Howard H. Bernstein

The Optimal Distance That a Multiorifice Epidural Catheter Should Be Threaded into the Epidural Space

Complications can occur during epidural placement for women in labor.As many as 23% of epidural anesthetics may not provide satisfactory analgesia. The cause of this may be technical. This study was undertaken to determine the optimal distance that a multiorifice catheter should be threaded into the epidural space to maximize analgesia and minimize complications. One hundred women in labor were enrolled in this prospective, randomized, and double-blind study. Patients were randomly assigned to have the epidural catheter threaded 3, 5, or 7 cm into the epidural space. After placement of the catheter and administration of a test dose with 3 mL of 0.25% bupivacaine, an additional 10 mL of 0.25% bupivacaine was administered in two divided doses. Fifteen minutes later, the adequacy of the analgesia was assessed by a blinded observer. We found that catheter insertion to a depth of 7 cm was associated with the highest rate of insertion complications while insertion to a depth of 5 cm was associated with the highest incidence of satisfactory analgesia. For women in labor who require continuous lumbar epidural anesthesia, we recommend threading a multiorifice epidural catheter 5 cm into the epidural space. (Anesth Analg 1995;81:301-4)

Quality of analgesia when air versus saline is used for identification of the epidural space in the parturient.

Background and Objectives Identification of the epidural space is often performed using the loss-of-resistance technique (LOR), commonly with air or saline. The effect of air or saline on the quality of labor epidural analgesia has not been adequately studied. Methods Women who requested labor epidural analgesia were randomly assigned to 1 of 2 groups depending on the syringe contents used for the LOR technique and injected into the epidural space. In the air group (n = 80) the anesthesiologist used 2 mL of air, and in the saline group (n = 80) the anesthesiologist used 2 mL of 0.9% saline. After LOR was obtained, a multiorifice epidural catheter was threaded 5 cm into the epidural space and 13 mL of bupivacaine 0.25% was administered in divided doses. The success of the epidural block was determined by asking the patient if she required additional medication 15 minutes later. The occurrence of paresthesias and intravascular or subarachnoid catheters was noted. Results In the air group, 36% of patients requested additional pain medication, and in the saline group 19% requested additional medication (P = .022). We were not able to find a statistically significant difference between groups in the incidence of paresthesias (42% air v 51% saline), intravascular catheters (5% air v 8% saline), or subarachnoid catheters (0 in both groups). Conclusions Using 0.9% saline for the LOR technique is associated with better analgesia as compared with air for labor analgesia, and this advantage should be considered when selecting the syringe contents for the LOR technique.

Local anesthetics and mode of delivery: bupivacaine versus ropivacaine versus levobupivacaine.

BACKGROUND:The influence of the labor epidural local anesthetic (LA) on mode of delivery has not been adequately studied. In this study, we sought to determine if there is a difference in mode of delivery among parturients who receive epidural bupivacaine, ropivacaine, or levobupivacaine. METHODS:Nulliparous women at term requesting labor analgesia with a cervical dilation <5 cm were randomized to receive epidural bupivacaine, ropivacaine, or levobupivacaine. Analgesia was initiated with a bolus of 15 mL of 0.0625% of the assigned LA with fentanyl 2 &mgr;g/mL. Analgesia was maintained with an infusion of the same solution at 10 mL/h. The primary endpoint was the operative delivery rate (instrumental assisted vaginal delivery plus cesarean delivery). RESULTS:Ninety-eight women received bupivacaine, 90 ropivacaine, and 34 levobupivacaine (before it was removed from the US market). There was no significant difference in the operative delivery rate (bupivacaine = 46%, ropivacaine = 39%, and levobupivacaine = 32%, P = 0.35) among groups. There was less motor block in the levobupivacaine group when compared with the ropivacaine and bupivacaine groups, P < 0.05. There was no significant difference in the duration of the first or second stage of labor, the total dose of LA received per hour of labor, or neonatal outcome among groups. CONCLUSIONS:Bupivacaine, ropivacaine, and levobupivacaine all confer adequate labor epidural analgesia, with no significant influence on mode of delivery, duration of labor, or neonatal outcome.

The ability of the Haemonetics 4 Cell Saver System to remove tissue factor from blood contaminated with amniotic fluid.

The purpose of this study was to determine whether functionally active tissue factor could be removed from blood contaminated with amniotic fluid (AF) after processing through a Haemonetics[registered sign] 4 Cell Saver System (Haemonetics Corporation, Braintree, MA).In Phase I, AF was collected from 29 women undergoing cesarean section. Nine experiments were performed. Forty-milliliter aliquots of pooled AF were mixed with 125 mL of packed red blood cells and processed in the Cell Saver. In Phase II, all the blood and AF lost at cesarean section was collected and processed through the Cell Saver. Pre- and postwash specimens were collected and analyzed for total tissue factor concentration and the concentration of functionally active tissue factor. In Phase I, total tissue factor concentration was reduced by 89%, and the concentration of active tissue factor was reduced to 0 after processing. In Phase II, no tissue factor was detected after processing through the Cell Saver. We have demonstrated the ability of the Haemonetics[registered sign] 4 Cell Saver System to remove tissue factor activity from blood contaminated with AF. Implications: Hemorrhage after childbirth may require massive transfusion. If the patients own blood can be collected and given back to the patient, this may avoid the use of regular banked blood. Amniotic fluid, which may mix with blood lost after delivery, contains tissue factor, a substance that may activate the coagulation system and cause further bleeding. The authors found that the Haemonetics[registered sign] 4 Cell Saver System (Haemonetics Corporation, Braintree, MA), which collects and washes blood, can remove tissue factor from blood contaminated with amniotic fluid. (Anesth Analg 1997;85:831-3)

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)

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.

Information and concerns about obstetric anesthesia: a survey of 320 obstetric patients.

This study was undertaken to assess womens knowledge and concerns about obstetric anesthesia and to determine if they perceive a need for an anesthesia interview before the onset of labor. A 17 item questionnaire was distributed to 407 women on postpartum day one. The women were questioned about their knowledge, anxiety and concerns regarding obstetric anesthesia. The questionnaire was completed by 320 women, 57% of whom were Caucasian and 28% of whom had some postgraduate education. Most of the women (74%) had either a regional or general anesthetic for their delivery and 86% of the women admitted to having some anxiety about anesthesia. Although 82% of the women attempted to obtain information about anesthesia before labor, 28% did not feel adequately informed. The majority (59%) of the women would have wanted a preoperative visit with an anesthesiologist before labor. These results illustrate that most women are anxious about obstetric anesthesia and do not feel adequately prepared. Efforts at educating women about obstetric anesthesia would be welcomed by them and methods to accomplish this goal are discussed.

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.