The effects of sevoflurane on isolated gravid human myometrium.

The volatile anaesthetic agents are known to influence uterine muscle tone. All of the agents studied to date have been found to produce uterine relaxation. This property has been used to produce therapeutic uterine relaxation for difficult obstetric deliveries and the Ex Utero Intrapartum Treatment (EXIT) procedure. This study describes the effects of sevoflurane on isolated human myometrium at concentrations of 0.1, 0.25, 0.5, 0.75, 1.0, 1.5, 2.5 and 3.5 MAC. Sevoflurane produces dose-dependent depression of uterine muscle contractility with an ED50 of 0.94 MAC. Frequency of contraction was increased at concentrations of 2.5 MAC and greater. At concentrations of 3.5 MAC and above, uterine activity was virtually abolished.

Airway management on placental support (AMPS)--the anaesthetic perspective.

Neonatal airway obstruction has been reported to have a high mortality. Antenatal diagnosis of this condition is now possible. Anaesthetic and surgical techniques have been developed that allow neonatal airway obstruction to be managed at delivery, while the fetus remains oxygenated via the placental circulation. Three case studies are presented, and the anaesthetic issues for mother and fetus/neonate are discussed with reference to previously published cases of airway management on placental support. In particular, techniques for uterine relaxation and maintenance of placental circulation are explored. The history of these procedures and issues of planning and logistics are also discussed.

Continuous extrapleural intercostal nerve block for post thoracotomy analgesia in children.

The safety and efficacy of continuous extrapleural intercostal nerve block has been well established in adults. This review of our initial paediatric experience suggests a role for this technique in children and discusses risks and benefits relative to other forms of regional analgesia for thoracotomy. Nine children aged one to twelve years received extrapleural infusions of bupivacaine 0.1-0.2% following lateral thoracotomy for lung resection. An extrapleural catheter was placed by the surgeon prior to thoracotomy closure, and correctly positioned under direct vision external to the parietal pleura alongside the vertebral column. An intraoperative loading dose of bupivacaine, 0.25-0.5% (0.28 +/- 0.1 ml/kg, mean +/- SD) was injected so as to raise a bleb under the parietal pleura which spread longitudinally to bathe several intercostal nerves in the paravertebral gutter. The chest wall was then closed. Infusions of bupivacaine were commenced in the recovery room and continued at a constant rate of 0.21 +/- 0.09 ml/kg/h for 72 +/- 15 hours. The mean dose of bupivacaine was 284 +/- 97 micrograms/kg/h. Patients also received standard analgesia as an intravenous morphine infusion (10-50 micrograms/kg/h), or patient-controlled analgesia. Nursing staff were specifically instructed not to alter their usual management of variable rate morphine infusions which are titrated to adequate analgesia. Morphine requirements in the first 48 postoperative hours remained less than 30 micrograms/kg/h, oral fluids were well tolerated after 31.2 +/- 19.1 hours, nasogastric tubes were removed at 16.7 +/- 11.2 hours. Postoperative nausea and vomiting and respiratory depression were not observed in any patient and all were able to comply with physiotherapy. There were no complications of catheter placement or bupivacaine administration. Our initial experience suggests that this is a safe technique which minimizes complementary opioid administration and provides adequate analgesia for children postthoracotomy for lung resection.