1 Department of Anaesthesiology and Intensive Care and 2 Department of Obstetrics and Gynaecology, Faculty of Medicine, Selçuk University, Konya, Turkey
Presented at the 2nd World Congress of the World Institute of Pain, I·stanbul, Turkey, June 2001.
Accepted for publication: November 11, 2002
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Method. Twenty-five parturients received ropivacaine 15 mg and morphine 150 µg (RM group) and twenty-five parturients received bupivacaine 15 mg and morphine 150 µg (BM group) for spinal anaesthesia. Sensory and motor block, haemodynamics, postoperative analgesia, fetal outcomes, and side-effects were evaluated.
Results. Intrathecal bupivacainemorphine and ropivacainemorphine provided effective sensory anaesthesia and motor block. Time to reach complete motor block was shorter and time to complete recovery from motor block was longer in the BM group than the RM group (P<0.05). The time to regression of two dermatomes and time for the block to recede to the S2 dermatome were similar in both groups (P>0.05). Time to first complaint of pain and the mean total consumption of tenoxicam were similar in both groups (P>0.05). APGAR scores at 1 and 5 min were similar in the two groups, as were mean umbilical blood pH values (P>0.05). Hypotension and pruritus were the most common side-effects in both groups during the operation.
Conclusion. Intrathecal isobaric ropivacaine 0.5% 15 mg plus morphine 150 µg provides sufficient anaesthesia for Caesarean delivery. The ropivacainemorphine combination resulted in shorter motor block, similar sensory and postoperative analgesia.
Br J Anaesth 2003; 90: 65964
Keywords: anaesthesia, obstetric; anaesthetic techniques, epidural; anaesthetics local, bupivacaine; anaesthetics local, ropivacaine; analgesics opioid, morphine
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The potential advantages of using ropivacaine compared with bupivacaine remain to be determined. In previous studies, intrathecal ropivacaine was either used for non-obstetric surgery510 or labour analgesia combined with sufentanyl or fentanyl.1113 Hyberbaric ropivacaine was used by Chung and colleagues14 and a doseresponse study with isobaric ropivacaine was conducted by Khaw and colleagues15 in CS anaesthesia. The optimal safe dose and baricity of ropivacaine for obstetric anaesthesia is still to be determined. An isobaric ropivacainemorphine combination has not been previously studied and compared with bupivacainemorphine combination.
The aim of this prospective, double-blind, randomized study was to compare the analgesia and spinal block characteristics of isobaric ropivacaine 0.5% plus morphine and isobaric bupivacaine 0.5% plus morphine given intrathecally for CS.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Using a computer-generated randomization table, patients were randomized to one of two groups. Group RM (n=25) received isobaric ropivacaine (Naropin, Astra Zeneca) 0.5% 15 mg plus preservative-free morphine hydrochloride 150 µg. Group BM (n=25) received isobaric bupivacaine (Marcain, Astra Zeneca) 0.5% 15 mg plus preservative-free morphine hydrochloride 150 µg at room temperature. The study solution was prepared by an anaesthetist not involved in data collection. The investigators who performed the spinal block and who collected the intraoperative and postoperative data, as well as the patients, were blinded to the contents of the study solutions.
After entering the operating theatre, patients were monitored (Poet II, Criticare Systems Inc., USA) for heart rate (HR), mean arterial pressure (MAP), peripheral oxygen saturation (SpO2) and respiratory rate (RR). Lactated Ringers solution was infused at 10 ml kg1 h1 during surgery. Spinal anaesthesia was performed with the patient in the sitting position, using a 25-gauge Quincke needle (Spinocan, Braun) at the L34 or L45 interspace. The study solution (3.7 ml) was administered within 30 s (approximately 0.12 ml s1) with the opening of the needle facing cephalad. The position of the needle was confirmed by aspiration and re-injection of 0.20.3 ml cerebrospinal fluid before and after administration of the study solution. The patient was turned gently and placed supine with left uterine displacement and a pillow was placed under the head. A fetal heart rate monitor was used until delivery.
After the spinal block, HR, RR, SpO2 and MAP were measured every min until delivery and then every 2 min. Hypotension was defined as 20% decrease from baseline MAP (baseline MAP was calculated from three measurements taken on the ward before surgery) and was treated with incremental i.v. boluses of ephedrine 510 mg. Total ephedrine requirements were recorded. Urine output was also monitored. Supplementary oxygen was given through a facemask.
The level of sensory anaesthesia, defined as the loss of pin-prick sensation (20G hypodermic needle) at midclavicular level, was measured every min until it reached the T5 dermatome level and then every 10 min during surgery. The following variables were recorded: time to initial onset of analgesia, time for sensory block to reach the T5 dermatome, time to maximum cephalad spread of analgesia, highest level of analgesia, time to two-segment regression of analgesic level, and regression of analgesic level to the S2 dermatome. Anaesthesia was considered adequate for surgery if pain sensation was lost at the T5 level.
Time to motor block was assessed every min using the Bromage scale (0=no motor block, 3=complete motor block of lower limbs) until complete motor block and then every 30 min until the return of normal motor function. The times to complete motor block and complete recovery were recorded. The motor block score when the sensory level reached T5 was also recorded. Time to first complaint of pain and total requirements for postoperative (48 h) analgesia (tenoxicam 20 mg i.v.) were recorded.
The time from skin incision to delivery was also recorded. After delivery, umbilical blood samples were taken for measurement of umbilical venous blood gases. APGAR scores at 1 and 5 min were evaluated and recorded. In the intraoperative period, side-effects and requirement for sedation or general anaesthesia were noted. Nausea and vomiting were treated with metoclopramide 10 mg i.v. Diphenhydramine 20 mg i.v. was administered for pruritus.
Maternal sedation scores were evaluated and recorded during and after surgery until the block wore off, using a 03 grading score (0=no sedation, 3=severe sedation, difficult to arouse). The patient remained in a semi-recumbent position in the post-anaesthesia care unit until full recovery from spinal block. During the first 48 h after surgery, side-effects, including pruritus, headache, backache, respiratory depression, nausea and vomiting, were recorded.
The quality of anaesthesia (judged by the anaesthetists), the quality of muscle relaxation (judged by the surgeon) and the degree of intraoperative comfort (judged by the patient) were recorded as excellent, good, fair or poor.
Statistical analysis
Data from previous studies,7 8 including SD of time to recovery from motor block and time to regression of two segments with ropivacaine, were used for power analysis. To detect a 30-min difference in mean duration of motor block or a 10-min difference in mean duration of two-segment regression between the groups (two-sided of 5% and ß of 20%), a group size of 16 or 17 was necessary. One-way and two-way ANOVA for repeated measures, and unpaired and paired t-tests were used for quantitative nominal data, as appropriate. Categorical data were compared using the
2-test. P<0.05 was considered significant.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
APGAR scores and umbilical venous pH values were within the normal range in both groups. The 1-min APGAR scores were 7.8 (1.1) and 7.6 (0.8) in the BM and RM groups, respectively, and 5-min APGAR scores were 9.9 (0.2) and 9.9 (0.3) (P>0.05). The umbilical blood pH values of the BM and RM groups were 7.29 (0.04) and 7.31 (0.03), respectively (P>0.05).
During surgery, vomiting was observed in two patients in the BM group and was not observed in any patient in the RM group (P>0.05); similar numbers of patients in each group experienced nausea. Shivering was not observed in any patient (Table 4). Other side-effects such as pruritus and headache were observed similarly between the groups (P>0.05).
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The optimal dose and baricity of ropivacaine for Caesarean delivery is unknown. The only study investigating plain isobaric ropivacaine during Caesarean delivery was a doseresponse study by Khaw and colleagues,15 who estimated the ED50 to be 16.7 mg (14.118.8 mg) and the ED90 as 26.8 mg for CS anaesthesia. This is higher than previous non-obstetric studies.69 It is known that spinal injections in full-term pregnant women produce higher-than-expected levels of anaesthesia.16 Therefore, the dose of ropivacaine should be kept at the minimum possible. When designing the study, we intended to use an equal dose of ropivacaine and bupivacaine (15 mg). Our ropivacaine dose is similar to the ED50 described by others.14 15
Prolonging effective postoperative analgesia after Caesarean delivery is considered to be an advantage of spinal anaesthesia. Chung and colleagues14 stated that adding an opioid to ropivacaine may improve the quality of analgesia. In our study, the ropivacainemorphine combination produced similar two-segment regression and time to regression to S2 as the bupivacainemorphine combination. Although ropivacaine is considered to be less potent than bupivacaine, the similar duration of sensory and postoperative analgesia is interesting. The equipotent ratio between bupivacaine and ropivacaine is considered as 3:2 or 2:1.2 5 7 Therefore, ropivacaine is expected to lead to less cephalad spread than similar bupivacaine doses.5 7 Parlow and colleagues17 demonstrated that adding opioid to local anaesthetics alters the density and spread of local anaesthetics in cerebrospinal fluid. Our findings suggest that cephalad spread and onset time of ropivacaine or bupivacaine with morphine are similar, which is contradictory to our expectations and previous data.14 Glucose-free ropivacaine 0.5% solution is slightly hypobaric at body temperature (density at 37 °C=0.9988);14 this may have resulted in a higher cephalad spread. Pharmacodynamic studies on morphineropivacaine combinations in spinal anaesthesia are not available, and we do not know why a ropivacaine morphine combination behaved similarly to the bupiva cainemorphine combination. Further studies are therefore needed.
Although motor block is a less important issue in CS anaesthesia, the quality of muscle relaxation during surgery, and early ambulation should be considered. Early studies on the motor block properties of ropivacaine showed less motor depressant effect when compared with bupivacaine.18 Later clinical studies disputed this finding.2 8 10 Buggy and colleagues19 observed unexpectedly high incidence and duration of motor block in patients receiving epidural ropivacaine for postoperative analgesia after spinal anaesthesia for CS. Studies of intrathecal ropivacaine also report similar results when ropivacaine was compared with bupivacaine.8 10 15 However, the studies comparing ropivacaine and bupivacaine were performed using doses with a 3:2 ratio.2 5 7 8 The properties of motor block have not been compared using similar doses. In studies of isobaric ropivacaine 1525 mg, the intensity and duration of motor block was found to be related to the dose.8 10 15 In our study, complete motor block occurred in all patients. Although a bupivacainemorphine combination was associated with a more rapid onset and longer duration of motor block, the differences were not clinically significant (220 (32.4) min vs 200 (34.9) min, respectively).
We did not record any postoperative neurological symptoms in any of our patients up to 48 h after administration of intrathecal ropivacaine. Kristensen and colleagues20 21 demonstrated that ropivacaine decreased spinal cord blood flow without causing neurotoxicity in two animal studies. Likewise, in other clinical studies, intrathecal ropivacaine did not induce any neurological symptoms.2 515 The available data regarding neurotoxicity suggest that ropivacaine is a suitable alternative spinal anaesthetic. Iida and colleagues22 pointed out that the vasoconstrictive effect of ropivacaine on spinal pial vessels could eliminate the need for addition of a vasopressor such as epinephrine into the ropivacaine solutions. This natural vasopressor property of ropivacaine may contribute to the prolongation of analgesia by reducing its local clearance.
Hypotension is the most commonly reported adverse event in studies in women undergoing CS with epidural ropivacaine 0.5% or 0.75% solutions, together with labour pain or postoperative pain.23 24 The incidence of hypotension increases with increasing dose and it is most likely to be a consequence of sympathetic block.1 In a study by McNamee and colleagues,10 the different doses of ropivacaine (18.75 and 25 mg) provided a high degree of cardiovascular stability. In our study, although the BM group required more ephedrine than the RM group, the number of patients requiring ephedrine was similar and the APGAR scores and umbilical blood pH values of the neonates were within normal ranges.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Capogna G, Celleno D, Fusco P, Lyons G, Columb M. Relative potencies of bupivacaine and ropivacaine for analgesia in labour. Br J Anaesth 1999; 82: 3713
3 Russel IF. Inadvertent total spinal for Caesarean section. Anaesthesia 1985; 40: 199200[ISI][Medline]
4 Kestin IG. Spinal anaesthesia in obstetrics. Br J Anaesth 1991; 66: 596608[ISI][Medline]
5 McDonald S, Spencer SL, Kopacz DJ, Stephenson CA. Hyperbaric spinal ropivacaine. Anesthesiology 1999; 90: 9717[ISI][Medline]
6 Wahedi W, Nolte H, Klein P. Ropivacaine in spinal anaesthesia. Anaesthesist 1996; 45: 73744[CrossRef][ISI][Medline]
7 Gautier E, DeKock M, Van Steenberge A, et al. Intrathecal ropivacaine for ambulatory surgery. Anesthesiology 1999; 91: 123945[ISI][Medline]
8 Malinovsky JM, Charles F, Kick O, et al. Intrathecal anesthesia: ropivacaine versus bupivacaine. Anesth Analg 2000; 91: 145760
9 Van Kleef J, Veering B, Burm AGL. Spinal anesthesia with ropivacaine: double-blind study on the efficacy and safety of 0.5% and 0.75% solutions in patients undergoing minor lower limb surgery. Anesth Analg 1994; 78: 112530[Abstract]
10 McNamee DA, Parks L, McClelland AM, et al. Intrathecal ropivacaine for total hip arthroplasty: double-blind comparative study with isobaric 7.5 mg ml1 and 10 mg ml1 solutions. Br J Anaesth 2001; 87: 7437
11 Levin A, Datta S, Camann WR. Intrathecal ropivacaine for labor analgesia: a comparison with bupivacaine. Anesth Analg 1998; 87: 6247[Abstract]
12 Sony AK, Miller CG, Pratt SD, et al. Low dose intrathecal ropivacaine with or without sufentanyl provides effective analgesia and does not impair motor strength during labour: a pilot study. Can J Anaesth 2001; 48: 67780
13 Shah MK, Sia AT, Chong JL. The effect of the addition of ropivacaine or bupivacaine upon pruritus induced by intrathecal fentanyl in labour. Anaesthesia 2000; 55: 100813[CrossRef][ISI][Medline]
14 Chung CJ, Choi SR, Yeo KH, Park HS, Lee SI, Chin YJ. Hyperbaric spinal ropivacaine for cesarean delivery: a comparison to hyperbaric bupivacaine. Anesth Analg 2001; 93: 15761
15 Khaw KS, Ngan Kee WD, Wong ELY, Liu JYW, Chung R. Spinal ropivacaine for cesarean section. Anesthesiology 2001; 95: 134650[ISI][Medline]
16 Mulroy MF. Regional Anesthesia, 2nd Edn. Boston: Little Brown & Co., 1996; 259
17 Parlow JL, Money P, Chan PSL, et al. Addition of opioids alters the density and spread of intrathecal local anesthetics. An in vitro study. Can J Anaesth 1999; 46: 6670[Abstract]
18 Bader AM, Datta S, Flanagan H, et al. Comparison of bupivacaine and ropivacaine induced conduction blockade in the isolated rabbit vagus nerve. Anesth Analg 1989; 68: 7247[Abstract]
19 Buggy DJ, Hall NA, Shah J, Brown J, Williams J. Motor block during patient-controlled epidural analgesia with ropivacaine or ropivacaine-fentanyl after intrathecal bupivacaine for Caesarean section. Br J Anaesth 2000; 85: 46870
20 Kristensen JD, Karlsten R, Gordh T. Spinal cord blood flow after intrathecal injection of ropivacaine: a screening for neurotoxic effects. Anesth Analg 1996; 82: 63640[Abstract]
21 Kristensen JD, Karlsten R, Gordh T. Spinal cord blood flow after intrathecal injection of ropivacaine and bupivacaine with or without epinephrine in rats. Acta Anaesthesiol Scand 1998; 42: 68590[ISI][Medline]
22 Iida H, Ohata H, Iida M, Watanabe Y, Nagase K, Dohi S. Attenuated additional hypocapnic constriction, but not hypercapnic dilation of spinal pial arterioles during spinal ropivacaine. Anesth Analg 1999; 89: 151013
23 Bjornestad E, Smedvig JP, Bjerkreim T, et al. Epidural ropivacaine 7.5 mg/ml for elective cesarean section: a double-blind comparison of efficacy and tolerability with bupivacaine 5 mg/ml. Acta Anaesthesiol Scand 1999; 43: 6038[CrossRef][ISI][Medline]
24 Cascio MG, Gaiser RR, Camann WR, et al. Comparative evaluation of four different infusion rates of ropivacaine (2 mg/mL) for epidural labor analgesia. Reg Anesth Pain Med 1998; 23: 54853[CrossRef]