Acute respiratory distress syndrome and nosocomial pneumonia
- Hospital Clinic I Provincial, Servei de Pneumologia I Al.lèrgia Respiratoria, Villarroel 170, E-08036 Barcelona, Spain
- Dr A Torres.
- Received 22 February 1999
- Revision requested 20 April 1999
- Revised 20 May 1999
- Accepted 21 June 1999
The acute respiratory distress syndrome (ARDS) and nosocomial pneumonia share aetiological, physiopathological, and diagnostic properties that justify consideration of the relationship between these two diseases. The aetiology of ARDS can be separated into direct and indirect lung injury. In cases with indirect lung injury such as necrotising pancreatitis the cause of the lung injury may not be readily apparent, whereas in direct lung injury due to aspiration of gastric contents or pneumonia the role of infection is more clear. Sloane and co-workers, in a series of 153 patients, reported pneumonia as the underlying aetiology in 31% of all patients who developed ARDS.1 Furthermore, most patients with ARDS require mechanical ventilation which increases the risk of nosocomial pneumonia.2-4 This report reviews recent studies on the prevalence, incidence, and impact of nosocomial pneumonia on outcome in patients with ARDS.
Data on the prevalence of nosocomial pneumonia causing ARDS are not readily available. Although post mortem studies have shown that nosocomial pneumonia can be diagnosed by lower respiratory tract sampling in combination with quantitative bacterial cultures—for example, endotracheal aspirates or protected specimen brush—the lack of a true gold standard decreases the validity of the interpretation in vivo.5 In addition, to obtain reliable data on the prevalence of nosocomial pneumonia the microbiological and clinical data must be obtained within 24 hours of the onset of ARDS.
From 1995 to 1998 a total of 50 cases of ARDS were investigated with all required measurements at the University Hospital of Barcelona and the prevalence of nosocomial pneumonia in patients with ARDS was estimated to be 8% (four of 50). This figure included the coexistence of three conditions: (1) evolutionary and clinical criteria of ARDS,6 7 (2) clinical criteria of pneumonia,8 and (3) microbiological criteria of pneumonia.9 It is noteworthy that …