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The study objective was to show that fentanyl given five minutes prior to induction improved insertion conditions for the Classic Laryngeal Mask Airway. Previous work had shown fentanyl at 90 seconds to be unpredictable. A probit analysis design was used in which success/failure rates of different doses of fentanyl were measured and dose-response curves drawn from which the ED50 and ED95 with 95% confidence intervals were determined. Adult Chinese patients with American Society of Anesthesiologists physical status classification I or II and requiring anaesthesia for minor surgery with a laryngeal mask were recruited. They were randomly assigned to one of six dosage groups: 0.25, 0.5, 1.0, 1.5, 2.0 and 3.0 microg x kg1. Fentanyl was given prior to propofol 25 mg x kg(-1), and insertion was assessed 90 seconds later using six categories of patient response. Ninety-six patients, aged 18 to 63 years, were studied. The six dosage groups were similar As the fentanyl dose increased, fewer patients responded to insertion (P < 0.01). Dose-responses could be predicted for all categories, except resistance to insertion and laryngospasm. Probit analysis predicted an ED50 of 0.5 microg x kg(-1) and ED, of 7.5 microg x kg(-1) for ideal insertion conditions (i.e., no swallowing, gagging, body movement or laryngospasm). Commonly used fentanyl doses of 1 to 2 microg x kg(-1) only prevented patients responding to insertion in 70 to 80% of cases. When using propofol 2.5 mg x kg(-1), administering fentanyl five minutes before laryngeal mask insertion does not provide ideal insertion conditions in 95% of cases unless excessively large doses are used. An ideal dose of fentanyl that produces optimum insertion conditions could not be determined.

We report the use of combined spinal-epidural analgesia during labour in three parturients with moderately severe mitral stenosis. In each case, rapid analgesia was achieved using intrathecal fentanyl 25 micrograms without major haemodynamic changes. Maintenance analgesia was then established gradually using a dilute epidural infusion of bupivacaine 0.1% and fentanyl 0.0002%, with the avoidance of large or rapid boluses of local anaesthetic. Supplementary analgesia in the latter stages of labour was provided using slow epidural boluses of fentanyl, with or without a low concentration of bupivacaine, which was sufficient to allow controlled instrumental deliveries. We conclude that combined spinal-epidural analgesia is a useful technique for providing analgesia and maintaining haemodynamic stability in parturients with mitral stenosis.

Pethidine is an effective epidural opioid for the treatment of acute pain. Its use has been well described in Australian and New Zealand practice, particularly in the field of obstetric anaesthesia. Reported methods of delivery have included bolus injection, continuous infusion and patient-controlled epidural analgesia. Areas of application have included treatment of postoperative pain, labour pain and intraoperative pain. Because of its intermediate lipid solubility, pethidine may have advantages over many other epidural opioids. However, potential for accumulation of norpethidine limits its use to relatively short durations of treatment.

Pethidine is the only member of the opioid family that has clinically important local anaesthetic activity in the dose range normally used for analgesia. Pethidine is unique as the only opioid in current use that is effective as the sole agent for spinal anaesthesia. In lower doses, intrathecal pethidine is also an effective analgesic for treating pain in labour. This paper reviews the pharmacology of intrathecal pethidine and clinical experience reported to date. Articles reviewed include those identified by a Medline search using keywords "intrathecal" or "spinal anaesthesia/ anesthesia" and "pethidine" or "meperidine". Reference lists from identified papers were scrutinized to identify further relevant articles.

We compared patient-controlled epidural analgesia (PCEA) with patient-controlled intravenous analgesia (PCIA) using pethidine or fentanyl in a randomized, double-blind crossover study of 80 patients after caesarean section. Patients received pethidine by PCEA or PCIA, or fentanyl by PCEA or PCIA, with a crossover of the route of administration at 12h. For pethidine, pain scores were lower with PCEA vs PCIA from 4 to 16h (P < 0.05). Pethidine consumption was lower with PCEA vs PCIA from 12 to 24h (P = 0.0005). Patients preferred PCEA to PCIA (P = 0.015). For fentanyl, pain scores were lower with PCEA vs PCIA at 12h (P = 0.045). Fentanyl consumption was lower with PCEA vs PCIA from 0 to 12h (P = 0.0007). Patients had similar preference for PCEA and PCIA. Pain scores and side-effects were similar between drugs. Plasma pethidine was similar between groups. Plasma fentanyl was higher with PCIA vs PCEA at 12h (P = 0.002). PCEA has advantages over PCIA and pethidine may be the preferred drug.

We evaluated a disposable device (Baxter PCA Infusor) for patient-controlled epidural analgesia (PCEA) using pethidine in twenty women after lower segment caesarean section. Efficacy, as measured by visual analogue pain scores, was comparable with historical controls from PCEA studies using electronic devices. Three patients reported inadequate analgesia, attributable in two cases to problems with epidural catheter. PCEA was stopped in one patient because of side-effects. Pethidine consumption ranged from 125 to 1500 mg (median 575 mg) in 48 hours. Plasma concentrations of pethidine varied widely. Disposable devices for PCEA after caesarean section provide an alternative to bolus administration or PCEA using more expensive and cumbersome electronic devices, although we suggest currently available apparatus requires modifications to improve clinical performance.

The Selectatec Vaporising System is a quick change system consisting of anaesthetic vaporisers of the Tec 3 and Tec 4 models and the compatibility manifold block on which these are seated on the anaesthetic machine backbar. There have been reports of difficulties with the seating and locking of the vaporisers which can cause a leak and failure of vapour delivery. The Faculty of Anaesthetists, Royal Australasian College of Surgeons (now Australian and New Zealand College of Anaesthetists) issued a hazard alert in March 1991 drawing attention to this potential fault. We present two cases of awareness associated with failure of internal seals within a Selectatec compatibility manifold block which did not have a detectable leak.