July 2005 - The Hong Kong College of Anaesthesiologists

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Bull HK Coll Anaesthesiol Volume 14, Number 2 July 2005Table 1. Patient characteristics and performance of regional block. Values are mean ± SD; Levels areexpressed as median (range)Spinal group(n = 30)CSE group(n = 30)P ValuesPatient characteristicsAge (year) 31.0 ± 0.9 32.8 ± 0.8 0.89Body height (cm) 155.4 ± 1.2 155.7 ± 1.5 0.91Body weight (kg) 65.8 ± 1.3 65.1 ± 1.5 0.96Maturity (weeks) 38.5 ± 0.2 38.4 ± 0.2 0.87Performance of regional blockMaximal dermatomal level [median (range)] T4 (T2‐5) T4 (T2‐6) 0.85Level at 10 min [median (range)] T4 (T2‐5) T4 (T2‐10) 0.99Time to maximal level after completion of block (min) 5.8 ± 0.4 8.0 ± 1.0 < 0.05Performance time (sec) 217.8 ± 23.1 336.5 ± 4.0 0.01Start of block to skin incision time (min) 10.3 ± 0.5 13.9 ± 1.2 0.01Start of block to delivery time (min) 20. 0 ± 0.7 22.2 ± 1.3 0.16Skin incision to delivery time (min) 9.7 ± 0.5 8.2 ± 0.5 0.05required an epidural top up.Incidence of complications was tabulated inTable 4. There were no statistically difference inthe occurrence of nausea, vomiting, pruritus andshivering between groups. No patients in thespinal group but three in the CSE groupdeveloped PDPH. One required epidural bloodpatch. There was no evidence of accidental duralpuncture by 18G Tuohy needle in all threepatients. The first patient had cesarean sectionfor breech presentation. She developed severePDPH on day 1 after delivery. She refused bloodpatch and was treated conservatively. Herheadache subsided five days afterwards. Thesecond patient had cesarean section formacrosomia. She developed PDPH on day 1. Shereceived epidural blood patch on Day 2.Headache completely resolved afterwards. Thethird patient received cesarean section fortransverse lie. She developed PDPH on day 2.She requested conservative treatment and theheadache resolved on day 5. No furtherheadache was reported in these patients afterdischarged from hospital.There was no difference in Apgar scores in 1and 5 minutes between the 2 groups (Table 2).None of the neonates had Apgar score below 7.The results of fetal blood gas were similar inboth groups. Patient assessment of anesthesiawas also similar in both groups (Table 3).DiscussionCSE combines the advantages of epiduraland spinal anesthesia. It provides a more intenseblock that is reliable and faster than epiduralanesthesia. CSE is more flexible because itprovides a means for extension of the blockthrough the epidural route. Hence smaller dosesof local anesthetic can be administeredintrathecally. This may reduce the incidence andseverity of hypotension. CSE can also beextended to provide postoperative pain relief.Hypotension is one of the major hazards ofregional anesthesia for cesarean section. Severehypotension induces maternal or neonatalmorbidity. 8 Prophylactic measures againsthypotension included fluid preloading,maternal positioning to minimize aortocavalcompression and vasopressors like ephedrine.Hypotension may also be reduced by usingsmaller intrathecal dose of local anesthetics. Thesubarachnoid doses of hyperbaric bupivacainefor cesarean section had been reviewedpreviously. 9,10 Various bodily parameters werefound to correlate with anesthetic dose for79
Bull HK Coll Anaesthesiol Volume 14, Number 2 July 2005Table 2. Complications and neonatal outcomes after spinal or combined spinal and epidural block.Values expressed as mean ± SD.Spinal group CSE group(n = 30) (n = 30)P ValuesHypotension (number, %) 28 (93%) 22 (73%) 0.08Percentage of maximal decrease in systolic pressure 30.4 ± 1.6 26.8 ± 1.9 0.l5Time to develop the lowest SBP (min) 4.5 ± 0.8 9.3 ± 2.3 0.05Dose of ephedrine consumed (mg) 17.5 ± 1.8 12.0 ± 1.7 0.03Time to first dose of ephedrine (min) 2.8 ± 0.4 3.1 ± 0.3 0.52Nausea and vomiting (number) 10 10 1.00Pruritus (number) 1 0 0.50Shivering (number) 2 2 1.00Postdural puncture headache (number) 0 3 0.12Apgar scoreat 1 min [median (range)] 8 (7‐9) 8 (7‐9) 0.44at 5 min [median (range)] 9(8 ‐ 10) 9(8 ‐ 9) 0.72Cord blood analysispH 7.31 ± 0.01 7.32 ± 0.01 0.38Carbon dioxide tension (kPa) 5.6 ± 0.2 5.8 ± 0.1 0.49Oxygen tension(kPa) 3.5 ± 0.2 3.5 ± 0.2 0.86Bicarbonate concentration (mmol/L) 21.2 ± 0.6 21.3 ± 0.5 0.18Base excess (mmol/L) ‐4.7 ± 0.6 ‐3.6 ± 0.4 0.15spinal anesthesia. Patient height is mostcommonly taken into account when determiningthe dose of spinal anesthesia. 11 Recent studiesshowed that the vertebral column length was animportant factor in dose selection. 12,13Satisfactory block has been reported withsmaller doses of hyperbaric bupivacaine rangingfrom 7.5 to 12.5 mg. This was associated with 33% hypotension. 6CSE allows the use of smaller dose of localanesthetics for the spinal component as theepidural catheter can be used to supplementinadequate block if necessary. It is stillcontroversial whether CSE is associated withless hypotension than spinal or epiduralanesthesia. Earlier study by Rawal et al showeda lower incidence of hypotension in CSEcompared with epidural anesthesia for cesareansection. 6 In this study, the incidence ofhypotension is high with respect to the doseadministered, 73 % of patients in CSE groupversus 93 % of patients in spinal groupdeveloped hypotension.Fentanyl has bupivacaine sparing effect andmay reduce the incidence of hypotension. 14,15Fentanyl has been added to the subarachnoidbupivacaine to enhance surgical analgesia andprolong the duration of anesthetic block. 16‐18Fentanyl produced many of its clinical effectsvery early after intrathecal administration in theintraoperative periods. Earlier study by Sergio etal (17) showed that the combination ofbupivacaine and a low dose of fentanyl (0.25Table 3. Patient assessment of surgical anesthesia.Data were number of patients (%).Spinal group CSE group(n=30)(n=30)Excellent 10 (33.3%) 11 (36.6%)Good 20 (66.6%) 18 (60%)Fair 0 1 (3.3%)Poor 0 080
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July 2005 - The Hong Kong College of Anaesthesiologists

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