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Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 12  |  Issue : 2  |  Page : 495-500  

Intrathecal tramadol for prevention of postanesthesia shivering after subarachnoid block: A prospective randomized placebo-controlled comparison of two different doses (10 and 20 mg)


Department of Anaesthesia, ICU and Pain, Shri Mahant Indiresh Hospital, Shri Guru Ram Rai Institute of Medical and Health Sciences, Dehradun, Uttarakhand, India

Date of Web Publication14-Jun-2018

Correspondence Address:
Dr. Mayank Gupta
Flat No. 9, G Block, College Campus, Shri Mahant Indiresh Hospital, Shri Guru Ram Rai Institute of Medical and Health Sciences, Dehradun - 248 001, Uttarakhand
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aer.AER_75_18

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   Abstract 

Background: Shivering is a common and distressing complication following subarachnoid block (SAB). Literature comparing the antishivering efficacy of different doses of intrathecal (IT) tramadol is lacking. Aims: This prospective randomized controlled study was undertaken to evaluate and compare the antishivering efficacy of IT tramadol 10 and 20 mg. Methods: Ninety adult patients undergoing lower limb orthopedic surgeries under SAB were randomized into three groups (n = 30) to receive IL 0.5% hyperbaric bupivacaine 3 ml with tramadol 0 mg (Group C), 10 mg (Group T10), or 20 mg (Group T20) in normal saline. Shivering was assessed using a 5-point intensity scoring system intraoperatively and up to 4-h postoperatively. The onset and duration of sensory and motor block, duration of analgesia, and adverse effects were assessed. Statistical Analysis Used: Analysis of variance and Pearson Chi-square test were used for statistical analysis. Results: The incidence and intensity of shivering were significantly reduced in Group T10 versus C (incidence, P = 0.007; intensity, P = 0.002) and T20 versus C (incidence, P < 0.001; intensity, P < 0.001) but comparable among groups T10 and T20 (incidence, P = 0.133; intensity, P = 0.142). There was a significant dose-dependent prolongation of duration of sensory block (121, 137, and 150.5 min; P = 0.001), motor block (242.83, 298.5, and 344 min; P < 0.001), and analgesia (289.17, 357, and 404.67 min; P < 0.001) with escalating doses of IT tramadol, respectively. All the groups were comparable with respect to hemodynamic variables, core temperature, and adverse effects. Conclusion: The addition of tramadol 10 or 20 mg IT to 0.5% hyperbaric bupivacaine for SAB is associated with significant reduction in the incidence and intensity of postanesthesia shivering and prolongation of the duration of postoperative analgesia. Tramadol 20 mg IT compared to 10 mg IT significantly prolonged the duration of postoperative analgesia but failed to demonstrate any significant attenuation of postanesthesia shivering.

Keywords: Anesthesia, bupivacaine, shivering, spinal, tramadol


How to cite this article:
Gupta P, Gupta M. Intrathecal tramadol for prevention of postanesthesia shivering after subarachnoid block: A prospective randomized placebo-controlled comparison of two different doses (10 and 20 mg). Anesth Essays Res 2018;12:495-500

How to cite this URL:
Gupta P, Gupta M. Intrathecal tramadol for prevention of postanesthesia shivering after subarachnoid block: A prospective randomized placebo-controlled comparison of two different doses (10 and 20 mg). Anesth Essays Res [serial online] 2018 [cited 2020 Apr 5];12:495-500. Available from: http://www.aeronline.org/text.asp?2018/12/2/495/234443


   Introduction Top


Postanesthesia shivering is a common complication following subarachnoid block (SAB); reported incidence varying from 40% to 70%.[1] It can be defined as spontaneous, involuntary and oscillatory fasciculations, or tremor-like hyperactivity of the skeletal muscles.[2] Shivering induced severe muscle movements and an awake state during the SAB makes it distressing both for the patient and the surgeon. It increases metabolic rate, oxygen consumption, carbon dioxide production, heart rate (HR), and blood pressure.[1],[2] These by increasing cardiac workload may prove deleterious, particularly in patients with limited cardiac reserves. It may increase wound pain, delay wound healing, and hospital discharge. Shivering also interferes with the perioperative vital monitoring and increases intraocular and intracranial pressures.[1] The abovementioned sequelae coupled with the high incidence of postanesthesia shivering makes its prophylaxis imperative. Prophylaxis with intravenous (IV) tramadol has been demonstrated to produce a dose-dependent reduction in the incidence of postanesthesia shivering.[3],[4] The routine administration of pharmacological shivering prophylaxis has however been questioned.[4] Tramadol is a commonly employed intrathecal (IT) adjuvant owing to its low cost, easy availability and its ability to prolong the duration of sensory block, motor block, and postoperative analgesia.[5],[6] A few studies have also shown IT tramadol to have antishivering efficacy.[2],[6] Administration of a single IT adjuvant like tramadol with multipronged benefits would obviate the need of administrating additional systemic drugs either for prophylaxis or treatment of pain and shivering; hence avoiding the associated side-effects. The literature evaluating the antishivering efficacy of different doses of IT tramadol is however lacking. We, therefore, conceptualized the present prospective randomized controlled study to elucidate the antishivering efficacy of two commonly used doses of IT tramadol (10 and 20 mg) as an adjuvant to 0.5% hyperbaric bupivacaine in patients undergoing lower limb orthopedic surgeries under SAB. Our primary outcome was the incidence of postanesthesia shivering while the secondary outcomes were the severity of postanesthesia shivering, duration of postoperative analgesia, perioperative adverse effects, and SAB characteristics. We hypothesized that there will be a dose-dependent reduction in the incidence of postanesthesia shivering with the addition of IT tramadol.


   Methods Top


This prospective randomized double-blind and placebo-controlled study was conducted after obtaining approval from the institutional ethical committee and written informed consent from all the participants. The ethical principles of medical research involving human participants as specified in the Declaration of Helsinki were strictly adhered to while conducting this trial. Ninety patients belonging to the American Society of Anesthesiologists Grade I/II, 18–60 years of age, either sex, and undergoing elective lower limb orthopedic surgeries under planned SAB from June 2017 to January 2018 were enrolled in the study. Patients with contraindications to SAB; allergy to any of the study drug; significant cardiorespiratory, renal, or hepatic impairment; uncontrolled hypertension or diabetes mellitus; on chronic analgesic or vasodilator therapy; and pregnant or lactating mothers were excluded from the study. A detailed preanesthetic checkup (PAC) was done. Fasting for 6 h was ensured and tablet alprazolam 0.25 mg orally was administered the night before and on the morning of surgery. All the patients were explained about the use of 11-point numerical rating scale (NRS) for pain (0: No pain, 10: Worst imaginable pain) during the PAC.

In the operation theater (OT), electrocardiography, pulse oximeter (SpO2), noninvasive blood pressure (NIBP), and nasopharyngeal probe (core body temperature) (using Datex-Ohmeda, cardiocap/5, GE Healthcare, Helsinki, Finland, multichannel monitor) were attached and baseline vitals recorded. An 18-gauge IV cannula was secured, preloading done with Ringer lactate (RL) 15 ml/kg, continued at 2 ml/kg/h intraoperatively and adjusted according to hemodynamics. All the IV fluids were at OT temperature; maintained at 22°C–24°C. All the patients were covered with a single level of surgical drapes over the chest, arms, and abdomen intraoperatively and blanket postoperatively. The patients were randomized using computer-generated random number list using Stat Trek random number generator (www.stattrek.com) into one of the three groups to receive following injectate IT: Group C: 3 ml of 0.5% hyperbaric bupivacaine + 0.5 ml normal saline (NS), Group T10: 3 ml of 0.5% hyperbaric bupivacaine + tramadol 10 mg (0.2 ml of preservative-free injection tramadol hydrochloride 50 mg/ml), or Group T20: 3 ml of 0.5% hyperbaric bupivacaine + tramadol 20 mg (0.4 ml). The total volume of the IT injectate was made 3.5 ml by adding appropriate volume of NS. The random number list was kept in sealed opaque envelopes to ensure allocation concealment; opened at the time of drug preparation. The IT injectate was prepared aseptically in identical 5 ml unlabeled syringes outside the OT by an independent anesthesiologist not involved further in the study. All the IT-administered drugs were preservative free and at room temperature. The patients, anesthesiologists performing the IT injection and collecting the trial data were unaware of the group allocation. The SAB was administered aseptically in the sitting position with a 26-gauge Quincke spinal needle in L3–L4 or L4–L5 interspace after confirming free flow and positive aspiration of cerebrospinal fluid. The patients were made supine immediately after the SAB block and monitored continuously.

The vitals (HR, NIBP, SpO2, and core body temperature) were recorded at 5 min interval throughout the intraoperative period. Hypotension was defined as systolic blood pressure <90 mmHg or >20% fall from baseline and was treated with additional IV RL bolus and injection ephedrine 6 mg IV boluses. Bradycardia was defined as HR <50 beats/min or >20% fall from baseline and was treated with injection atropine 0.6 mg IV. The sensory block level was assessed by the loss of pinprick sensation to 25 G hypodermic needle in the mid-clavicle line checked every minute until stabilization of highest sensory block level upon thrice repeated testing. Thereafter, the sensory block level was assessed every 15 min until two-segment sensory regression. The onset and duration of the sensory block were defined as time to loss of pinprick sensation at T10 dermatome and two-segment sensory regression time (TSSRT), respectively. The motor block was assessed using the Bromage score: Bromage 0: No motor block, Bromage 1: Unable to flex hip but able to flex knee and ankle, Bromage 2: Unable to flex hip and knee but able to flex ankle, and Bromage 3: Unable to flex hip, knee, and ankle. The onset and duration of motor block were defined as the time to onset of Bromage 3 and return to Bromage 0, respectively. Patients with incomplete or partial block necessitating conversion to general anesthesia were excluded from the analysis. The patients were monitored for shivering intraoperatively and up to 4-h postoperatively, using a five-point intensity scale: Grade 0: no shivering; Grade 1: one or more of the following: piloerection, peripheral vasoconstriction, and peripheral cyanosis but without visible muscle activity; Grade 2: visible muscle activity confined to one muscle group; Group 3: visible muscle activity in more than one muscle group; and Grade 4: gross muscle activity involving the whole body.[7] Injection tramadol 1 mg/kg IV was administered if shivering score was ≥2 (moderate-to-severe shivering). All the time periods were calculated from the time of completion of IT injection as time 0. The time of skin incision and closure were noted to calculate the duration of surgery. In the recovery room, the patients were monitored for HR, NIBP, SpO2, and shivering scores at 15 min intervals up to 4 h. In the postoperative period, Bromage score was assessed every 15 min until recovery to Bromage 0. The patients were monitored for pain at rest (using NRS) till patient complained of NRS ≥4. Injection diclofenac sodium 50 mg IV in 100 ml NS was administered as the rescue analgesic when the NRS was ≥4. The duration of analgesia was calculated as the time from completion of IT injection to the time of requirement of the first rescue analgesic. The patients were continuously monitored for any postoperative complications such as hypotension, bradycardia, pruritus, respiratory depression (respiratory rate <8/min), nausea, and vomiting for 24 h postoperatively; by an anesthesiologist unaware of the group allocation. Injection metoclopramide 10 mg IV was administered as the rescue anti-emetic for nausea and/or vomiting.

Statistical analysis

The data were tabulated in MS Excel 2010 and statistical analysis performed using SPSS 17.0 for Windows (Statistical Package for the Social Sciences, Chicago, IL, USA). The normally distributed continuous variables are expressed as mean ± standard deviation and were compared using analysis of variance. Nonnormally distributed continuous variables are expressed as median (range), were compared using Kruskal–Wallis test and further paired comparisons done using Mann–Whitney U-test. Nominal categorical data are expressed as frequencies (percentages) and were compared using Chi-squared or Fisher's exact test as appropriate. For all statistical tests, P < 0.05 was considered statistically significant. The primary outcome of our study was the incidence of postanesthesia shivering. Assuming a 50% incidence of shivering in the control group (on the basis of a pilot study) and 20% difference among the groups as clinical significant, a sample size of 30 patients per group was estimated with a power of 90% and an α error = 0.05. The intensity of shivering and the duration of analgesia constituted the secondary outcomes.


   Results Top


Out of 105 consecutive patients assessed for eligibility, 90 patients were randomized into three groups (n = 30 each) [Figure 1]. All the groups were comparable with respect to demographic characteristics [Table 1]. Shivering was observed in 16, 6, and 2 patients in Group C, T10, and T20, respectively [Figure 2]. The incidence of shivering was significantly reduced in Group T10 versus C (20% vs. 53.33%; P = 0.007) and T20 versus C (6.67% vs. 53.33%; P < 0.001) but comparable among Groups T10 and T20 (6.67% vs. 20%; P = 0.133). The intensity of shivering was significantly reduced in Groups T10 versus C (P = 0.002) and T20 versus C (P< 0.001) but comparable among Groups T10 and T20 (P = 0.142). Similarly, shivering requiring IV tramadol (Grade ≥2) was significantly reduced in Group T10 versus C (10% vs. 46.67%, P = 0.002) and T20 versus C (3.33% vs. 46.67%, P < 0.001) but comparable among groups T10 and T20 (10% vs. 3.33%, P = 0.133) [Figure 2]. An intragroup decrease in the core body temperature was observed after SAB in all the groups [Figure 3]. The core temperature was however comparable among the groups at all the time points. [Table 2] depicts the SAB characteristics in all the three groups. The sensory block onset time was significantly earlier in Group T10 versus C (P = 0.009) and T20 versus C (P< 0.001) but comparable among Group T10 versus T20 (P = 0.44). The peak sensory block level was comparable among all the groups (P = 0.72). The TSSRT was significantly prolonged in T10 (P = 0.002) and T20 (P< 0.001) compared to Group C and T20 versus T10 (P = 0.024). The motor block onset time was significantly earlier in Group T20 versus C (P = 0.002) but comparable among Group T10 versus C (P = 0.113) and T10 versus T20 (P = 0.102). The duration of motor block and analgesia was significantly prolonged in Group T10 versus C (P< 0.001), T20 versus C (P< 0.001), and T20 versus T10 (P< 0.001). The incidence of various side effects such as nausea, vomiting, and hypotension was comparable among the groups [Table 3].
Figure 1: Consort flow diagram

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Table 1: Demographic and baseline characteristics

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Figure 2: Intensity of shivering

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Figure 3: Core body temperature in different groups

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Table 2: Subarachnoid block characteristics

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Table 3: Adverse effects

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   Discussion Top


To the best of authors knowledge, this is the first study evaluating and comparing the antishivering efficacy of different doses of IT tramadol in adult patients undergoing lower limb orthopedic surgeries under SAB. Earlier studies evaluating the antishivering efficacy of IT tramadol have shown its low dose (10 mg) to attenuate but not completely eliminate postspinal shivering.[2],[6] In the present study, we sought to compare the antishivering efficacy of two commonly used doses of IT tramadol (10 and 20 mg) with the aim to find the dose with best antishivering efficacy with least adverse effects. We observed a significant reduction in the incidence and severity of postspinal shivering. Postspinal shivering has been hypothesized to be a physiological response to intraoperative hypothermia.[1] SAB-associated sympathetic blockade induces loss of thermoregulatory vasoconstriction below the level of block; causing core-to-peripheral redistribution of the body heat and core hypothermia.[8],[9] SAB has also been proposed to alter thermoregulation with an increase in the sweating and decrease in vasoconstriction threshold.[8] This drop-in core body temperature is sensed by the hypothalamic receptors to induce shivering in an attempt to increase the metabolic heat production.[9] However, shivering has also been found to occur even in normothermic patients; other contributing mechanisms being sympathetic overactivity, uninhibited spinal reflexes, apprehension, postoperative pain, pyrogen release, adrenal suppression, and respiratory alkalosis.[10] A number of drugs acting on different receptors such as the opioid, alpha-2 adrenergic, anticholinergic, N-methyl-D-aspartate, and serotonergic receptors have been shown to have prophylactic antishivering efficacy.[1],[3],[4],[7],[8],[9],[10] Different opioids with varying receptor profiles have been shown to reduce but not completely eliminate postspinal shivering.[6],[7],[8],[11],[12] Respiratory depression, pruritus, nausea, vomiting, sedation, and restricted availability remain some of the problems associated with their use.[13],[14] Tramadol, a synthetic opioid, is unique owing to its low propensity to cause respiratory depression, pruritus, tolerance, and depression; it is easy available owing to it lying outside the realm of Narcotic Drugs and Psychotropic Substances Act.[14] Its IT administration has also been found to be safe with no neural toxicity.[15] Tramadol's following novel antinociceptive actions have been postulated behind its antishivering efficacy: opioid receptor agonism, inhibition of the neurosynaptic reuptake of serotonin (R [+] enantiomer) and noradrenaline (L [-] enantiomer), and promotion of hydroxytryptamine secretion (R [+] enantiomer), which resets the thermoregulatory center and possible agonistic action on the spinal alpha-2 adrenoreceptors.[9],[16],[17] We observed a significant two and a half and eight times dose-dependent reduction in the incidence of shivering in Groups T10 and T20, respectively. Similar four-fold reduction (16% vs. 66%) in the incidence of shivering has been reported with tramadol 10 mg IT in parturients undergoing cesarean section under SAB.[2] In another study, tramadol 10 mg IT (5%) was found to have significantly better antishivering efficacy compared to fentanyl 10 μg IT (32%) in parturients undergoing cesarean section under SAB.[6] Although a clinically significant reduction in the incidence of shivering was observed in Group T20 compared to T10 (6.67% vs. 20%); the results were statistically insignificant. A significant four and a half and 14 times reduction in the incidence of moderate-to-severe shivering, i.e. Grade ≥2 was observed in Groups T10 and T20, respectively [Figure 2]. None of the patient in either of the treatment groups (T10 and T20) had Grade 4 shivering. This is in agreement with similar findings of a previous study which also reported the absence of Grade 4 shivering in parturients receiving tramadol 10 mg IT compared to the placebo group (18.2%).[2] The high incidence of Grade 4 shivering in the control group (18.2%) in their study compared to ours (3.33%) could be due to the difference in the demographic profile.[2] The various risk factors for postanesthesia shivering such as the type and duration of surgery, age, operating room temperature, and the level of block were found to be comparable among all the groups; thereby not influencing our results.[18]

A significant dose-dependent increase in the duration of sensory block, motor block, and analgesia was observed with IT tramadol in the present study. Similar significant increase in the duration of analgesia has been reported with tramadol 10, 20, and 25 mg IT in patients undergoing cesarean sections, elective gynecological surgeries, and open appendectomies, respectively, under SAB.[2],[5],[19] Our study observed a significant faster onset of both sensory (10 and 20 mg) and motor block (20 mg) with the addition of IT tramadol. Similar faster onset of sensory block has been reported with addition of tramadol 25 mg IT in patients undergoing open appendectomy.[19] The incidence of various adverse effects was comparable among the groups [Table 3]. A dose-dependent but insignificant increase in the incidence of perioperative nausea and vomiting (PONV) was observed with addition of IT tramadol [Table 3]. Other than hypotension and PONV, any other side effect such as pruritus, sedation, and respiratory depression were not observed in any of the groups. This is in support with the findings by previous authors.[6] In contrast, a higher incidence of PONV has been reported with IT tramadol by other authors.[2],[19] This might be due to their studies being done in the population (parturient) and surgical procedures (cesarean section or appendectomy with visceral and peritoneal manipulation) with the established high incidence of nausea and vomiting.[2],[19]

Our study has certain limitations. We studied only two doses of IT tramadol (10 mg and 20 mg). Higher doses of IT tramadol (25 mg) have been shown to beneficially influence the SAB characteristics.[19] Other IT adjuvants have been shown to have significant antishivering efficacy.[20],[21] Future studies evaluating higher doses of IT tramadol and comparing IT tramadol with other adjuvants with respect to their antishivering efficacy are therefore warranted.


   Conclusion Top


Tramadol 10 and 20 mg as an IT adjuvant to hyperbaric bupivacaine significantly attenuates the postanesthesia shivering in addition to producing a significant dose-dependent prolongation of the duration of sensory block, motor block, and analgesia; without any significant increase in the incidence of adverse effects. Tramadol 20 mg IT compared to 10 mg IT produced a statistically significant prolongation in the duration of sensory block, motor block, and postoperative analgesia but failed to demonstrate any significant reduction in the incidence and intensity of postanesthesia shivering. To conclude, tramadol 20 mg IT provides the best combination of antishivering and analgesic efficacy without any significant increase in adverse effects.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

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