RESUMO
OBJECTIVE: To evaluate the prevalence of "likely overassistance" (categorised by respiratory rate [RR] ≤ 17 breaths/min or rapid shallow breathing index [RSBI] ≤ 37 breaths/min/L) during invasive pressure support ventilation (PSV), and the additional prevalence of fixed ventilator settings. DESIGN: Multicentre prospective observational study of invasive PSV practice in six general Victorian intensive care units with blinding of staff members to data collection. PATIENTS: At each hospital, investigators collected data between 11 am and 2 pm on all invasive PSV-treated patients on 60 sequential days, excluding weekends and public holidays, between 22 February and 30 August 2017. Each patient was included for maximum of 3 days. MAIN RESULTS: We studied 231 patients, with a total of 379 observations episodes over the study period. There were 131 patients (56.7%) with at least one episode of RR ≤ 17 breaths/min; 146 patients (63.2%) with at least one episode of RSBI ≤ 37 breaths/min/L, and 85 patients (36.8%) with at least one episode of combined RR ≤ 17 breaths/min and RSBI ≤ 37 breaths/min/L. Moreover, the total number of observations with "likely overassistance" (RR ≤ 17 or RSBI ≤ 37 breaths/min/L) was 178 (47%) and 204 (53.8%), respectively; while for both combined criteria, it was 154 (40.6%). We also found that 10 cmH2O pressure support was delivered on 210 of the observations (55.4%) and adjusted in less than 25% of observations. Finally, less than half (179 observations) of all PSV-delivered tidal volumes (VT) were at the recommended value of 6-8 mL/kg predicted body weight (PBW) and more than 20% (79 observations) were at ≥ 10 mL/kg PBW. CONCLUSION: In a cohort of Victorian hospitals in Australia, during invasive PSV, "likely overassistance" was common, and the pressure support level was delivered in a standardised and unadjusted manner at 10 cmH2O, resulting in the frequent delivery of potentially injurious VT.