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Low dose intrathecal morphine and pain relief following caesarean section
Low dose intrathecal morphine and pain relief following caesarean section A. Uchiyama*, H. Ueyamat, S. Nakano*, M. Nishimurat.
C. Tashirol
*Intensive Care Unit and f Department of Anesthesiology, Osaka University Hospital, Suita, Osaka, Japan, IDepartment of Anesthesiology, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka, Japan S UMMA R Y. Healthy women who underwent caesarean section under spinal anaesthesia were studied to determine the extent of postoperative analgesia and side-effects produced by low doses of intrathecal morphine. Patients were randomly allocated to receive, in double-blind fashion, 0 mg (group 1: control group), 0.05 tug (group 2), 0.1 mg (group 3), or 0.2 mg (group 4) of morphine, with 10 mg tetracaine in 10% dextrose 2.5 ml. (n =20 x 4 groups). The effect of intrathecal morphine was examined in terms of the duration until the 6rst supplemental analgesic was needed and the numbers of the doses within the 6rst postoperative 48 h. Pain relief was significantly greater in groups 3 and 4 than in group 1. The incidence of nausea, vomiting and pruritus increased in a dosedependent manner. No patient developed respiratory depression. Our results suggest that postoperative analgesia lasts more than 24 h with 0.1 mg or 0.2 mg of intrathecal morphine. Since the incidence of side-effects was higher at 0.2 mg, 0.1 mg may be the optimum dose for caesarean section.
Intrathecal morphine has been shown to produce excellent postoperative analgesia for a variety of surgical procedures.’ Spinal anaesthesia is commonly used for caesarean section, and the simultaneous introduction of opioid into the intrathecal space is convenient at this time. This mode of analgesia is, however, often accompanied by side-effects such as nausea, vomiting, urinary retention, pruritus and delayed respiratory depression. In recent studies smaller doses of morphine, less than 0.5 mg, have been administered with minimal side effects,2-8 but the effective intrathecal morphine dose with the minimum side effects has not yet been established. In the present study, we evaluated the efficacy and side-effects of intrathecal morphine when given in dosages of 0.05-0.2 mg to patients undergoing caesarean section.
or urgent caesarean delivery under spinal anaesthesia at Osaka Medical Center and Research Institute for Maternal and Child Health were included in the study with their informed consent. One hour before the operation 20 mg famotidine was administered intravenously to control gastric secretion. No sedative was given as premeditation. Patients were randomly assigned to receive, in doubleblind fashion, 0 mg (control: group l), 0.05 mg (group 2), 0.1 mg (group 3), or 0.2 mg (group 4) of morphine mixed with 10 mg tetracaine in 2.5 ml 10% dextrose intrathecally. With the patient in the right lateral position, the dura was punctured with a 25 gauge Quincke point needle at the L 3/4 intravertebral space. She was then turned supine with a right hip wedge to maintain left uterine displacement. Intravenous ephedrine was used as a vasopressor agent as necessary. Surgery was started when analgesia to pin prick reached Th5. At the clamping of the umbilical cord, 1 mg of droperidol as an antiemetic and ergometrine as an oxytocic were administered intravenously. Intrauterine prostaglandin Farr and/or an oxytocin infusion were given if required. At the end of the operation, we investigated the levels of residual block by pinprick and asked the patients about nausea and other symptoms. If patients requested postoperative pain relief, a nurse administered 25 mg of indomethacin rectally. For 48 h after dural puncture, the duration of
METHODS The study was approved by the Institutional Ethics Committee. Eighty women who underwent elective A. Uchiyama MD, S. Nakano MD, Intensive Care Unit, H. Ueyama MD, M. Niiura MD, Department of Anesthesiology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 556 Japan, C. Tasbiro MD, Department of Anesthesiology, Osaka Medical Centre and Research Institute for Maternal and Child Health, Izumi, Osaka, 590-02 Japan. Correspondence to A. Uchiyama. 87
88 International Journal of Obstetric Anesthesia Table 1. Patient clmracteristics
Group Morphine (mg)
1 0 (n=20)
2 0.05 (n=20)
3 0.1 (n=20)
4 0.2
Age (years) Height (cm) Weight (kg) Parity Primiparas Multiparas Gestational age (wk)
32.2k5.8 156k5.4 61.6+ 14.5
31.5k5.4 154k4.1 61.1k11.3
31.3k5.6 156k5.4 64.7k9.1
28.7k4.8 157k4.7 63.8k7.2
5 15 36.9k3.3
7 13 35.6 +4.7
I 13 36.7h4.5
9 11 36.6k4.1
(n=20)
Values of age, height, weight and gestational age are mean *SD.
analgesia and the appearance of side-effects were observed. Analgesic duration was recorded as the time from the administration of intrathecal morphine to the first request for postoperative analgesia. If no analgesia was needed during the observation period, the duration was recorded as 48 h. The efficacy of morphine was estimated by the numbers of analgesic doses required over the 48-hour period. Nausea and vomiting were scored on a four-point scale (0: neither nausea nor vomiting, 1: nausea, but no vomiting, 2: single incident of vomiting, and 3: vomiting more than once). Pruritus was also scored on a four-point scale (0: no itching, 1: slight itching, 2: tolerable itching, and 3: intolerable itching). Nurses observed the patients’ sedation level. For 24 h after the operation, respiratory rates were monitored continuously with a thoracic impedance detector incorporating ECG electrodes. Oxytocin or prostaglandin Faa was used for postoperative uterine stimulation. In statistical analysis, numerical variables were compared using one way analysis of variance. When significance was observed, Scheffe’s multiple comparison test was used. x2 test was used to compare categorical variables. Kruskal-Wallis test followed by Scheffe’s multiple comparison test was used for postoperative nausea and pruritus. A value of Table 2. Anaesthetic variables
Group Morphine (mg)
1 0 (n=20)
Intraoperative use of drugs 4 Sedatives 0 Narcotics Uterine stimulants 15 Erg. 2 Erg. + Oxy. Erg. + Oxy. + Pg. 3 Anaesth. dermatome 3.9kl.O level (Th) 4 Nausea 0 Vomiting Postop. uterine stimulants 9 oxy. 11 Pg.
2 0.05 (n=20)
3 0.1 (n=20)
4 ;:=20)
4 2
2 0
2 0
13 4 3
13 5 2
12 7
3.9k1.2 2 0
3.3kl.O 5 0
3.6kO.9 8 0
11 9
9 11
8 12
1
P < 0.05 was considered statistically significant. Data were expressed as mean + SD.
RESULTS
There was no significant difference in the age, height, weight, gestational age, or parity among the groups (Table 1). Nor were any significant differences among the groups in relation to dermatome level of residual analgesia at the end of the operation, need for intraoperative sedatives or the incidence of intraoperative nausea. Intraoperative and postoperative use of oxytocics was not significantly different among the groups (Table 2). The duration of analgesia was 7.7 +6.9 h in group 1, 18.7+18.0 h in group 2, 28.9kl3.2 h in group 3, and 28.3f 14.7 h in group 4. Durations in groups 3 and 4 were significantly longer than that in group 1 (P< 0.05). The numbers of patients given no supplemental analgesics are plotted against the time from the initial intrathecal morphine (Fig. 1). The numbers needing no analgesics during the first 24-hour period in groups 2,3, and 4 were significantly higher than in group 1. Figure 2 shows the numbers of analgesic doses administered in 12-hour periods for 48 h after the morphine administration. Those for the O-12 and the 12-24-hour periods in groups 3 and 4 were significantly lower than those in group 1. Those for the 24-36 and 36-48-hour periods show no significant differences between the groups. The incidence of nausea and vomiting during 48 h was significantly higher in group 4 than in group 1 (Fig. 3). The incidence of pruritus in groups 3 and 4 was significantly higher than that in group 1 (Fig. 4). No patients had a respiratory rate below 8 per min. There was no clinical evidence of respiratory depression in any patient.
DISCUSSION
Values of anaesthesia dermatome level mean + SD. Erg. = ergometrine; Oxy. = oxytocin; Pg. = prostaglandin Fzu.
Since Wang et al reported the administration of intrathecal morphine for pain relief in 1979,g this technique has been used to treat many types of pain.
Low-dose intrathecal morphine and pain relief following caesarean section
15
10
5
0 0
12
24
48
36
Hours from morphine administration -
lntrathecal morphine (mg) 0.1 0 -.-.- 0.05
-
0.2
Fig. I-Time to first postoperative supplemental analgesic. *PcO.O5, as compared with group 1. The numbers of patients needing no analgesics during the first 24-hour period in groups 2. 3, and 4 were significantly higher than those in group 1.
Intrathecal administration of opioids has several advantages: simplicity, reliability, low-dose requirements, and no need for a catheter in the epidural space. Opioids can conveniently be given intrathecally concurrently with local anesthetics for spinal anaesthesia. Unless a catheter is used, however, intrathecal administration is limited to a single injection.”
12-24 Hours
89
Consequently the choice of dose is crucial. It should produce a optimum duration with minimum sideeffects. Intrathecal morphine has been employed for postoperative analgesia in a wide range of doses.’ A dose reduction to less than 0.5 mg has been reported in recent years to decrease the side-effects.2a Effective intrathecal morphine doses for post-caesarean analgesia are 0.3-0.5 mg. according to Chadwick and Ready,’ 0.25 and 0.1 mg according to Abboud et al3 and 0.2 mg according to Abouleish et al.J Doses of less than 0.1 mg have not been reported for post caesarean pain. In this study, the analgesic effect of 0.1 mg was seen to be greater than that of 0.05 mg and similar to that of 0.2 mg of morphine, indicating that 0.1 mg is very likely the minimum effective dose for post caesarean pain. Yamaguchi et al have investigated the postoperative analgesia produced by OSO.1mg of intrathecal morphine following transabdominal hysterectomy,5 and O-O.2 mg following cholecystectomy.6 Doses of 0.04-o. 1 mg for hysterectomy and 0.06-0.2 mg for cholecystectomy had comparable analgesic effects. There are several reasons why 0.05 mg proved insufficient to produce analgesia in our study. Older people have been shown to gain more effective pain relief from epidural morphine than did younger patients,” and our patients were younger than those in the study of Yamaguchi.“,’ Post partum patients also have uterine contraction pain in addition to incisional pain. Up to 24 hours duration of analgesia provided by
36-48
24-36
from morphine administration
lntrathecal morphine (mg) 0 0 q 0.05 q 0.1 H
0.2
Fig. 2---The numbers of supplemental analgesic doses per 12-hour period in the first 48 h after intrathecal morphine administration (Mean &-SD). *P
90
1ntemationa.l Journal of Obstetric Anesthesia
201 15
5 0 lntrathecal morphine (mg)
n
3: Vomiting more than once 2: Vomiting only once
0 Fig. 3-Nausea administration.
1: Nausea, but no vomiting and vomiting for 48 h after morphine *Pi 0.05, as compared with group 1.
20 15
*
2 .G 10 z a 5 0
d
lntrathecal morphine (r ng)
n
References
3: Intolerable itching 2: Torelable itching
0
differences between the groups. Our results are in Because the analgesics line with previous studies. 3*7~10 needed in group 1 decreased after 24 h, a 24-hour duration of intrathecal morphine analgesia may be adequate for post caesarean pain. Higher doses of intrathecal morphine were more often associated with nausea, vomiting and pruritus. In addition the symptoms were more severe as the amount of morphine increased. According to other post caesarean studies the incidence of nausea and vomiting was 34% (morphine 0.3-0.5 mg),2 41% (morphine 0.2 mg),4 27% (morphine 0.25 mg),3 and 10% (morphine 0.1 mg).j The incidence of pruritus was 78% (morphine 0.3-0.5 mg),2 65% (morphine 0.2 mg),4 64% (morphine 0.25 mg),3 and 40% (morphine 0.1 mg).3 Our result agree with previous studies. Thus doses of intrathecal morphine should be as small as possible to reduce the side-effects. Although use of uterine stimulants may be related to nausea and vomiting, no significant differences in their use was apparent in any of the groups. The disparity of nausea and vomiting among the groups is considered to result from the difference in morphine doses. Delayed respiratory depression is the most serious side-effect with the use of intrathecal morphine.12 In clinical reports relating to doses below 0.5 rngZa there is no marked respiratory depression. Stoelting has reported that small doses of intrathecal morphine (0.2-0.5 mg) are not associated with an unacceptable incidence of life-threatening respiratory depression.” In this study no patient revealed any life-threatening decrease in respiratory rate. We believe that in doses less than 0.2 mg, intrathecal morphine can be used without risk of respiratory depression. In conclusion, intrathecal morphine doses of 0.1 and 0.2 mg are equally effective for pain relief after caesarean section. Since 0.1 mg results in fewer and less serious postoperative side-effects, it appears to be the appropriate supplement for intrathecal local anesthetic solutions.
1: Light itching
Fig. 4-Pruritus for 48 h after morphine administration. *PiO.O5, as compared with group 1.
intrathecal morphine has been reported.3v7v’0 Duration in groups 3 and 4 in our study averaged about 28 h. In the first 24 h the numbers of analgesic doses administered in groups 3 and 4 were significantly smaller than those in group 1. In the subsequent 24 h, however, there were no significant
1. Cousins M J, Mather L E. Intrathecal and epidural administration of opioids. Anesthesiology 1984; 61: 276-310. 2. Chadwick H S, Ready L B. Intrathecal morphine sulfate for post-cesarean analgesia - a clinical comparison. Anesthesiology 1988; 68: 9255929. 3. Abboud T K, Dror A, Mosaad P et al. Mini-dose intrathecal morphine for the relief of post-cesarean section pain: safety, efficacy, and ventilatory responses to carbon dioxide. Anesth Analg 1988; 67: 137-143. 4. Abouleish E, Rawal N, Fallen K, Hemandez D. Combined intrathecal morphine and bupivacaine for cesarean section. Anesth Analg 1988; 67: 370-374. 5. Yamaguchi H, Watanabe S, Fukuda T, Takahashi H, Motokawa K, Ishizawa Y. Minimal effective dose of intrathecal morphine for pain relief following transabdominal hysterectomy. Anesth Analg 1989; 68: 537-540. 6. Yamaguchi H, Watanabe S, Motokawa K,
Low-dose intrathecal mornhine and nain relief following caesarean section Ishizawa Y. Intrathecal morphine dose-response data for pain relief after cholecystectomy. Anesth Analg 1990; 70: 168-171. Jacobson L, Chabal C, Brody M C. A dose-response study of intrathecal morphine. Anesth Analg 1988; 67: 1082-1088. Kirson L E, Goldmann J M, Slover R B. Low-dose intrathecal morphine for postoperative pain control in patients undergoing transurethal resection of prostate. Anesthesiology 1989; 71: 192-195. Wang J D, Nauss L A. Thomas J D. Pain relief by
intrathecally applied morphine in man. Anesthesiology 1979; 50: 149-151. 10. Stoelting R K. Intrathecal morphine - an underused combination for postoperative pain management. Anesth Analg 1989; 68: 7077709. 11. Moore A K. Differences in epidural morphine requirements between elderly and young patients after abdominal surgery. Anesth Analg 1990; 70: 316-320. 12. Abouleish E. Apnoea associated with intrathecal administration of morphine. Br J Anesth 1988: 60: 592-594.
91
C. Tashirol
*Intensive Care Unit and f Department of Anesthesiology, Osaka University Hospital, Suita, Osaka, Japan, IDepartment of Anesthesiology, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka, Japan S UMMA R Y. Healthy women who underwent caesarean section under spinal anaesthesia were studied to determine the extent of postoperative analgesia and side-effects produced by low doses of intrathecal morphine. Patients were randomly allocated to receive, in double-blind fashion, 0 mg (group 1: control group), 0.05 tug (group 2), 0.1 mg (group 3), or 0.2 mg (group 4) of morphine, with 10 mg tetracaine in 10% dextrose 2.5 ml. (n =20 x 4 groups). The effect of intrathecal morphine was examined in terms of the duration until the 6rst supplemental analgesic was needed and the numbers of the doses within the 6rst postoperative 48 h. Pain relief was significantly greater in groups 3 and 4 than in group 1. The incidence of nausea, vomiting and pruritus increased in a dosedependent manner. No patient developed respiratory depression. Our results suggest that postoperative analgesia lasts more than 24 h with 0.1 mg or 0.2 mg of intrathecal morphine. Since the incidence of side-effects was higher at 0.2 mg, 0.1 mg may be the optimum dose for caesarean section.
Intrathecal morphine has been shown to produce excellent postoperative analgesia for a variety of surgical procedures.’ Spinal anaesthesia is commonly used for caesarean section, and the simultaneous introduction of opioid into the intrathecal space is convenient at this time. This mode of analgesia is, however, often accompanied by side-effects such as nausea, vomiting, urinary retention, pruritus and delayed respiratory depression. In recent studies smaller doses of morphine, less than 0.5 mg, have been administered with minimal side effects,2-8 but the effective intrathecal morphine dose with the minimum side effects has not yet been established. In the present study, we evaluated the efficacy and side-effects of intrathecal morphine when given in dosages of 0.05-0.2 mg to patients undergoing caesarean section.
or urgent caesarean delivery under spinal anaesthesia at Osaka Medical Center and Research Institute for Maternal and Child Health were included in the study with their informed consent. One hour before the operation 20 mg famotidine was administered intravenously to control gastric secretion. No sedative was given as premeditation. Patients were randomly assigned to receive, in doubleblind fashion, 0 mg (control: group l), 0.05 mg (group 2), 0.1 mg (group 3), or 0.2 mg (group 4) of morphine mixed with 10 mg tetracaine in 2.5 ml 10% dextrose intrathecally. With the patient in the right lateral position, the dura was punctured with a 25 gauge Quincke point needle at the L 3/4 intravertebral space. She was then turned supine with a right hip wedge to maintain left uterine displacement. Intravenous ephedrine was used as a vasopressor agent as necessary. Surgery was started when analgesia to pin prick reached Th5. At the clamping of the umbilical cord, 1 mg of droperidol as an antiemetic and ergometrine as an oxytocic were administered intravenously. Intrauterine prostaglandin Farr and/or an oxytocin infusion were given if required. At the end of the operation, we investigated the levels of residual block by pinprick and asked the patients about nausea and other symptoms. If patients requested postoperative pain relief, a nurse administered 25 mg of indomethacin rectally. For 48 h after dural puncture, the duration of
METHODS The study was approved by the Institutional Ethics Committee. Eighty women who underwent elective A. Uchiyama MD, S. Nakano MD, Intensive Care Unit, H. Ueyama MD, M. Niiura MD, Department of Anesthesiology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 556 Japan, C. Tasbiro MD, Department of Anesthesiology, Osaka Medical Centre and Research Institute for Maternal and Child Health, Izumi, Osaka, 590-02 Japan. Correspondence to A. Uchiyama. 87
88 International Journal of Obstetric Anesthesia Table 1. Patient clmracteristics
Group Morphine (mg)
1 0 (n=20)
2 0.05 (n=20)
3 0.1 (n=20)
4 0.2
Age (years) Height (cm) Weight (kg) Parity Primiparas Multiparas Gestational age (wk)
32.2k5.8 156k5.4 61.6+ 14.5
31.5k5.4 154k4.1 61.1k11.3
31.3k5.6 156k5.4 64.7k9.1
28.7k4.8 157k4.7 63.8k7.2
5 15 36.9k3.3
7 13 35.6 +4.7
I 13 36.7h4.5
9 11 36.6k4.1
(n=20)
Values of age, height, weight and gestational age are mean *SD.
analgesia and the appearance of side-effects were observed. Analgesic duration was recorded as the time from the administration of intrathecal morphine to the first request for postoperative analgesia. If no analgesia was needed during the observation period, the duration was recorded as 48 h. The efficacy of morphine was estimated by the numbers of analgesic doses required over the 48-hour period. Nausea and vomiting were scored on a four-point scale (0: neither nausea nor vomiting, 1: nausea, but no vomiting, 2: single incident of vomiting, and 3: vomiting more than once). Pruritus was also scored on a four-point scale (0: no itching, 1: slight itching, 2: tolerable itching, and 3: intolerable itching). Nurses observed the patients’ sedation level. For 24 h after the operation, respiratory rates were monitored continuously with a thoracic impedance detector incorporating ECG electrodes. Oxytocin or prostaglandin Faa was used for postoperative uterine stimulation. In statistical analysis, numerical variables were compared using one way analysis of variance. When significance was observed, Scheffe’s multiple comparison test was used. x2 test was used to compare categorical variables. Kruskal-Wallis test followed by Scheffe’s multiple comparison test was used for postoperative nausea and pruritus. A value of Table 2. Anaesthetic variables
Group Morphine (mg)
1 0 (n=20)
Intraoperative use of drugs 4 Sedatives 0 Narcotics Uterine stimulants 15 Erg. 2 Erg. + Oxy. Erg. + Oxy. + Pg. 3 Anaesth. dermatome 3.9kl.O level (Th) 4 Nausea 0 Vomiting Postop. uterine stimulants 9 oxy. 11 Pg.
2 0.05 (n=20)
3 0.1 (n=20)
4 ;:=20)
4 2
2 0
2 0
13 4 3
13 5 2
12 7
3.9k1.2 2 0
3.3kl.O 5 0
3.6kO.9 8 0
11 9
9 11
8 12
1
P < 0.05 was considered statistically significant. Data were expressed as mean + SD.
RESULTS
There was no significant difference in the age, height, weight, gestational age, or parity among the groups (Table 1). Nor were any significant differences among the groups in relation to dermatome level of residual analgesia at the end of the operation, need for intraoperative sedatives or the incidence of intraoperative nausea. Intraoperative and postoperative use of oxytocics was not significantly different among the groups (Table 2). The duration of analgesia was 7.7 +6.9 h in group 1, 18.7+18.0 h in group 2, 28.9kl3.2 h in group 3, and 28.3f 14.7 h in group 4. Durations in groups 3 and 4 were significantly longer than that in group 1 (P< 0.05). The numbers of patients given no supplemental analgesics are plotted against the time from the initial intrathecal morphine (Fig. 1). The numbers needing no analgesics during the first 24-hour period in groups 2,3, and 4 were significantly higher than in group 1. Figure 2 shows the numbers of analgesic doses administered in 12-hour periods for 48 h after the morphine administration. Those for the O-12 and the 12-24-hour periods in groups 3 and 4 were significantly lower than those in group 1. Those for the 24-36 and 36-48-hour periods show no significant differences between the groups. The incidence of nausea and vomiting during 48 h was significantly higher in group 4 than in group 1 (Fig. 3). The incidence of pruritus in groups 3 and 4 was significantly higher than that in group 1 (Fig. 4). No patients had a respiratory rate below 8 per min. There was no clinical evidence of respiratory depression in any patient.
DISCUSSION
Values of anaesthesia dermatome level mean + SD. Erg. = ergometrine; Oxy. = oxytocin; Pg. = prostaglandin Fzu.
Since Wang et al reported the administration of intrathecal morphine for pain relief in 1979,g this technique has been used to treat many types of pain.
Low-dose intrathecal morphine and pain relief following caesarean section
15
10
5
0 0
12
24
48
36
Hours from morphine administration -
lntrathecal morphine (mg) 0.1 0 -.-.- 0.05
-
0.2
Fig. I-Time to first postoperative supplemental analgesic. *PcO.O5, as compared with group 1. The numbers of patients needing no analgesics during the first 24-hour period in groups 2. 3, and 4 were significantly higher than those in group 1.
Intrathecal administration of opioids has several advantages: simplicity, reliability, low-dose requirements, and no need for a catheter in the epidural space. Opioids can conveniently be given intrathecally concurrently with local anesthetics for spinal anaesthesia. Unless a catheter is used, however, intrathecal administration is limited to a single injection.”
12-24 Hours
89
Consequently the choice of dose is crucial. It should produce a optimum duration with minimum sideeffects. Intrathecal morphine has been employed for postoperative analgesia in a wide range of doses.’ A dose reduction to less than 0.5 mg has been reported in recent years to decrease the side-effects.2a Effective intrathecal morphine doses for post-caesarean analgesia are 0.3-0.5 mg. according to Chadwick and Ready,’ 0.25 and 0.1 mg according to Abboud et al3 and 0.2 mg according to Abouleish et al.J Doses of less than 0.1 mg have not been reported for post caesarean pain. In this study, the analgesic effect of 0.1 mg was seen to be greater than that of 0.05 mg and similar to that of 0.2 mg of morphine, indicating that 0.1 mg is very likely the minimum effective dose for post caesarean pain. Yamaguchi et al have investigated the postoperative analgesia produced by OSO.1mg of intrathecal morphine following transabdominal hysterectomy,5 and O-O.2 mg following cholecystectomy.6 Doses of 0.04-o. 1 mg for hysterectomy and 0.06-0.2 mg for cholecystectomy had comparable analgesic effects. There are several reasons why 0.05 mg proved insufficient to produce analgesia in our study. Older people have been shown to gain more effective pain relief from epidural morphine than did younger patients,” and our patients were younger than those in the study of Yamaguchi.“,’ Post partum patients also have uterine contraction pain in addition to incisional pain. Up to 24 hours duration of analgesia provided by
36-48
24-36
from morphine administration
lntrathecal morphine (mg) 0 0 q 0.05 q 0.1 H
0.2
Fig. 2---The numbers of supplemental analgesic doses per 12-hour period in the first 48 h after intrathecal morphine administration (Mean &-SD). *P
90
1ntemationa.l Journal of Obstetric Anesthesia
201 15
5 0 lntrathecal morphine (mg)
n
3: Vomiting more than once 2: Vomiting only once
0 Fig. 3-Nausea administration.
1: Nausea, but no vomiting and vomiting for 48 h after morphine *Pi 0.05, as compared with group 1.
20 15
*
2 .G 10 z a 5 0
d
lntrathecal morphine (r ng)
n
References
3: Intolerable itching 2: Torelable itching
0
differences between the groups. Our results are in Because the analgesics line with previous studies. 3*7~10 needed in group 1 decreased after 24 h, a 24-hour duration of intrathecal morphine analgesia may be adequate for post caesarean pain. Higher doses of intrathecal morphine were more often associated with nausea, vomiting and pruritus. In addition the symptoms were more severe as the amount of morphine increased. According to other post caesarean studies the incidence of nausea and vomiting was 34% (morphine 0.3-0.5 mg),2 41% (morphine 0.2 mg),4 27% (morphine 0.25 mg),3 and 10% (morphine 0.1 mg).j The incidence of pruritus was 78% (morphine 0.3-0.5 mg),2 65% (morphine 0.2 mg),4 64% (morphine 0.25 mg),3 and 40% (morphine 0.1 mg).3 Our result agree with previous studies. Thus doses of intrathecal morphine should be as small as possible to reduce the side-effects. Although use of uterine stimulants may be related to nausea and vomiting, no significant differences in their use was apparent in any of the groups. The disparity of nausea and vomiting among the groups is considered to result from the difference in morphine doses. Delayed respiratory depression is the most serious side-effect with the use of intrathecal morphine.12 In clinical reports relating to doses below 0.5 rngZa there is no marked respiratory depression. Stoelting has reported that small doses of intrathecal morphine (0.2-0.5 mg) are not associated with an unacceptable incidence of life-threatening respiratory depression.” In this study no patient revealed any life-threatening decrease in respiratory rate. We believe that in doses less than 0.2 mg, intrathecal morphine can be used without risk of respiratory depression. In conclusion, intrathecal morphine doses of 0.1 and 0.2 mg are equally effective for pain relief after caesarean section. Since 0.1 mg results in fewer and less serious postoperative side-effects, it appears to be the appropriate supplement for intrathecal local anesthetic solutions.
1: Light itching
Fig. 4-Pruritus for 48 h after morphine administration. *PiO.O5, as compared with group 1.
intrathecal morphine has been reported.3v7v’0 Duration in groups 3 and 4 in our study averaged about 28 h. In the first 24 h the numbers of analgesic doses administered in groups 3 and 4 were significantly smaller than those in group 1. In the subsequent 24 h, however, there were no significant
1. Cousins M J, Mather L E. Intrathecal and epidural administration of opioids. Anesthesiology 1984; 61: 276-310. 2. Chadwick H S, Ready L B. Intrathecal morphine sulfate for post-cesarean analgesia - a clinical comparison. Anesthesiology 1988; 68: 9255929. 3. Abboud T K, Dror A, Mosaad P et al. Mini-dose intrathecal morphine for the relief of post-cesarean section pain: safety, efficacy, and ventilatory responses to carbon dioxide. Anesth Analg 1988; 67: 137-143. 4. Abouleish E, Rawal N, Fallen K, Hemandez D. Combined intrathecal morphine and bupivacaine for cesarean section. Anesth Analg 1988; 67: 370-374. 5. Yamaguchi H, Watanabe S, Fukuda T, Takahashi H, Motokawa K, Ishizawa Y. Minimal effective dose of intrathecal morphine for pain relief following transabdominal hysterectomy. Anesth Analg 1989; 68: 537-540. 6. Yamaguchi H, Watanabe S, Motokawa K,
Low-dose intrathecal mornhine and nain relief following caesarean section Ishizawa Y. Intrathecal morphine dose-response data for pain relief after cholecystectomy. Anesth Analg 1990; 70: 168-171. Jacobson L, Chabal C, Brody M C. A dose-response study of intrathecal morphine. Anesth Analg 1988; 67: 1082-1088. Kirson L E, Goldmann J M, Slover R B. Low-dose intrathecal morphine for postoperative pain control in patients undergoing transurethal resection of prostate. Anesthesiology 1989; 71: 192-195. Wang J D, Nauss L A. Thomas J D. Pain relief by
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