Evolution of pattern of breathing during a spontaneous breathing trial predicts successful extubation.
OBJECTIVE
Rapid shallow breathing may occur at any time during spontaneous breathing trials (SBT), questioning the utility of a single determination of the rapid shallow breathing index (RSBI). We hypothesize that change in RSBI during SBT may more accurately predict successful extubation than a single determination.


METHODS
Prospective observational study. Seventy-two subjects were extubated. At 24 h, 63/72 remained extubated (Extubation Success), and 9 were re-intubated (Extubation Failure). Respiratory rate (RR), tidal volume (VT) and RSBI were measured every 30 min during 2-h T-piece SBT. Change in respiratory parameters was assessed as percent change from baseline.


RESULTS
Initial RSBI was similar in Extubation Success and Extubation Failure groups (77.0 +/- 4.8, 77.0 +/- 4.8, p = ns). Nevertheless, RSBI tended to remain unchanged or decreased in the Extubation Success group; in contrast RSBI tended to increase in the Extubation Failure group because of either increased RR and/or decreased VT (p < 0.001 for mean percent change RSBI over time), indicating worsening of the respiratory pattern. Quantitatively, only 7/63 subjects of the Extubation Success group demonstrated increased RSBI >or=20% at any time during the SBT. In contrast, in the Extubation Failure group, RSBI increased in all subjects during the SBT, and eight of nine subjects demonstrated an increase greater than 20%. Thus, with a 2-h SBT the optimal threshold was a 20% increase (sensitivity = 89%, specificity = 89%). Similar results were obtained at 30 min (threshold = 5% increase). Percent change of RSBI predicted successful extubation even when initial values were >or=105.


CONCLUSIONS
Percent change of RSBI during an SBT is a better predictor of successful extubation than a single determination of RSBI.
Segal
Leopoldo N
LN
Division of Pulmonary and Critical Care Medicine, Department of Medicine, New York University School of Medicine, 462 First Ave 7W54, New York, NY 10016, USA. Leopoldo.Segal@nyumc.org
Oei
Erwin
E
Oppenheimer
Beno W
BW
Goldring
Roberta M
RM
Bustami
Rami T
RT
Ruggiero
Salvatore
S
Berger
Kenneth I
KI
Fiel
Stanley B
SB
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019370:Observation; D017063:Outcome Assessment, Health Care; D011446:Prospective Studies; D012131:Respiratory Insufficiency / Q000503:physiopathology; D015656:Respiratory Mechanics / Q000502:physiology*; D015300:Ventilator Weaning; D014939:Work of Breathing / Q000502:physiology*