The usefulness of weaning protocols for reducing the time critically ill adult patients spend on mechanical ventilation

Review question: We reviewed the evidence about the effect of weaning protocols (guidelines) used by clinicians on reducing the time that critically ill patients spent on a breathing machine.

Background: Helping patients to breathe with the use of a mechanical ventilator can be life saving. Yet the longer someone stays on a ventilator, the greater the likelihood of harmful effects including infection of the lungs and complications of prolonged immobility such as blood clots in the legs or lungs. It is important, therefore, to recognize early on when patients are ready to breathe for themselves so they can gradually come off the ventilator (this is called weaning). Usually, weaning is left to the judgement of clinicians, but recently protocols for weaning have been found to be safe for patients and useful for clinicians. Some studies said protocols led to better practice, but there was no clear evidence that using them actually produced beneficial results for patients.

Search date: The evidence is current to January 2014.

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.

Authors' conclusions: 

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.

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Background: 

This is an update of a review last published in Issue 5, 2010, of The Cochrane Library. Reducing weaning time is desirable in minimizing potential complications from mechanical ventilation. Standardized weaning protocols are purported to reduce time spent on mechanical ventilation. However, evidence supporting their use in clinical practice is inconsistent.

Objectives: 

The first objective of this review was to compare the total duration of mechanical ventilation of critically ill adults who were weaned using protocols versus usual (non-protocolized) practice.

The second objective was to ascertain differences between protocolized and non-protocolized weaning in outcomes measuring weaning duration, harm (adverse events) and resource use (intensive care unit (ICU) and hospital length of stay, cost).

The third objective was to explore, using subgroup analyses, variations in outcomes by type of ICU, type of protocol and approach to delivering the protocol (professional-led or computer-driven).

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2014), MEDLINE (1950 to January 2014), EMBASE (1988 to January 2014), CINAHL (1937 to January 2014), LILACS (1982 to January 2014),  ISI Web of Science and ISI Conference Proceedings (1970 to February 2014), and reference lists of articles. We did not apply language restrictions. The original search was performed in January 2010 and updated in January 2014.

Selection criteria: 

We included randomized controlled trials (RCTs) and quasi-RCTs of protocolized weaning versus non-protocolized weaning from mechanical ventilation in critically ill adults.

Data collection and analysis: 

Two authors independently assessed trial quality and extracted data. We performed a priori subgroup and sensitivity analyses. We contacted study authors for additional information.

Main results: 

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.

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