Abstract: We included 17 trials (with 2434 patients) in this updated review. The original review included 11 trials. The total geometric mean duration of mechanical ventilation in the protocolized weaning group was on average reduced by 26% compared with the usual care group (N = 14 trials, 95% confidence interval (CI) 13% to 37%, P = 0.0002). Reductions were most likely to occur in medical, surgical and mixed ICUs, but not in neurosurgical ICUs. Weaning duration was reduced by 70% (N = 8 trials, 95% CI 27% to 88%, P = 0.009); and ICU length of stay by 11% (N = 9 trials, 95% CI 3% to 19%, P = 0.01). There was significant heterogeneity among studies for total duration of mechanical ventilation (I2 = 67%, P < 0.0001) and weaning duration (I2 = 97%, P < 0.00001), which could not be explained by subgroup analyses based on type of unit or type of approach. There is evidence of reduced duration of mechanical ventilation, weaning duration and ICU length of stay with use of standardized weaning protocols. Reductions are most likely to occur in medical, surgical and mixed ICUs, but not in neurosurgical ICUs. However, significant heterogeneity among studies indicates caution in generalizing results. Some study authors suggest that organizational context may influence outcomes, however these factors were not considered in all included studies and could not be evaluated. Future trials should consider an evaluation of the process of intervention delivery to distinguish between intervention and implementation effects. There is an important need for further development and research in the neurosurgical population.

Plain-language summary: Study characteristics: This updated Cochrane review included 17 studies involving 2434 critically ill men and women who were being cared for in medical, surgical, neurosurgical and mixed medical/surgical intensive care units (ICUs). The studies compared the use of protocols to wean patients from the ventilator against usual practice. They were conducted in ICUs in America, Europe, Asia and Australia. The ICUs cared for patients with heart conditions, breathing difficulties, head injuries, trauma and following major surgery. In 13 studies, clinicians used weaning protocols to guide them to reduce the ventilator support. In four studies ventilator support was reduced automatically by programmed computers following a protocol. Results: In comparison with usual practice without protocols, the average total time spent on the ventilator was reduced by 26%. The duration of weaning was reduced by 70% and length of stay in the ICU reduced by 11%. Using protocols did not result in any additional harms. We found considerable variation in the types of protocols used, the criteria for considering when to start weaning, the medical conditions of the patients and usual practice in weaning. This means that we cannot say exactly which protocols will work best for particular patients, but we do know they have not been beneficial in neurosurgical patients. Quality of evidence: We graded the quality of the available evidence as moderate for duration of ventilation and harmful effects, and low for the duration of weaning and ICU length of stay. The reasons for our grading were that results were not consistent across the studies, and studies lacked sufficient detail about usual care practices.