Hyperbaric intrathecal morphine analgesia during labor in a patient with Wolff-Parkinson-White syndrome.

The Wolff-Parkinson-White syndrome can complicate the anesthetic management of the pregnant patient. These patients are prone to arrhythmia that can be accompanied by hypotension. Maintenance of a stable heart rhythm is necessary for both maternal and fetal well-being. An optimal anesthetic regimen that provides minimal cardiac and hemodynamic changes has not been determined. Intrathecal administration of opiates for obstetric analgesia has been found to provide hemodynamic stability because no motor or sympathetic blockade occurs. The authors report the successful use of intrathecal injection of morphine for labor analgesia in a patient with Wolff-Parkinson-White syndrome.

Effect of intrathecal morphine during labor on maternal plasma beta-endorphin levels.

Plasma beta-endorphin was measured in 16 patients in labor prior to and after complete onset of analgesia with 1 mg of morphine administered intrathecally. Human beta-endorphin levels were determined by radioimmunoassay following silicic acid extraction of plasma samples and separation of the beta-endorphin fraction by gel chromatography. Plasma beta-endorphin levels decreased significantly (p less than 0.005) after intrathecal morphine from 76 +/- 9.7 to 46.3 +/- 9.1 fmol/ml (mean +/- SE), possibly because of decreased pituitary beta-endorphin secretion in response to alleviation of labor pain.

Epidural morphine analgesia after cesarean delivery.

The effectiveness and safety of 5 mg of epidurally administered morphine for postoperative analgesia was determined in 276 healthy women undergoing cesarean delivery. Overall pain relief, time to administration of additional analgesic medications, and adverse side effects were evaluated. Epidural injection of 5 mg of morphine provided good to excellent pain relief lasting 24 to 36 hours for 83% of patients. Also, review of hospital records for a subset of 34 patients revealed that requirements for additional systemic analgesics were markedly less when postoperative pain relief was provided by epidural administration of morphine than by conventional analgesia therapy. Pruritus, nausea, and vomiting occurred frequently, but were easily treated. Although late respiratory depression did not occur in this group, the authors continue to observe patients closely and monitor respiratory rates for 24 hours.

Bupivacaine-induced cardiac arrhythmias in sheep.

Controversy persists about the cardiac toxicity of bupivacaine if accidentally administered intravenously during regional anesthesia. Using awake, unanesthetized sheep, we evaluated the cardiac effects of low and high equivalent doses of lidocaine and bupivacaine given intravenously over 10 s. All animals convulsed within 30 s of injections. Although both drugs significantly increased heart rate and systemic and pulmonary arterial blood pressure for up to 10 min, cardiac output was affected variably. The magnitude of hemodynamic changes that each drug produced did not differ significantly from each other at either dose level. However, of the sheep receiving intravenous lidocaine, none developed arrhythmias other than mild sinus tachycardia and minimal ST-T wave changes (which occurred in 25% of the animals). After intravenous bupivacaine injection, all sheep had transient changes on the EKG and/or arrhythmias (e.g., supraventricular tachycardia; atrioventricular condition blocks; ventricular tachycardia; multiform premature ventricular contractions; wide QRS complexes; ST-T wave changes; and in one animal, fatal ventricular fibrillation). Normal sinus rhythm usually returned within 8-10 min. Arterial blood gas and acid-base values stayed within the normal range during the studies, and serum potassium did not change significantly from control. In conclusion, in conscious adult sheep, equivalent doses of lidocaine or bupivacaine produced similar central nervous system (CNS) toxicity when rapidly injected intravenously. In the absence of marked hypoxia, respiratory or metabolic acidosis, hyperkalemia, or hypotension, serious cardiac arrhythmias occurred after bupivacaine but not lidocaine.