Effect Of One-lung Ventilation On The Relationship Between The Systemic Oxygen Supply And Oxygen Consumption, The Hemodynamic Changes During The Perioperative Period

The reverse Fick method was used to evaluate the characteristic of oxygen metabolism during thoracic surgical procedures, and examine the changes of oxygen supply and oxygen consumption balance during one-lung ventilation. Transesophageal Doppler echocardiograph (HemosonicTM 100) was used to evaluate the changes of hemodynamics during the perioperative period.Methods30 patients(18 male, 12 female) aged(41 ± 12 yr),undergoing pneumonectomy were studied. The patients were premedicated with pethidine 50mg promethazine 25mg and atropine 0. 5mg im 30 min before operation. Anesthesia was induced with fentanyl 2ug kg-1 , midazolam 0.1-0. 2mg kg-1, vecuronium 0.12-0.15mg kg-1, propofol 1. 5-2. 5 mg kg-1 and maintained with inhalation of 50% nitrous oxide in oxygen and TCI propofol and intermittent iv boluses of fentanyl and vecuronium. Radial artery was cannulated, central venous pressure catheter was placed via internal jugular vein. Arterial blood gas analasis and mixed venous blood gas analasis were respectively done from the sober state to closure of the pleura cavity. Hemodynamic parameters including mean arterial pressure(MAP) heart rate(HR) cardiac output index(CI) stroke volume(SV) total systemic vascular resistance for aortic circuit(TSVR) HR-corrected left ventricular ejection time (LVETi) and peak aortic flow acceleration (ACC) were measured and recorded. Oxygen delivery (DO2) oxygen consumption(VO2) oxygen extraction rate(ERO2) mixed venousoxygen saturation(SvO2) arterial oxygen partial pressure(PaO2) and arterial blood lactate(ABL) were monitored during anesthesia.ResultsDuring OLV, PaO2 was decreased significantly(P < 0. 05). After the induction of anesthesia, oxygen delivery was decreased significantly compared with that of the sober state. During OLV, VO2 and ERO2 were increased gradually, while D02 was kept at a certain level(404-421 ml min-1 m-2).After pleural cavity closure, DO2 was increased significantly (from 404 to 457 ml min-1 m-2)and VO2 was kept at a certain level (91 ml min-1 m -2). After the induction of anesthesia, the myocardial contractility decreased significantly. When the pleura cavity was closed, the myocardial contractility returned to the baseline. During the one-lung ventilation, the base excess decreased gradually.ConclusionsAmong patients undergoing pneumonectomy during one-lung ventilation, oxygen supply demand balance was kept and tissue hypoxia did not occur. During the thoracotomy period, the hemodynamic parameters including CI SV, MAP and LVETi were kept at a balance state.