Temporal trends of patients who require complex weaning, 2006-2018

Most patients are weaned successfully from invasive mechanical ventilation(IMV) within 7 days of intubation. Those unable to wean may require complex weaning interventions delivered at a specialised weaning unit (SWU). Admission criteria to SWU are not well-defined and clinical decision-making about admission has changed over time. We sought to assess temporal changes in characteristics and outcomes of consecutive patients admitted to our SWU, 2006-2018. Demographics, time to wean(TTW), length of stay(LoS) at SWU and weaning outcomes were recorded. Continuous data are reported as median[IQR]. Differences between continuous variables were assessed using a Kruskal-Wallis test. Temporal changes were assessed with a Chi-square test for trend. We included 444 patients (60%male, age 64[52–74]yrs). Age at admission did not change over time. Primary cause of respiratory failure was neuromuscular/chest wall disease(44%),COPD (19%),post-operative(17%),sleep disordered-breathing (5%) or other(15%). Charlson comorbidity index(CCI) was 3[1-4]. CCI reduced over the course of this study (p=0.001).TTW was 20[10-43] days and SWU LoS was 37[21-81] days. TTW(p=0.0002) and LoS(p<0.0001) increased over time. 287/444(65%) patients were successfully weaned from IMV. There was no difference in the proportion of patients being successfully weaned over time. 1-yr survival increased over time from 47%(2006-2009) to 64%(2010-2013) to 66%(2014-2018, p=0.001). Despite similar weaning outcomes, patients are requiring longer to wean from IMV. The reasons for this are unclear but may suggest that more complex patients are being admitted to our SWU. CCI does not appear to be a good predictor of weaning outcome. 1-yr survival has improved over time.