B Padmavathi¹, Gandhay Madhavi^2*

^1,2Assistant Professor, Department of Anaesthesiology. Gandhi Medical College, Secunderabad. Telangana INDIA.

Email: padmavathi.jatin@gmail.com

DISCUSSION
The study was done at Niloufer hospital attached to Osmania General Hospital, Hyderabad, involving 100 ASA I and II parturients who underwent caesarean section under subarachnoid block. Time of onset of sensory block at T10 The duration of onset of sensory block, i.e. the time taken from administration of the drug intrathecally to the loss of pinprick sensation at T10 dermatome level bilaterally. All patients receiving either drug achieved adequate level of anaesthesia. Most of the patients in group 1 had onset of analgesia at T10 between 1-2 mins. (50%). 36% of patients had onset of analgesia at T10 between 2-3 mins. 14% had onset of analgesia at T10 between 3-4 mins. Most of the patients in group 2 had onset of analgesia at T10 between 3-4 mins (50%), 30% had onset of analgesia at T10 between 2-3 mins, 14% had between 4-5 mins and 6% had onset of analgesia at T10 between 5-6 mins. The mean time of onset of analgesia at T10 in group 1 is 2.28 ± 0.56 mins and in group 2 is 3.6 ± 0.7 mins. The difference in the mean time of onset of analgesia at T10 between group 1 and group 2 was statistically strongly significant (p<0.01). Chan-Jong Chung and colleagues used 18 mg of hyperbaric ropivacaine compared to 12 mg of hyperbaric bupivacaine for caesarean delivery and found that mean onset time of block to T10 was 3.2 min.4 In our study, we noted that mean time for onset at T10 was 3.6 mins with 15 mg ropivacaine, which was similar. Ropivacaine had a slower onset of sensory analgesia compared to bupivacaine. Similar results were obtained in the study by Jean-Marc Malinovsky and others where the mean time of onset of analgesia at T10 was 11 min with isobaric bupivacaine 10 mg and 13 min with isobaric ropivacaine 15 mg for subarachnoid block.5 Highest level of sensory analgesia It is the time taken from the completion of the injection of the study drug to the maximum sensory blockade attained. In group 1, maximal dermatomal level achieved was T4 and time taken to achieve T4 ranged from 3-8 mins (total 16 cases). In 9 cases, maximal dermatomal level achieved was T5, time taken to achieve this level ranged from 3-8 mins. In 25 cases, maximal dermatomal level achieved was T6, time taken to achieve this ranged from 3-9 mins. In group 2, 21 cases achieved maximal dermatomal level of T2, time taken to achieve this level ranged from 3-9 mins. In 14 cases, maximal dermatomal level achieved was T3 and time taken to achieve this level was 3-8 mins. In 10 cases, maximal dermatomal level achieved was T4 and time taken to achieve this level was 3-8 mins. In 4 cases, maximal dermatomal level was T5 and time taken to achieve this level was 3-8 mins. Only 1 case had maximal dermatomal level at T6 and time taken to achieve this level was 4 mins. Chan-Jong Chung and colleagues used 18mg of hyperbaric ropivacaine for caesarean delivery and found that the median peak level of analgesia was T3 (T1-5) in the bupivacaine group and T3 (T1-4) in the ropivacaine group. 4 However, higher level of sensory blockade was noticed in ropivacaine group (T2 – T6) compared to bupivacaine group (T4 – T6) in our study. This may be attributed to use of isobaric solution of ropivacaine 15 mg in our study. In our study, 52% of the patients were multipara with CPD with previous LSCS, but none of the patients experienced visceral discomfort during exteriorization of the uterus or traction on abdominal viscera. This may be due to the higher level of sensory blockade by ropivacaine. In the study by Helena Kallio and all the highest median extent of sensory block was T7 (T4-10),T7 (T4-12) and T9-10 (T6-1 1) in the isobaric ropivacaine 20 mg, isobaric ropivacaine 15 mg and isobaric bupivacaine 10 mg groups for spinal anaesthesia in lower extremity surgeries, respectively. 6Time for two segment sensory regression It is the time from maximum attainment of sensory block to regression of blockade by two segments In group 1, the time taken for two segment sensory regression in 29 patients (58%) was 80-99 mins. Maximum time taken was 150 mins. The minimum time taken was 65 mins. Mean time taken for two segment sensory regression was 90.40±20.7 mins. In group 2, the time taken for two segment sensory regression in 28 patients (56%) was 80-99 mins. Maximum time taken was 150 mins and minimum time was 60 mins. Mean time taken for two segment sensory regression was 89.6±20.7 mins. The difference in the mean time taken for two segment sensory regression between group 1 and group 2 is not significant (p>0.05). The time for two segment regression was slightly faster with ropivacaine compared to bupivacaine but was not statistically significant. Chan-Jong Chung38 and colleagues used 18 mg of hyperbaric ropivacaine compared to 12 mg of hyperbaric bupivacaine for caesarean delivery and found that the mean time for two segment regression was faster with ropivacaine (64.3 mins) compared to bupivacaine (70.9 mins). In our study also, the time for two segment regression was faster with ropivacaine (89.6 mins) compared to bupivacaine (90.4 mins). Our results concurs with findings of the above study. In the study by Gautier P, Huberty L7 and all, the time for two segment regression was 64 min with isobaric ropivacaine 12 mg and 60 min with isobaric bupivacaine 8 mg and in the study by Helena Kallio and all, the time for two segment regression was 24 min with isobaric ropivacaine 15 mg and 33 min with isobaric bupivacaine 10 mg. 6 Time for sensory regression to L1 In group 1, the time taken for sensory regression to L1 was 150 -199 mins. in 23 patients (46%) . Maximum time taken for sensory regression to L1 was 240 mins. Minimum time taken was 100 mins. The mean time taken for sensory regression to L1 was 164.10±31.19 mins. In group 2, the time taken for sensory regression to L1 was 100-149 mins in 22 patients (44%) and 150-199 mins in 24 patients (48%). Maximum time taken for sensory regression to L1 was 220 mins. Minimum time was 1 10 mins. The mean time taken for sensory regression to L1 was 152.6±25.6 mins. The difference in the mean value between group 1 and group 2 for sensory regression to L1 was statistically significant (p<0.05). Chan-Jong Chung and colleagues used 1 8 mg of hyperbaric ropivacaine compared to 12 mg of hyperbaric bupivacaine for caesarean delivery and found that regression of block to L1 was faster with ropivacaine (162.5 mins) than with bupivacaine (1 88.5 mins), which was significant. 4 Gautier P and colleagues compared the effects of intrathecal isobaric ropivacaine, isobaric levobupivacaine and isobaric bupivacaine for caesarean section.7 They noted that regression to L1 was faster with ropivacaine (124 mins) than with bupivacaine (131 mins). Malinovsky14 and others compared 10 mg of isobaric bupivacaine with 15 mg of isobaric ropivacaine for prostate surgery and the mean time for sensory regression to L1 was 105 mins with ropivacaine and 127 mins with bupivacaine, which was significant. We also observed that regression to L1 with ropivacaine (152.6 mins) was faster compared to bupivacaine (164.1 mins) and this augers well with results of above mentioned studies. Time for complete sensory recovery It is taken from the time of injection of the study drug till the patient has sensation at S1. In group 1, 2 1 patients (42%) showed complete sensory recovery in 151-190 mins, and 16 patients (32%) showed complete sensory recovery in 1 10-150 mins. The maximum time for complete sensory recovery was 240 mins. The minimum time for complete sensory recovery was 1 10 mins and the mean time for complete sensory recovery was 169.6±30.43 mins. In group 2, 22 patients (44%) showed complete sensory recovery in 11 0-1 50 mins and 22 patients (44%) in 1 5 1 - 1 90 mins. The maximum time for complete sensory recovery was 220 mins. The minimum time was 130 mins and the mean time for complete sensory recovery was 160.00±24.8 mins. The difference in the mean time for complete sensory recovery between group 1 and group 2 is statistically not significant. (p>0.05) Gautier P Steenberge and others compared isobaric bupivacaine 8 mg with isobaric ropivacaine 10 mg for knee arthroscopy. 8 The time for complete sensory recovery was shorter with ropivacaine (1 52 mins) than with bupivacaine (181 mins). However, we observed that complete sensory recovery was comparable in both the groups in our study (Ropivacaine 1 60.0 mins and Bupivacaine 169.6 mins). Total duration of analgesia It is taken from the time of injection of study drug till the patient complains of pain at the site of surgery. In group 1, the maximum duration of analgesia was 230 mins and minimum duration was 100 mins. In 21 patients (42%) total duration of analgesia was 100-140 mins and in 21 patients (42%) it was 141-180 mins. The mean time of total duration of analgesia was 153.60±29.94 mins. In group 2, the maximum duration of analgesia was 220 mins and minimum duration was 110 mins. In 26 patients (52%) total duration of analgesia was 100-140 mins and in 20 patients (40%) it was 141-180 mins. The mean time of total duration of analgesia was 143.80±25.14 mins. The mean difference of total duration of analgesia between the two groups is statistically not significant. Chan Jong Chung and all, noted that the duration of analgesia was shorter with ropivacaine (96.9 mins) than with bupivacaine (101.0 mins), which was not significant. 4 The duration of analgesia was 132 mins with ropivacaine and 157 mins with bupivacaine in the study of Gautier P and colleagues who compared the effects of intrathecal isobaric ropivacaine, levobupivacaine, and bupivacaine for caesarean section. 7 In our study the total duration of analgesia was shorter in the ropivacaine group (143.8 mins) than in the bupivacaine group (153.6 mins), and this concurs with the above studies. Time for onset of motor block It is taken from the completion of the injection of the study drug till the patient develops modified Bromage scale grade 1 motor blockade. In group 1, in 33 patients (66%) the time of onset of grade 3 motor block was 2-4 mins. In 16 patients (32%) it was 1-2 mins. The maximum time for the onset of motor block was 5 mins and minimum time was 1 min 12 sec. The mean time of onset of grade 3 motor block was 3.06±0.9 mins. In group 2, in 22 patients (44%) the time of onset of motor block was 6-8 mins. In 12 patients (24%) time of onset of grade 3 motor block was 8-10 mins. The maximum time for the onset of grade 3 motor block was 12 min and minimum time was 3 mins. The mean time of onset of grade 3 motor block was 8.46±2.48 mins. The difference in mean time of onset of grade 3 motor block was statistically highly significant ( p<0.01).Gautier P et al. compared of the effects of intrathecal isobaric bupivacaine (8mg), levobupivacaine (8mg) and ropivacaine (12mg) for caesarean section and found that the mean time for onset of Gr3 bromage motor block was 9min and 14min for bupivacaine and ropivacaine respectively. In our study, patients receiving ropivacaine had delayed onset of G3 motor blockade compared to bupivacaine, (8.46 min vs 3.06 min), this is in agreement with the above mentioned study. Kim S Khaw39 and others compared plain and hyperbaric ropivacaine 25 mg for caesarean section and found that onset of motor block was faster in the hyperbaric group (9.9 min) than in the plain group (13.8 min). 7Duration of motor block It is taken from the time of injection of the study drug till the patient attains complete motor recovery. In group 1, duration of grade 3 motor block in 52% of patients was between 75-125 mins, and in 48% of patients it was between 126- 185 mins. The mean time of duration of grade 3 motor block was 129.30±21.09 mins. In group 2, all the patients had grade 3 motor block between 75-125 mins. The mean time of duration of grade 3 motor block was 93.20±11.10 mins. The difference in the mean time of total duration of motor block in group 1 and group 2 was statistically highly significant. (p<0.01) In our study, the mean duration of motor blockade was 93.20 min with ropivacaine and 129.30 min with bupivacaine. We observed a shorter duration of motor blockade with ropivacaine compared to bupivacaine. Our findings are in affirmation with that of Chan Jong Chung and colleagues where motor blockade with hyperbaric ropivacaine 18 mg was 113.7 min compared to 158.7 min with hyperbaric bupivacaine 12 mg. 4 Helena Kallio and others also found shorter duration of motor blockade with isobaric ropivacaine (150 min) when compared to isobaric bupivacaine (210 min).6 Gautier P and colleagues, and Malinovsky and others found shorter duration of motor block with isobaric ropivacaine (116 min vs 142 min and 165 min vs 184 min).7,5 So also with Gautier P,Steenberge and all who found that duration of motor block was 135 min with isobaric ropivacaine 12 mg and 169 min with isobaric bupivacaine 8 mg. 8 Chan Jong Chung and colleagues observed complete motor block in all patients receiving either bupivacaine or ropivacaine for caesarean section.4 All patients in our study receiving either ropivacaine or bupivacaine developed complete motor block and is in agreement with the above mentioned study. Quality of anaesthesia Excellent – no discomfort or pain Good – mild pain or discomfort, no need for analgesics Fair – pain that required additional analgesics Poor – moderate or severe pain that needed fentanyl or GA. The anaesthesia was well accepted by all patients belonging to both groups. Majority of patients opined that the quality of anaesthesia was excellent with both the drugs. Cardiovascular changes Hypotension is considered as fall in systolic blood pressure of more than 20% of the baseline systolic pressure or systolic pressure less than 100 mm Hg. Heart rate less than 60 bpm is considered as bradycardia. Bradycardia was observed in 6% of patients in group 1 and 4% of patients in group 2, and these patients responded to treatment with injection atropine 0.6 mg i.v. In our study hypotension occurred in 42% of patients in group 1 and 40% of patients in group 2. Incidence of hypotension was comparable in both groups, which was easily managed by i.v. boluses of 6 mg injection mephentermine and rapid infusion of i.v. fluids. This augers well with results of Chan Jong Chung and others who also observed comparable haemodynamics in their study.4 Hypotension occurred in 24 patients in the bupivacaine group and in 20 patients in the ropivacaine group. The mean values of pulse rate changes per minute recorded in group 1 and group 2 were almost similar, statistically not significant. The mean values of mean arterial pressure changes in mmHg between group 1 and group 2 were almost similar, statistically not significant. Complications All the babies delivered in either groups were healthy. None of the babies had APGAR score less than 7. Incidence of nausea and vomiting were comparable between groups in our study. Nausea and vomiting was seen in 2% of patients in group 1 and in 4% of patients in group 2. Shivering was seen in 4% of patients in group 1, which was not significant. None of the patients in group 1 and in group 2 complained of postdural puncture headache or neurological complications. No other side effects were noted in the study.

CONCLUSION
Hence it can be concluded that 15 mg of 0.75% isobaric ropivacaine provides effective spinal anaesthesia with shorter duration of sensory recovery and faster motor recovery when compared to 8 mg of 0.5% hyperbaric bupivacaine. 15 mg of 0.75% isobaric ropivacaine did not produce any change in haemodynamic characteristics in the mother or alteration in APGAR score in the baby. Therefore 0.75% of isobaric ropivacaine 15 mg is a suitable agent, as a possible alternative to 0.5% hyperbaric bupivacaine 8 mg, for spinal anaesthesia in caesarean delivery, where early ambulation of the mother is a necessity.

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