 32 patients were assessed. ICU mortality was 31%. 84% of patients had co-morbidity. The average age was 58.5 (SD 17.4) years and the average APACHE 11 score was 20.37 (SD 9.12). A microbiological diagnosis was made in 40%. Mortality was not increased in those in whom a bacterial diagnosis was not made. Commonest pathogens isolated were Streptococcus pneumoniae (46%), gram negative organisms (29%) and Staphylococcus aureus (23%). Prognostic factors on and during ICU admission were the need for mechanical ventilation (p=0.0003), septic shock (p=0.02), inotrope requirement (p=0.003), low serum albumin (p=0.041), base deficit (p=0.04), INR (p=0.02) and inspired oxygen concentration (p=0.003). On initial admission to hospital the presence of bilateral pneumonia was the only variable correlated with outcome (p=0.01). The British Thoracic Society 'rule one' did not correlate with death either on admission to hospital or ICU.

CONCLUSIONS: Severe community acquired pneumonia carries a high mortality despite ICU management. Bacterial diagnostic rate was low but made no difference to mortality. Streptococcus pneumoniae was the commonest causative pathogen. The development of septic shock, requirement for mechanical ventilation and bilateral disease are important adverse prognostic indicators.