Table 1

Incidence of nosocomial pneumonia and ARDS: methods used

Authors	Study			Diagnosis of pneumonia
Authors	No. of patients	Inclusion criteria		Design	Mean (SD) MV	Clinical criteria	Sampling method
Seidenfeld et al 10	129		ARDS	Observational for infections		—		1. Positive sputum culture	—
								2. New radiographic infiltrates
								3. Clinical evidence of infection
Sutherlandet al 12	105		ARDS	Surveillance, specimens on days 3, 7, 14, and 21		25^1-a		1. Fever (>38.3°C, rectal)	PSB, BAL
								2. Leucocytosis (>10 000/mm³)
								3. Purulent sputum with bacterial growth or positive Gram stain
								4. Focal radiographic infiltrate^1-b
Delclaux et al 13	30		ARDS	Surveillance, specimens taken every 48–72 h		19 (12)		1. Fever (⩾38.3°C)	PTC, BAL
								2. Leucocytosis (>10 000/mm³)
								3. Increased volume or purulent sputum
								4. Focal radiographic infiltrate^1-b
Meduriet al 14	111		ARDS and clinical criteria of pneumonia	Diagnostic comparison		23 (14)^1-c		Fever (⩾38.3°C) and at least one of the following:	Bilateral BAL
								1. New and persistent infiltrates in
								2. The chest radiograph
								3. Leucocytosis (>10 000/mm³)
								4. Purulent tracheal aspiration
Chastre et al 15	56		MV ⩾48 hours, ARDS identified during ICU stay	Observational, specimens taken on clinical suspicion of pneumonia		26 (26)		1. Clinical deterioration	PSB, BAL, ICO
								2. Fever, or
								3. Modification of chest radiograph

BAL = bronchoalveolar lavage; EA = endotracheal aspirate; MV = duration of mechanical ventilation during the study period; ICO = intracellular organisms; PSB = protected specimen brush; PTC = single-sheathed plugged telescopic catheter.
↵1-a No standard deviation given.
↵1-b At least three criteria for possible pneumonia; all four criteria for probable pneumonia.
↵1-c For all episodes.