Anaesthesia for cholecystectomy in two non-parturients with Eisenmenger's syndrome.

Eisenmenger's syndrome consists of high pulmonary vascular resistance with reversed or bidirectional shunt at aortopulmonary, ventricular or atrial level. We describe the anaesthetic management of two adult females with Eisenmenger's syndrome admitted for laparoscopic cholecystectomy. One patient suffered post-operative complications, but the other case was uncomplicated. We used sevoflurane and total intravenous anaesthesia to provide general anaesthesia. Both techniques were tolerated.

Accidental subdural catheterization: radiological evidence of a possible mechanism for spinal cord damage.

We describe the inadvertent subdural insertion of a lumbar extradural catheter in a primiparous woman in labour. A small quantity of local anaesthetic resulted in extensive motor and sensory block. Computed tomography performed after contrast injection demonstrated unequivocally that the catheter was in the subdural space. The catheter and injected fluid produced considerable displacement of the arachnoid within the thecal sac. We postulate that this could result in arterial compression or direct damage to the spinal nerve roots. Such a mechanism might explain some of the cases of permanent neurological damage associated with extradural analgesia.

Sedation following cardiac surgery: evaluation of alfentanil and morphine in the presence of a computerized closed loop arterial pressure controller.

Forty patients who had undergone coronary artery graft surgery and who required vasodilator therapy for postoperative hypertension were given infusions of either alfentanil or morphine together with bolus doses of midazolam for sedation and analgesia while ventilation was controlled artificially. Sodium nitroprusside (SNP) was administered to both groups using a computer-controlled closed loop system which adjusted the infusion rate to maintain a preset target arterial pressure. Target pressure +/- 5, 10, 15 and 20 mm Hg was maintained longer in the group receiving alfentanil. This group also required less SNP per hour. No difference was noted between the groups in the time taken to regain spontaneous ventilation and to extubation of the trachea, although the alfentanil group tended to be sedated more deeply during the infusion. The main advantage of alfentanil over morphine at doses used in this study was its superior ability to attenuate hypertensive responses to noxious stimuli, providing improved haemodynamic stability.

A computer controlled non-invasive haemodynamic monitoring system.

A system for the non-invasive monitoring, recording and storing haemodynamic indices has been developed using an Apple II microcomputer, a Dinamap automatic arterial pressure monitor and a non-invasive cardiac output monitor based on bio-electrical impedance. This system was used during the induction and maintenance of anaesthesia. Numerical and graphical displays of heart rate, arterial pressure, cardiac output and systemic vascular resistance are available. A print-out of data can be produced for later analysis.

Comparison of the effects of subanaesthetic concentrations of isoflurane or nitrous oxide in volunteers.

A cross-over trial was performed in 12 volunteers to compare the relative potency of 25% nitrous oxide and 0.4% isoflurane when breathed for a period of 20 min. Oxygen was used as a control. The effects were observed for 35 min after drug administration. Choice reaction time, ability to tap two areas on a board and ability to perform mathematical problems were significantly impaired when inhaling nitrous oxide, the maximum effect being obtained within 5 min. With isoflurane, the effects were significantly greater than with nitrous oxide. The effect obtained after 15 min inhalation was greater than that at 5 min. Tests returned promptly to the base line after the discontinuation of the test agent. Subjective assessments were made using a series of eight visual analogue scales. Results of the scales represented by physical and mental sedation indicated that 0.4% isoflurane was more potent than 25% nitrous oxide. Significant effects were detected up to 15 min after the inhalation of the agent was stopped. Subanaesthetic concentrations of isoflurane warrant further study in patients undergoing dental treatment in which a rapid recovery from sedation is important.