[Evaluation of the performance of a negative extra-thoracic pressure ventilator (OKT-86)]

We evaluated the performance of a new negative extra-thoracic pressure ventilator (OKT-86, which was designed by the authors) applying it on ten patients with ASA Physical Status I (mean body weight: 54.4 +/- 12.1 kg) during anesthesia. Uneven distribution of negative extra-thoracic pressure was not observed within the chamber that a patient was wearing. Tidal volumes of more than 10ml.kg-1 were obtained at a respiratory rate of 10 or 16 breath.min-1 and a peak negative extra-thoracic pressure of -18 to -20 cmH2O. The values of delta FRC were 5.4 and 11.9 ml.kg-1 at continuous negative extra-thoracic pressure of -5 and -10 cmH2O, respectively, and these values were three times as those of the conventional cuirass ventilator. Consequently, sufficient tidal volumes and delta FRC were obtained using OKT-86.