Efficacy and adverse events of high-frequency oscillatory ventilation in adult patients with acute respiratory distress syndrome: a meta-analysis

Table 1 Characteristics of the five adult studies included in the review

	Derdak et al. 2002[12]	Shah et al. 2004[13]	Bollen et al. 2005[14]	Ferguson et al. 2013[18]	Young et al. 2013[17]
Patients, number	148	28	61	548	795
Mean age, year	49.5	49.2	52.5	54.5	55.4
Male sex, number (%)	86 (58%)	18 (64%)	42 (69%)	320 (58%)	495 (62%)
APACHE II, mean^a	22	19.0	20.7	29	21.8
Enrollment period	1997-2000	Not reported	1997-2001	2007-2012	2007-2012
Enrollment criteria	PaO₂/F_IO₂ ≦200 with PEEP ≧10 cmH₂O	ARDS^b	PaO₂/F_IO₂ < 200	PaO₂/F_IO₂ ≦200 with F_IO₂ ≧0.5	PaO₂/F_IO₂ ≦200 with PEEP ≧5 cmH₂O
Mean PaO₂/F_IO₂ at enrollment	112.5	110.6	22.4^c	117.5	113
Ventilator days prior to study	3.5 (mean)	<5	1.9 (mean)	2.2 (mean)	2.2 (mean)

^aScored at randomization, except the study by Ferguson et al., in which scored at admission to the intensive care unit; ^bbased on the American-European Consensus Conference definition of the acute respiratory distress syndrome; ^coxygenation index. APACHE II, Acute Physiology and Chronic Health Evaluation II; PaO₂, partial pressure of oxygen in arterial blood; F_IO₂, fraction of inspired oxygen; PEEP, positive end-expiratory pressure; ARDS, acute respiratory distress syndrome.

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