Labour anaesthesia

Kuczkowski KM. Respiratory arrest in a parturient following intrathecal administration of fentanyl and bupivacaine as part of a combined spinal-epidural analgesia for labour. Anaesthesia 2002 57(9) 939 0. 

The effect of the sympathomimetic drugs on the pregnant uterus is Vciriable and difficult to predict, but serious fetal distress can occur, due to reduced placental blood flow as a result both of contraction of the uterine muscle (a) and arterial constriction (a). Pj-agonists are used to relax the uterus in premature labour, but unwanted cardiovascular actions can be troublesome. Sympathomimetics were particularly likely to cause cardiac arrhythmias (p, effect) in patients who received halothane anaesthesia (now much less used). 

Perriss BW, Malins AF. Pain relief in labour using epidural pethidine with adrenaline. Anaesthesia 1981 36(6) 631-3. 

Nitrous oxide has a low potency and must be used in combination with other inhalation anaesthetics for general anaesthesia. Nitrous oxide provides rapid induction and recovery. It also has an analgesic action and is used as a 50% mixture with oxygen to provide analgesia without loss of consciousness during labour and manipulations of injured body parts. 

It has a slow onset of action, up to 30 minutes, and a long duration of action, up to eight hours when used for nerve block. Bupivacaine can also be used with adrenaline. Bupivacaine is often used to produce continuous epidural anaesthesia during labour. 

Any mode of pain relief during labour has the potential capacity to retard the progress of the second stage because.of a diminution in the reflex urge to push with each contraction (8 ), although improvement of uterine contraction by continuous epidural anaesthesia is also possible Of 200 cases of induced labour, 7 out of 76 patients who had a good uterine action before... 

A total of 3 cases of Homer s syndrome after obstetric epidural anaesthesia have recently been described (17 -, 18 -). In itself, this complication is not dangerous, but it may be a warning sign of an extensive block of serious consequence. Parturient women are more likely to develop this complication than are other patients because epidural injection with the patient in the lithotomy position can promote dissemination to higher levels (18 ). In some cases at least, the complication may be due to dissemination of the anaesthetic by way of the vertebral venous plexus (17 -). In view of the engorgement of the epidural veins during labour, this explanation is by no means improbable. 

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