Introduction: Systolic pressure variation has previously been used to detect the presence of hypovolemia in mechanically ventilated patients but remains difficult to measure.
Methods: We describe the application of a commercially available physiological data acquisition system, PowerLab (ADI Instruments Castle Hill, NSW, Australia), to acquire and graphically display simultaneous recordings of the airway pressure, as well as systemic and pulmonary arterial pressures. The technique involves the use of standard pressure transducers to record each pressure reading and has been used to obtain measurements in patients undergoing elective cardiac surgery.
Results: The technique permits calculation of systolic pressure variation of both the systemic and pulmonary arterial pressure waveforms. In addition it is possible to estimate plateau airway pressure and perform expiratory hold maneuvers to determine its constitutive components delta-up and delta-down. Waveforms can be exported into MS-windows Paint and saved in JPEG or bitmap format.
Conclusions: The technique described will permit future analysis of the factors affecting the systolic pressure variation for the systemic and pulmonary arterial pressure waveforms in the clinical context.