Elisabet U. M. Nystrom

Combined Spinal and Epidural Anesthesia for Labor and Cesarean Delivery in a Patient With Guillain-Barre Syndrome

Background and Objectives The anesthetic management of labor, delivery, and cesarean delivery in patients with active or resolving Guillain-Barre syndrome is not well defined. Using a combined spinal and epidural (CSE) technique in such a rare clinical situation has not been previously reported. Case Report A 32-year-old woman gravida 2, para 0 was diagnosed with Guillain-Barre syndrome at 21 weeks of pregnancy. Paralysis spread up to the T4 level. Three months later, she was admitted for labor at term. She presented in severe labor pain and it was decided to proceed with CSE analgesia. No unusual hemodynamic instability, signs of autonomic dysfunction, or increased sensitivity to local anesthetics was noted. After several hours, delivery by cesarean section was required and epidural anesthesia was then used. The patient had an uncomplicated postpartum course. Conclusion Careful evaluation and documentation of the patient’s baseline neurological status, a thorough discussion with the patient regarding the risks and benefits of the technique for labor analgesia, and an appreciation of the limited experience with this kind of clinical situation are important.

Blood pressure is maintained despite profound myocardial depression during acute bupivacaine overdose in pigs.

UNLABELLED Bupivacaine-induced cardiovascular collapse is a feared complication because of the difficulty in restoring stable circulation (1). Early recognition is important so that the injection of bupivacaine can be discontinued. We used an animal model of near-cardiac arrest from bupivacaine infusion to identify the sequence of hemodynamic events that precedes bupivacaine-induced cardiovascular collapse. Twelve pigs (23-25 kg) were sedated with ketamine and anesthetized with halothane. Arterial blood pressure and cardiac output were measured. Bupivacaine (3.75 mg/mL) was administered at a rate of 5.73 mL/min (approximately 1 mg x kg(-1) x min(-1)) through a central venous catheter until severe ventricular arrhythmia occurred. Blood pressure and heart rate were unchanged, but cardiac output decreased by 40% with increasing doses of bupivacaine. Calculated peripheral resistance increased by 54%. The QRS complex of the surface electrocardiogram widened, and the R-wave amplitude decreased 80%, together with the decrease in cardiac output. T-wave amplitude increased initially but returned toward baseline at the largest bupivacaine doses. The plasma concentration of bupivacaine after the infusion was 16+/-6.8 microg/mL. IMPLICATIONS The increase in vascular resistance that accompanies acute bupivacaine overdose maintains blood pressure but masks severe myocardial depression.

Transmural pressure of epidural veins in the thoracic and lumbar spine of pigs.

Background The aim of this study was to determine the transmural pressure gradient of epidural veins located within the spinal column and to investigate the effects of increased intra‐abdominal and intrathoracic pressure on this gradient. Methods Fourteen pigs were sedated with ketamine and anesthetized with halothane. Ventilation was controlled after tracheotomy. Needles were inserted into the epidural and subarachnoid space, and a catheter was threaded into an epidural vein. Pressures in these structures were measured during controlled and spontaneous ventilation, increased abdominal pressure, and thoracic compression. Measurements were made in both the thoracic and lumbar regions. Results The pressure gradient between the epidural vein and the surrounding epidural space was low ‐ 1 or 2 mmHg ‐ in both the lumbar and thoracic areas. This gradient was not affected by the mode of ventilation or increased abdominal or thoracic pressure (or both), even though the absolute intramural pressure increased. Conclusion The pressure gradient between the epidural vein and the surrounding space is low and does not change when abdominal or thoracic pressures are increased.

Chloroprocaine is less painful than lidocaine for skin infiltration anesthesia.

Skin infiltration of local anesthetics causes pain. In a double-blinded protocol, 22 volunteers received random intradermal injections to the volar surface of the forearm with each of the following solutions: normal saline solution 0.9% (NSS), lidocaine 1% (L), lidocaine 1% and sodium bicarbonate 8.4% (L+BIC), 2-chloroprocaine 2% (CP), 2-chloroprocaine 2% and sodium bicarbonate 8.4% (CP+BIC), and NaCHO3 8.4% (BIC). Initially, each volunteer received an open-labeled injection of NSS. A 100-mm visual analog scale (VAS, 1–100) was used to assess pain with each injection. The pH of each solution was stable for the length of the study. Repeated measures of variance were used for analysis. The VAS scores (mean ± sd) for open-label and blinded NSS injections were 15.5 ± 15.9 and 14.0 ± 18.1, respectively. The scores for the studied solutions were as follows: BIC, 47.2 ± 25.5; L, 25.8 ± 27.6; L+BIC, 16.0 ± 14.2; CP, 8.6 ± 7.4; and CP+BIC, 6.8 ± 6.7. No significant difference was found between CP and alkalinized CP, but the injection of both solutions was significantly less painful than that of all other solutions (P < 0.05). The pH of the solutions was not related to the pain score. We found that chloroprocaine caused less pain at injection than the more commonly used lidocaine.