A prospective, blinded evaluation of indexes proposed to predict weaning from mechanical ventilation.
OBJECTIVE
To conduct a blinded evaluation of the predictors of weaning from mechanical ventilation.


METHODS
A prospective clinical study.


METHODS
A 23-bed general intensive care unit.


METHODS
Ninety-three non-selected patients, ventilated for more than 48 h.


METHODS
The study had two steps: at first, patients' data were used to select the cut-off value for weaning predictors (the minimal false classification). The cut-off value for each index was prospectively assessed in a group of 52 patients. The predictive performance of these indexes was evaluated by calculating the area under the receiver operating characteristic curve. In the prospective-validation set we used Bayes' theorem to assess the probability of each test in predicting weaning. The physicians making decisions about the weaning process were always unaware of the predictive values. Weaning was considered successful if spontaneous breathing was sustained for more than 48 h after extubation.


RESULTS
During the first 2 min after discontinuation of mechanical ventilation the following tests were performed: vital capacity, tidal volume, airway occlusion pressure (P(0.1)), minute ventilation, respiratory rate, maximal inspiratory pressure (MIP), respiratory frequency to tidal volume (f/V(T)), P(0.1)/MIP and P(0.1) x f/V(T). The areas under the curve showed that the tests had not the ability to distinguish between successful and unsuccessful weaning.


CONCLUSIONS
Our results show that all the evaluated indexes are poor predictors of weaning outcome in a general intensive care unit population.
Conti
Giorgio
G
Istituto Anestesiologia e Rianimazione, Policlinico Agostino Gemelli, Università Cattolica del Sacro Cuore, Largo Agostino Gemelli 8, 00168 Rome, Italy. g.conti@rm.unicatt.it
Montini
Luca
L
Pennisi
Mariano Alberto
MA
Cavaliere
Franco
F
Arcangeli
Andrea
A
Bocci
Maria Grazia
MG
Proietti
Rodolfo
R
Antonelli
Massimo
M
D000368:Aged; D001499:Bayes Theorem; D005260:Female; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012119:Respiration; D012121:Respiration, Artificial; D012131:Respiratory Insufficiency / Q000209:etiology / Q000628:therapy*; D015300:Ventilator Weaning