Anaesthesia, 1992, Volume 47, pages 435-437
Epidural pethidine and bupivacaine in labour
N. D. Edwards,* MB. BS, FRCAnaes, M. Hartley, M B , ChB, F R C A n a e s , Registrars, P. Clyburn, M B , BS, F R C A n a e s , M. H a r m e r , M B , BS, FRCAnaes, Consultant Anaesthetists, University Hospital of Wales, H e a t h Park, Cardiff CF4 4XW.
Summary
A double-blind randomised study was performed io assess ihe value of the addition of peihidine 50 mg to the initial dose of bupivacaine given for epidural analgesia in labour. Forty-nine patients received either I ml of saline ( n = 24), or SO mg of pethidine ( n = 25). added to 9 ml of 0.2S% bupivacaine as an iniiial injection for intraparium epidural analgesia. There was a signjjicant increuse in the mean duration of analgesia in ihe pethidine group. However, pethidine did not increase the speed of onset of analgesia, or improve the quality of analgesia. Key words
Analgesics: pet h id i ne . Anaesthesia, obstetric; epidural. Anaesthetic agents, locak bupivacaine.
Epidural analgesia with local anaesthetics is an effective, reliable method of pain relief in labour. However, it is also associated with potentially troublesome side effects including hypotension, motor block, shivering and the possibility of systemic toxicity. In an attempt to reduce the overall dose of local anaesthetic required, and hence the incidence of side effects. opioids have been combined with the local anaesthetic. Combinations of bupivacaine with fentanyl. butorphanol. sufentanil or diamorphine have been shown to give a more rapid onset of action, increase the duration of effect, and lower the total dose of bupivacaine used when compared to bupivacaine alone [ 1-51. The combination of morphine with bupivacaine is less effective [6]. We have investigated the effect of adding 50 mg of pethidine to the initial dose of epidural bupivacaine used for analgesia in labour. Method
All patients requesting epidural analgesia during labour were considered as to their eligibility for inclusion in the study, which was approved by the local hospital ethics committee. Written informed consent was obtained from all participants. Patients with multiple pregnancy, weight greater than 100 kg at the initial antenatal visit, cervical dilatation greater than 6 cm, or who had received opioid analgesia within 2 h of epidural insertion, were not studied. Following establishment of intravenous access, all patients were given 500 ml of compound sodium lactate solution. The epidural space was located between the second and third. or the third and fourth lumbar vertebrae, using the loss-of-resistance-to-air technique and an epidural catheter inserted. The patients were randomly allocated to receive one of two solutions. The solutions were prepared by the staff in the delivery suite and consisted of either 1 ml (50 mg) of pethidine, or I ml of saline added to 9 ml of 0.25% bupivacaine. The anaesthetist was unaware of the identity of the solution. Initially 4 ml of this solution was given as a test dose to check for correct placement of the catheter. This was followed 5 min later by the remaining 6 ml. The patient’s blood pressure
was measured every 5 min for 20 min following the epidural injection. The height and distribution of sensory block was assessed using ethyl chloride spray, at 10, 20 and 30 rnin following the main injection. The pain of uterine contractions was assessed by the patient using a 100 mm visual analogue scale (VAS), where 0 = no pain, and 100 = the worst pain imaginable. Assessments were made immediately before the epidural was inserted, and at 10, 20 and 30 min following completion of the injection. The time taken from epidural completion to the first painless contraction was also noted. After 30 min, the adequacy of the pain relief was assessed, and the presence of perineal pain or incomplete analgesia was noted. If pain relief was inadequate, further bolus doses of 5 ml of 0.5% bupivacaine were given, and the patient took no further part in the study. The degree of motor block was assessed using a modified Bromage scale (4 = n o weakness, 3 = impaired movement at the hip joint, 2 = impaired movement at the knee, 1 = impaired movement at the ankle). Patients were also asked about the presence of itching, nausea, drowsiness or shivering. When the patient requested a ‘top-up’, the height of the sensory block was ascertained, and the level of pain assessed with a VAS. Ten ml of 0.25% bupivacaine was given as a ‘top-up’ dose, and a n epidural infusion of bupivacaine 0.125% started at 7 m1.h-l. Further ‘top-ups’ of 10 ml 0.25% bupivacaine were given as required throughout the remainder of labour. The mode of delivery, and the neonatal Apgar scores at 1 and 5 rnin were noted. Statistical analysis was performed using Student’s 1-test, and the Mann-Whitney U-test as appropriate. Significance was accepted at the p < 0.05 level. Results Forty-nine patients were recruited into the study; 24 entered the saline group, and 25 the pethidine group. The two groups were comparable for age, weight, height, gestational age, cervical dilatation, and pain score prior to epidural catheter insertion (Table I). Of the 24 patients in the saline group, 18 (75%) patients
*Present appointment: Lecturer, Department of Anaesthesia, University of Sheffield, Beech Hill Road, Sheffield SIO 2RX. Accepted 4 October 1991.
436
Forum
Table 1. Demographic data. Values are expressed as mean (SD).
Age; years Height; cm Weight; kg Primiparous; % Gestational age; weeks Cervical dilatation; cm Pain score prior to epidural insertion
Saline group (n = 24)
Pethidine group (n = 25)
26.8 (4.1) 162 (4.8) 65.9 (10.0) 75% 40 (1 .O) 3.7 (1.1)
25.9 (5.8) 163 (4.4) 69.2 (11.2) 80% 40 ( I .4) 4.2 (1.1)
70.6 (17.6)
67.0 (18.7)
Table 2. Effectiveness of epidural 30 rnin after bolus; number of patients (%). Effect after 30 rnin Satisfactory analgesia Perineal pain ‘Missed’ segment No noticeable effect
Saline group (n = 24)
Pethidine group (n = 25)
18 (75%)
19 (76%) 2 4 0
4 1
1
achieved satisfactory analgesia from the initial dose. Of the six other patients, three required a further 5 ml of 0.5% bupivacaine and one patient required 10 ml of 0.5% bupivacaine to achieve satisfactory analgesia. Two patients did not achieve adequate analgesia, one of whom had her epidural catheter resited. Of the 25 patients in the pethidine group, 19 (76%) patients achieved satisfactory analgesia from the initial dose, two patients required a further 5 ml of 0.5% bupivacaine and two patients required a further 10 ml of 0.5% bupivacaine to achieve satisfactory analgesia. As in the saline group, two patients did not achieve adequate analgesia, of whom one had her epidural catheter resited (Table 2). There was no difference between the groups in the time taken for the onset of analgesia, or in the pain scores following epidural insertion. However, the length of time between the initial dose and the first top-up injection was significantly longer in the pethidine group, p < 0.001 (Tables 3 and 4). Tables 5 and 6 show the degree of motor blockade, incidence of side effects, and the mode of delivery in the two groups. The saline group experienced greater motor blockade than the pethidine group (p < 0.05). Patients in the pethidine group experienced a higher incidence of vomiting, and a lower incidence of shivering, compared to the saline group, although these differences did not reach statistical significance. No patients in either of the groups
Table 4. Pain scores following epidural insertion (0 = no pain, 100 = very severe pain). Values are expressed as mean (SEM). Time after epidural completion
Time to first painless contraction; min Time to first top-up; rnin
Pethidine group (n = 19)
15.2 (7.1)
12.8 (3.9)
87.5 (16.4) (n = 17)
‘122.2 (23.3) (n = 15)
Four patients in the pethidine group delivered vaginally and one patient in the saline group underwent Caesarean section, before requiring a top-up. These patients are not included in the data for the time to first top-up. * Pethidine group > saline group, p i0.001.
Pethidine group
(n = 24)
(n = 2 5 )
34.6 (5.4) 19.4 (4.7) 19.4 (5.0) 48.1 (5.5) n = 17
25.8 (4.6) 16.7 (3.8) 11.8 (3.4) 52.3 (5.5) n = 15
10 min 20 min 30 min At time of 1st top-up
Table 5. Motor block 30 rnin after completion of epidural (4 = no motor block, I = complete motor block); number of patients. Motor block
Saline group (n = 24)
Pethidine group (n = 25)
10 10 4
I8 6 I
4 3 pethidine group, p
i0.05.
suffered pruritus. There were n o significant differences between the groups in the mode of delivery. Table 7 shows the neonatal Apgar scores at 1 and 5 min. There were no significant differences between the groups. One neonate in the pethidine group had an Apgar score of only 2 at 5 min and required ventilation. The epidural had been in position for 10 h and the patient had failed to progress in labour, severe fetal distress then developed, requiring an emergency Caesarean section under general anaesthesia. Discussion
Epidural pethidine, used alone or in combination with adrenaline, has been shown to be of value in labour, but its analgesic effect is unpredictable [7-91. The combination of 25 mg of pethidine with 10 mlO.125% bupivacaine used as the initial bolus dose and for subsequent top-ups has been reported as being very effective, with a high rate of patient satisfaction [lo], but no previous study has compared a pethidine/bupivacaine mixture with plain bupivacaine for epidural analgesia in labour. We have shown that the addition of 50 mg of pethidine to 9 ml 0.25% bupivacaine significantly prolongs the duration of epidural analgesia (from a mean of 87 min to a Table 6. Incidence of side effects; number of patients. Mode of delivery; number of patients (YO).
Table 3. Top-up requirement of patients who had satisfactory analgesia at 30 min. Values are expressed as mean (SD). Saline group (n = 18)
Saline group
Saline group (n = 24)
Pethidine group (n = 25)
13 (54%) 5 (21%) 2 (8%) 4 (17%)
12 (48%) 3 (12%) 4 (16%) 6 (24%)
Decrease in systolic blood pressure ( > 20%) Nausea only Nausea with vomiting Pruritus Drowsiness Shivering
Mode of delivery Spontaneous vaginal Forceps Ventouse Caesarean section
Forum Table 7. Neonatal data.
5 min
1 min
Apgar scores 9-10 7-8 5-6
Epidural pethidine and bupivacaine in labour
N. D. Edwards,* MB. BS, FRCAnaes, M. Hartley, M B , ChB, F R C A n a e s , Registrars, P. Clyburn, M B , BS, F R C A n a e s , M. H a r m e r , M B , BS, FRCAnaes, Consultant Anaesthetists, University Hospital of Wales, H e a t h Park, Cardiff CF4 4XW.
Summary
A double-blind randomised study was performed io assess ihe value of the addition of peihidine 50 mg to the initial dose of bupivacaine given for epidural analgesia in labour. Forty-nine patients received either I ml of saline ( n = 24), or SO mg of pethidine ( n = 25). added to 9 ml of 0.2S% bupivacaine as an iniiial injection for intraparium epidural analgesia. There was a signjjicant increuse in the mean duration of analgesia in ihe pethidine group. However, pethidine did not increase the speed of onset of analgesia, or improve the quality of analgesia. Key words
Analgesics: pet h id i ne . Anaesthesia, obstetric; epidural. Anaesthetic agents, locak bupivacaine.
Epidural analgesia with local anaesthetics is an effective, reliable method of pain relief in labour. However, it is also associated with potentially troublesome side effects including hypotension, motor block, shivering and the possibility of systemic toxicity. In an attempt to reduce the overall dose of local anaesthetic required, and hence the incidence of side effects. opioids have been combined with the local anaesthetic. Combinations of bupivacaine with fentanyl. butorphanol. sufentanil or diamorphine have been shown to give a more rapid onset of action, increase the duration of effect, and lower the total dose of bupivacaine used when compared to bupivacaine alone [ 1-51. The combination of morphine with bupivacaine is less effective [6]. We have investigated the effect of adding 50 mg of pethidine to the initial dose of epidural bupivacaine used for analgesia in labour. Method
All patients requesting epidural analgesia during labour were considered as to their eligibility for inclusion in the study, which was approved by the local hospital ethics committee. Written informed consent was obtained from all participants. Patients with multiple pregnancy, weight greater than 100 kg at the initial antenatal visit, cervical dilatation greater than 6 cm, or who had received opioid analgesia within 2 h of epidural insertion, were not studied. Following establishment of intravenous access, all patients were given 500 ml of compound sodium lactate solution. The epidural space was located between the second and third. or the third and fourth lumbar vertebrae, using the loss-of-resistance-to-air technique and an epidural catheter inserted. The patients were randomly allocated to receive one of two solutions. The solutions were prepared by the staff in the delivery suite and consisted of either 1 ml (50 mg) of pethidine, or I ml of saline added to 9 ml of 0.25% bupivacaine. The anaesthetist was unaware of the identity of the solution. Initially 4 ml of this solution was given as a test dose to check for correct placement of the catheter. This was followed 5 min later by the remaining 6 ml. The patient’s blood pressure
was measured every 5 min for 20 min following the epidural injection. The height and distribution of sensory block was assessed using ethyl chloride spray, at 10, 20 and 30 rnin following the main injection. The pain of uterine contractions was assessed by the patient using a 100 mm visual analogue scale (VAS), where 0 = no pain, and 100 = the worst pain imaginable. Assessments were made immediately before the epidural was inserted, and at 10, 20 and 30 min following completion of the injection. The time taken from epidural completion to the first painless contraction was also noted. After 30 min, the adequacy of the pain relief was assessed, and the presence of perineal pain or incomplete analgesia was noted. If pain relief was inadequate, further bolus doses of 5 ml of 0.5% bupivacaine were given, and the patient took no further part in the study. The degree of motor block was assessed using a modified Bromage scale (4 = n o weakness, 3 = impaired movement at the hip joint, 2 = impaired movement at the knee, 1 = impaired movement at the ankle). Patients were also asked about the presence of itching, nausea, drowsiness or shivering. When the patient requested a ‘top-up’, the height of the sensory block was ascertained, and the level of pain assessed with a VAS. Ten ml of 0.25% bupivacaine was given as a ‘top-up’ dose, and a n epidural infusion of bupivacaine 0.125% started at 7 m1.h-l. Further ‘top-ups’ of 10 ml 0.25% bupivacaine were given as required throughout the remainder of labour. The mode of delivery, and the neonatal Apgar scores at 1 and 5 rnin were noted. Statistical analysis was performed using Student’s 1-test, and the Mann-Whitney U-test as appropriate. Significance was accepted at the p < 0.05 level. Results Forty-nine patients were recruited into the study; 24 entered the saline group, and 25 the pethidine group. The two groups were comparable for age, weight, height, gestational age, cervical dilatation, and pain score prior to epidural catheter insertion (Table I). Of the 24 patients in the saline group, 18 (75%) patients
*Present appointment: Lecturer, Department of Anaesthesia, University of Sheffield, Beech Hill Road, Sheffield SIO 2RX. Accepted 4 October 1991.
436
Forum
Table 1. Demographic data. Values are expressed as mean (SD).
Age; years Height; cm Weight; kg Primiparous; % Gestational age; weeks Cervical dilatation; cm Pain score prior to epidural insertion
Saline group (n = 24)
Pethidine group (n = 25)
26.8 (4.1) 162 (4.8) 65.9 (10.0) 75% 40 (1 .O) 3.7 (1.1)
25.9 (5.8) 163 (4.4) 69.2 (11.2) 80% 40 ( I .4) 4.2 (1.1)
70.6 (17.6)
67.0 (18.7)
Table 2. Effectiveness of epidural 30 rnin after bolus; number of patients (%). Effect after 30 rnin Satisfactory analgesia Perineal pain ‘Missed’ segment No noticeable effect
Saline group (n = 24)
Pethidine group (n = 25)
18 (75%)
19 (76%) 2 4 0
4 1
1
achieved satisfactory analgesia from the initial dose. Of the six other patients, three required a further 5 ml of 0.5% bupivacaine and one patient required 10 ml of 0.5% bupivacaine to achieve satisfactory analgesia. Two patients did not achieve adequate analgesia, one of whom had her epidural catheter resited. Of the 25 patients in the pethidine group, 19 (76%) patients achieved satisfactory analgesia from the initial dose, two patients required a further 5 ml of 0.5% bupivacaine and two patients required a further 10 ml of 0.5% bupivacaine to achieve satisfactory analgesia. As in the saline group, two patients did not achieve adequate analgesia, of whom one had her epidural catheter resited (Table 2). There was no difference between the groups in the time taken for the onset of analgesia, or in the pain scores following epidural insertion. However, the length of time between the initial dose and the first top-up injection was significantly longer in the pethidine group, p < 0.001 (Tables 3 and 4). Tables 5 and 6 show the degree of motor blockade, incidence of side effects, and the mode of delivery in the two groups. The saline group experienced greater motor blockade than the pethidine group (p < 0.05). Patients in the pethidine group experienced a higher incidence of vomiting, and a lower incidence of shivering, compared to the saline group, although these differences did not reach statistical significance. No patients in either of the groups
Table 4. Pain scores following epidural insertion (0 = no pain, 100 = very severe pain). Values are expressed as mean (SEM). Time after epidural completion
Time to first painless contraction; min Time to first top-up; rnin
Pethidine group (n = 19)
15.2 (7.1)
12.8 (3.9)
87.5 (16.4) (n = 17)
‘122.2 (23.3) (n = 15)
Four patients in the pethidine group delivered vaginally and one patient in the saline group underwent Caesarean section, before requiring a top-up. These patients are not included in the data for the time to first top-up. * Pethidine group > saline group, p i0.001.
Pethidine group
(n = 24)
(n = 2 5 )
34.6 (5.4) 19.4 (4.7) 19.4 (5.0) 48.1 (5.5) n = 17
25.8 (4.6) 16.7 (3.8) 11.8 (3.4) 52.3 (5.5) n = 15
10 min 20 min 30 min At time of 1st top-up
Table 5. Motor block 30 rnin after completion of epidural (4 = no motor block, I = complete motor block); number of patients. Motor block
Saline group (n = 24)
Pethidine group (n = 25)
10 10 4
I8 6 I
4 3 pethidine group, p
i0.05.
suffered pruritus. There were n o significant differences between the groups in the mode of delivery. Table 7 shows the neonatal Apgar scores at 1 and 5 min. There were no significant differences between the groups. One neonate in the pethidine group had an Apgar score of only 2 at 5 min and required ventilation. The epidural had been in position for 10 h and the patient had failed to progress in labour, severe fetal distress then developed, requiring an emergency Caesarean section under general anaesthesia. Discussion
Epidural pethidine, used alone or in combination with adrenaline, has been shown to be of value in labour, but its analgesic effect is unpredictable [7-91. The combination of 25 mg of pethidine with 10 mlO.125% bupivacaine used as the initial bolus dose and for subsequent top-ups has been reported as being very effective, with a high rate of patient satisfaction [lo], but no previous study has compared a pethidine/bupivacaine mixture with plain bupivacaine for epidural analgesia in labour. We have shown that the addition of 50 mg of pethidine to 9 ml 0.25% bupivacaine significantly prolongs the duration of epidural analgesia (from a mean of 87 min to a Table 6. Incidence of side effects; number of patients. Mode of delivery; number of patients (YO).
Table 3. Top-up requirement of patients who had satisfactory analgesia at 30 min. Values are expressed as mean (SD). Saline group (n = 18)
Saline group
Saline group (n = 24)
Pethidine group (n = 25)
13 (54%) 5 (21%) 2 (8%) 4 (17%)
12 (48%) 3 (12%) 4 (16%) 6 (24%)
Decrease in systolic blood pressure ( > 20%) Nausea only Nausea with vomiting Pruritus Drowsiness Shivering
Mode of delivery Spontaneous vaginal Forceps Ventouse Caesarean section
Forum Table 7. Neonatal data.
5 min
1 min
Apgar scores 9-10 7-8 5-6
