ABSTRACT
BACKGROUND: Clonidine, an alpha-agonist has been postulated to produce analgesia centrally by stimulating the post-synaptic activity of norepinephrine through receptors distinct from opioid receptors and peripherally through a mechanism similar to local anesthetics. It has been suggested that the use of a combination of local anesthetics and clonidine both at lower doses may be effective in providing adequate analgesia at the same time minimizing the deleterious side effects of each drug when used alone at higher doses. The objective of the study was the determination of the minimum dosage of clonidine in combination with bupivacaine necessary for epidural administration that would provide optimal intraoperative and postoperative analgesia with the least occurrence of side effects such as hypotension and bradycardia. METHODOLOGY: One hundred randomly selected, healthy ASA l and 2 gynecologic patients undergoing lower abdominal surgery under epidural anesthesia were given bupivacaine 0.5 percent epidurally compounded with either saline as placebo (Group 1), or clonidine in variable doses: 0.5 ug/kg (Group 2), 1.0 ug/kg (Group 3), and 1.5 ug/kg (Group 4) in a randomized, double-blind fashion. The vital signs were noted every 5 minutes. Analgesia was monitored and recorded using the Visual Analog Scale (VAS), Verbal Rate Scoring and the systemic indicators of pain perception (SBP 30 min Hg increase from baseline or heart rate 20 percent from baseline). A top-up dose of Lidocaine 2 percent was given with systemic indications of pain perception noted intraoperatively or rescue doses of opioids were given when the systemic indications of pain perception were noted at the post anesthesia care unit, upon which data collection was terminated Eighty two patients completed the course of data collection while eighteen were dropped out because of sacral sparing, retraction pain and extension of incision. The statistical tool utilized to test significant differences between the groups was the Kruskal-Wallis Analysis of Variance test and the Partitioned Chi-square test. RESULTS: There is prolongation in the duration of analgesia with incremental increase in clonidine dose. Hypotension occurred even without the addition of clonidine with higher incidence as the dose of clonidine increased. The least side effects occurred with doses of clonidine between 0.5 and 1.0 ug/kg. CONCLUSION: The optimal dosage of clonidine for intraoperative analgesia that would extend to the postoperative period in Filipino women would fall between 0.5 to 1.0 ug/kg. (Author)
Subject(s)
Humans , Analgesia , Bupivacaine , Clonidine , Analgesia, EpiduralABSTRACT
BACKGROUND: Cisatracurium , an R-cis, R-cis isomer of atracurium, is a benzoquinolinium non-depolarizing muscle relaxant with intermediate duration of action that has the advantage of minimal histamine release compared to the parent compound atracurium. Similar studies have described cisatracurium to have cardiovascular stability up to 7 times the ED95 dose. However, few have been conclusive owing to concomitant use of agents that can cause potential histamine release and hemodynamic effects. This study was specifically designed to minimize these variables. The promise of the clinical advantages of the use of cisatracurium merits investigation against its parent compound atracurium in the Filipino population especially in terms of hemodynamic stability when utilized intraoperatively. The study was conducted to evaluate the onset of action, conditions for intubation, duration of neuromuscular block and side effects of cisatracurium compared to atracurium among Filipino surgical patients METHODOLOGY: A prospective, randomized, double-blind study was performed in eighty one (81) healthy patients of ASA Physical Status 1 and 2 undergoing elective surgical procedures treated with either 0.15 mg/kg cisatracurium (3 x ED 95) n=39 or 0.5 mg/kg atracurium (3 x ED 95) n=42 administered over 5 seconds intravenous bolus under adequate anesthesia, before surgical stimulation. We compared the time course of the neuromuscular block and determined whether the muscle relaxants caused cutaneous and systemic evidence of histamine release. Induction of general anesthesia commenced with the use of propofol-fentanyl in oxygen. Stabilization of the Neuromuscular junction was achieved prior to the administration of the muscle relaxants with the use of tetanic stimulation of 50 Hz; for 5 seconds followed by single twitch stimuli for 2 minutes. Neuromuscular transmission was assessed by recording the mechanical twitch response to train-of-four nerve stimulations every 10 seconds. Cutaneous manifestations, blood pressures and heart rates were recorded periodically. RESULTS: Time to 95 percent block were 77.09-155.99 seconds with cisatracurium. and 64.60 - 128.21 seconds with atracurium. The administration of either muscle relaxant resulted in complete neuromuscular block in all patients providing good to excellent intubating conditions. The time to spontaneous recovery (T4:T1 ratio 80 percent) were noted to be within the range of 63.48 - 103.48 minutes for cisatracurium whereas those treated with atracurium recovered within the range of 74.76 - 92.64 minutes and none necessitated reversal from the muscle relaxants. One patient from the cisatracurium group and two from the atracurium group were noted to have cutaneous flush. CONCLUSION: When given a dose of 3 x ED 95, except for onset, cisatracurium group did not differ significantly from the atracurium group with regard to onset, duration, intubating conditions, and hemodynamic stability.