Comparison of Analgesic Efficacy of Butorphanol and Fentanyl in Various Surgeries

Abstract               Background: An ideal perioperative analgesic should offer protection against the pressor response should provide intense analgesia sufficient to relieve pain of surgical incision, maintain the haemodynamic parameters and should provide adequate postoperative analgesia. Aim and objective: To compare analgesic efficacy of butorphanol and fentanyl quantitatively Methodology: 60 patients of either sex between age groups 18-55 years ASA I and II who were posted for surgeries under general anaesthesia. After premedication with inj. glycopyrrolate 5 µg/kg intravenously patients were given butorphanol 20 µg/kg intravenously or fentanyl 1µg/kg intravenously in equianalgesic doses. Results and discussion: Time required to achieve VAS score 4 was higher in butorphanol group as compared to fentanyl group. VAS score at 60 min 2.90 ± 0.19(butorphanol) Vs 3.53 ± 0.17(fentanyl) and VAS score at 90 min. 3.23 ± 0.17(butorphanol ) Vs4.33 ± 0.15(fentanyl)].

Key Word: Butorphanol, Fentanyl.

INTRODUCTION

Painful surgical procedure in patients are possible only with high quality anaesthesia which include adequate sedation, amnesia, muscle relaxation and analgesia. Balanced anaesthesia¹ implies rational use of intravenous inhalational agents, barbiturates, opioids. Narcotic analgesics are widely used as adjuncts to general anaesthesia. They act to smooth the intraoperative course and decrease the requirement for other anaesthetic agents as well as to minimize postoperative pain. It is however imperative that any agent used in anaesthesia have short duration of action and minimum side effects, so those patients can be discharged safely. Opium was used throughout 19^th century often as 'Laudanum' or 'tincture of opium and alcohol'. It was the juice from the unripe seed capsule of the poppy Papaver somniferUm. The revolution in the treatment of pain began with advent of morphine, isolated crystals of crude opium by Friedrich Wilhem Serturner in 1803. Since past time, opioids are used alone or in combination with other agents like sedatives or anticholinergics as premedicant. Fentanyl citrate a 4-anilino piperidine derivative, synthesized in 1960, is a completely synthetic opioid. It is more potent and has a better margin of safety (ratio of median lethal dose to lowest effective dose for surgery) than meperidine. Butorphanol tartarate synthesized by Bristol laboratories in 1960s is a totally synthetic narcotic antagonist analgesic, which does not require opium alkaloids for its synthesis. This drug with its combined antinarcotic and potent analgesic properties offers promise as an agent with a low propensity for producing addiction and respiratory depression. The purpose of this study was to compare Butorphanol, a new opioid with Fentanyl a popular short duration opioid as a component of balanced general endotracheal anaesthesia.

MATERIAL AND METHODS

Study was carried out in a tertiary care centre. Study population was patients undergoing general anaesthesia for various surgeries in a tertiary care centre. Inclusion criteria: ¹Physical status of ASA I and ASA II ²Age group between 18 to 55years. ³Gender-Both Males and Females. Exclusion criteria: ¹Patients with Cardiovascular diseases like hypertension, ischemic heart disease, valvular heart disease ²Respiratory diseases like asthma, pulmonary tuberculosis, COPD ³Renal or hepatic derangement, Haematological derangements ⁴Those taking psycho therapeutic drugs. ⁵Pregnant females ⁶History of narcotic abuse. In our study 60 cases were divided randomly into two groups. Group A patients received inj. butorphanol tartarate 20µg/kg intravenously prior to induction and Group B patients received inj. fentanyl citrate 1µg/kg intravenously prior to induction. Study was approved by ethical committee. A valid written consent was taken from patients after explaining study and procedure to them. Patients under the study were thoroughly assessed preoperatively regarding detailed history, physical examination and all necessary investigations. No premedication was given except Inj. Glycopyrrolate 5 µg/kg intravenously. Vital parameters like pulse, blood pressure both systolic and diastolic, respiratory rate, oxygen saturation were measured. After keeping complete resuscitation and anaesthesia instruments ready, intravenous line was secured with an intracath. 3 minutes prior to induction patients were given an equianalgesic dose of Inj. Butorphanol 20µg/kg intravenously or Inj. Fentanyl 1µg/kg intravenously based on body weight in double blind fashion. Following preoxygenation for 5 minutes, general anaesthesia was induced with Inj. Thiopentone sodium 4 mg/kg intravenously slowly followed by tracheal intubation under direct laryngoscopic vision with adequate sized endotracheal tube facilitated by Inj. Succinyl Choline 2 mg/kg intravenously. Anaesthesia was maintained with 40%02:60% N20 with intermittent isoflurane depending on the depth of anaesthesia and long acting depolarizing muscle relaxant. Inj.Vecuronium bromide 0.08 mg/kg intravenously on controlled ventilation with Bains' circuit. Vital parameters including pulse, blood pressure, oxygen saturation, were monitored just prior to induction, 1 and 2 minute after induction and 1 and 3 minute after tracheal intubation and 15 minutes interval thereafter. single observer made all observations. During recovery patient's activity, respiration, alertness, color was evaluated every 30 minutes for 90 minutes. Sedation and pain was assessed using Ramsay Sedation scale and Visual Analog Scale at every 30 minutes interval for first 90 minutes. Baseline visual analogue scale and sedation score were assessed. Visual Analog Scale consisted of a 10 cm Scale, representing varying intensity of pain from 0 (no pain) to 10 (worst imaginable pain).

Ramsay Sedation Scale was based on following points.

• Anxious, Restless or both – 1
• Cooperative, oriented, tranquil – 2
• Responding to oral commands – 3
• Brisk response to stimulus – 4
• Sluggish response to stimulus – 5
• No response – 6

Monitoring facility and 0₂supplementation was kept ready in recovery room. Statistical analysis was done by using appropriate statistical tests.

RESULTS

Table 1: Age and Weight distribution of cases in study.

Unpaired t test . Ns:-not significant, s:-significant

Figure 1: Distribution of patients according to sex

Unpaired t test. Ns:-not significant, S:-significant

Table 1, 2 and fig 1 show the mean age, sex and duration of surgery of patients. By statistical analysis, they were found comparable.

Figure 2: Baseline VAS and Sedation score of patients in Group A and Group B

Baseline VAS score in Group A and Group B were 1.133 ± 1.432 and 1.133 ± 1.709 respectively. Baseline sedation score in Group A and Group B were 1.333 ± 4795 and 1.267 ± 4498 respectively. Both the groups were comparable. Figure 2)

Table 3: Sedation score in Group A and Group B during surgery

Mann-Whitney test ns:-not significant s:-significant Sedation score was observed postoperstively at 30 minutes interval till 90 minutes (table 4). It has been oserved that sedation scores were higher in group A (butorphanol) than goup B (fentanyl). statistical analysis showed that postoperative sedation score of group A (butorphanol) at 30 minutes(2.333 ± 0.1465 )and 60 minutes(1.600 ± 0.1135) was significantly higher than postoperative sedation score in group B(fentanyl) at 30 minutes (1.800 ± 0.1114) and 60 minutes (1.300 ± 0.08510) respectively. (table 3)

Table 4: Comparison of Group A and Group B according to VAS score (pain)

Mann-Whitney test. Ns:-not significant s:-significant

Table 4. shows mean VAS score at 30 minutes interval in recovery room .It was used to assess the postoperative pain. VAS scores after 60 minutes were 2.900±0.199(group A) and 3.533±0.177(group B) ,while after 90 minutes scores were 3.233±0.170 (group A ) and 4.333±0.1541 (group B). It was observed that mean VAS scores were significantly higher in group B (Fentanyl) than group A (Butorphanol) 60 and 90 minutes postoperatively, this indicates that fentanyl does not have postoperative analgesia

Figure 3: Postoperative comparison of visual analogue scale(VAS) for pain

Figure 4: Comparison of Group A and Group B according to Rescue analgesia.

Rescue analgesia was given as intramascular Diclofenac sodium when the VAS score was ≥4.

Fig 4 shows no of patients who were given rescue analgesia at 30 minutes interval postoperatively. Sedation was significantly greater in the butorphanol group but none of the patient required extension of postoperative observation period and sedation scores were acceptable for discharge from recovery room after 90 minutes of postoperative monitoring.

DISCUSSION

The assessment of analgesic drugs is difficult because of the subjective nature of pain. Although many methods have been described, no evaluation process has proven itself to be entirely satisfactory. Pain can be assessed by the patient himself with the help of linear visual analog scale or objectively by observing the patient for facial expression, complaints of pain and side effects like tachycardia, hypertension, tachypnea and restlessness. The subjective method by far is the best method which we have used in our study. The visual analog scale (VAS) is linear 10cm scale with lowest score of 0 corresponding to no pain and highest score of 10corresponding to worst or intolerable pain perceived by patients.VAS score was assessed at the interval of 30 minutes postoperatively. When VAS in both groups were compared butorphanol was significantly superior than fentanyl.VAS score at 60 min 2.90 ± 0.19(butorphanol) Vs 3.53 ± 0.17(fentanyl) and VAS score at 90 min. 3.23 ± 0.17(butorphanol ) Vs4.33 ± 0.15(fentanyl)]. This can be explained by the fact that fentanyl has significantly shorter duration of action. We have chosen 60 cases. The mean duration of surgery of fentanyl group was 83.83 ± 2.57 minutes.So in majority of cases, by the time the surgery was completed the action of fentanyl had weaned off. The mean duration of surgery of butorphanol group was 90.17 ± 2.40 minutes. Because butorphanol has a longer duration of action, the dose given at the time of induction continued to have analgesic effects in the immediate postoperative period, proving superior to fentanyl for conferring postoperative analgesia. Because of superior postoperative analgesia number of patients who were given rescue analgesic was less in butorphanol group .4 patients of group A were given rescue analgesic as compared to6 of group B 30 minutes postoperatively. While 60 and 90 minutes postoperatively no of patients of group A requiring rescue analgesic were 9 and 10 as compared to 14 and 24 of group B respectively. Rescue analgesia was given as a non narcotic NSAID diclofenac sodium 75 mg intramuscularly when .the VAS scores reached≥4. We wanted to compare the severity of side effects in both the groups. Sedation is one of the important side effects of opioids. To assess the effect of sedation of both groups, it was necessary that the rescue analgesia had no sedative property. Hence, we used a non narcotic NSAID diclofenac sodium 75 mg intramuscularly.^2,3 In 1994, Atkinson BD, Truitt LT et al., in their study compared the analgesic properties of butorphanol and fentanyl. They concluded that butorphanol provided better postoperative analgesia than fentanyl with fewer patient requests for more pain relief. ⁴ Del Pizzo studied butorphanol in comparison to morphine for postoperative pain and„ observed that duration of action of butorphanol appeared in every aspect to approximate that

CONCLUSION

Both butorphanol and fentanyl are cardiostable and provide intense intraoperative analgesia. Butorphanol provides significant postoperative analgesia for a longer duration as compared to fentanyl.

REFERENCES

• W. W. Mushin BALANCED” ANAESTHESIA Br Med J. 1955 March 19; 1(4915): 710.
• Roscow CE. Butorphanol in perspective. Acute Care 1988; 12(suppl 1):2-7
• Smith JE, King MJ, Yanny HF, Pottinger KA, Pomirska MB.Effect of fentanyl on the circulatory responses to orotracheal fibreoptic intubation. Anaesthesia. 1992 Jan;47(1):20-3         
• Atkinson BD, Truitt LJ, Rayburn WF, Turnbull GL, Cristensen HD, Wlodaver A. double-blind comparison of intravenous butorphanol (Stadol) and fentanyl (Sublimaze) for analgesia during labor. Am J Obstet Gynecol. 1994 Oct; 171(4);993-84
• Del Pizzo A. Butorphanol, a new intravenous analgesic: Doubie blind comparison with morphine sulfate in postoperative patients with moderate or severe pain. Current Therapeutic Research VoI.20.No.3, Sept.1976 221-232
• Usmani H, Quadir A, Jamil S.N., Bahl N, Rizvi A Comparison of Butorphanol and Fentanyl for BalancedAnaesthesiain Patients Undergoing Laparoscopic CholecystectomyJ Anaesth Clin Pharmacol 2004; 20(3):251-254.