The aim of our study is to compare the duration, density of motor blockade and hemodynamic instability produced by similar volumes of equipotent doses of isobaric ropivacaine(0.75%) with hyperbaric bupivacaine (0.5%) when administered intrathecally.
REVIEW OF LITERATURE
Quincke in 1891 demonstrated a safe, predictable means of performing lumbar puncture.
In 1899, August Bier used Quincke's technique to inject cocaine in order to produce operative anaesthesia in six patients, the first real spinal anaesthesia. The first phase in the history of spinal anaesthesia, from 1899 to 1905, was characterized by the use of only cocaine for spinal anaesthesia.4
Around 1965, spinal anaesthesia began a recovery that has persisted and even accelerated over the last 50 years.6
In 1979, Albright published an alarming editorial which associated the long acting local anaesthetics, bupivacaine and etidocaine with cardiac arrest during regional anaesthesia. Albright reported six cases of accidental intravascular injection of either bupivacaine or etidocaine which caused sudden ventricular arrhythmias at the same time as convulsions. Albright subsequently presented his findings to the United States Food and Drug Administration (FDA). This sequence of events provided the impetus to develop a new local anaesthetic drug.7
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In 1989 a study was conducted to compare the in vitro potency, onset and recovery from block of ropivacaine and bupivacaine using an isolated rabbit vagus nerve model. The effect of varying concentration of ropivacaine and bupivacaine and the compound action potential of A and C nerve fibres was assessed to determine, whether motor and sensory fibres have different sensitivities to the two agents. The results showed that depressant effect of bupivacaine was 16% greater than that of ropivacaine on motor fibres but only 3% greater on sensory fibres.10
McDonald SB et al in 2000 performed a study to find out the relative potencies of low dose hyperbaric spinal ropivacaine and bupivacaine and to assess the suitability of spinal ropivacaine for outpatient anaesthesia, ropivacaine and bupivacaine provided dose dependent prolongation of sensory and motor block.12
In 1999, Gautier PE et al evaluated intrathecal ropivacaine for ambulatory surgery. One hundred fifty patients with ASA physical status 1 scheduled for knee arthroscopy were randomly assigned
to receive 4 ml of one of five isobaric intrathecal solutions: Patients in group 1 (n = 30) received 8 mg of bupivacaine; patients in group 2 (n = 30) received 8 mg ropivacaine; patients in group 3(n = 30) received 10 mg ropivacaine; patients in group 4 (n = 30) received 12 mg ropivacaine;and patients in group 5 (n = 30) received 14 mg ropivacaine. The level and duration of sensory anaesthesia were recorded along with the intensity and duration of motor block. Intrathecal ropivacaine 10 mg producedshorter sensory anaesthesia and motor blockade than bupivacaine 8mg. However, the qualityof intraoperative analgesia was significantly lower in the 10 mg ropivacaine group (P < 0.05).Ropivacaine 12 mg produced sensory and motor block almost comparable to bupivacaine 8mg. Ropivacaine 14 mg produced sensory and motor block comparable to ropivacaine 12 mg butsignificantly increased the time to void. No sign of transient radicular irritation were noted.Intrathecal ropivacaine 12 mg is approximately equivalent to bupivacaine 8 mg. At this dose,
ropivacaine offers no significant advantage compared with bupivacaine.24
Jean-Marc Malinovsky et al. in 2000 compared intrathecal ropivacaine to bupivacaine in patients scheduled for transurethral resection of bladder or prostate. Doses of ropivacaine and
bupivacaine were chosen according to a 3:2 ratio found to be equipotent in orthopedic surgery.One hundred patients were randomly assigned to blindly receive either 10 mg of isobaric bupivacaine (0.2%, n 5 50) or 15 mg of isobaric ropivacaine (0.3%, n 5 50) over 30 s through a 27-gauge Quincke needle at the L2-3 level in the sitting position. Onset and offset times for sensory and motor blockades and mean arterial blood pressure were recorded. Pain at surgical site requiring supplemental analgesics was recorded. Cephalad spread of sensory blocks was higher with bupivacaine (median level, cold T4 and pinprick T7 ) than with ropivacaine (cold T6 and pinprick T9) (P ,0.001). Total duration of motor blockade was not different. No difference in hemodynamic effects was detected between groups. No patient reported back pain. They
concluded that 15 mg of intrathecal ropivacaine provided similar motor and hemodynamiceffects but less potent anesthesia than 10 mg of bupivacaine for endoscopic urological surgery.25
Mantouvalou et al. in 2008 compared the anesthetic efficacy and safety of three local anesthetic agents : racemic bupivacaine and its two isomers : ropivacaine and levobupivacaine, in patients undergoing lower abdominal surgery. One hundred-twenty patients,ASA I-III, were randomized to receive an intrathecal injection of one of three local anesthetic solutions. Group A (n = 40) received 3 ml of isobaric bupivacaine 5 mg/ml(15 mg). Group B (n = 40) received 3 ml of isobaric ropivacaine 5 mg/ml (15 mg). Group C (n = 40) received 3 ml of isobaric levobupivacaine 5 mg/ml (15 mg). The onset and duration of sensory block at dermatome level T8, maximum upper spread of sensory block, time for 2-segment regression of sensory block as well as the onset,intensity and duration of motor block were recorded, as were any adverse effects, such as bradycardia , hypotension,hypoxia, tremor, nausea and/or vomiting. Time to unassisted standing up and voluntary micturition was also recorded. The onset of motor block was significantly faster in the bupivacaine group compared with that in the ropivacaine group and almost the same of that in the levobupivacaine group (P < 0.05). Ropivacaine presented a shorter duration of both motor and sensory block than bupivacaine and levobupivacaine (P < 0.05).Bupivacaine required more often the use of a vasoactive drug (ephedrine) compared to both ropivacaine and levobupivacaine and of a sympathomimetic drug (atropine) compared to the ropivacaine group.
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Jack W. van Kleef et al (1994) compared the efficacy and safety of 0.5% and 0.75% solutions of ropivacaine for spinal anaesthesia in patients undergoing minor lower limb surgery. Forty patients who underwent minor lower limb surgery were randomly allocated to receive either 3ml glucose free 0.5% (15mg) or 0.75% (22.5mg) ropivacaine in a double blind fashion. They compared the onset of analgesia, median (range) upper level of analgesia, the total duration of analgesia, the degree of motor block and total duration of motor block in the two groups. They found out that the onset of analgesia to pinprick was similar with both concentrations (2 min in both the groups). The median (range) upper level of analgesia obtained with 0.5% solution was T11 (L4-T5) and was T10-11 (L4-T4) with 0.75% solution. The total duration of analgesia (P<0.002) were longer in the 0.75% group. The incidence of complete motor block of the lower limbs was higher (P<0.02) and the total duration of motor block was longer (P<0.002) in the 0.75% group. They concluded that subarachnoid injection of glucose free ropivacaine solutions results in a variable spread of analgesia accompanied by a good quality of motor block, in particularly with 0.75% solution.
J.F.Luck et al (2008) compared hyperbaric solutions of racemic bupivacaine, levobupivacaine and ropivacaine in spinal anaesthesia for elective surgery. Sixty ASA I and II patients undergoing elective surgery were randomized to receive 3 ml of bupivacaine, levobupivacaine and ropivacaine each 5mg/ml and made hyperbaric by addition of glucose 30mg/ml. Level, duration of sensory block(pin prick), intensity and duration of motor block, time to mobilise and micturate were also recorded. They found out that there was no significant differences between the groups with regard to mean time of onset of sensory block at T10, the extend of spread, or mean time to maximum spread. Regression of sensory blockade in the ropivacaine group was more rapid as demonstrated by duration at T10 (P<0.0167) and total duration of sensory block (P<0.0167) and shorter times of independent mobilization (P<0.0167). They concluded that hyperbaric ropivacaine provides reliable spinal anaesthesia of shorter duration than bupivacaine or levobupivacaine and the recovery profile of ropivacaine is better when compared with the two.
Boztug N et al(2006) performed a randomized, single-blinded and compared the effects of intrathecal ropivacaine with bupivacaine in a dose ratio of 2:1 for outpatient arthroscopic knee surgery. Ninety patients scheduled for outpatient arthroscopic knee surgery received 3 mL solution of either 15 mg of isobaric ropivacaine or 7.5 mg of isobaric bupivacaine and recorded the onset and offset times for sensory and motor block, highest level of sensory block, duration of the sensory and motor block, first ambulation, urination, and discharge time, mean arterial pressure, and heart rate were recorded. Authors reported that, isobaric ropivacaine 15 mg provided a higher sensory block level and shorter sensorial onset and offset times than 7.5 mg of isobaric bupivacaine. 15 mg of ropivacaine intrathecally is adequate for lower extremity surgery of short duration. Hemodynamic changes were similar between the groups.20
Y.Y.Lee et al (2005) performed a prospective randomized double-blind study in 34 ASA I-III patients scheduled for urological surgery were randomly assigned to receive intrathecal injection of either plain ropivacaine 10 mg with fentanyl 15 µg (ropivacaine group) or plain bupivacaine 10 mg with fentanyl 15 µg (bupivacaine group).All patients achieved sensory block to the T10 dermatome or higher at 15 min after intrathecal injection.The primary outcome, the duration of motor block, was shorter in the ropivacaine group (median, 126 min; interquartile range, 93-162 min) compared with the bupivacaine group (median, 189 min; interquartile range, 157-234 min; difference between medians, 71 min; 95% confidence interval, 28-109 min; P = 0.003). The duration of complete motor block was also shorter in the ropivacaine group compared with the bupivacaine group. There was no difference in the onset time of motor block. The characteristics of sensory block and the haemodynamic changes were similar between the groups.
Koltka k et al(2009) performed a randomized controlled study of fifty-two male patients of ASA physical status I to II, between 18 and 75 years of age and undergoing lower abdominal or urological surgery under spinal anaesthesia were recruited. The patients were randomized and allocated with a sealed envelope technique to receive 2.6 ml ropivacaine 7.5 mg/ml (19.5 mg) with 0.4 ml of fentanyl 50 [micro]g/ml (3 ml total) or 2.6 ml of bupivacaine 5 mg/ml (13 mg) with 0.4 ml fentanyl 50 [micro]g/ml (3 ml total). The groups did not differ in haemodynamic parameters in the operating room. Intraoperative hypotension requiring treatment with ephedrine occurred in eight of the patients in the bupivacaine group (32%) and five of the patients in the ropivacaine group (20%) (P=non-significant). The number needing treatment with atropine for bradycardia did not differ. The primary outcome, the duration of motor block, was significantly shorter (P=0.010) in the ropivacaine group, as was the duration of complete motor block and the number of patients with complete motor block (Bromage=3). The patients mobilised sooner in the ropivacaine group.Spread of sensory block was higher with bupivacaine than ropivacaine . The duration of sensory blockade at the level of at least T10 did not significantly differ between groups. No patient had pruritus eczema, shivering, respiratory depression or nausea and vomitingNausea and Vomiting Definition
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..... Click the link for more information.. No patient had residual neurological deficit, post-dural puncture headache or transient neurological symptoms at the postoperative follow-up.