Comparative evaluation of the cardiorespiratory effects of assist control ventilation vs pressure support ventilation in patients following orthotopic liver transplantation.

OBJECTIVE: 1) To compare the haemodynamic tolerance of ACV and PSV in patients mechanically ventilated after orthotopic liver transplantation; 2) to compare patients comfort during ACV and PSV.

DESIGN: Prospective randomized cross-over study.

SETTING: General ICU of the University of Rome "La Sapienza".

PATIENTS: Eighteen patients admitted in ICU after orthotopic liver transplantation.

MEASUREMENT AND RESULTS: Haemodynamic, oxygen transport and blood gas data were compared during an ACV and PSV trial (30'). A statistically significant decrease of mean pulmonary and systemic arterial pressure, PCOP, LVSWI, occurred during the PSV trial. PaO2 and DO2I decreased during PSV, but were still in supranormal range; 16 out of 18 patients described PSV as more comfortable.

CONCLUSIONS: ACV and PSV provided a comparable haemodynamic tolerance in our patients, although during PSV the PaO2 was slightly decreased, probably due to decreased mean airway pressure (from 9.3 +/- 1.2 cmH2O during ACV to 6.6 +/- 1 cmH2O during PSV). PSV can be considered as a good alternative to the standard weaning techniques following orthotopic liver transplantation.