Summary. To investigate the safety and efficacy of 0.25 % hyperbaric bupivacaine for spinal anaesthesia in. Caesarean section, we studied 60 parturients allo-.
British Journal of Anaesthesia 1996; 77: 145–149
Spinal anaesthesia with 0.25 % hyperbaric bupivacaine for Caesarean section: effects of volume C. J. CHUNG, S. H. BAE, K. Y. CHAE AND Y. J. CHIN
Summary To investigate the safety and efficacy of 0.25 % hyperbaric bupivacaine for spinal anaesthesia in Caesarean section, we studied 60 parturients allocated randomly to one of three groups. According to the patient’s height, groups 1, 2 and 3 received 3.2–3.6 ml (8–9 mg), 3.6–4.0 ml (9–10 mg) and 4.0–4.4 ml (10–11 mg) of 0.25 % bupivacaine in 5 % glucose, respectively. Subarachnoid injection was performed in the right lateral decubitus position, and parturients were then turned immediately supine with left uterine displacement. Mean spread of sensory analgesia was significantly higher in group 3 (T2–3) than in groups 1 and 2 (T4–5 in each group). Duration of sensory analgesia was significantly longer in groups 2 and 3 than in group 1. Complete motor block of the lower extremities occurred in all patients but in only one in group 1. Onset time and duration of motor block were not significantly different between the three groups. The incidence of hypotension was significantly higher in group 3 (75 %) than in groups 1 and 2 (40 % in each group). The efficacy of intraoperative analgesia was significantly greater in groups 2 and 3 than in group 1. The incidence of patients requiring analgesics during operation was significantly lower in groups 2 (25 %) and 3 (10 %) than in group 1 (70 %). There was no difference in neonatal condition between the three groups. Spinal anaesthesia with 3.6–4.0 ml of 0.25 % bupivacaine in 5 % glucose was satisfactory for Caesarean section. (Br. J. Anaesth. 1996; 77: 145–149) Key words Anaesthetics local, bupivacaine. Anaesthetic techniques, subarachnoid. Anaesthesia, obstetric.
Amylocaine is a drug used frequently for spinal anaesthesia in Caesarean section. However, this agent often fails to provide good maternal sensory block [1, 2]. Recently, bupivacaine has gained popularity in obstetric anaesthesia but 0.5 % plain bupivacaine has been shown to be unreliable and produced occasional high block [3, 4]. Therefore, hyperbaric bupivacaine has been used more often than plain bupivacaine for spinal anaesthesia in Caesarean section. The total dose of bupivacaine is more important than volume or concentration of anaesthetic solution in determining spread of anaesthetic solution in the
CSF [5–7]. However, the effect of volume of hyperbaric spinal anaesthetic solution injected may be additive to the effects of gravity, position and dose [8–10]. Almost all parturients given 0.5 % hyperbaric bupivacaine 7.5–10 mg for spinal anaesthesia in Caesarean section required supplementary analgesia because of visceral pain during surgery [11, 12]. When hyperbaric bupivacaine 10–15 mg was used for spinal anaesthesia in Caesarean section, good sensory block developed and the incidence of supplementary analgesia was decreased [2, 12]. However, the volume exceeded 3 ml in those cases. When 0.25 % hyperbaric bupivacaine solution 10–15 mg is used for spinal anaesthesia in Caesarean section, the volume reaches 4–6 ml, which may influence spinal anaesthesia because of easily cephalad spread of local anaesthetic solution in CSF. The aim of this investigation was to assess the safety and efficacy of 0.25 % bupivacaine in 5 % glucose for spinal anaesthesia in Caesarean section. Sensory and motor block, haemodynamic changes, quality of intraoperative analgesia and complications were compared.
Patients and methods We studied 60 term parturients, ASA I or II, chosen to have spinal anaesthesia for elective Caesarean section. The study was approved by the Hospital Ethics Committee and written informed consent was obtained from all patients at the preoperative visit. Parturients who had obstetric complications or evidence of fetal compromise were excluded. Hyperbaric bupivacaine solution 0.25 % was made with the same volume of 0.5 % bupivacaine hydrochloride (Marcaine, Astra, Sweden) and 10 % glucose monohydrate (Daehan Pharmaceutical Co., Seoul, Korea). The specific gravity of 0.25 % bupivacaine in 5 % glucose was 1.022 at 23 ⬚C. Patients were allocated randomly to one of three groups. Each group had 10 mothers who were 156–160 cm tall and 10 mothers 161–165 cm tall. Group 1 mothers (156–160 cm tall) were given 3.2 ml of 0.25 % bupivacaine in 5 % glucose, and those 161–165 cm received 3.6 ml.
CHAN JONG CHUNG*, MD, SEUNG HWAN BAE, MD, KI YOUNG CHAE, MD, YOUNG JHOON CHIN, MD, Department of Anesthesiology, College of Medicine, Dong-A University, Pusan, Korea. Accepted for publication: March 13, 1996. * Address for correspondence: Department of Anaesthesiology, Dong-A Medical Centre, 1-3 ga Tongdaesin-dong, Seo-gu, Pusan, 602-103, Korea.
146 In groups 2 and 3, the corresponding bupivacaine volumes were 3.6 and 4.0 ml, and 4.0 and 4.4 ml, respectively. All subarachnoid blocks were performed by one anaesthetist and data were collected by two registrars who were blinded to the solutions used. All parturients received ranitidine 10 mg and glycopyrronium 0.2 mg i.m., 1 h before arrival in the operating room. All patients received an infusion of lactated Ringer’s solution 1000 ml over 10–20 min before induction. They were also given ephedrine 40 mg i.m., approximately 10 min before subarachnoid injection. Subarachnoid injection was performed in the right lateral decubitus position with a 25-gauge Quincke spinal needle, using a midline approach at the L2–3 or L3–4 interspace. The predetermined volume of local anaesthetic was injected over 20–30 s without barbotage. After subarachnoid injection, mothers were immediately turned supine with left uterine displacement. The parturient’s head was rested on a pillow. The spread of sensory block to pinprick was measured at 2-min intervals during the first 10 min and then at 5-min intervals. The degree of motor block of the lower extremities was also assessed at the same interval, using the modified Bromage scale: 0 no paralysis; 1 unable to raise the extended leg; 2 unable to flex knee; 3 unable to flex ankle. Maternal arterial pressure and heart rate were recorded every minute until delivery and every 5 min thereafter, using an automated, non-invasive device (Sirecust 404, Simens, Germany). If hypotension (systolic arterial pressure less than 100 mm Hg or a 20 % reduction in systolic arterial pressure) occurred, it was treated promptly by increasing uterine displacement and the rate of fluid administration. If hypotension persisted despite these measures, ephedrine 10 mg was given i.v. and repeated as needed. Oxygen was administered routinely by face mask at 6 litre min1 until the end of operation. When sensory block at or above T6 was established, surgery were commenced. The incidence and frequency of complications were noted. The efficacy of intraoperative analgesia was assessed by the following four categories: excellent no discomfort during the procedure; good mild discomfort but required no systemic analgesia; fair pain that required additional analgesia; and poor moderate or severe pain that needed more than fentanyl 100 g or general anaesthesia. When the patient complained of pain, fentanyl 50 g was given i.v. and repeated as needed. I.v. midazolam 2.5 mg was administered if the patient requested to sleep after the birth of the baby. I.v. droperidol 0.625 mg was used to treat nausea or vomiting. The times of bupivacaine injection, start of surgery, delivery and termination of surgery were recorded. The condition of the neonates was assessed by Apgar score at 1 and 5 min after delivery. All mothers received oxytocin by continuous infusion after delivery. Return of sensory and motor function was assessed at 15-min intervals until complete recovery from anaesthesia. All data are expressed as number or mean (SD or range). The results were analysed using one-way and
British Journal of Anaesthesia two-way ANOVA followed by Tukey’s test for parametric data, and the chi-square test with Yates’ correction, the Kruskall-Wallis followed by the Mann–Whitney U test for non-parametric data. P 0.05 was considered statistically significant.
Results There were no statistically significant differences in mean age, weight, height and gestational age between the three groups (table 1). In four patients in group 1, the spinal was converted to general anaesthesia 10–15 min after delivery of the neonate because surgical anaesthesia was inadequate. These patients were excluded from further analysis of sensory and motor block. Onset and segmental spread of sensory analgesia are shown in figure 1. Cephalad spread of sensory analgesia was increased significantly with an increase in volume, and the differences between groups 1 and 3 and between groups 2 and 3 were significant. Onset time of sensory analgesia to T6 was significantly faster in group 3 than in group 1. The mean maximal level of analgesia in group 3 (T2–3) was significantly higher than that in groups 1 and 2 (T4–5 in each), and the times to achieve the maximal level were similar, with an average of 10–15 min between the three groups. Sensory analgesia at or above T6 was obtained in all patients, but sensory analgesia below Table 1 Patient characteristics (mean (SD or range)) Group 1 (n 20) Age (yr) Height (cm) Weight (kg) Gestation (weeks)
Group 2 (n 20)
Group 3 (n 20)
30.0 (23–34) 29.9 (25–35) 29.4 (24–36) 159.5 (2.4) 158.8 (2.2) 160.6 (2.7) 65.0 (8.5) 65.6 (5.9) 68.4 (8.5) 37.8 (0.9) 38.3 (0.8) 37.9 (2.1)
Figure 1 Onset and segmental spread of sensory analgesia after subarachnoid injection of 0.25 % bupivacaine in 5 % glucose for term parturients in group 1 (3.2–3.6 ml (●)), group 2 (3.6–4.0 ml (■)) and group 3 (4.0–4.4 ml (▲). *P 0.05 vs group 1, †P 0.05 vs groups 1 and 2.
Spinal anesthesia for Caesarean section
147
Table 2 Comparison of times of onset and regression of subarachnoid block (mean (SD)). *P 0.05 vs group 1 Group 1 (n 16) Sensory block (min) Time to T6 Time to maximal level Regression time to T10 Regression time to L5 Motor block (min) Time to complete block Time to complete regression
Group 2 (n 20)
7.7 (2.4)
6.9 (1.8)
13.8 (3.2)
12.7 (2.7)
Group 3 (n 20) 5.5 (2.4)* 11.9 (3.0)
85.0 (15.3) 103.0 (14.3)* 108.5 (20.8)* 164.0 (20.3) 185.5 (20.9)* 198.0 (26.8)* 11.6 (3.7)
12.1 (3.2)
122.0 (25.9) 137.3 (24.5)
Table 3 Incision direction and surgical times (mean (SD) or number). Long/trans Longitudinal/transverse
10.7 (3.7)
Incision direction Long/trans Induction to operative start time (min) Induction to operative end time (min) Uterine incision to delivery time (s)
T4 was obtained significantly more in group 1 (70 %)
Figure 3 Changes in maternal heart rate during the first 30 min after subarachnoid injection of 0.25 % bupivacaine in 5 % glucose for term parturients in group 1 (3.2–3.6 ml (●)), group 2 (3.6–4.0 ml (■)) and group 3 (4.0–4.4 ml (▲)). C Control.
than in groups 2 and 3 (30 % and 10 %, respectively). Two patients in group 3 had a block up to C6 and C7, respectively. Total time for regression of sensory analgesia to T10 and L5 was significantly longer in groups 2 and 3 than in group 1 (table 2). Complete motor block of the lower extremities was obtained in all patients at an average time of
Group 2 (n 20)
Group 3 (n 20)
6/14
7/13
6/14
16.6 (4.5)
16.5 (3.2)
15.9 (3.5)
82.3 (9.3)
84.6 (10.3) 83.2 (8.1)
91.6 (23.2) 78.3 (33.0) 82.5 (26.7)
Table 4 Efficacy of sensory block during surgery (number). *P 0.05 vs group 1
142.2 (33.3)
Figure 2 Changes in maternal systolic arterial pressure (SAP) during the first 30 min after subarachnoid injection of 0.25 % bupivacaine in 5 % glucose for term parturients in group 1 (3.2–3.6 ml (●)), group 2 (3.6–4.0 ml (■)) and group 3 (4.0–4.4 ml (▲)). C Control. *P 0.05 compared with control value in each group.
Group 1 (n 20)
Category
Group 1 (n 20)
Group 2* (n 20)
Group 3* (n 20)
Excellent Good Fair Poor
4 2 9 5
10 5 5 0
16 2 2 0
10–13 min, except for one patient in group 1 (Bromage scale 2). Duration of complete motor block was longer with an increase in volume, but this was not statistically significant (table 2). There were no significant differences in systolic arterial pressure and heart rate during the first 30 min between the three groups (figs 2, 3). Compared with control preanaesthetic values, systolic arterial pressure was significantly decreased at 4 min in groups 1 and 2, and at 4 and 6 min in group 3. The percentage maximal decreases in systolic arterial pressure were 16.1 (9.9) %, 17.8 (10.1) % and 25.7 (13.2) % in groups 1, 2 and 3, respectively, recorded 4–6 min after induction of spinal anaesthesia. Hypotension developed in eight of 20 patients in group 1 (40 %), and six required i.v. ephedrine, compared with eight of 20 patients in group 2 (40 %), and seven required i.v. ephedrine and 15 of 20 patients in group 3 (75 %), and 14 required i.v. ephedrine. The incidence of hypotension and need for ephedrine were significantly greater in group 3 than in groups 1 and 2. The various time intervals from induction of anaesthesia to end of surgery are shown in table 3. There were no significant differences in these times between the groups. No patient in any group complained of discomfort at incision from skin to the uterus. The efficacy of intraoperative analgesia was significantly greater in groups 2 and 3 than in group 1 (table 4). In group 1, only four patients (20 %) were totally painless; 14 patients (70 %) required supplementary analgesia 40–50 min after induction, four of whom required general anaesthesia about 10–15 min after delivery. Five patients in group 2 (25 %) and two in group 3 (10 %) required supplementary analgesia 50–60 min after induction of spinal anaesthesia. Neonatal weight and Apgar scores at 1 and 5 min were similar between the three groups (table 5). The condition of the neonates was good. Two infants in group 3 had an Apgar score of 5 and 6, but more than 8 at 5 min.
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British Journal of Anaesthesia
Table 5 Neonatal status (mean (SD))
Neonatal weight (kg) Apgar score 1 min 5 min
Group 1 (n 20)
Group 2 (n 20)
Group 3 (n 20)
3.3 (0.3)
3.2 (0.2)
3.4 (0.3)
8.3 (0.5) 9.5 (0.4)
8.4 (0.5) 9.6 (0.3)
8.2 (0.8) 9.4 (0.7)
Table 6 Intraoperative complications (number). † Patients in whom droperidol was used. *P 0.05 vs groups 1 and 2
Hypotension Bradycardia Nausea/vomiting † Dyspnoea Transient headache
Group 1 (n 20)
Group 2 (n 20)
Group 3 (n 20)
8 4 2 1 0
8 5 3 2 0
15* 7 6 4 2
The incidences of complications after spinal anaesthesia are shown in table 6. Complications occurred more in group 3 than in groups 1 and 2, but this was not significant.
Discussion Our data indicated that 0.25 % bupivacaine in 5 % glucose could be used safely and effectively for spinal anaesthesia in Caesarean section. Lignocaine, amylocaine and bupivacaine can be used for spinal anaesthesia in Caesarean section but some mothers who received amylocaine spinal anaesthesia needed supplementary analgesia because of intraoperative visceral pain [1, 2]. Recently, bupivacaine has gained popularity in obstetric anaesthesia for extradural and also spinal anaesthesia. Hyperbaric bupivacaine provided better intraoperative analgesia and produced shorter duration of motor block than hyperbaric amylocaine [2]. Within the range of 7.5–12 mg of 0.5 % hyperbaric bupivacaine, similar levels of sensory block to T3 occurred, despite the varying doses of drug injected, but the duration of sensory block was longer with the large than the small dose. Increasing the dose increased the intensity of motor block, but the duration of motor block was similar [11, 12]. In our study, increasing the dose increased the level and duration of sensory block, but the intensity and duration of motor block were similar between the three groups. Several reports [5–7] have suggested that the total dose of bupivacaine is more important than volume or concentration of anaesthetic solution in determining spread of anaesthetic solution in the CSF. The relationship between volume of anaesthetic injected for spinal anaesthesia and final level of block have not been defined clearly. Baricity determines primarily the spread of subarachnoid local anaesthetic in the CSF. In recent studies of plain spinal infusion in pregnancy, final levels of block were similar with volumes and concentrations ranging from 3 ml of 0.5 % to 18 ml of 0.083 % plain bupivacaine [13–15]. However, increasing the vol-
ume administered into the subarachnoid space, especially in a hyperbaric solution, resulted in significantly greater cephalad spread [8–10]. The effect of volume of hyperbaric spinal anaesthetic solution injected may be additive to the effects of gravity, position and dose. High volumes of hyperbaric local anaesthetic solution may influence the spread of local anaesthetic in CSF and final block. In the clinical dose range (10–15 mg) of 0.5 % or 0.75 % hyperbaric bupivacaine, the volume does not exceed 3 ml. When 0.25 % hyperbaric bupivacaine solution is used, the dose of 10–15 mg reaches 3.0–6.0 ml. The large volume itself may influence the spread of local anaesthetic in CSF and final block, especially in the narrow subarachnoid space of term parturients. In our preliminary study with 5–6 ml of 0.25 % bupivacaine in 5 % glucose, sensory block occurred at the cervical level of dermatome in a few minutes after subarachnoid injection in all parturients. Severe hypotension developed and nausea or vomiting, dyspnoea, and transient headache occurred in all patients. The one cause limiting the choice of spinal anaesthesia for Caesarean section is the possibility of neonatal depression because of severe hypotension after spinal anaesthesia. Petersen and co-workers [12] reported incidences of hypotension in patients given 7.5–10 mg and 10–12.5 mg of 0.5 % hyperbaric bupivacaine solution of 24 % and 26 %, respectively. In our study, despite adequate hydration and i.m. ephedrine before induction of spinal anaesthesia, the incidence of hypotension in the 4.0–4.4-ml group (75 %) was significantly greater than in the 3.2–3.6ml and 3.6–4.0-ml groups (40 % in each group). The percentage maximal decrease in systolic arterial pressure and the incidence of patients requiring supplementary ephedrine were significantly greater in the 4.0–4.4-ml group than in the two other groups. The condition of the neonates, assessed by Apgar score, was good and similar in the three groups. Two neonates in the 4.0–4.4-ml group had an Apgar score of 5 and 6 at 1 min, respectively, but the scores at 5 min were more than 8. In these two neonates, maternal systolic arterial pressure decreased transiently to 70 and 75 mm Hg a few minutes after induction of spinal anaesthesia. A large volume of 0.25 % hyperbaric bupivacaine solution could easily spread in a cephalad direction in CSF and influence sensory block and also sympathetic block. Therefore, simply increasing the volume of 0.25 % hyperbaric bupivacaine solution to increase the dose must be considered for spinal anaesthesia for Caesarean section. It is generally accepted that sensory analgesia to at least the fourth thoracic dermatome is necessary for Caesarean section. However, despite seemingly adequate levels of sensory block regardless of the local anaesthetic used, many parturients required supplementary analgesia during exteriorization of the uterus and traction on the abdominal viscera [11, 12]. In our study, all parturients experienced a block at or above T6 in sensory analgesia. Sensory block above T4 was obtained significantly more often in the 3.6–4.0-ml and 4.0–4.4-ml groups than in the 3.2–3.6-ml group. No patient complained of dis-
Spinal anesthesia for Caesarean section comfort at incision from skin to the uterus. Petersen and co-workers [12] reported that similar spread of sensory block to above T3 developed in patients who received 7.5–10 mg and 10–12.5 mg of 0.5 % hyperbaric bupivacaine solution, but the use of a larger dose of bupivacaine resulted in a lesser frequency of moderate to severe visceral pain. In our study, the frequency of visceral pain and requirement for supplementary opioids were significantly less in the 3.6–4.0-ml and 4.0–4.4-ml groups than in the 3.2–3.6-ml group. A variety of ways have been tried to improve the quality of spinal anaesthesia during Caesarean section. Injecting larger doses of local anaesthetic can improve the quality of sensory block [12, 16]. In 0.25 % hyperbaric bupivacaine solution, increasing volume to increase the dose is not recommended because the large volume itself would cause cervical spinal block and severe hypotension. The addition of adrenaline [17], morphine [18] or fentanyl [19] to hyperbaric bupivacaine solution improved the quality of bupivacaine intraoperative analgesia. In our study with 0.25 % hyperbaric bupivacaine, a larger dose improved the quality of sensory analgesia, but the incidence of hypotension and its severity were greater with volumes exceeding 4.0 ml.
Acknowledgements This work was supported in part by a grant from Dong-A University, Korea.
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