Investigation of continuous effect modifiers in a meta-analysis on higher versus lower PEEP in patients requiring mechanical ventilation - protocol of the ICEM study

Kasenda, Benjamin; Sauerbrei, Willi; Royston, Patrick; Briel, Matthias

doi:10.1186/2046-4053-3-46

Table 1 Characteristics of ALVEOLI, LOVS, and ExPress studies

From: Investigation of continuous effect modifiers in a meta-analysis on higher versus lower PEEP in patients requiring mechanical ventilation - protocol of the ICEM study

	ALVEOLI (2004)	LOVS (2008)	ExPress (2008)
Inclusion criteria	Diagnosis of acute lung injury^a with PaO₂/FIO₂ ≤ 300	Diagnosis of acute lung injury^a and PaO₂/FIO₂ ≤ 250	Diagnosis of acute lung injury^a with PaO₂/FIO₂ ≤ 300
Recruitment period	1999 to 2002	2000 to 2006	2002 to 2005
Number of recruiting hospitals, countries	23, United States	30, Canada, Australia, Saudi Arabia	37, France
Patients randomized to higher versus lower PEEP	276 versus 273	476 versus 509^b	385 versus 383^c
Validity:
Concealed allocation	Yes	Yes	Yes
Follow-up for hospital mortality until day 60	100%	100%	100%
Blinded outcome assessors and data analysts	Yes	Yes	Yes
Early stopping	Stopped for perceived futility	No	Stopped for perceived futility
Experimental intervention	Higher PEEP according to FiO₂ chart, recruitment maneuvers for first 80 patients	Higher PEEP according to FiO₂ chart, required plateau pressures ≤ 40 cmH₂O, recruitment maneuvers	PEEP as high as possible without increasing the maximum inspiratory plateau pressure > 28 to 30 cmH₂O
Control intervention	Conventional PEEP according to FiO₂ chart, required plateau pressures ≤ 30 cmH₂O, no recruitment maneuvers	Conventional PEEP according to FiO₂ chart, required plateau pressures ≤ 30 cmH₂O, no recruitment maneuvers	Conventional PEEP (between 5 and 9 cmH₂O) to meet oxygenation goals
Ventilator procedures	Target tidal volumes of 6 ml/kg of predicted body weight; plateau pressures ≤ 30 cmH₂O (with exception as above); respiratory rate ≤ 35 breaths/minute, adjusted to achieve arterial pH 7.30 to 7.45; ventilator mode: volume-assist control (except higher PEEP group in LOVS required pressure control); oxygenation goals: PaO₂ 55 to 80 mmHg and SPO₂ 88 to 95%; standardized weaning)

Abbreviations: ALVEOLI Assessment of Low tidal Volume and Elevated end-expiratory pressure to Obviate Lung Injury, LOVS Lung Open Ventilation Study, ExPress Expiratory Pressure study, PaO ₂ partial pressure of arterial oxygen, FiO ₂ fraction of inspired oxygen, PEEP positive end-expiratory pressure, SPO ₂ oxygen saturation as measured by pulse oximetry.
^aAccording to the American-European Consensus Conference [Bernard GR et al., American journal of respiratory and critical care medicine. 1994 Mar;149(3 Pt 1):818-24. PubMed PMID: 7509706].
^bIncludes two patients for whom consent was withdrawn prior to protocol initiation, without patient, family, and caregivers being aware of group assignment (which is 983 patients included in the analysis).
^cIncludes one patient for whom consent was withdrawn prior to protocol initiation, without patient, family, and caregiver awareness of assignment (which is 767 patients included in the analysis).

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