Jeffrey Zahn

Safe Epidural Analgesia in Thirty Parturients with Platelet Counts Between 69,000 and 98,000 mm-3

Regional anesthesia is a popular form of pain relief for the management of labor and delivery.Thrombocytopenia is considered a relative contraindication to the administration of regional anesthesia. Some authorities have recommended that an epidural anesthetic be withheld if the platelet count is <100,000 mm-3. For the period of March 1993 through February 1996, we reviewed the charts of all parturients who had a platelet count <100,000 mm-3 during the peripartum period. Eighty women met this criterion. Of these 80,30 had an epidural anesthetic placed when the platelet count was <100,000 mm-3 (range 69,000-98,000 mm-3), 22 had an epidural anesthetic placed with a platelet count >100,000 mm-3 that subsequently decreased below 100,000 mm-3, and 28 did not receive a regional anesthetic. We found no documentation of any neurologic complications in the medical records. We conclude that regional anesthesia should not necessarily be withheld when the platelet count is <100,000 mm-3. (Anesth Analg 1997;85:385-8)

Subhypnotic doses of propofol do not relieve pruritus induced by intrathecal morphine after cesarean section.

The purpose of this study was to determine whether subhypnotic doses of propofol effectively relieve pruritus in women who received intrathecal morphine for postoperative analgesia after cesarean delivery.Twenty-nine women who developed pruritus after undergoing an elective cesarean section and receiving intrathecal morphine (0.25 mg) for postoperative analgesia were enrolled in this randomized, prospective, double-blind study. The women were randomly assigned to receive either 1 mL of propofol (n=17) or 1 mL of placebo (n=12) IV. Pruritus was evaluated 5 min after treatment. In the absence of successful treatment, the women received another 1 mL of the same drug. Pruritus was again evaluated 5 min after the second dose. We found that pruritus was successfully treated twice in the propofol group and once in the placebo group (P = not significant). The antipruritic action of propofol lasted for up to 6 h in one woman and 15 min in the other. The one success in the placebo group lasted for 15 min. We conclude that the success rate of propofol in treating pruritus in women who received intrathecal morphine for postoperative analgesia after cesarean delivery is not significantly different from that of placebo. Implications: Pruritus is a common and bothersome side effect of neuraxial opioids after cesarean section. Subhypnotic doses of IV propofol (10 mg) have been used to treat pruritus caused by neuraxial opioids. In this prospective, randomized, double-blind study, we found that propofol does not relieve pruritus in women who underwent cesarean section and received intrathecal morphine sulfate (0.25 mg) for postoperative pain relief. (Anesth Analg 1998;86:310-3)

Epidural ropivacaine for the initiation of labor epidural analgesia: a dose finding study.

The purpose of our study was to determine the lowest concentration of ropivacaine that offers pain relief for the initiation of labor epidural analgesia.Women in active labor were enrolled in this prospective, randomized, double-blinded study to receive either ropivacaine 0.20% (Group I), ropivacaine 0.15% (Group II), or ropivacaine 0.10% (Group III). After placement of the epidural catheter, 13 mL of the study medication was administered. Fifteen minutes later, the adequacy of analgesia was assessed. If the woman reported that her degree of analgesia was not adequate, an additional 5 mL of the study medication was given, the degree of pain relief was reassessed 15 min later, and the study was concluded. A sequential study design was used to assess the success rates. We found that 26 of 28 (93%) women in Group I had adequate analgesia, compared with only 18 of 28 (64%) in Group II (P = 0.014) and 4 of 12 (33%) in Group III (P = 0.003). We conclude that ropivacaine 0.20% offers adequate analgesia significantly more often than either ropivacaine 0.15% or ropivacaine 0.10%. If one selects ropivacaine as the sole local anesthetic for the initiation of labor epidural analgesia, the minimal concentration should be 0.20%. Implications: The lowest effective concentration of ropivacaine for the initiation of labor epidural analgesia has not been determined. We found that ropivacaine 0.20% offers adequate analgesia significantly more often than either ropivacaine 0.15% or ropivacaine 0.10%. If one selects ropivacaine as the sole local anesthetic for the initiation of labor epidural analgesia, the minimal concentration should be 0.20%. (Anesth Analg 1999;88:1340-5)

Treatment of Incomplete Analgesia after Placement of an Epidural Catheter and Administration of Local Anesthetic for Women in Labor

Background Approximately 15% of women still have pain after placement of an epidural catheter and administration of local anesthetic for labor analgesia. Two techniques frequently used to treat this pain were compared: (1) withdrawal of the catheter 1 cm and repeated dosing with additional local anesthetic, and (2) repeated dosing with additional local anesthetic without any catheter manipulation. Methods Fifteen minutes after placement of a multiple‐orifice epidural catheter 5 cm into the epidural space and administration of 13 ml 0.25% bupivacaine to the parturient in labor, the adequacy of analgesia was assessed. All women who had incomplete analgesia were randomized (first intervention) to receive and additional 5 ml 0.25% bupivacaine (local‐anesthetic‐only only group) or to receive 5 ml 0.25% bupivacaine after first withdrawing the epidural catheter 1 cm (catheter‐manipulation group). If after 15 min the woman still bad pain, then (second intervention) the catheter was withdrawn 1 cm and an additional 5 ml 0.25% bupivacaine was administered to the local‐anesthetic‐only group, whereas 5 ml 0.25% bupivacaine was given to the catheter‐manipulation group without further catheter manipulation. The success rate of the second intervention was assessed 15 min later. Results Seventy‐eight women were enrolled in the study, 39 to each group. In the local‐anesthetic‐only group, 29 (74%) women were successfully treated with the first intervention and remaining 10 (100%) were successfully treated with the second intervention. In the catheter‐manipulation group, 30 (77%) were successfully treated with the first intervention and 7 (100%; 2 patients were not studied because of investigator error) were successfully treated with the second intervention (P = NS). Conclusions Administration of additional local anesthetic without first withdrawing the epidural catheter will effectively treat most women for whom analgesia is incomplete after the placement of an epidural catheter during labor.

A comparison of epidural infusions in the combined spinal/epidural technique for labor analgesia.

We compared the clinical effects of three epidural infusions initiated after subarachnoid medication was administered as part of the combined spinal/epidural technique for labor analgesia. Fifteen minutes after administering subarachnoid fentanyl 25 &mgr;g and 1 mL of bupivacaine 0.25%, and 5 min after an epidural test dose of 3 mL of bupivacaine 0.25%, women were randomized to receive an epidural infusion of saline, bupivacaine 0.125%, bupivacaine 0.0625%, or bupivacaine 0.04% with epinephrine 1:600,000. All epidural infusions were started at 10 mL/h, and all except the Saline Group also received fentanyl 2 &mgr;g/mL. The end point of the study was delivery or request for additional medication for analgesia. We found that time until request for additional analgesia was longest in women who received bupivacaine 0.125% (median duration, 300 min) versus saline (median duration, 118 min) (P = 0.0001) and was intermediate for bupivacaine 0.0625% and bupivacaine 0.04% (median duration, 162 and 180 min, respectively) (P = 0.0001 versus saline). Women who received bupivacaine 0.125% had the most motor block. We conclude that all the bupivacaine-based infusions we tested maintained the analgesia from subarachnoid medication longer than saline, with the longest duration, but the most motor block, from bupivacaine 0.125%.

Subarachnoid Small-dose Bupivacaine Versus Lidocaine for Cervical Cerclage

Cervical cerclage is often performed as an outpatient procedure under subarachnoid anesthesia. Lidocaine was historically the drug of choice for short procedures but has fallen out of favor because of concerns of transient neurologic symptoms (TNS). We performed this study to determine whether small-dose bupivacaine is an acceptable alternative to lidocaine for cervical cerclage. We randomized 59 women to receive either subarachnoid isobaric lidocaine 30 mg or hyperbaric bupivacaine 5.25 mg. Fentanyl 20 &mgr;g was added to both local anesthetics, and the total volume was diluted to 3 mL with 0.9% saline. Onset and highest dermatomal level of sensory block; quality of anesthesia; hypotension; and times until T12 regression, return of lower extremity motor function, ambulation, and micturition were recorded. Symptoms of TNS were evaluated by telephone interview 24 h after surgery. We did not find any significant difference in onset or recovery times between the groups, with the exception of a longer duration until return of lower extremity motor strength in the lidocaine group. Symptoms consistent with TNS that resolved spontaneously within 48 h were reported by two women in the lidocaine group but by none in the bupivacaine group. We conclude that subarachnoid bupivacaine offers a satisfactory alternative to subarachnoid lidocaine for cervical cerclage.

Comparison of Non-invasive Blood Pressure Measurements on the Arm and Calf During Cesarean Delivery

Objective. Shivering may occur in 75% of women undergoing spinal anesthesia for cesarean delivery and may render an automated noninvasive blood pressure (ANIBP) device incapable of determining blood pressure (BP). When patients shiver under spinal anesthesia, the lower extremities do not exhibit the same involuntary muscle movements as do the upper extremities. This study was undertaken to determine if a correlation exists between ANIBP measurements in the arm and calf of women undergoing cesarean delivery under spinal anesthesia. Methods. We enrolled 73 women in this blinded, prospective study. Simultaneous arm and calf BP were measured with an ANIBP and differences between the two were determined. Results. We found significant differences between the average difference in systolic and in diastolic BP, no significant difference between the average mean BP, and a tendency for the systolic BP to be higher and the diastolic BP to be lower in the calf than in the arm; however, there was a large degree of variability among patients. Conclusion. We conclude that there is a poor correlation between the BP measured by an ANIBP on the calf and one on the arm. In the parturient undergoing cesarean section, lower extremity BP as measured by an ANIBP does not correlate with the arm ANIBP and should not be used to assure fetal wellbeing.

The Effect of Adding Subarachnoid Epinephrine to Hyperbaric Bupivacaine and Morphine for Repeat Cesarean Delivery: A Double-blind Prospective Randomized Control Trial

BACKGROUND: Spinal anesthesia has become the most common type of anesthetic for cesarean delivery. The major limitation to spinal anesthesia is that the duration of the anesthetic may not be adequate in the event of a prolonged surgery. Some practitioners add epinephrine to hyperbaric bupivacaine to increase the duration, although its effect has not been fully studied. We therefore aimed to evaluate whether adding epinephrine to the spinal medication prolongs the duration of action of the resultant block in women presenting for repeat cesarean delivery. METHODS: Sixty-eight patients were randomized to receive no epinephrine (NE group), epinephrine 100 µg (low-dose [LD] group), or epinephrine 200 µg (high-dose [HD] group) with a standardized spinal mixture (1.5 mL 0.75% hyperbaric bupivacaine with 0.25 mg morphine). Sixty-five patients were included for primary analysis. Our primary outcome was time to intraoperative activation of the epidural catheter or postoperative regression of sensory blockade to T-10 dermatome level as measured by pinprick sensation; motor recovery was a secondary outcome, and graded via a Modified Bromage scale. RESULTS: Block onset time, vital sign changes, and the incidence of hypotension; nausea, and vomiting were similar among groups. Median difference in time to T-10 regression was greatest in the HD group compared to the NE group (median difference [min] [95% confidence interval]: 40 [15–60]; P = .007), followed by the HD group to the LD group (30 [15–45]; P = .007). Comparisons of LD to NE were not significant, but trended to an increase in T-10 regression time (10 [−15 to 30]; P = .76). Median difference in time to knee extension (Bromage 3) was also greatest in the HD group when compared to both the LD and NE group (median difference [min] [95% confidence interval]: 30 [0–60]; P = .034, 60 [0–93]; P = .007). Median difference time to knee extension (min) between the LD and NE group was also significant (37.5 [15–60]; P = .001]. Pain scores during the procedure were higher in the NE group (median [interquartile range] HD: 0 [0–0], LD: 0 [0–0], NE: 0 [0–3]; P = .02) during uterine closure and were otherwise not significantly different from the other groups. CONCLUSIONS: In this single center, prospective, double-blind, randomized control trial, the addition of epinephrine 200 µg to hyperbaric bupivacaine and preservative-free morphine for repeat cesarean delivery prolonged the duration of the sensory blockade. Motor blockade was similarly prolonged and block quality may have been enhanced.