A pilot study on the hemodynamic effects of negative pressure ventilation in patients after cardiac surgery focussing on right ventricular function.

Right ventricular dysfunction and right ventricular failure are important complications in cardiac surgical patients and typically observed after complex surgical cases. Treatment options for optimizing the hemodynamic status in patients presenting with these complications are limited. Negative pressure ventilation has been shown to ameliorate the effects of conventional positive pressure ventilation (PPV) and to improve cardiac output in patients with Fontan circulation and patients undergoing coronary artery bypass surgery. No data are available on the effects of negative pressure ventilation on systemic hemodynamics and right heart function after complex on-pump cardiac surgery. Hypothesis of the present study is that right ventricular function improves under condition of negative pressure ventilation after complex on-pump surgery. Thirty patients after complex cardiac surgery were examined using basic hemodynamic monitoring, transesophageal ultrasound, a 3rd generation pulmonary artery catheter, cerebral oximetry and arterial and venous blood gases. The first 15 patients were ventilated for 15 min using standard PPV followed by 15 min of extrathoracal continuous negative pressure ventilation (CNPV) combined with PPV, and 15 min of extrathoracal biphasic negative pressure ventilation (BCV, biphasic cuirass ventilation) combined with an as far as possible reduced PPV. In the second 15 patients, the sequence of negative pressure ventilation was changed and BCV was performed before CNPV. Finally, every patient was ventilated for 15 min with standard PPV again. A full dataset of hemodynamics and a respiratory dataset was collected during each observation period. CNPV und BCV reduced central venous pressure and pulmonary artery occlusion pressure by 2 mmHg. During BCV cardiac index increased by + 24% (+ 0.5 l/min/m