Comparison of plasma bupivacaine concentrations during continuous extradural infusion for labour

Cesarean section in a patient with familial cardiomyopathy and a cardioverter-defibrillator

PURPOSE

To describe the impact of maternal automatic implantable cardioverter-defibrillator (AICD) therapy on pregnancy outcome, and discuss the clinical rationale for regional anesthesia in parturients with AICDs.

CLINICAL FEATURES

A 20-yr-old primigravida with a history of familial cardiomyopathy and AICD placement presented at 39 weeks gestational age for elective labour induction. Ultimately, the patient underwent a Cesarean section for a failed induction. Her AICD was deactivated during the peripartum period, although the pacing function remained active as she had an underlying heart rhythm of less than 34 beat.min(-1). The patient had continuous electrocardiogram monitoring via an external defibrillating unit to which she remained connected by external defibrillator pads. Labour analgesia and surgical anesthesia were provided with a lumbar epidural dosed with varying concentrations of bupivacaine. This management resulted in an excellent maternal and fetal outcome.

CONCLUSIONS

Automatic implantable cardioverter-defibrillators are being utilized more frequently in the obstetric population, and appear compatible with good fetal outcomes. Experience with the anesthetic management of these patients is markedly limited - primarily involving reports of general anesthesia for Cesarean section. Epidural anesthesia, however, offers distinct advantages in this patient population including easy conversion from labour analgesia to surgical anesthesia, preservation of fetal-maternal hemodynamics, prevention of increases in plasma catecholamines due to labour or operative pain, and, finally, possible direct suppression of arrhythmias by pharmacologically-active plasma levels of local anesthetic.

Long-term epidural analgesia for pregnancy-induced intercostal neuralgia

Intercostal neuralgia is one of many possible neurological disorders associated with pregnancy. A woman presented in the 34th week of her 4th pregnancy with progressing right-sided pain and hypoesthesia in the ribs, right upper quadrant of the abdomen, and mid-thoracic area of her back. With a clinical diagnosis of pregnancy-related intercostal neuralgia, we inserted an epidural catheter at T8 for ambulatory pain management. A continuous infusion of bupivacaine was titrated by concentration and rate until adequate analgesia was obtained. The final effective dose consisted of 0.125% bupivacaine at 6 ml/h with a patient-controlled bolus dose of 2 ml every 30 min as needed (4-6 boluses per 24-h period). This allowed the patient to continue to work full-time and perform daily activities with minimal discomfort. The epidural infusion was continued until the patient went into spontaneous labor 28 days after the initial clinical visit. A full-term infant was delivered without incident. No major complications occurred such as local anesthetic toxicity, hypotension, motor weakness, or infection. Minor complications included disconnection of the catheter cap and accidental dislodgment, which required placement of a second epidural catheter. For this patient, an appropriately placed chronic epidural catheter and a titrated continuous infusion of bupivacaine provided adequate and safe analgesia for pregnancy-associated intercostal neuralgia.

Epidural analgesia in labour: constant infusion plus patient-controlled boluses

A randomised, single-blind study to investigate patient-controlled epidural analgesia during labour was conducted using a solution of low-dose bupivacaine-fentanyl. Two groups (n = 25 in each) received a constant infusion supplemented by patient demand boluses, and midwife-administered boluses if required, the size of the infusion and patient increments varying between groups. The quality of analgesia, as assessed by pain scores and patient ratings, was high and participant acceptability very high in both groups. Fourteen per cent of participants were withdrawn due to cephalad extension of block to T5 or supplementary bolus requirements outside the study protocol. Epidural side-effects were not troublesome and drug dose utilisation was low. Significantly greater pain relief (P less than 0.04) three hours after commencing patient-controlled epidural analgesia and a trend to fewer women requiring more than two supplementary midwife-administered boluses (P = 0.11) was seen in the group receiving a higher infusion rate. This group used significantly more bupivacaine (P less than 0.04) and fentanyl (P less than 0.001), but this did not appear to be clinically important with respect to degree of motor block or side-effects. Patient-controlled epidural analgesia appears to be an effective and well accepted method of obstetric analgesia and warrants further investigation.