Tissue oxygenation during liver transplantation.

OBJECTIVES: a) To assess perioperative changes in tissue oxygenation parameters during liver transplantation; b) to evaluate the need for venovenous bypass as hemodynamic support; and c) to assess the efficacy of mixed venous oxygen saturation monitoring and the importance of lactate determinations in the management of patients following liver transplantation. DESIGN: Prospective case series. SETTING: Liver transplant unit in a university hospital. PATIENTS: A total of 68 consecutive patients undergoing liver transplantation. The entire population was analyzed before and after transplantation, dividing the patients into two groups, based on whether their initial cardiac index was higher (n = 37) or lower (n = 31) than 4.5 L/min/m2. MEASUREMENTS: Hemodynamic measurements and blood gas analyses were made before incision, before vascular clamping (including hepatic artery, portal vein and inferior vena cava), during the anhepatic phase, and at 5, 30, 60, and 120 mins following unclamping. Oxygen transport and oxygen consumption values were calculated. Serum lactate concentrations were measured by enzymatic technique. MAIN RESULTS: Mixed venous oxygen saturation was correlated with oxygen transport (Do2) in the whole population in which an abnormal oxygen consumption (Vo2)-Do2-dependent relationship occurred from the beginning of operation until 30 mins following unclamping. The comparison between hyperdynamic patients (initial cardiac index greater than 4.5 L/min/m2) with impaired tissue oxygenation and normodynamic patients showed that mixed venous oxygen saturation failed to correlate with Do2 when the cardiac index was greater than 4.5 L/min/m2 and that the Vo2-Do2 dependency was only noted in these patients. The serum lactate concentrations were similar in both groups. CONCLUSIONS: The Vo2-Do2-dependent relationship and mixed venous oxygen saturation-Do2 correlation noted in the 68 studied patients suggest the need for venovenous bypass and the reliability of mixed venous oxygen saturation monitoring in all patients scheduled for liver transplantation. However, a sharper comparison between hyperdynamic and normodynamic patients demonstrated the lack of efficacy of mixed venous oxygen saturation monitoring in predicting adequate tissue oxygenation in the first group and the mandatory need for venous shunting to limit tissue hypoxia which occurred despite its use only in these patients. Lactic acidosis appeared similarly in both groups and could not be linked to tissue hypoxia.

[Effects of urapidil on the cardiovascular response to intratracheal intubation]. / Effets de l'urapidil sur la réponse cardiovasculaire à l'intubation.

The effects of urapidil on the haemodynamic response to endotracheal intubation were compared to that of placebo in two groups of 25 patients scheduled for general surgery. Normal saline solution or 0.4 mg.kg-1 urapidil were injected 3 min before induction of anaesthesia with 3 micrograms.kg-1 fentanyl, 0.3 mg.kg-1 etomidate and 0.1 mg.kg-1 vecuronium. Blood pressure (Pasys, Padia, Pa) and heart rate were measured continuously by servoplethysmomanometry before giving the test drug (T0), at the time when the lowest blood pressure was recorded during the three minute period between giving the drug and induction (T1), at the time when the lowest blood pressure was recorded during the three minute period between induction and endotracheal intubation (T2), at the time when the highest blood pressure was recorded immediately after intubation (T3), three minutes after intubation (T4), five minutes after intubation (T5), and at the time when the lowest blood pressure was recorded after surgery had been started (T6). It was planned to give a 25 mg urapidil dose to any patient, from either group, who had a Pasys greater than 200 mmHg for more than 60 sec. Giving urapidil lowered Pasys (T1) by 16%, whilst heart rate increased by 12%. The blood pressure peak due to endotracheal intubation was lower in those patients who had been given urapidil than in the placebo group (T3; p less than 0.05). Six patients in the latter group required the 25 mg urapidil dose, versus 2 in the urapidil group. The preventive effects of urapidil seem to be similar to those obtained with other antihypertensive agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Recovery from total intravenous anaesthesia. Propofol versus midazolam-flumazenil.

The aim of this study was to compare recovery assessed with the Newman, deletion af a's and postbox tests after total intravenous anaesthsia for procedures lasting more than 90 min, with either propofol (PPF) or midazolam (MDZ), reversed or not by flumazenil (FMZ). Thirty patients scheduled for peripheral surgery were randomly allocated to 3 groups of 10, receiving by continuous infusion until the end of surgery either PPF (n = 10) or MDZ (n = 20) combined with alfentanil. FMZ was administered thereafter to 10 patients receiving MDZ until they opened their eyes on command or to a maximum dose of 1 mg. Recovery tests were performed 45, 90 and 180 min after the end of anaesthesia. Results were analysed with non-parametric tests. Recovery scores were significantly better in the PPF group at all times, reaching control values at 180 min for the three first tests. FMZ reversal did not improve the scores compared to those resulting from MDZ alone. This study provides further data in favour of PPF as far as rapid and complete recovery is concerned. The efficiency of FMZ is incomplete and only transient when administered in a single dose.

Long-chain versus medium and long-chain triglyceride-based fat emulsion in parental nutrition of severe head trauma patients.

In order to assess the metabolic value of medium-chain triglycerides (MCT) in severely stressed intensive care unit patients, two fat emulsions containing either long-chain triglycerides (LCT), or a mixture of 50% MCT and 50% LCT were compared in 24 head trauma patients over a 10 day period. Variations of serum triglyceride, non-esterified fatty acid, glycerol and phospholipid concentrations remained comparable after both lipid infusions. Bilirubin, alkaline phosphatase and transaminase plasma levels were altered in both groups without any significant differences or clinical consequences. Cumulative nitrogen balance remained negative (-10 g N. day-1 i.e. -100 g N. 10 days-1) and comparable in both groups. However, thyroxin-binding prealbumin concentrations increased significantly in patients receiving the MCT/LCT mixture. It is concluded that MCT might have a beneficial effect on visceral protein metabolism after trauma.

[Hemodynamics and hepatic transplantation using a veno-venous shunt: influence of the preoperative hyperkinetic state]. / Hémodynamique et transplantation hépatique avec shunt veino-veineux: influence de l'état hyperkinétique préopératoire.

The routine use of a veno-venous bypass is not accepted by all surgical liver transplantation teams. The putative benefits (maintaining haemodynamic stability during the anhepatic phase, reducing blood losses, avoiding renal failure) are counterbalanced by the real risks of air embolism or thromboembolism. A severe preclamping hyperkinetic haemodynamic status represents an elective indication for some authors, whilst it is a reduced cardiac function for others. Two groups of ten patients undergoing liver transplantation, with a porto-femoro-axillary venous bypass (flow rate 2 to 2.5 l.min-1), were studied retrospectively. They differed by their pre-clamping cardiac index (CI), greater than 5 l.min-1.m-2 in group A and less than 4.5 l.min-1.m-2 in group B. The same anaesthetic protocol was used in all patients consisting in fentanyl, thiopentone, pancuronium, and midazolam. The use of blood products and biological parameters did not differ between the two series of patients. The CI decreased by 30% and systemic vascular resistances (Rsa) increased by 48% in group A after clamping, without any deleterious effects on oxygen delivery; similarly, in group B, CI fell by 15% and Rsa increased by 20%. After unclamping, CI rose by greater than 50%, and Rsa decreased in both groups. No differences were seen between the two series 5 min after revascularisation. The release of vasoactive agents by the cold ischaemic graft could explain this. These results suggest that veno-venous bypass could be beneficial in the 2 different preoperative haemodynamic profiles studied. The low decrease in CI in hyperkinetic patients allowed tissue oxygenation to be maintained at adequate levels during the anhepatic phase.(ABSTRACT TRUNCATED AT 250 WORDS)

[Perforation of the pulmonary artery during the insertion of a Swan-Ganz catheter]. / Perforation de l'artère pulmonaire lors de la mise en place d'un cathéter de Swan-Ganz.

An accidental rupture of the pulmonary artery in a 77 year old female patient is reported. She was admitted for total mastectomy, but her past medical history revealed an old myocardial infarct, treated arterial hypertension and asthma. She was under heparin as well for her varicose veins. Her clinical examination revealed a patient in mild chronic heart failure. It was therefore decided to carry out invasive monitoring during surgery and the recovery period. A Swan-Ganz catheter was put up. Its progression was controlled by looking at the pressure curves. Several attempts were made to obtain a wedge pressure, with no success. During these attempts, the patient developed a cough followed by massive haemoptysis. Despite adequate resuscitative measures, the patient died before a surgical procedure could be attempted. Postmortem examination showed the rupture to be 9 cm away from the origin of the pulmonary artery. This unfortunate accident confirmed that the following three factors, all present in this patient, should call for extreme care in the setting-up of Swan-Ganz catheters: age greater than 60 years, pulmonary arterial hypertension and anticoagulant therapy.

[Perforation of the pulmonary artery following Swan-Ganz catheterization]. / Perforations de l'artère pulmonaire consécutives à l'utilisation du cathéter de Swan-Ganz.

Pulmonary arterial rupture due to the use of a Swan-Ganz catheter is a rare accident, with an estimated 2% incidence rate. It is fatal in almost 50% of cases. Predisposing factors are age greater than 60 years, pulmonary arterial hypertension and anticoagulant treatment. In patients older than 60 years, changes in the arterial wall increase the risk of rupture; pulmonary hypertension leads to too distal a movement of the catheter, and a concomitant treatment with anticoagulant drugs increases the amount of blood lost. Handling errors when setting up the catheter are often the cause of these accidents, especially a balloon too blown up and a catheter pushed too far. A subsequent movement of the catheter can be a cause of rupture during cardiac surgery. Haemoptysis is the major symptom of this accident, being found in 90% of cases. It can however be of minor importance; if it is ignored, this can lead to a secondary overwhelming haemorrhage. The haemorrhage can be life-threatening because of the cardiovascular collapse and acute respiratory failure by asphyxia. The treatment can only be carried out in intensive care. It will depend on the severity of the accident. It can go from an expectant wait after partial or total removal of the catheter, to an emergency thoracotomy for vascular suture, segmentectomy or even lobectomy. Intermediate measures include turning the patient onto the healthy side, injecting adrenaline or a clot of the patient's blood by the distal end of the catheter, placing a Fogarty catheter in the affected bronchus, or tracheal intubation with a double-lumen catheter and using mechanical ventilation with PEEP.(ABSTRACT TRUNCATED AT 250 WORDS)