title: [A clinical study of rapid-shallow-breathing index in spontaneous breathing trial with pressure support ventilation and T-piece].
abstract: OBJECTIVE
  To determine the threshold value of rapid-shallow-breathing index (RSBI) and its increased percentage (Delta RSBI) as predictors for successful weaning in spontaneous breathing trial (SBT) with pressure support ventilation (PSV) and T-piece.
  
  
  METHODS
  In 2007, there were 208 patients on ventilators with oral intubation. They were divided into two groups: the PSV group (93 patients) and the T-piece group (115 patients). The duration of SBT was 30 minutes. Weaning indexes [mouth occlusion pressure 0.1 (P0.1), breathing rate (f), tidal volume (V(T))] of SBT 3 minutes and 30 minutes were recorded in each group. The averages of RSBI and Delta RSBI were calculated and compared between two groups.
  
  
  RESULTS
  Among 208 patients, in 168 patients weaning was successful and the ratio was 80.77%. The successful ratios of PSV and T-piece group were 83.87% and 78.26%, respectively (P > 0.05). In PSV and T-piece groups the average of RSBI value (SBT 30 minutes) was (67.18+/-11.55) breaths x min(-1) x L(-1) and (99.11+/-15.53) breaths x min(-1) x L(-1), respectively (P < 0.01); the average of Delta RSBI was (69+/-33)% and (119+/-35)% (P < 0.01). In PSV group, the area under receiver operating characteristic (ROC) curve of RSBI was 0.747+/-0.045 (P = 0.000); when RSBI =75 breaths x min(-1) x L(-1), the diagnostic accuracy was 87%; the area under ROC curve of Delta RSBI was 0.709+/-0.065 (P = 0.001), and when Delta RSBI=90%, the diagnostic accuracy was 82%. In T-piece group, the area under ROC curve of RSBI was 0.821+/-0.049 (P = 0.000); when RSBI =100 breaths x min(-1) x L(-1), the diagnostic accuracy was 82%; the area under ROC curve of Delta RSBI was 0.738+/-0.046 (P = 0.000); when Delta RSBI =130%, the diagnostic accuracy was 77%.
  
  
  CONCLUSIONS
  The average values of RSBI (SBT 30 minutes) are significantly different between the two groups. In PSV and T-piece groups, using RSBI = 75 breaths x min(-1) x L(-1) and 100 breaths x min(-1) x L(-1) as the threshold value for predicting successful weaning is more valuable than other values. Sequential observation of Delta RSBI is also valuable in predicting a successful extubation.
authors.affiliation: Intensive Care Unit, Tianjin Third Hospital, Tianjin 300170, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: Ying-zhi
authors.initials: YZ
authors.lastname: Qin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001944:Breath Tests / Q000379:methods*; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012121:Respiration, Artificial; D015300:Ventilator Weaning; D055815:Young Adult