A comparison of continuous infusion of vecuronium and atracurium in midline and paramedian laparotomies.LS Chaudhari, AN Shetty, M Buddhi, G Krishnan
Department of Anaesthesia, Seth G.S. Medical College and K.E.M. Hospital, Parel, Mumbai, India., India
Correspondence Address: Source of Support: None, Conflict of Interest: None PMID: 0010734323
Source of Support: None, Conflict of Interest: None
This was a study to compare continuous intravenous infusion of atracurium with continuous intravenous infusion of vecuronium for intraoperative muscle relaxation in 62 ASA I / II patients. Scheduled for laparotomies and pelvic surgeries under general anaesthesia. They were randomly allocated in two groups to receive either vecuronium infusion of 50 microg/kg/hour following a bolus dose of 0.1 microg/kg, or atracurium infusion of 400 microg/kg/hour following a bolus dose of 0.5 microg/kg. The mean infusion dose of atracurium was 478 +/- 44.11 microg/kg/hour and that of vecuronium was 63.2 +/- 74 microg/kg/hour for adequate muscle relaxation. The depth of neuromuscular blockade was monitored by using peripheral nerve stimulator so that only one twitch of train of four was present, resistance to ventilation, surgical relaxation and haemodynamic changes. Vecuronium infusions produced more haemodynamic stability than atracurium infusions. Vecuronium produced lesser change in systolic blood pressure (mean change of 3. 46 +/- 3.33%) from baseline values as compared to atracurium (mean change of 5.81 +/- 3.73%) from baseline values ( p < 0.01) which was statistically significant. The difference in mean pulse rate change from baseline value in the atracurium group (4.78 +/- 2.745%) was less than that in the vecuronium group (5.99 +/- 2.67%), which was not statistically significant. Spontaneous recovery was faster with vecuronium (540.94 +/- 76.46 seconds) as compared to atracurium (596. 33 +/- 72.48 seconds). 84.4% of patients who received vecuronium fell within good to very good category of muscle relaxation as compared to 63.3% in atracurium group. There were no cost benefits when either agents were used in infusion form.
Keywords: Adolescent, Adult, Atracurium, administration &dosage,Comparative Study, Hemodynamics, drug effects,Human, Infusions, Intravenous, Laparotomy, methods,Middle Age, Neuromuscular Depolarizing Agents, administration &dosage,Vecuronium Bromide, administration &dosage,
The advent of muscle relaxation into the practice of anaesthesia is an important milestone in modern development of the speciality. Good muscle relaxation along with analgesia, hypnosis and suppression of reflexes form part of balanced anaesthesia.
With proper and optimal monitoring of the depth of neuromuscular blockade, infusions are safe to use and give a stable and easily reversible neuromuscular blockade. The fear of accumulation and prolonged recovery time is becoming less and less as administration of short to moderate acting muscle relaxants like vecuronium and atracurium as continuous infusions have increased.
Vecuronium Bromide is devoid of cumulative effects, has good cardiovascular stability, does not release histamine and is excreted mainly in the bile.
Atracurium Besylate undergoes spontaneous biodegradation at body pH and temperature and does not depend on renal or biliary route for termination of action, If not for the side effects like histamine release, central nervous system active metabolite (Laudanosine) and problems of storage it would be closest to an ideal muscle relaxant.
In our study we have compared the two muscle relaxants, vecuronium bromide and atracurium besylate as continuous infusions. The main aim of the study was to assess the total requirements, need for top ups, haemodynamic changes, clinical recovery, gauge the quality of muscle relaxation and compare cost benefits.
A total of sixty-two patients between 18-60 years of age in American Society of Anaesthesiology (ASA) grade I and II categories posted for laparotomy were randomly allocated into two groups of 32 patients receiving vecuronium infusion and 30 patients receiving atracurium, infusions. Patients with hepatic, renal or neuromuscular diseases and those on medications known to affect neuromuscular blocking drugs were excluded.
All patients were premedicated with injection atropine 0.01 mg/kg. intramuscularly 30 minutes before surgery. All of them received injection pentazocine 0.4 mg/kg. intravenously as analgesic and injection diazepam. 0.1 mg/kg, Intravenously as sedation before induction of anaesthesia.
Monitoring devices like blood pressure cuff, ECG leads, finger probe of pulse oximeter and surface electrodes on the wrist were applied to monitor blood pressure, heart rate, oxygen saturation and neuromuscular blockade respectively.
Fischer and Daykel NS 242 peripheral nerve stimulator was used to stimulate the ulnar nerve, supramaximal stimulus of 0. 1 Hz. at duration of 0.2 ms. was used. Visual assessment of the number of obvious responses to the train of four (TOF) stimulation was observed.
After adequate preoxygenation general anaesthesia was induced in all patient with injection thiopentone sodium 4-5 mg/kg followed by injection succinylcholine 2 mg/kg intravenously. Following tracheal intubation anaesthesia was maintained with 60% nitrous oxide in oxygen at a respiratory rate of 14-16/min and manually ventilated. Once the patient showed recovery from succinylcholine as detected clinically and by appearance of twitch response to peripheral nerve stimulation, loading dose of atracurium besylate 0.5 mg/kg, or vecuronium. bromide 0.1 mg /kg was given followed by infusion of atracurium besylate at a rate of 400 (g/kg/hour readjusted at steps of 50 (g/kg/hour or vecuronium bromide at rate of 40 (g/kg/hour and readjusted at steps of 5 (g/kg/hour. No inhalation agents were used.
Up-titration was done with a small bolus dose (1/8th loading dose) and increasing rate of infusion. The infusion was titrated by assessment of the depth of neuromuscular blockade using peripheral nerve stimulator so that only one twitch of TOF was present, resistance to ventilation, surgical relaxation and haemodynamic changes. The patients were also monitored for spontaneous respiration, movement of the limbs and signs of histamine release like flushing of the face, hypotension bronchospasm and changes in pulse rate.
Quality of muscle relaxation was assessed by the surgical team. It involved estimating the degree of difficulty in retracting the abdominal wall and closing the muscle layer. It was a subjective assessment. The quality of muscle relaxation was graded into 4 categories - very good, good, fair and poor.
Immediately after muscle layer was approximated infusion was cut off and spontaneous recovery monitored using peripheral nerve stimulator and clinical criteria on completion of surgery, when three responses to TOF stimulation were observed residual neuromuscular blockade was reversed with injection neostigmine 0.05 mg/kg and injection atropine 0.02 mg/kg intravenously. Complete reversal of neuromuscular blockade was confirmed with the help of double burst stimulation (DBS) mode of the peripheral nerve stimulator. When patients were fully awake, moving all four limbs to oral commands and good muscle tone and power extubation was done. Recovery time-1 (RT-1) of relaxant was from termination of infusion until two twitches appeared on the stimulator (TOFC-2).
Recovery time-2 (RT-2): The period from pharmacological reversal of relaxation to the point at which no fade on DB S was observed.
A total of sixty-two patients were studied in the two groups.
Vecuronium Bromide and atracurium, besylate are non-depolarising muscle relaxants of intermediate duration of action requiring frequent top ups after initial loading dose. This form of administration is usually associated with periods of marked haemodynamic changes due to waning of muscle relaxation before each top up resulting in inadequate depth of neuromuscular blockade. In procedures of intermediate to long duration, these agents may be administered as a continuous infusion with the advantage of uninterrupted muscle relaxation. Whenever a muscle relaxant infusion is used, inappropriately intense neuromuscular blockade should be guarded against by strictly titrating the rate of infusion by using a peripheral nerve stimulator.
Many studies indicate both vecuronium and atracurium have no cumulative potential and therefore can be safely used in infusion form,,.
In this study we have compared two groups of patients, one numbering 30 individuals who received atracurium infusions and other numbering 32 individuals who received vecuronium infusions. The patients were posted for elective laparotomies and belonged to ASA I / II categories.
The average infusion rate of vecuronium for stable muscle relaxation was 63.2 + 7.42 (g/kg/hour, which was lower than the value determined by Swen et al (fentanyl based anaesthesia) but higher than one determined by Canon et a1 (Isoflurane and enflurane based at anaesthesia).
The average infusion rate of atracurium for stable muscle relaxation was 476 + 44.11 (g/kg/hour which was lower than the value determined by Brandon et al (fentanyl based anaesthesia) but was higher than one determined by Eagar et al (inhalation based anaesthesia).
Hence, intraoperative inhalation agents produced more reduction in infusion requirements as compared to narcotic. Bolus top ups along with an increase in the infusion rates was 36 times in 14 of patients of the vecuronium groups as compared to 12 times in six patients of the atracurium group. The reason for this difference might be explained by the fact that initial infusion rate was started closer to the final calculated mean infusion dose in the atracurium group as compared to vecuronium group.
Satisfactory haemodynamic stability was observed throughout the period of infusion. The pulse rate showed a mean change of 4.78 + 2.74% from the preinduction baseline values in the atracurium group as compared to 5.99 + 2.67% in the vecuronium group but the pulse rate did not fall sufficiently low to warrant administration of atropine. The systolic blood pressure showed a change from the pre-induction baseline values by less than 10%, which was clinically not significant.
The fall in blood pressure was more in the atracurium group (5.81 + 3.73%) as compared to the vecuronium group (3.46 + 3.33%) and the difference was statistically significant.
There was no incidence of bronchospasm cutaneous flushing or any other signs of histamine release in any of the patients. Gallo et al have shown that atracurium produces a significant fall in blood pressure and significant increase in histamine levels.
The quality of surgical muscle relaxation was assessed by the surgical team. It was subjective assessment with wide individual variations. The quality of muscle relaxation was graded as very good, good, fair and poor. 27 patients (84.4%) who received vecuronium infusions fell within good to very good category as compared to 19 patients (63.3%) in the atracurium group.
The difference in the mean spontaneous recovery time was statistically significant and faster in the vecuronium group as compared to atracurium group. This was in agreement with Gramstad et al .
There was no incidence of postoperative recurarisation in our study. Fawcelt et al have shown that 24% of patients who had received atracurium and vecuronium infusions has postoperative residual curarisation as compared to 12% when these agents were administered as bolus doses.
In our study we found that vecuronium infusions produced lesser changes in systolic blood pressure and more haemodynamic stability. The spontaneous recovery was faster with vecuronium as compared to atracurium. Surgical muscle relaxation was better in the vecuronium group as compared to atracurium group. The number of top ups were more in the vecuronium group as compared to atracurium group which might be explained by the fact that the initial infusion rate was started closer to the final calculated mean infusion dose in the atracurium group as compared to vecuronium group. There are no cost benefits on using either agent over the other in the infusion form.
Hence we conclude that vecuronium infusions are superior to atracurium infusions in ASA-I/ASA-II risk grades in surgical procedures of intermediate to long duration.
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]