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Sensory analgesia for vaginal deliveries: a preliminary report of continuous spinal anesthesia with a 32-gauge catheter.

Our initial experience in providing pain relief during labor and delivery for 20 parturients using a 32-gauge continuous spinal microcatheter using 1% lidocaine is described. The technique significantly reduced the pain of labor, which was assessed as severe by 18 of the patients, and provided adequate perineal anesthesia for vaginal delivery with 18 patients indicating pain during delivery to be minimal. The major advantage of continuous spinal anesthesia is the ability to rapidly establish sensory anesthesia with the flexibility to reinject additional local anesthetic should a complete sensory or sensory and motor block be required for forceps or cesarean delivery. Technical difficulty was the main disadvantage with the use of the 32-gauge microcatheter. An inability to thread the catheter (two patients) through the 26-gauge spinal needle or kinking of the catheter (two patients) making injection impossible, and unintentional catheter removal (one patient) resulted in a 25% failure rate with this technique.

Adolescent↗

PubMedDate not supplied

Warming 0.5% bupivacaine to 37 degrees C increases duration of spinal anesthesia.

The effect of warming glucose-free 0.5% bupivacaine to 37 degrees C before injection for spinal anesthesia was studied in 20 patients having total knee replacement. Twenty additional patients having spinal anesthesia for the same procedure were given glucose-free 0.5% bupivacaine at room temperature (approximately 20 degrees C). Onset, maximum cephalad spread, quality of sensory anesthesia, and duration and degree of motor blockade were the same in both groups. However, the duration of sensory anesthesia was significantly prolonged in patients who received bupivacaine at 37 degrees C. The mechanism by which warming bupivacaine prolongs the duration of sensory spinal anesthesia is uncertain. However, a decrease in the dissociation constant (pKa) of bupivacaine owing to increasing the temperature to 37 degrees C may account for some of this effect.

Adult↗

PubMedDate not supplied

Spinal anesthesia. Volume or concentration--what matters?

BACKGROUND AND OBJECTIVES: An investigation was made of the effects of volume and concentration of a constant dose of subarachnoid lidocaine on the extent and duration of sensory and motor anesthesia produced, as well as of the lidocaine concentration of the cerebrospinal fluid (CSF) as a function of time. METHODS: In a prospective study, 40 American Society of Anesthesiologists (ASA) status 2 or 3 patients were assigned to one of five groups, who received a 70-mg subarachnoid dose of lidocaine hydrochloride as a 0.5, 1, 2, 5, or 10% solution. Dural puncture was performed at the L3-L4 interspace with a 19.5-gauge Periquick needle (Pajunk, Germany), and a 24-gauge catheter was inserted 3-4 cm into the subarachnoid space. The patient remained in the lateral position during injection of the local anesthetic and was then turned to the supine horizontal position. The level of anesthesia and the motor block were measured at 5, 10, 15, 20, 30, 40, 50, and 60 minutes and then at 15-minute intervals until the effect of the anesthesia had ceased. Samples of CSF were collected at the same times that the pinprick and motor block measurements were made. RESULTS: Five minutes after injection, a median sensory block height of T4 or T5 was observed in all groups. The range of mean total times to complete recovery of the sensory blocks was 139-152 minutes, while that for the motor blocks of the lower extremities was 100-122 minutes. The values were similar in all groups (P > .05). The motor block was complete in all patients 10 minutes after the lidocaine injection. Five minutes after injection, the mean CSF lidocaine concentration was highest in the 10% group (P < .001 vs. the other four groups). At 15 minutes, the only statistical difference was found between the 0.5% and the 10% group (P = .026). At 20 minutes, the CSF lidocaine concentrations were similar in all groups (P > .05). CONCLUSIONS: A constant 70-mg dose of subarachnoid lidocaine produced the same pinprick level of analgesia, degree of motor block, and duration of spinal anesthesia in spite of being injected over an extremely broad range of concentrations and volumes. Despite the fact that all patients received the same dose of lidocaine, the CSF concentrations at 5, 10, and 15 minutes were different and directly related to the concentration of the solution injected. at 20 minutes, the CSF concentrations were similar in all groups. These results indicate a relatively uniform distribution of lidocaine in the CSF for all solutions tested.

Aged↗