WEAN SAFE and the definition of the first separation attempt

On 21 Jan, 2023, the results of the WEAN SAFE study were published in The Lancet Respiratory Medicine. It is an international observational study about weaning from mechanical ventilation with one of the largest cohorts ever published.1Pham T Heunks L Bellani G et al.Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study.Lancet Respir Med. 2023; (published online Jan 21.)https://doi.org/10.1016/S2213-2600(22)00449-0Summary Full Text Full Text PDF PubMed Google Scholar One of the main conclusions of this study is that a considerable number of patients (22·4%) could have made an earlier separation attempt. However, the authors defined an uncommon, even arbitrary, weaning criteria. The authors modified the Boles and colleagues’ weaning criteria2Boles JM Bion J Connors A et al.Weaning from mechanical ventilation.Eur Respir J. 2007; 29: 1033-1056Crossref PubMed Scopus (1241) Google Scholar by increasing the fractional oxygen in inspired air (FiO2) from less than 0·4 to less than 0·5 and positive end-expiratory pressure (PEEP) from 8 to 10. In addition, most of the clinical criteria were omitted (adequate cough, not excessive tracheobronchial secretions, resolution of the acute disease, etc), including the adequate level of consciousness, which they considered a criterion for extubation but not for weaning. The results’ presentation is contradictory, as the days of delayed weaning were defined between meeting the modified weaning criteria and the first ventilation separation attempt. This statement is an oxymoron because, as standard of care, if the patients are not ready for extubation, they are not ready for a true attempt of separation. Any spontaneous breathing trial whose final objective is not to separate the patient from the ventilator is not considered weaning by present guidelines.3Girard TD Alhazzani W Kress JP et al.An official American Thoracic Society/American College of Chest Physicians clinical practice guideline: liberation from mechanical ventilation in critically ill adults. Rehabilitation protocols, ventilator liberation protocols, and cuff leak tests.Am J Respir Crit Care Med. 2016; 195: 120-133Crossref Scopus (176) Google Scholar One can discuss whether it can be good or bad for patients but, to our knowledge, there is no evidence in favour of starting a weaning process if extubation is not considered. We do not know whether the site researchers were aware that the criteria to define weaning was going to be modified. If the researchers did not, it makes sense that despite meeting the modified weaning criteria the separation attempt started later in more sedated, comatose, and weak patients. According to daily practice, the physicians or the respiratory therapists would wait until the patient met consensus weaning criteria. Moreover, the results might suggest that some professionals did not feel safe to perform a spontaneous breathing trial in patients with elevated FiO2 and PEEP levels and not completely ready to be separated from the ventilator. Nevertheless, we could not agree more to the conclusion that the level of sedation might increase the days on the ventilator and delay readiness for weaning (but not the weaning process itself). We would like to caution against starting weaning in patients with still high levels of FiO2 and PEEP and not meeting the clinical criteria. There is a need for real evidence to support this strategy, which is nowadays under study in a randomised controlled trial (NCT04758546). We declare no competing interests. Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort studyIn critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates. Full-Text PDF