Abstract: We included 11 studies in our synthesis, involving 267 participants (one study did not report the number of participants). Five more studies are awaiting classification and will be dealt with when we update the review. The quality of the evidence was mixed; of the 35 summary statements, we assessed 17 as ‘low’, 13 as ‘moderate’ and five as ‘high’ confidence. Our synthesis produced nine analytical themes, which report potential barriers and facilitators to the use of protocols. The themes are: the need for continual staff training and development; clinical experience as this promotes felt and perceived competence and confidence to wean; the vulnerability of weaning to disparate interprofessional working; an understanding of protocols as militating against a necessary proactivity in clinical practice; perceived nursing scope of practice and professional risk; ICU structure and processes of care; the ability of protocols to act as a prompt for shared care and consistency in weaning practice; maximizing the use of protocols through visibility and ease of implementation; and the ability of protocols to act as a framework for communication with parents. There is a clear need for weaning protocols to take account of the social and cultural environment in which they are to be implemented. Irrespective of its inherent strengths, a protocol will not be used if it does not accommodate these complexities. In terms of protocol development, comprehensive interprofessional input will help to ensure broad-based understanding and a sense of ‘ownership’. In terms of implementation, all relevant ICU staff will benefit from general weaning as well as protocol-specific training; not only will this help secure a relevant clinical knowledge base and operational understanding, but will also demonstrate to others that this knowledge and understanding is in place. In order to maximize relevance and acceptability, protocols should be designed with the patient profile and requirements of the target ICU in mind. Predictably, an under-resourced ICU will impact adversely on protocol implementation, as staff will prioritize management of acutely deteriorating and critically-ill patients.

Plain-language summary: Our synthesis included 11 studies, involving around 267 participants; five more studies are awaiting classification. We identified several potential barriers and facilitators to the use of protocols. First, doctors used protocols only in certain circumstances; otherwise they preferred to wean using their own knowledge and skills. Relatively inexperienced nurses often lacked confidence. A protocol could encourage their involvement in weaning because it set out clear instructions and also helped them to feel more secure. Although more experienced nurses also recognized these positive qualities, they criticized protocols as sometimes instructing them to wean contrary to their own clinical judgement. Second, the practical arrangements for care within an ICU could either help or hinder healthcare professionals to work together, and in this way influence how (well) a protocol was used. Third, the use of a protocol reflected how healthcare professionals interact with one another generally. For example, the degree of experience a nurse or doctor possessed could influence the confidence others had that they could wean safely. For this reason, doctors tended to be reluctant to involve nurses they considered to be relatively inexperienced in weaning, even when there was a protocol in place. Furthermore, the fact that doctors occupied a higher professional status or position meant that it was difficult for nurses to be involved in weaning, including by using a protocol, unless the doctors s/he worked with permitted this to happen. We developed 35 summary statements. Of these: we assessed 17 statements as ‘low’ confidence, largely because the evidence used to develop them came from only a small number of studies. We rated 13 statements as ‘moderate’ confidence, largely because the evidence used to develop them came from very well-conducted studies, and we rated five statements as ‘high’ confidence, largely because the evidence used to develop them came from a majority of the studies.