A COMPARATIVE STUDY OF INTRATHECAL HYPERBARIC 0.5% BUPIVACAINE VERSUS INTRATHECAL 0.5% ISOBARIC LEVOBUPIVACAINE

BACKGROUND \nBupivacaine is a long-acting agent capable of producing prolonged anaesthesia and analgesia that can be prolonged even \nfurther by the addition of epinephrine. It is substantially more cardiotoxic than lidocaine. The cardiotoxicity of bupivacaine is \ncumulative and substantially greater than would be predicted by its LA potency. At least part of the cardiotoxicity of bupivacaine \nmaybe mediated centrally because direct injection of small quantities of bupivacaine into the medulla can produce malignant \nventricular arrhythmias. Bupivacaine-induced cardiotoxicity can be difficult to treat.[1] Levobupivacaine contains a single \nenantiomer of bupivacaine hydrochloride and is less cardiotoxic than bupivacaine. It is extensively metabolised with no \nunchanged drug detected in urine or faeces. Research results suggest that levobupivacaine is a suitable less toxic alternative \nto bupivacaine.[2] \nMETHODS \nThe study entitled “A Randomised Controlled Double-Blind Comparative Study of 0.5% Levobupivacaine vs. 0.5% Heavy \nBupivacaine For Surgeries Below Umbilicus During Spinal Anaesthesia” for various procedures done in the Department of \nAnaesthesiology at Andhra Medical College at King George Hospital, Visakhapatnam, from November 2011 to October 2012. \nThe study was undertaken after obtaining Hospital Ethics Committee clearance as well as written informed consent from all \npatients after explaining and reassuring about the spinal procedure. A total of 100 patients of both sexes scheduled for elective \nlower abdominal surgeries under spinal anaesthesia in the age group of 18 to 55 years and belonging to American Society of \nAnaesthesiologists (ASA) Physical Status I and II were enrolled for the study. The enrolled patients were randomised to one \nof the two groups of equal-sized prospective, comparative study group using a double-blind protocol design Group B (n=50) \nreceived 3.0 mL volume of 0.5% hyperbaric bupivacaine intrathecally and Group L (n=50) received 3.0 mL volume of 0.5% \nisobaric levobupivacaine intrathecally. Routine preanaesthetic checkup of all the patients was done to exclude coexisting \nmedical conditions and to assess airway and spine. Routine investigations like haemoglobin%, blood group and typing, urine \nexamination, etc. were done. \nRESULTS \nThe mean time of onset of sensory blockade in group B is 1.78±0.708 mins. and in group L is 2.5±0.863 mins. There is no \nclinical significance between group B and L regarding mean time for onset of sensory blockade. Five out of 50 in group B, \ntwelve out of 50 in group L attained level T4 of sensory blockade. Nineteen out of 50 in group B and fourteen out of 50 in \ngroup L attained T6, nineteen out of 50 and seventeen out of 50 attained level T8. Five out of 50 and seven out of 50 attained \nT9 level of sensory blockade. Two out of 50 in group B and none from group L attained T10 level of sensory blockade. The \nmean time taken for attaining maximum sensory blockade is 8.98±1.477 mins. in Group B and 8.08±1.70 mins. in group L. \nThere is no clinical significant difference between group B and L regarding the mean time for attaining maximum sensory \nblockade. The mean time taken for regression of sensory blockade by two segments is 86.3±6.22 mins. in group B and \n86.0±6.08 mins. in group L. The mean duration of analgesia for group B is 161.0±12.66 mins. and group L is 164.20±9.55 \nmins. The mean duration of sensory regression to S1 in group B is 201.2±12.59 mins. and in group L is 200.7±12.25 mins. \nThe mean time taken for the onset of motor blockade is 1.98±0.55 mins. in group B and in group L is 2.08±0.70 mins. The \nmean time taken for attaining maximum motor blockade in group B is 6.56±0.97 mins. and in group L is 6.26±0.92 mins. The \nmean duration of motor blockade for group B is 280.8±27.09 mins. and for group L is 279.0±18.10 mins. Changes in systolic \ndiastolic and mean blood pressures along with changes in heart rate with time were depicted in (Table 2, 3). \nCONCLUSIONS \nFrom the present study, it can be concluded that intrathecal 0.5% isobaric levobupivacaine is a safe alternative to 0.5% \nhyperbaric bupivacaine in patients undergoing elective lower abdominal surgeries. There are no intergroup differences with \nrespect to onset and duration of sensory blockade, maximum sensory level achieved, onset and duration of motor blockade, \nmean duration of analgesia, haemodynamic changes and incidence of complications. Because of less cardiotoxicity and \nneurotoxicity, it is concluded that levobupivacaine is an interesting and safer alternative to racemic bupivacaine. \n