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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 injurya with PaO2/FIO2 ≤ 300 Diagnosis of acute lung injurya and PaO2/FIO2 ≤ 250 Diagnosis of acute lung injurya 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 509b 385 versus 383c
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)
  1. 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.
  2. 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].
  3. 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).
  4. 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).