[Anesthesia-relevant changes in metabolic parameters with different circulatory and liver functions]

The relationship between oxygen consumption (VO2) and oxygen delivery (DO2) is of interest in critically ill patients. Various studies of these parameters have resulted in different concepts for optimizing DO2 and VO2. During liver transplantation without anhepatic veno-venous bypass, caval cross-clamping initiates a series of haemodynamic and metabolic alterations including the rapid change from hyperdynamic to hypodynamic conditions. In addition, simultaneous changes in DO2 and VO2 occur in these patients. The goal of our present study was to test the clinical relevance of therapeutic interventions based on metabolic monitoring in patients with terminal liver disease undergoing orthotopic liver transplantation. PATIENTS AND METHODS. One hundred sixty-two consecutive patients were evaluated. According to outcome, patients were divided into survivors (n = 115, group A), nonsurvivors (n = 30, group B), and patients with primary nonfunction of the liver graft (n = 17, group C). One hundred twenty patients were cirrhotics due to either alcohol (n = 36), aggressive hepatitis (n = 30), or biliary cirrhosis (n = 54); 42 had a neoplastic disease. Haemodynamic measurements, data for calculations of DO2 and VO2, and blood samples for arterial and mixed-venous blood gases and subsequent laboratory analysis were taken during the surgical procedure at six timepoints: after induction of anaesthesia (I); during preparation of the recipient liver, before cross-clamping (II); 10 min after clamping of the inferior vena cava (III); 10 min before unclamping (IV); with all vessels open, 10 min after declamping during reperfusion (V); and 60 min after declamping (VI). Anaesthesia was induced with thiopentone (3-5 mg/kg i.v.) and fentanyl (15 micrograms/kg min i.v.). Muscle relaxation was achieved with pancuronium (0.1 mg/kg i.v.). Anaesthesia was maintained with i.v. supplements of fentanyl (5-10 micrograms/kg) and pancuronium (4 mg) as required. Volume-cycled ventilation was established with a mixture of O2 in air with a positive end-expiratory pressure of 5 mm H2O to keep the PaO2 above 100 mm Hg and the PaCO2 around 35 mm Hg (Servo 900 C-Ventilator, Siemens). To maintain body temperature, all patients were positioned on a heating blanket set at 38 degrees C. The inspired gases were warmed and humidified using a dual servo-heated humidifier. Mannitol (20-40 g i.v.) or sorbitol (16-24 g i.v.) was given to prevent renal dysfunction during the cross-clamping procedure. Lactated Ringer's solution and fresh frozen plasma administration was guided by cardiovascular performance and requirements for clotting factors, respectively. Cardiac output was measured by the thermodilution method using a pulmonary artery catheter. Blood lactate, haemoglobin concentration, arterial and mixed-venous oxygen content, and oxygen saturation were measured (Hemoxymeter OSM3). VO2 and DO2 were calculated according to standard formulas. STATISTICAL ANALYSIS. The data from groups A, B, and C were compared using a multivariate analysis of variance with Tukey's method for multiple comparisons. A least-square regression was used to correlate metabolic data. RESULTS. The perioperative course of the determinants of oxygen transport is shown in Table 1. After cross-clamping, the cardiac index (CI) decreased in groups A (47%), B (53%), and C (51%) and increased to pre-anhepatic levels after reperfusion of the new liver. This was associated with distinct decreases in DO2 (A: 42%, B: 47%, and C: 45%) and VO2 (A: 8%, B: 19%, C: 25%). After reperfusion of the new allograft (V), VO2 increased in groups A (24%) and B (18%) as compared to controls (I). By contrast, in group C, a distinct further decrease in VO2 (13%) was detected. In these patients, there was a significantly greater increase in mixed-venous saturation accompanied by a further decrease in body temperature. As shown in Figures 1 and 2, no significant relationship was found between O2 transport, VO2, and blood lactate. DISC