Inflation static pressure-volume curves of the total respiratory system determined without any instrumentation other than the mechanical ventilator

Objective To assess the accuracy of static pressure-volume (PV) curves of the total respiratory system performed with the data directly obtained from the Servo 900C vs. the data obtained from an external calibrated device.Design Performance of the PV curve by the method of Levy with simultaneous recording of data obtained from both systems.Setting The general ICU of Hospital de Sabadell.Patients Ten sedated and paralyzed patients ventilated in the control mode for acute respiratory failure were evaluated.Interventions and measurements Inflation static PV curves were performed by the method of Levy. We simultaneously measured airway pressure and volume by means of calibrated pressure tranducer and pneumotachograph and by the internal devices built in the ventilator Siemens Servo 900C. Statistics were concordance analysis between the two methods and covariance analysis between derived curves.Results concordance analysis between both methods showed a 95% confidence interval of (+4%, –5%) in volume and (+2.2 cmH₂O, –1.7 cmH₂O) in pressure. Derived PV curves analyzed by MANOVA showed no significant differences whichever the method used within subject (p=0.579).Conclusion Inflation static pressure volume curves of the total respiratory system can be accurately performed with the data directly obtained from the Servo Ventilator 900C without the need of any other external device.Supported by Grant 91/1084 from FIS, Ministerio de Sanidad y Consumo, Spain