Abstract: We included three RCTs that randomly assigned a total of 1089 participants recruited from 43 ICUs in Australia, Canada, Saudi Arabia, Spain and the USA. Risk of bias of the included studies was low. Only data for mortality and barotrauma could be combined in the meta-analysis. We downgraded the quality of evidence for the three mortality outcomes on the basis of serious imprecision around the effect estimates. For mortality in hospital, the RR with PCV compared with VCV was 0.83 (95% CI 0.67 to 1.02; three trials, 1089 participants; moderate-quality evidence), and for mortality in the ICU, the RR with PCV compared with VCV was 0.84 (95% CI 0.71 to 0.99; two trials, 1062 participants; moderate-quality evidence). One study provided no evidence of clear benefit with the ventilatory mode for mortality at 28 days (RR 0.88, 95% CI 0.73 to 1.06; 983 participants; moderate-quality evidence). The difference in effect on barotrauma between PCV and VCV was uncertain as the result of imprecision and different co-interventions used in the studies (RR 1.24, 95% CI 0.87 to 1.77; two trials, 1062 participants; low-quality evidence). Data from one trial with 983 participants for the mean duration of ventilation, and from another trial with 78 participants for the mean number of extrapulmonary organ failures that developed with PCV or VCV, were skewed. None of the trials reported on infection during ventilation or quality of life after discharge. Currently available data from RCTs are insufficient to confirm or refute whether pressure-controlled or volume-controlled ventilation offers any advantage for people with acute respiratory failure due to acute lung injury or acute respiratory distress syndrome. More studies including a larger number of people given PCV and VCV may provide reliable evidence on which more firm conclusions can be based.

Plain-language summary: The three randomized trials compared PCV versus VCV in a total of 1089 adults with ALI/ARDS from 43 ICUs in five high-income countries. None of the trials were industry-funded. The evidence is current to October 2014. We could not be sure whether the proportions of patients who died in hospital were very different between those treated with PCV and with VCV. For every 1000 persons treated with VCV, 636 deaths were reported. On the basis of our results, we could expect to see between 210 fewer deaths and 13 more deaths with PCV. We found that effects on mortality in the ICU and on mortality at 28 days were similarly uncertain. Our results include the possibility that VCV or PCV could be better for reducing the duration of ventilation or the development of traumatic lung damage caused by ventilation (barotrauma). None of the studies provided reliable information regarding to what extent failure of other organs would be impacted by the type of ventilation, nor did they provide information on differences in infection risk or quality of life following discharge from intensive care. The overall evidence for mortality was of moderate quality. For outcomes such as duration of ventilation, barotrauma and organ failure, evidence was limited by the small numbers studied, the different methods used in the studies or differences in reporting of results, which made interpretation difficult. Available evidence is insufficient to confirm whether PCV offers any advantage over VCV in improving outcomes for people with acute lung injury on ventilator machines. More studies including a larger number of people given PCV and VCV may provide reliable evidence on which more firm conclusions can be based.