I.v. anaesthetic agents, including propofol, have not been shown to inhibit hypoxic pulmonary vasoconstriction (HPV). This may encourage the use of propofol in thoracic surgery where one lung ventilation (OLV) is required. We have compared the effects of maintaining anaesthesia with either isoflurane or propofol infusion on right ventricular function and shunt fraction. We studied 10 patients who received isoflurane and 12 who received propofol. When OLV commenced there was a greater reduction in both mean cardiac index (3.2 (SEM 0.2) to 2.4 (0.1) litre min-1 m-2 for propofol, and 3.4 (0.2) to 3.3 (0.4) litre min-1 m-2 for isoflurane) and right ventricular ejection fraction (0.45 (0.03) to 0.37 (0.02) for propofol, and 0.48 (0.02) to 0.42 (0.02) for isoflurane) in patients who received propofol. Furthermore, these reductions were sustained for longer in the propofol group. However, propofol was not associated with a significant increase in shunt fraction during OLV, which increased threefold in patients who received isoflurane.

SummaryA case is described of the intra-operative failure of an implanted pacemaker during transurethral prostatic resection caused by a diathermy-related increase in capture threshold which coincided with massive haemorrhage from the operative site. Key wordsEquipment; pacemakers, diathermy. Complications; pacemaker failure. Surgery; prostatectomy. Haemorrhage.There are more than 25000 patients in the United Kingdom with an implanted permanent pacemaker [I]. It is likely that this number will steadily increase, so that pacemaker-dependent patients will present for surgery more frequently. Although it is generally assumed that modern pacemakers are immune from the effects of surgical diathermy, problems may still occur. This report describes a patient in whom the use of unipolar diathermy for transurethral resection of the prostate (TURP) was associated with pacemaker failure. Case historyA 70-year-old man with a history of benign prostatic hypertrophy was admitted for elective transurethral prostatic resection. Three years prior to surgery he had developed complete heart block resulting in syncopal episodes for which a Biotronik Diplos 05 pacemaker had been implanted. This is a modern programmable device designed for atrial and ventricular pacing and it was programmed accordingly in the D D D mode (dual chamber sensing and pacing). It had been checked 6 months before surgery when it had been noticed that the ventricular capture threshold was higher than the lower output setting of the pulse generator (2.5 volts) so that, in order to achieve ventricular stimulation, the device had to be set on its maximum output of 5.0 volts. The threshold of the atrial lead was not elevated.The patient was taking enalapril 5 mg once daily for hypertension and was otherwise well. He was seen preoperatively by the cardiologists, who changed his pacemaker from D D D mode to VVI (on-demand ventricular pacing). His pre-operative electrocardiogram (ECG) showed pacemaker-generated potentials before each ventricular complex, implying that ventricular contractions were pacemaker-dependent. Two years previously he had undergone an uneventful T U R P under spinal anaesthesia with the existing pacemaker in place and he was keen to have the same anaesthetic technique on this occasion.He was premedicated with temazepam 10 mg and on arrival in the anaesthetic room a 14-G cannula was inserted under local anaesthesia, after which his circulation was volume preloaded with 1 I of Ringer lactate solution. He was monitored with continuous ECG, pulse oximetry and automatic noninvasive sphygmomanometry. A 26-G spinal needle was inserted into the L,, interspace, after infiltration with local anaesthetic, and isobaric 0.5% bupivacaine 3.5 ml was injected into the subarachnoid space. This produced a dense sensory and motor block to T, in 10 min and a decrease in blood pressure from 110/70 mmHg to 98/65 mmHg. He was then moved into the operating theatre where he was given oxygen 5 1.min-I by face mask and sedated with midazolam 2.5 mg, which produced no ...

Summary Anaesthetists will encounter increasing numbers of patients who are receiving lorig-term treatment with A C E inhibitors

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