Background and importance
Critically ill patients receiving assistance from breathing machines (ventilators) may be restored to normal breathing using clinical methods (collectively termed weaning) that require both expertise and continuous monitoring. Inefficient weaning may result in a prolonged time on a ventilator, putting patients at risk of lung injury, pneumonia and death. At times, delivery of the most effective and efficient care can be difficult due to organizational constraints. Computerized weaning systems may provide a solution to inefficient weaning methods. In this Cochrane review we evaluated if computerized weaning systems were more effective than clinical methods used by clinicians for reducing inappropriate delays in weaning, the overall duration of ventilation, and the length of intensive care unit (ICU) and hospital stays.
Findings
We identified 21 studies that provided information on a total of 1676 people including 1628 adults and 48 children. The evidence was current to 30th September 2013. Studies were conducted in people with medical reasons such as pneumonia and other infections for needing admission to ICU, people admitted following trauma, and people admitted after heart or other forms of surgery. As well, various commercially available computerized weaning systems were studied. We found that computerized weaning systems resulted in a reduced weaning duration as well as reduced overall time on the ventilator and stay in an ICU. The average time required for a person to be weaned off the ventilator was reduced by 30%. The overall time on the ventilator was reduced by 10% and the length of stay in ICU by 8%. Not all studies demonstrated these reductions. Studies conducted only in people admitted to ICU following surgery did not demonstrate reductions in weaning, overall time on a ventilator or ICU stay.
Limitations
Because of differences in the methods and results of some studies included in this review, further large scale research is warranted. There is also a need for more studies that examine the effect of computerized weaning systems in children.
Automated closed loop systems may result in reduced duration of weaning, ventilation and ICU stay. Reductions are more likely to occur in mixed or medical ICU populations. Due to the lack of, or limited, evidence on automated systems other than Smartcare/PS™ and Adaptive Support Ventilation no conclusions can be drawn regarding their influence on these outcomes. Due to substantial heterogeneity in trials there is a need for an adequately powered, high quality, multi-centre randomized controlled trial in adults that excludes 'simple to wean' patients. There is a pressing need for further technological development and research in the paediatric population.
Automated closed loop systems may improve adaptation of mechanical support for a patient's ventilatory needs and facilitate systematic and early recognition of their ability to breathe spontaneously and the potential for discontinuation of ventilation. This review was originally published in 2013 with an update published in 2014.
The primary objective for this review was to compare the total duration of weaning from mechanical ventilation, defined as the time from study randomization to successful extubation (as defined by study authors), for critically ill ventilated patients managed with an automated weaning system versus no automated weaning system (usual care).
Secondary objectives for this review were to determine differences in the duration of ventilation, intensive care unit (ICU) and hospital lengths of stay (LOS), mortality, and adverse events related to early or delayed extubation with the use of automated weaning systems compared to weaning in the absence of an automated weaning system.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 8); MEDLINE (OvidSP) (1948 to September 2013); EMBASE (OvidSP) (1980 to September 2013); CINAHL (EBSCOhost) (1982 to September 2013); and the Latin American and Caribbean Health Sciences Literature (LILACS). Relevant published reviews were sought using the Database of Abstracts of Reviews of Effects (DARE) and the Health Technology Assessment Database (HTA Database). We also searched the Web of Science Proceedings; conference proceedings; trial registration websites; and reference lists of relevant articles. The original search was run in August 2011, with database auto-alerts up to August 2012.
We included randomized controlled trials comparing automated closed loop ventilator applications to non-automated weaning strategies including non-protocolized usual care and protocolized weaning in patients over four weeks of age receiving invasive mechanical ventilation in an ICU.
Two authors independently extracted study data and assessed risk of bias. We combined data in forest plots using random-effects modelling. Subgroup and sensitivity analyses were conducted according to a priori criteria.
We included 21 trials (19 adult, two paediatric) totaling 1676 participants (1628 adults, 48 children) in this updated review. Pooled data from 16 eligible trials reporting weaning duration indicated that automated closed loop systems reduced the geometric mean duration of weaning by 30% (95% confidence interval (CI) 13% to 45%), however heterogeneity was substantial (I2 = 87%, P < 0.00001). Reduced weaning duration was found with mixed or medical ICU populations (42%, 95% CI 10% to 63%) and Smartcare/PS™ (28%, 95% CI 7% to 49%) but not in surgical populations or using other systems. Automated closed loop systems reduced the duration of ventilation (10%, 95% CI 3% to 16%) and ICU LOS (8%, 95% CI 0% to 15%). There was no strong evidence of an effect on mortality rates, hospital LOS, reintubation rates, self-extubation and use of non-invasive ventilation following extubation. Prolonged mechanical ventilation > 21 days and tracheostomy were reduced in favour of automated systems (relative risk (RR) 0.51, 95% CI 0.27 to 0.95 and RR 0.67, 95% CI 0.50 to 0.90 respectively). Overall the quality of the evidence was high with the majority of trials rated as low risk.