SAFETY AND EFFICACY OF FENTANYL VERSUS SODIUM BICARBONATE IN AXILLARY BRACHIAL PLEXUS BLOCK Darshna D Patel 1*, Varsha N Swadia 2 1

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1 ORIGINAL ARTICLE SAFETY AND EFFICACY OF FENTANYL VERSUS SODIUM BICARBONATE IN AXILLARY BRACHIAL PLEXUS BLOCK Darshna D Patel 1*, Varsha N Swadia 2 1 Assistant professor, 2 Professor and Head of Department, Dept.of Anaesthesia,S.S.G.Hospital.Medical college,vadodara ABSTRACT BACKGROUND: Recent clinical studies have suggested that alkalinization of local anaesthetic mixture may shorten the time to onset and lengthen its duration of action. Purpose of this study is to see how PH change affects the onset time of sensory & motor block and duration of post operative analgesia. MATERIALS AND METHODS: The patients were randomly allocated to two groups of 25 patients in each. Group F: patients received Inj. Lignocaine Hydrocloride 2% 15 cc +inj. Bupivacaine Hydrocloride 0.5% 15 cc +inj. Adrenaline (1:200,000) 5 mcg/ml +inj. Fentanyl Citrate 100 mcg +inj. Sterile water 5 cc. Group SB: patients received Inj. Lignocaine Hydrocloride 2% 15 cc +inj. Bupivacaine Hydrocloride 0.5% 15 cc +inj. Adrenaline (1:200,000) 5 mcg/ml +inj. Sodium Bicarbonate 7.5% w/v 2 cc +inj. Sterile water 5 cc. RESULTS: The mean time for onset of sensory block was ± seconds in Group F and ± 41.4 seconds (p<0.001) in Group SB. The mean time for onset of motor block was 338 ± seconds in Group F and ± seconds in Group SB (p<0.001) and thus highly significant. At 9 hours, 14 patients were given rescue analgesia as they had a VAS score of The duration of analgesia was ± minutes in Group F while it was minutes in Group SB (p<0.001). In Group F, 64% patients required 2 doses and 36% required 1 dose of rescue analgesia. In Group SB, 96% patients required 3 doses and 4% required 2 doses. CONCLUSION: We conclude that alkalinization of local anaesthetics significantly improved axillary brachial plexus block characteristics without any increase in side effects. It also prolongs duration of analgesia but fentanyl is better in this respect. Keywords: Lignocaine, Bupivacaine, Sodium Bicarbonate, Fentanyl, Axillary brachial plexus block INTRODUCTION The brachial plexus block is the most commonly used technique for anaesthesia of upper limb surgery due to its easy accessibility and simplicity with predictable landmarks. Lignocaine and bupivacaine are the two most commonly administered drugs in brachial plexus block. Commercially available preparations of local anesthetics are hydrochloride salts which are acidic, those with epinephrine being even more acidic. Increasing the ph of the local anesthetic solution towards the physiological range has been reported to improve the quality of neural blockade in vitro. Also, to improve the clinical efficacy of regional blocks various adjuvants including opioids, clonidine 1,dexamethasone 2,neostigmine,hyaluronid ase 3 etc have been co-administered with local anesthetics.if peripheral opioid administration *Corresponding Author Dr. Darshna D. Patel 202/Vaidehi residency,44/1 Arunoday society, AlkapuriVadodara ,GujaratIndia dr.darshna1968@yahoo.com improves regional anesthesia without centrally mediated side effects it would be useful in clinical practice.we selected fentanyl to be added to local anesthetic mixture in axillary brachial plexus block.with this background concept of alkalinization of local anesthetic mixture and evidence of peripheral opioid receptor as well as the availability of fentanyl as a citrate salt which is acidic in nature, we decided to perform a study to compare the addition of sodium bicarbonate to local anesthetic mixture (2% Lignocaine and 0.5% Bupivacaine) with that of addition of fentanyl to local anesthetic mixture, in terms of onset, time to achieve complete block and duration of analgesia. S. P. Singh et al (2009) 4 carried out a study to evaluate the effect of alkalinized bupivacaine and fentanyl mixture in supraclavicular brachial plexus block and observed that alkalinisation of plain bupivacaine significantly improved the supraclavicular brachial plexus block characteristics without any increase in side effects. It also prolonged the duration of anaesthesia but fentanyl was better in this respect. MATERIALS AND METHODS This prospective,randomized study was carried out on 50 patients ofasa grade1 & 2, aged between years of either sex scheduled for elective hand and forearm orthopaedic surgeries under 132 Int J Res Med. 2013; 2(2); e ISSN: p ISSN:

2 axillary brachial plexus block, after approval by ethical committee. Exclusion criteria: 1. Patients with known hypersensitivity to local anesthetic drugs. 2. Bleeding disorders 3. Patients on anticoagulant drugs 4. Progressive neurological disorder, nerve palsy, neuromuscular disease 5. Patient having opposite side pneumothorax or collapsed lung 6. Bilateral upper limb surgery. The procedure was explained to the patients and written informed consent was taken. Blood pressure cuff, pulse oximeter and ECG electrodes were applied. The initial pulse, blood pressure, respiratory rate and arterial oxygen saturation were noted. Premedication was given in the form of inj. Atropine mg/kg I.V. All the patients were given axillary brachial plexus block.the patients were randomly allocated to two groups of 25 patients in each. Group F: was given Inj. Lignocaine Hydrocloride 2% 15 cc +inj. Bupivacaine Hydrocloride 0.5% 15 cc +inj. Adrenaline (1:200,000) 5 mcg/ml +inj. Fentanyl Citrate 100 mcg +inj. Sterile water 5 cc. Group SB: was given Inj. Lignocaine Hydrocloride 2% 15 cc +inj. Bupivacaine Hydrocloride 0.5% 15 cc +inj. Adrenaline (1:200,000) 5 mcg/ml +inj. Sodium Bicarbonate 7.5% w/v 2 cc +inj. Sterile water 5 cc. The ph of solution was measured with a digital ph meter. To decide the volume of sodium bicarbonate 7.5% w/v to be added to local anesthetic mixture, we went on adding sodium bicarbonate drop by drop to a mixture of 15 cc 2% lignocaine with 15 cc 0.5% bupivacaine with adrenaline 1:200,000 5 mcg/ml till the solution became just turbid without causing precipitation and the ph approaching nearer to physiological ph. 1. 2%LignocaineHydrochloride+Bupivacaine Hydrochloride +Adrenaline 1:200,000 5 mcg/ml +Sterile water (ph 5.9) 2. 2% ignocaine Hydrochloride + 0.5% Bupivacaine Hydrochloride + Adrenaline 1:200,000 5 mcg/ml +Sterile water +Sodium bicarbonate 7.5% w/v 2cc (ph 7.6) 3. 2%LignocaineHydrochloride + 0.5% Bupivacaine Hydrochloride +Adrenaline 1:200,000 5 mcg/ml+ Sterile water + Fentanyl Citrate 100 mcg (ph 5.7) The solution was freshly prepared just prior to performing a block. Sensory block was assessed by pin-prick method. Grade 0 Sharp pain felt Grade 1 Analgesia: dull sensation felt Grade 2 Anaesthesia: no sensation felt Assessment of sensory block was carried out every minute till 30 minutes after completion of drug injection.time to sensory onset was considered when there was dull sensation to pinprick. Motor block was assessed as under: Grade 0 Grade 1 Grade 2 Normal grip strength Paresis: reduced grip strength and heaviness felt on raising arm above head Paralysis: no grip strength and inability to raise arm above head. Onset of motor block was considered when there was Grade 1 blockade. Time to peak motor effect was considered when there was Grade 2 blockade.success rate of block was assessed at 30 minutes after drug injection and was graded as: Complete: When all segments supplied by median, radial, ulnar and musculocutaneous nerves had analgesia or anaesthesia. Incomplete: When any of the segments supplied by median, radial, ulnar and musculocutaneous nerves did not have analgesia or anaesthesia. Failed: When more than one nerve remained unaffected. General anaesthesia was administered to patients in case of incomplete or failed blocks and these patients were excluded from the study. Patients were monitored for hemodynamic variables such as pulse, blood pressure, respiratory rate and SpO 2 and sedation score intraoperatively as well as post operatively. Sedation score: 1. Awake and alert 2. Sedated, responding to verbal commands 3. Sedated, responding to mild physical stimulus 4. Sedated, responding to moderate or strong physical stimulus 5. Not aroused Post-operatively patients were examined at regular intervals to note the duration of analgesia. It is time from administration of block to 1 st request of analgesics.rescue analgesia was given when VAS > 4/10 and it was given in the form of Inj. Diclofenac Sodium 1.5 mg/kg intramuscularly. The number of rescue analgesia doses were noted. All the patients were observed for any side effects and complications like Nausea, Vomiting, Bradycardia, Hypotension, Pruritus, Respiratory depression, Urinary retention, Local anesthetic toxicity, Hypersensitivity, Inadvertent arterial 133 Int J Res Med. 2013; 2(2); e ISSN: p ISSN:

3 puncture, Hematoma, Post block neuropathy in the intra and post-operative period. RESULTS All qualitative data were analyzed using Chi- Square test and quantitative data using the Student s t-test. Results were expressed as Mean ± SD. p value 0.05 was taken as statistically significant. Table 1: Demographic Data Parameters Group F Group SB P value No. of patients Age in years ± ± >0.05 (Mean ± SD) Sex (M:F) 21:4 20:5 Weight (kgs.) 57 ± ± 4.47 >0.05 (8%) were sedated and responding to moderate or strong physical stimulus. In Group SB, majority of the patients (84%) were awake and alert while 4 patients (16%) were sedated and responding to verbal commands.there was no statistically significant difference in haemodynamic parameters and oxygen saturation measured intraoperatively as well as post operatively. Graph 2 : Changes in mean VAS score There was no statistically significant difference among two groups in terms of demographic data. Graph 1: Mean onset time for sensory & motor blockade In Group F: only 4 patients were given rescue analgesia at the end of 12 hours. Majority of the patients (21) did not require rescue analgesia upto 12 hours.in Group SB: 9 patients were given rescue analgesia at the end of 6 hours. At 9 hours, 14 patients were given rescue analgesia.the remaining 2 patients were given rescue analgesia at the end of 12 hours. Graph 3: Duration of analgesia The mean time for onset of sensory block was ± seconds in Group F and ± 41.4 seconds (p<0.001) in Group SB. Thus it was found statistically highly significant. The mean time for onset of motor block was 338 ± seconds in Group F and ± seconds in Group SB (p<0.001) and thus highly significant. Table 2: Sedation score Sedation Group F Group SB P value score Mean ± SD 2.92 ± ± 0.38 <0.001 In Group F majority of the patients (76%) were found to be sedated but responding to mild physical stimulus, 4 patients ( 16%) were sedated and responding to verbal commands while 2 patients The duration of analgesia was ± minutes in Group F while it was 429 ± minutes in Group SB, the p value being <0.001 i.e. highly significant. Table 3: No. of rescue analgesic doses No. o f Group F Group SB doses No. % No. % In group F 9 patients (36%) required one dose and 16 patients (64%) required two doses of rescue analgesia in 24 hours post-operatively. In Group SB, 2 patients (8%) required two doses while 23 patients (96%) required three doses of rescue analgesia in 24 hours post-operatively. Intraoperatively, bradycardia was seen in two 134 Int J Res Med. 2013; 2(2); e ISSN: p ISSN:

4 patients and nausea and vomiting was seen in one patient in Group F, while no complications were observed in any patients of group SB. No complications were observed in any patients in either group in the postoperative period. DISCUSSION Peripheral nerve blocks with local anaesthetics provide excellent operating conditions with good muscle relaxation. However two major drawbacks encountered are latency of block and duration of post-operative analgesia.it is well known that relative alkalinity of local anesthetics may be a major determining factor in altering the onset of action of local anesthetics. Increasing the ph towards pka of a drug by alkalinization increases the concentration of non ionized form and it is this non ionized fraction that diffuses rapidly to the inner axonal surface producing quicker onset of analgesia. 5 The analgesia produced by opiates has classically been thought of as a centrally mediated phenomenon. However animal studies have shown that opiate receptors are present peripherally on primary afferent nerves and that activation of these receptors can produce analgesia. The mu-opiate receptor seems to be the most important receptor for antinociception and the majority of studies indicate that these receptors are located at the peripheral terminals of primary afferent nociceptive fibers.fentanyl is available as Fentanyl Citrate, which is acidic in nature and having a ph of 4.7. Also, in contrast to morphine, Fentanyl is a highly lipid soluble compound. Fentanyl has also been studied in peripheral nerve blocks such as brachial plexus block by Kohki Nishikawa et al (2000) 6, Karakaya Deniz et al (2001) and S.P. Singh et al (2009), femoral block by Md. Ashraf Abd Elmawgoud et al (2008) 7 and in peribulbar block by Mostafa El Hamid El Enin et al (2009) 8. Also Mark Tverskoy et al 9 in 1998 and PT Vijay Kumar et al 10 in 2006 demonstrated increased duration of analgesia by wound infiltration with fentanyl. Dr. B.N. Biswas et al (2002) 11 used fentanyl as an adjunct for intrathecal anesthesia and Chen-Hwan Chergn (2005) 12 in their study on fentanyl as an adjuvant in epidural block demonstrated early onset of block by use of fentanyl. They attributed this effect to the increased lipophilic nature of the drug. In contrast, Kohki Nishikawa et al (2000) demonstrated the addition of fentanyl to lignocaine in axillary block prolonged the onset of block. They postulated that the acidic nature of Fentanyl caused a decrease in the ph of local anesthetic solution which increased the latency of the block.the amount of fentanyl used in our study was 100 mcg which is same as that used in the study of Fletcher et al (1994) 13, Kohki Nishikawa et al (2000). In our study the change in ph after the alkalinization was Safety And Efficacy Of Fentanyl Versus Sodium Bicarbonate from 5.9 to 7.6, while that after addition of fentanyl was from 5.9 to 5.7, which is in consonance with a study done by Ruby Mehta et al(2003) 14,Kohki Nishikawa et al (2000) and Mark Chow et al (1998) 15. Majority of the patients (76%) were found to be sedated(sedation score 4) in Group F While in Group SB 84% of patients were alert (sedation score 1). The sedative effect of fentanyl can be explained by the peripheral uptake of fentanyl into the systemic circulation and its subsequent action in the CNS.Post-operative analgesia was judge on the basis of visual analogue score.the mechanism of action of opioids upon antinociception is not known. Mostafa Abdel Hamid Abo El Enin et al (2009) 8 8postulated the possible mechanisms of action for the improved analgesia produced by the peripheral application of fentanyl. First, fentanyl could act directly on the peripheral opioid receptor. Primary afferent tissues (dorsal roots) have been found to contain opioid binding sites. Because the presence of bidirectional axonal transport of opioid binding protein has been shown fentanyl may penetrate the nerve membrane and act at the dorsal horn. This could also account for the prolonged analgesia. However, fentanyl is reported to have a local anesthetic action. Gormley et al 16 suggested that alfentanil also prolonged postoperative analgesia by local anesthetic action. Second, fentanyl may potentiate local anesthetic action via central opioid receptor-mediated analgesia by peripheral uptake of fentanyl to systemic circulation. We conclude that alkalinization of local anesthetics significantly improved axillary brachial plexus block characteristics without any increase in side-effects. It also prolongs duration of analgesia but fentanyl is better in this respect. ACKNOWLEDGEMENT The authors would like to acknowledge the faculty and residents of the Department of Anaesthesiology, Medical College, Vadodara for valuable suggestions and cooperation. REFERENCES 1. Eriacher W, Scsuschnig C et al. The effect of clonidine on ropivacaine 0.75%in axillary perivascular brachial plexus block. Acta Anaesthesiol Scand 2000 Jan; 44(1): Estebe JP, Le Corre et al. Effect of dexamethasone on motor brachial plexus block with bupivacaine & with bupivacaine loaded microspheres in a sheep model. Eur J. Anaesthesiol 2003 Apr;20(4): Col R. P. Gupta, Maj G. Kapoor: Safety and efficacy of sodium bicarbonate versus hyaluronidase in peribulbar anesthesia. MJAFI 2006; 62: S. P. Singh, Vinita Singh, Dinesh Kaushal, S. Jafa: Effect of alkalinized bupivacaine and 135 Int J Res Med. 2013; 2(2); e ISSN: p ISSN:

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