Table of Content - Volume 18 Issue 2 - May 2021
Comparative study of postoperative analgesia intrathecal addition of fentanyl versus clonidine in lower limb surgeries
Palak Gupta1*, Neha Sharma2*, Rajdeep Kour3
1Post Graduate Student, 2,3Lecturer, Department of Anaesthesia, Government Medical College, Jammu, INDIA. Email: nehas310sharma@gmail.com, palakgupta.pk1991@gmail.com
Abstract Background: Local anesthetic drugs like bupivacaine are commonly used in spinal anesthesia for lower limb surgeries but the duration of spinal anaesthesia is very short. However, the duration of action of bupivacaine in spinal anaesthesia can be prolonged by using adjuvants such as midazolam, opioids, neostigmine, dexmedetomidine and clonidine. The present study is being undertaken to evaluate and compare the effects of clonidine and fentanyl as intrathecal adjuvants to hyperbaric bupivacaine in patients undergoing lower limb orthopaedic surgery. Material and Methods: Present study was conducted in the Department of Anaesthesiology and Intensive Care, Government Medical College, Jammu in patients of either sex ranging in age from 20-60 years belonging to ASA I/ II scheduled for lower limb orthopaedic surgeries. 90 patients were randomly allocated in three groups of 30 each in order to compare the duration and quality of analgesia of clonidine and fentanyl used as adjuvants to intrathecal bupivacaine. Results: All the three groups were comparable in age, gender, height, weight, ASA grade distribution and the difference between them was not statistically significant. The difference between the time to reach the T10 block, mean time taken for first request for analgesia and duration of motor block in all three groups were found out to be statistically significant (p<0.0001). It was found that group with clonidine had better results than fentanyl and bupivacaine alone. In our study 1 patient in bupivacaine (15mg) with fentanyl (25µg) group and 2 patients in clonidine(37.5ugm) group had hypotension but the difference was statistically insignificant. Only 1 patient in each fentanyl and clonidine group had 1 episode of bradycardia but no patient in bupivacaine alone group had bradycardia and the difference was also insignificant. Postoperative vomiting was experienced by 3.33% of patients receiving Bupivacaine (15mg) with fentanyl (25µg) and it was treated by giving injection Ondansetron 4 mg i/v whereas no case was reported in clonidine group. This difference was statistically insignificant. 2 patients in bupivacaine (15mg) with fentanyl (25µg) group had itching but no such case was reported in clonidine group and the difference was also statistically insignificant. No respiratory depression, nausea was noted in study patients. Conclusion: It can be concluded that intrathecal clonidine (37.5ugm) provides quicker onset and prolonged duration of sensory and motor blocks simultaneously increasing the duration of analgesia when compared to fentanyl (25ugm). Keywords: postoperative analgesia, intrathecal additives, fentanyl, clonidine.
INTRODUCTION Local anesthetic drugs like bupivacaine is commonly used in spinal anesthesia for lower limb and abdominal surgeries but the duration of spinal anaesthesia is short and limited with higher doses of rescue analgesics requirement in post-operative period. The duration of action of bupivacaine in spinal anaesthesia can be prolonged by using adjuvants such as midazolam, opioids, neostigmine, dexmedetomidine and clonidine. Various additives has been used with local anesthetics and evaluated in quest for an ideal adjuvant which can enhance the quality of analgesia and prolong the duration of spinal anesthesia with minimal side effects.1 Opioids and local anaesthetics administered together intrathecally are known to have synergistic analgesic effects. It has been seen that the addition of intrathecal opioid to spinal anesthetics prolongs sensory blockade without prolonging motor blockade.2 Lipophilic opioid fentanyl is increasingly being administered intrathecally as an adjunct to local anesthetics. Fentanyl is a µ receptor agonist and has the advantage of being 75-100 times more potent than morphine.3 It prolongs sensory blockade when given intrathecally but is also associated with side effects like pruritus, nausea, vomiting and respiratory depression. Clonidine, an alpha-2 adrenergic agonist has been used as an antihypertensive agent for many years. Recently its desirable anaesthetic properties in human have been highlighted, which includes reducing anesthetic requirements, improving hemodynamic stability and providing analgesia.4 It prolongs both the sensory and motor blockade produced by spinal lidocaine, bupivacaine and ropivacaine. Clonidine in doses as small as 15µg has been shown to improve the quality of ropivacaine and bupivacaine, spinal anesthesia without producing the side effects.5 The present study is being undertaken to evaluate and compare the effects of clonidine and fentanyl as intrathecal adjuvants to hyperbaric bupivacaine in patients undergoing lower limb orthopaedic surgery.
MATERIAL AND METHODS After obtaining approval from Hospital Ethical Committee, the present study was conducted in the Department of Anaesthesiology and Intensive Care, Government Medical College, Jammu. Inclusion Criteria Patients of either sex ranging in age from 20-60 years of age, belonging to ASA I/ II, scheduled for lower limb orthopaedic surgeries. Exclusion Criteria
An informed and written consent was taken from all patients to be enrolled in the study. Detailed history, general as well systemic examination was done. Baseline values of heart rate, blood pressure, respiratory rate, oxygen saturation was recorded. Baseline demographic values including weight, height, age and sex were also recorded. Routine investigations like Haemoglobin, Bleeding time, Clotting time, Renal function tests, Serum electrolytes, blood sugar level, electrocardiogram and chest radiograph was also carried out. Any other specific investigations was carried out as necessary for the patient. 90 patients were randomly allocated in three groups of 30 each in order to compare the duration and quality of analgesia of clonidine and fentanyl used as adjuvants to intrathecal bupivacaine. PATIENT GROUPS GROUP 1: Received 15mg of 0.5% bupivacaine and 1 ml of normal saline. GROUP 2: Received 15mg of 0.5% bupivacaine and 25ugm of fentanyl. GROUP 3: Received 15mg of 0.5% bupivacaine and 37.5mg of clonidine. Under all aseptic precautions, part was cleaned and draped. 25 G Quienkes needle was inserted in L3-L4 space with patients in sitting position and the drug combination was then given slowly depending on the group after confirming free of cerebrospinal fluid. All patients then received 6 l/min of oxygen through venture mask throughout surgical procedure. Sensory block was assessed using pin prick method. An upper level of T10 was considered satisfactory. Motor block was assessed using Modified Bromage Score. Hemodynamic parameters HR, BP, SPO2 and RR were recorded at an interval of 5 mins for 1 hr and thereafter every 10 mins till the end of surgery. Duration of pain relieve was defined as the time from spinal injection to first request for rescue analgesia or VAS<4 or whichever was earlier. I/V injection of diclofenac sodium 75 mg in 100ml of NS was used as rescue analgesia. Duration of motor block was time interval between time of intrathecal drug injection and beginning of movement of toes. All data was collected and compiled in Microsoft excel and analysed using SPSS software version 21. The quantitative data was represented as their mean ± SD. Categorical and nominal data was expressed in percentage. Chi square test was applied for qualitative type if data and t- test for quantitative type of data for statistical analysis. p <0.05 was considered statistically significant.
RESULTS The mean age in the group 1 is 33.4 ± 9.58 with a range of 20-60 years. The mean age in the group 2 is 34.8 ± 10.77 with a range of 20-60 years. The mean age in the group 3 is 33.4 ± 9.58 with a range of 20-60 years. The Group 1 had 73.33 % males and 26.67 % females. The Group 2 had 93.33% males and 6.67 % females. The Group 3 had 73.33% males and 26.67 % females. All the three groups were comparable in age, gender, height, weight, ASA grade distribution and the difference between them was not statistically significant .
Table 1: Age Distribution in two groups
We compared mean Heart Rate, mean systolic Blood Pressure, mean diastolic Blood pressure, mean MAP (Mean Arterial pressure), mean SpO2, mean respiratory rate measurements taken at time interval of 0, 5, 10, 15, 20, 30, 40, 50, 60 and 70 minutes of intraoperative period and the difference between the measurements was statistically not significant (p>0.05). The difference between the time to reach the T10 block, mean time taken for first request for analgesia and duration of motor block in all three groups were found out to be statistically significant (p<0.0001). It was found that group with clonidine had better results than fentanyl and bupivacaine alone.
Table 2: Comparison of duration of motor block (seconds) between group 1, 2 and 3.
In our study 1 patient in bupivacaine (15mg) with fentanyl (25µg) group and 2 patients in clonidine(37.5ugm) group had hypotension but the difference was statistically insignificant. Only 1 patient in each fentanyl and clonidine group had 1 episode of bradycardia but no patient in bupivacaine alone group had bradycardia, and hence, the difference was insignificant. Postoperative vomiting was experienced by 3.33% of patients receiving Bupivacaine (15mg) with fentanyl (25µg) and it was treated by giving injection Ondansetron 4 mg i/v and whereas no case was reported in clonidine group. This difference was statistically insignificant. 2 patients in bupivacaine (15mg) with fentanyl (25µg) group had itching but no such case reported in clonidine group and also the difference was statistically insignificant. No respiratory depression, nausea was noted in study patients.
Table 3: Comparison of side effects between group 1, 2 and 3.
DISCUSSION Spinal anesthesia is the technique of choice for many anaesthesiologist for lower limb surgery because of its rapid onset, adequate motor and sensory blockade, long duration of action, minimal cardiovascular changes and adequate postoperative analgesia though for limited duration. Fentanyl is highly potent drug because of its high lipophilicity. It is preferred as adjuvant in spinal anaesthesia because of its rapid onset and short duration of action with minimal cephalic spread. Fentanyl given intrathecally or IV lowers the VAS intraoperatively and a delay in request for supplemental analgesia. In clinical setting, fentanyl exerts its principal pharmacological effects on central nervous system. Its primary pharmacological action of therapeutic value is analgesia. It does not migrate to 4th ventricle in significant concentration to cause delayed respiratory depression.6 Clonidine is an α2-agonist which block the conduction of Aδ and C fibers, thereby prolongs the action of local anesthetics. When used intrathecally, it activates the postsynaptic α2-receptors in substantia gelatinosa of spinal cord and produces analgesia. In our study onset of sensory block was earlier in clonidine group (4.77± 0.68 mins) when compared with the fentanyl group (6.17±0.7 mins) and normal saline group (6.3± 0.7 min), which was found to be statistically significant. Our findings were in accordance with the study of Singh R et al.,6 they found that on adding clonidine (75µg) to bupivacaine, the time of onset of sensory block was earlier and difference was statistically significant. The possible mechanisms involved in potentiating spinal block in clonidine group is due to the fact that clonidine suppress the activity of wide dynamic range neurons and release of substance p, norepinephrine and acetylcholine in spinal cord dorsal horn and direct inhibition of impulse conduction in especially C- fibers and A𝛿 delta, possible by increasing potassium conductance.7,8 In our study, we found that intrathecal clonidine as adjuvant to bupivacaine provided prolonged analgesia compared to intrathecal fentanyl and bupivacaine alone. Similar findings were noted by Khezri et al.9 Bajwa et al.10 and Chhabra et al. 11. However, Mahendru et al.12 in their study opined that intrathecal 30 μg clonidine is comparable to 25 μg fentanyl regarding sensory and motor block characteristics which was not in agreement with our study. Bhure et al.13. demonstrated that addition of clonidine, fentanyl, and midazolam to bupivacaine significantly improves the onset and duration of sensory and motor block with relative hemodynamic stability, prolongs the duration of analgesia, and reduces the consumption of systemic analgesics in comparison to bupivacaine alone. They concluded that clonidine is an excellent additive to bupivacaine in spinal anesthesia and provides prolonged duration of analgesia without any deleterious effects. Bhattacharjee et al.14 concluded from their study that perioperative analgesia for cesarean section was prolonged by the addition of 75 μg of clonidine and 25 μg fentanyl to bupivacaine. However, prolongation of postoperative analgesia was more with fentanyl compared to clonidine and side effects such as nausea, vomiting, and hypotension were more with clonidine. These observations were not in agreement with our study. Local anesthetics are routinely injected solely intrathecally in spinal anesthesia but various adjuvants to these agents have been used with purpose of improving the quality of subarachnoid block and enhancing the action of local anesthetics. In recent years,the use of intrathecal adjuvants have gained popularity with the aim of prolonging the duration of block, patient satisfaction, decreased resource utilization compared with general anesthesia and faster recovery. Clonidine also has other beneficial effects such as antiemesis, reduced post-operative shivering, anxiolysis and sedation thereby avoiding unwanted opioid related side effects such as pruritis and respiratory depression.4 Present study was a small sample, single institution based study conducted in elective surgeries. Larger, multicenter trials are required to confirm our findings.
CONCLUSION It can be concluded that intrathecal clonidine (37.5ugm) provides quicker onset and prolonged duration of sensory and motor blocks simultaneously increasing the duration of analgesia when compared to fentanyl (25ugm).
REFERENCES
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