Leg blood flow during total hip replacement under spinal or general anaesthesia.

Calf blood flow was studied using venous occlusion impedance plethysmography during 122 total hip arthroplasties. Patients were randomly allocated to receive spinal or general anaesthesia. Blood flow was measured nine times perioperatively. In the non-surgical leg, mean blood flow rose by over 50% in both groups following anaesthetic induction, remaining significantly elevated with spinal but falling back gradually to baseline with general anaesthesia. In the surgical leg, surgical manipulations produced marked falls in flow in many patients, particularly with femoral component insertion. If this occurred, hyperaemia was commonly seen with spinal anaesthesia but rarely with general anaesthesia once the joint was relocated. Venous outflow resistance rose slightly during anaesthesia in both groups, more so with general anaesthesia. In the surgical leg, marked rises occurred with surgical manipulations, but resistance fell abruptly once the joint was relocated. No clear relationship between these observations and the occurrence of deep vein thrombosis postoperatively was established.

Deep vein thrombosis after total hip replacement. A comparison between spinal and general anaesthesia.

The effect of hypobaric spinal anaesthesia or narcotic-halothane-relaxant general anaesthesia on the incidence of postoperative deep vein thrombosis was studied in 140 elective total hip replacements in a prospective randomised manner. Deep vein thrombosis was diagnosed using impedance plethysmography and the 125I fibrinogen uptake test, combined, in selected cases, with ascending contrast venography. The overall incidence of deep vein thrombosis was 20%. Nine patients (13%) developed deep vein thrombosis in the spinal group and nineteen (27%) in the general anaesthetic group (p less than 0.05). The incidences of proximal thrombosis and of bilateral thrombi were also less with spinal anaesthesia than with general anaesthesia. It is concluded that spinal anaesthesia reduces the risks of postoperative thromboembolism in hip replacement surgery. The presence of varicose veins, being a non-smoker and having a low body mass index were associated with an increased incidence of deep vein thrombosis.

Metabolic response to total hip arthroplasty under hypobaric subarachnoid or general anaesthesia.

Whole blood glucose concentration was estimated in 93 patients undergoing total hip arthroplasty under either subarachnoid or general anaesthesia. In 77, plasma cortisol concentration was also estimated before and after surgery. There were no preoperative differences between the two groups. Blood glucose concentration increased slightly following induction in both groups, but with spinal anaesthesia it decreased again, whereas with general anaesthesia it continued to increase (P less than 0.0001). Plasma cortisol concentration with spinal anaesthesia was 291 (SD 145) nmol litre-1 before, and 279 (253) nmol litre-1 30 min after operation. With general anaesthesia there was a three-fold increase from 301 (159) nmol litre-1 (preoperative) to 987 (474) nmol litre-1 30 min after operation (P less than 0.0001). Low spinal anaesthesia with a predominantly unilateral block appears sufficient to suppress the neuroendocrine response to hip surgery.

Influence of spinal and general anaesthesia on haemostasis during total hip arthroplasty.

One hundred and one patients with osteoarthritis were randomly allocated to undergo total hip arthroplasty under either spinal (subarachnoid) or general anaesthesia. Venous blood was sampled before, during and after surgery and on the 5th day after operation to study the haemostatic mechanism. There were no preoperative differences between the two anaesthetic groups. Although there was pronounced individual variability, similar patterns of change in coagulation, platelets and fibrinolysis were seen in both groups. However, there were significant differences between the two groups in platelet count, thrombin production, and Factor VIIIRAg in the intra- and immediate postoperative periods. Also, compared with general anaesthesia, there was less intraoperative activation of fibrinolysis, as measured by the euglobulin clot lysis time, with spinal anaesthesia. These differences suggest slight modification of the haemostatic response to surgery with spinal anaesthesia, which could be consistent with a neuroendocrine mechanism. By the 5th day both groups exhibited a very similar "hypercoagulable" postoperative state.

Halothane hepatitis: toxicity or hypersensitivity?

A 32 year old female developed a severe hepatitis (serum bilirubin 544 mumol/l) one week after a halothane anaesthetic. Six months later a general anaesthetic was administered via a halothane free circuit without incident. A year later a further non halothane anaesthetic was administered this time utilising the routine circuit after briefly flushing the rubber tubing with oxygen. That evening she became febrile and the following day abnormal liver function tests were documented. She remained asymptomatic.

A computer-based audit of anaesthetic registrar training.

A computerised summary of all anaesthetics administered by the North Canterbury Hospital Board's Department of Anaesthesia was used to examine the work patterns of registrars in the vocational training program over a two-year period. There was a considerable difference in the case load of some registrars even allowing for holidays and other leave. The exposure to surgical specialities and the degree of supervision were examined and problem areas identified. From a relatively simple data base it is possible to obtain information of value in the monitoring of a graduate training program.

Spinal anaesthesia or general anaesthesia for emergency hip surgery in elderly patients.

One hundred and thirty-two elderly patients undergoing emergency hip surgery were randomly allocated to receive subarachnoid block (SAB) or general anaesthesia (GA). Using the 125.I fibrinogen uptake test, deep vein thrombosis was found to occur in 17 of 37 patients in the SAB group and 30 of 39 patients in the GA group (P 0.05). Blood loss was 513 ml (+/- SEM 44) in the SAB group and 714 ml (+/- SEM 67) in the GA group (P less than 0.01). Hypoxaemia was present preoperatively (mean PaO2 9.2 kPa). Immediately following general anaesthesia, the mean fall in PaO2 was 0.86 kPa compared with preoperative values but only 0.16 kPa following subarachnoid block (P less than 0.01). At 24 hours postoperatively the fall in PaO2 was similar in both groups and recovered only slowly during the first week. Twelve patients died, three in the SAB group and nine in the GA group. This difference in mortality was not statistically significant.