• Leonardo Cordeiro de Souza, Cyro Teixeira da Silva, Jorge Reis Almeida, and Jocemir Ronaldo Lugon.
• Department of Medicine, Hospital Universitário Antonio Pedro, Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brazil. leonardo.uti@gmail.com
• Resp Care. 2012 Aug 1;57(8):1285-90.

ObjectiveTo investigate the predictive value of the maximal inspiratory pressure obtained by a digital vacuometer using a unidirectional valve (P(ImaxUV)) as to weaning outcome, and to compare its performance with the respiratory drive using airway occlusion pressure at 0.1 second (P(0.1)), and P(0.1)/P(ImaxUV).MethodsPatients on mechanical ventilation for > 24 hours who fulfilled the weaning criteria were prospectively enrolled. Measurements of P(ImaxUV) and P(0.1) were accomplished with a digital vacuometer with a unidirectional valve that allows only exhalation. Measured values were electronically recorded and stored on the digital vacuometer measurement device. Cutoff points for the used parameters were: absolute values of P(ImaxUV) > 30 cm H(2)O, P(0.1) < 2.3 cm H(2)O, and P(0.1)/P(ImaxUV) < 0.10. Receiver operating characteristic curves were calculated to compare the predictive values of the indexes.ResultsOne hundred three subjects completed the test. The areas under the receiver operating characteristic curve were 0.79 ± 0.04, 0.65 ± 0.05, and 0.74 ± 0.04 for P(ImaxUV), P(0.1), and P(0.1)/P(ImaxUV), respectively. The area under the receiver operating characteristic curve for P(ImaxUV) was higher than for P(0.1) and P(0.1)/P(ImaxUV), but statistical significance was only found against P(0.1) (P = .007).ConclusionsEvery studied index had only a modest performance regarding prediction of weaning outcome. Of note, P(ImaxUV) values obtained by digital technology using a unidirectional valve performed better than historically reported using a conventional techniques, surpassing P(0.1) and P(0.1)/P(ImaxUV) in this regard.

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