Helping patients to breathe with the use of a mechanical ventilator can be life saving. Yet as the duration of ventilation increases so does the likelihood of harmful effects such as (1) mechanical injury to the throat or vocal cords, (2) injury to or infection of the lungs and (3) complications of prolonged patient immobility such as clots in the legs or lungs and various infections (for example in the urinary tract). It is important therefore to recognize straight away when patients are ready to breathe for themselves so that the ventilator support can be reduced and stopped (this is known as weaning) as soon as possible. Usually weaning decisions are left to the judgement of the staff but recently protocols (or written guidelines) for weaning have been found to be both safe for patients and useful for staff. Some studies claimed that using protocols led to better practice, but there was no clear evidence that using them actually produced beneficial results for patients.
This review looked at the results of 11 studies involving 1971 critically ill patients. The studies compared the use of protocols to wean patients from the ventilator against usual practice and were conducted in America, Europe and Australia. The varied intensive care units cared for patients with heart conditions, breathing difficulties, head injuries, trauma and following major surgery. In eight studies, intensive care staff followed protocol guidelines to reduce the ventilator support; in three studies ventilator support was reduced by programmed computers according to a protocol. Overall, results showed that in comparison with usual practice, the average total time spent on the ventilator was reduced by 25%. The duration of weaning was reduced by 78% and length of stay in the intensive care unit reduced by 10%. However, these reductions were not consistent across all studies.
Among the 11 studies, there was considerable variation in the types of protocols used, the criteria for considering when to start weaning, the methods of weaning (by professionals or computers), the medical conditions of the patients and usual practice in weaning. There were insufficient studies to enable us to explore whether or not these factors were responsible for inconsistencies in individual studies. Caution will need to be applied when generalizing our findings to other intensive care units.