A randomized, observer-blind comparison between the Neurotip mounted Neuropen and a disposable plastic neurological wheel for assessing the level of spinal blockade at cesarean section.

BACKGROUND: Various methods are used to assess the height of sensory block to touch under spinal anesthesia for cesarean section. We tested a novel, inexpensive, miniature, user-dependent plastic neurological wheel against the user-independent Neurotip mounted Neuropen. METHODS: Patients received either spinal or combined spinal-epidural anesthesia. For each patient assessment, the devices were randomly assigned to one of two independent investigators. The order of device application was randomly permuted. Neither researcher was involved with anesthetic care. At 5-min intervals for 20 min after spinal injection, and again at the end of the operation, the levels of block to loss-of-touch sensation were assessed. While one investigator evaluated the block, the other left the operating room and vice versa. Mixed-effects regression and Bland-Altman analysis were used to weigh agreement between devices. RESULTS: The mean difference in level-to-touch was 0.04 (95% CI -0.18, 0.27) dermatome levels. Measurement error standard deviation associated with the Neurotip mounted Neuropen and plastic neurological wheel was 1.36 (95% CI 1.26, 1.41) and 1.33 (95% CI 1.26, 1.46) dermatome levels, respectively. The difference in measurement error standard deviation was -0.03 (95% CI -0.16, 0.24). This evidence excludes the possibility, with 95% confidence, of clinically significant bias or measurement error differences between methods. Occasional wide variances in dermatome level were observed with both instruments at the initial assessment only. CONCLUSION: The compact plastic neurological wheel is as clinically reliable as the Neurotip mounted Neuropen.

Hemodynamic changes during laparoscopic cholecystectomy monitored with transesophageal echocardiography.

Although pneumoperitoneum has been well tolerated in a predominantly healthy population, there is concern that an increased intraperitoneal pressure may be poorly tolerated in patients with marginal cardiopulmonary function. The purpose of this study was to demonstrate noninvasively the hemodynamic effects of carbon dioxide pneumoperitoneum utilizing biplane transesophageal echocardiography. Fourteen otherwise-healthy patients undergoing nonemergent laparoscopic cholecystectomy were studied using bi-plane transesophageal echocardiography under a standardized anesthetic protocol utilizing isoflurane, fentanyl, and vecuronium bromide. End-tidal CO2, oxygen saturation, cardiac rhythm, temperature, and blood pressure were monitored noninvasively. Minute ventilatory volume was adjusted as needed to keep end-tidal CO2 less than 38 mmHg. Data were recorded at baseline, following abdominal insufflation to 15 mmHg with CO2, with head-up tilt of 20 degrees, following exsufflation, and with the patient level. Significance was determined using a paired Student t-test. Insufflation to 15 mmHg decreased cardiac index (C.I.) by 3% (3.34 to 3.23 l/min/m2) while both heart rate (HR) and mean arterial pressure (MAP) increased (by 7% and 16%), respectively, and stroke volume index decreased by 10% (from 51.6 to 46.6 ml/beat/m2). Head-up tilt of 20 degrees further decreased CI to 2.98 l/min/m2 (-11%) and SVI to 40.3 ml/beat/m2 (-22%) while HR increased by a total of 14% and MAP by 19%. As laparoscopic techniques are applied to a broader population, the impact of small but significant decrements in cardiac function become increasingly important. This study demonstrates that the combination of CO2 pneumoperitoneum and the reverse Trendelenburg position does adversely effect cardiac output.

Possible intraoperative anesthetic-sparing effect of parenteral ketorolac.

OBJECTIVE: Because the analgesic effects of ketorolac are equivalent to those of narcotic analgesics, we investigated the possibility that this non-steroidal antiinflammatory drug might also exhibit anesthetic-sparing properties similar to those described for narcotic agents. DESIGN: A nonrandomized, double-blind convenience sample. The treatment group received a preoperative dose of ketorolac 60 mg im 45 minutes prior to the induction of anesthesia. All other preoperative medications were identical. SETTING: Brooke Army Medical Center, a primary care setting. PARTICIPANTS: Six women requiring vaginal hysterectomies from American Society of Anesthesiologists class I/II, all of similar age, weight, and body surface area. OUTCOME MEASURES: End-tidal concentrations of the anesthetic gas were measured at five-minute intervals using a gas analyzer. A mean percent end-tidal concentration versus time curve was generated for each group. RESULTS: The area under the concentration curves for the anesthetic gas in the ketorolac and control group were 15.9 +/- 5.1 and 52.3 +/- 13.4, respectively (p = 0.006). CONCLUSIONS: Ketorolac exhibits an anesthetic-sparing quality similar to that observed with narcotic analgesics.

Epidural hydromorphone with and without epinephrine for post-operative analgesia after cesarean delivery.

The efficacy of epidural hydromorphone alone or in combination with epinephrine for postoperative analgesia was evaluated in 30 healthy women who underwent cesarean delivery with epidural anesthesia. They were assigned randomly to receive either 1.5 mg hydromorphone alone (N = 15) or 1.5 mg hydromorphone with 1/200,000 epinephrine (N = 15). Duration of analgesia (mean +/- SD) was 24.3 +/- 9.4 hours after the epidural injection of hydromorphone plus epinephrine. This was significantly greater (p less than 0.01) than the duration of 18.2 +/- 5.9 hours after the same dose of plain hydromorphone. Analgesia was more rapid in onset and significantly better at the 0.5, 1, 3, and 12 hours postoperatively in the hydromorphone-epinephrine group. Side effects including pruritus (73%), nausea (20%), and vomiting (15%) were of similar frequency with and without epinephrine. Although mean venous PCO2 (PvCO2) levels three and six hours after the hydromorphone-epinephrine dose were elevated significantly over the pre-drug PvCO2 levels, no respiratory depression was detected by an apnea monitor to which all patients were connected. The addition of epinephrine to epidural hydromorphone hastened onset and prolonged the duration of analgesia after cesarean section.

Cervical epidural anesthesia for surgery of the shoulder.

Regional anesthesia has some advantages over general anesthesia for shoulder surgery. Cervical epidural anesthesia, a regional technique not previously described for shoulder operations, was successfully used for surgical procedures on or near the shoulder joint. The technique provided good surgical anesthesia and postoperative analgesia, with few complications and a high degree of patient acceptance. Cervical epidural anesthesia offers some advantages over previously described techniques of regional anesthesia for shoulder operations, including a single needle insertion with no need to elicit paresthesias, lesser volumes of local anesthetic agents, and the ability to easily reinject the catheter intraoperatively if necessary and postoperatively for pain relief.

Intrathecal administration of hyperbaric morphine for the relief of pain in labour.

Thirty healthy women in active labour received an intrathecal injection of morphine 0.5 mg (n = 12) or 1 mg (n = 18) in 7.5% dextrose. Both doses provided excellent analgesia for labour, 93% of patients obtaining at least 50% pain relief. Analgesia began 15-60 min after injection and did not decrease until 6-8 h after injection. Analgesia was satisfactory until distension of the perineum, either by forceps or the infant's head. The intrathecal injection of morphine did not adversely affect the condition of the infant. Eighty per cent of patients developed pruritus; 53%, nausea or vomiting, or both; 43%, urinary retention; and 43%, drowsiness. These side effects were decreased by naloxone, which did not affect the degree of analgesia. There was no significant depression of ventilation in any patient. These results suggest that morphine 0.5 mg or 1 mg, administered intrathecally, effectively decreases the pain of labour, and that i.v. administration of naloxone can alleviate the common side effects.

Pharmacokinetics, placental transfer, and neonatal effects of vecuronium and pancuronium administered during cesarean section.

Vecuronium and pancuronium were compared for placental transfer, pharmacokinetic variables, and neonatal effects during cesarean section under general anesthesia. Eighteen women underwent rapid-sequence intravenous induction using d-tubocurarine, succinylcholine, thiopental, and oxygen. Immediately after tracheal intubation, an intravenous injection of vecuronium (n = 11) or pancuronium (n = 7), 0.04 mg/kg, was given. Maternal venous blood samples were obtained before induction and at frequent intervals for 4 h after administration of vecuronium or pancuronium. Also, maternal venous and umbilical-cord arterial and venous blood samples were obtained at delivery. To describe placental transfer and maternal pharmacokinetics of the drugs, serum drug concentrations were determined using single-ion-monitoring mass spectrometry. The Apgar score and Neurologic and Adaptive Capacity Score (NACS) were used to evaluate neonatal condition. Both drugs crossed the placenta, as demonstrated by low concentrations of vecuronium (8.5-26.4 ng/ml) or pancuronium (12.2-34.2 ng/ml) found in umbilical venous blood. At delivery, the ratio of the drug concentration in umbilical venous blood to that in maternal venous blood was 0.11 +/- 0.02 for vecuronium and 0.19 +/- 0.03 for pancuronium. Vecuronium had a more rapid clearance (6.4 +/- 0.4 ml X kg-1 X min-1, mean +/- SE) and a shorter elimination half-life (36 +/- 1.8 min) than pancuronium (3.0 +/- 0.1 ml X kg-1 X min-1 and 72 +/- 6 min, respectively). No other pharmacokinetic differences were found between the drugs. Neonatal outcome was not affected adversely by either muscle relaxant, as assessed by Apgar scores and NACSs . The short duration of action, the minimal placental transfer, and the apparent lack of clinical neuromuscular effects on the newborn suggest that vecuronium should be a useful muscle relaxant for cesarean section.

Evaluation of neurotoxicity after subarachnoid injection of large volumes of local anesthetic solutions.

Recent case reports describing prolonged neurologic deficit after accidental spinal anesthesia with large volumes of 2-chloroprocaine have led to the suggestion that chloroprocaine may be more likely to cause such complications than other local anesthetics. We evaluated the neurologic effects of lumbar puncture alone and of large-volume subarachnoid administration of 2-chloroprocaine (3%), bupivacaine (0.75%), lidocaine (2%), Elliott's solution B (which is similar to CSF), or the carrier solution of 2-chloroprocaine (Nesacaine) in 48 sheep and 8 monkeys. Cerebrospinal fluid of sheep was collected on days 1 and 7 for biochemical and biological analyses, and CSF pressures of monkeys were recorded before and after injection. Animals were observed for neurologic deficits for seven days. Twelve sheep were unable to stand. Monkeys, on the other hand, had no apparent neurologic deficits. Autopsies revealed that 5 of the 12 sheep had lumbar subpial demyelination with macrophage infiltration: two of the five had received lidocaine; two received 2-chloroprocaine; and one had only a lumbar puncture. Two other sheep also had subpial demyelination: one had received lidocaine and one received 2-chloroprocaine. Three of the eight monkeys had lumbar subpial demyelination with macrophage invasion; two had received bupivacaine, and one received 2-chloroprocaine. No solution produced significant abnormalities in sheep CSF composition. We conclude that no local anesthetic or solution was more neurotoxic than another when injected in large volumes into the subarachnoid space of sheep or monkeys.