|Year : 2016 | Volume
| Issue : 3 | Page : 116-120
Efficacy of intravenous tramadol in the control of shivering following spinal anaesthesia for caesarean section
Fidelis Anayo Onyekwulu1, Edith Ebere Agu2, Adaobi Obianuju Amucheazi1
1 Department of Anaesthesia, University of Nigeria Teaching Hospital, Ituku Ozalla, Enugu, Nigeria
2 Department of Anaesthesia, Federal Medical Centre, Lokoja, Kogi State, Nigeria
|Date of Web Publication||12-Sep-2016|
Fidelis Anayo Onyekwulu
Department of Anaesthesia, University of Nigeria Teaching Hospital, Ituku Ozalla, Enugu
Source of Support: None, Conflict of Interest: None
Aims and Objectives: The aim of this study was to evaluate the efficacy of intravenous tramadol in control of shivering in obstetric patients under spinal anaesthesia and to determine the minimal dose of tramadol that is effective.
Patients and Methods: This was a prospective, randomised, double-blind, cross-sectional study of 144 pregnant women at term who had an indication for caesarean section. The patients were randomly allocated into three groups at the occurrence of shivering. Group T0.5 received 0.5 mg/kg of tramadol (n = 47), Group T0.25 received 0.25 mg/kg tramadol (n = 47) and Group TNS received 0.05 ml/kg of normal saline (n = 46). Statistical analysis was performed using Statistical Package for Social Sciences version 17.
Results: There were no significant differences between the groups with regard to age, weight and duration of surgery. There was a statistically significant difference in the time of cessation of shivering after the treatment for various groups (P = 0.000). A total of 80.1% responded to the treatment in Group T0.5, while for Group T0.25 and TNS, a total of 44.7% and 4.3%, respectively, responded. There were statistically significant differences in the recurrence rates of shivering among the groups (P = 0.000).
Conclusion: Tramadol is effective in control of shivering during spinal anaesthesia in obstetric patients. Tramadol 0.5 mg/kg controlled shivering better than 0.25 mg/kg. Therefore, 0.5 mg/kg of tramadol can be used to manage shivering following caesarean section under spinal anaesthesia.
Keywords: Parturient, shivering, spinal anaesthesia, tramadol
|How to cite this article:|
Onyekwulu FA, Agu EE, Amucheazi AO. Efficacy of intravenous tramadol in the control of shivering following spinal anaesthesia for caesarean section. Niger Postgrad Med J 2016;23:116-20
|How to cite this URL:|
Onyekwulu FA, Agu EE, Amucheazi AO. Efficacy of intravenous tramadol in the control of shivering following spinal anaesthesia for caesarean section. Niger Postgrad Med J [serial online] 2016 [cited 2019 Aug 19];23:116-20. Available from: http://www.npmj.org/text.asp?2016/23/3/116/190343
| Introduction|| |
Shivering is a frequent problem encountered by obstetric patients undergoing caesarean section under spinal anaesthesia with an incidence of about 29%–54%., The prolonged impairment of thermoregulatory autonomic control under anaesthesia along with the cold environment of operating rooms and cold infusion fluids contributes to a fall in core body temperature and hence causes shivering. Shivering causes artifacts in monitors and increases post-operative pain, heart rate, cardiac output, oxygen consumption by 5-fold and metabolic rate by 600%. This may lead to myocardial ischaemia, hypoxaemia, hypercarbia and lactic acidosis that could complicate recovery from anaesthesia.
Non-pharmacological methods available to control shivering include the use of warming blanket, warm intravenous fluid and application of radiant heat and warming the operating room. Several pharmacological agents have been used, which include pethidine, alfentanil, tramadol, dexmedetomidine and clonidine. Their exact mechanisms of action are not well understood, but opioids probably act on the thermoregulatory centre via the mu and/or kappa receptors, while clonidine and dexmedetomidine are α-adrenergic receptor agonists that act by reducing vasoconstriction and shivering threshold. This study was conducted to determine the efficacy and the minimal effective dose of tramadol in the treatment of shivering under spinal anaesthesia in obstetric patients.
| Patients and Methods|| |
The study was a prospective, randomised, double-blind, cross-sectional study carried out at the University of Nigeria Teaching Hospital, Enugu, Nigeria, between 1st April and 30th November 2012. The ethical approval for the study was obtained from the hospital's Ethics Committee (NHREC/05/01/2008b approval date 25/10/2011) and written informed consent was obtained from the patients.
The detailed pre-operative assessment was performed in all the patients before recruiting them into the study. Included in the study were 144 American Society of Anesthesiologists Grade 1 or 2 pregnant women at term presenting for elective caesarean section who did not have any contraindication to spinal anaesthesia. Excluded from the study were patients with fever (temperature >38.0°C), hypothermia (temperature <36.5°C) and known hypersensitivity to tramadol. Also excluded were patients diagnosed with coagulopathy and allergy to local anaesthetics. Investigations such as full blood count and platelet count, serum electrolytes, urea and creatinine and urinalysis were done and were all within normal range. Blood grouping and cross-matching of two units of whole blood and retroviral screening were also carried out. All the patients fasted for 8 h before surgery.
Based on the previous study incidence, the sample size required to detect a 50% reduction at 5% level of significance and 80% power was 44 patients per group. The addition of 10% attrition gave a total of 48 patients per group. On arrival in theatre, standard monitors were used, which included non-invasive blood pressure, pulse rate and arterial oxygen saturation (SpO2) using Dash 4000 multi-parameter monitor (GE Medical Inc., USA 2005). Ear infrared thermometer (placed about 2 cm into the aural canal) was used for core temperature measurement pre-operatively, immediately after subarachnoid block, then at 5 min intervals at the onset of shivering for 15 min and post-operatively. The theatre ambient temperature was maintained between 22°C and 24°C.
Intravenous access was secured on the dorsum of the hand of the patient with large bore size 16-gauge cannula, and intravenous ranitidine 50 mg was administered. The patients' circulation was preloaded with warmed normal saline 10 ml/kg over 20–30 min before induction of spinal anaesthesia. The patients were placed in the sitting position; the anaesthetist scrubbed and gloved, cleaned and draped the patients' lower back. Using the iliac crest as a landmark, L3/L4 or L4/L5 was identified. The puncture site was identified, and the skin was infiltrated with 1 ml of 1% lidocaine. Spinal needle 25-gauge (pencil-point) through a 21-gauge needle introducer was used. With the appearance of clear cerebrospinal fluid, 2–2.5 ml of 0.5% hyperbaric bupivacaine was introduced into the subarachnoid space to achieve a desirable level at T6 dermatome (considering height and weight of the patients). After the withdrawal of the needles, the site of injection was covered with sterile gauze and the patient was placed supine with a wedge under the right hip to prevent aortocaval compression. The level of maximum block height was assessed after 5 min using cotton wool soaked in alcohol.
Randomisation of patients into three groups was done intraoperatively at the occurrence of shivering. Sealed brown envelopes containing either of numbers 1–3 (each 48 in number) were put in a box and reshuffled. The total number of sealed envelopes was equal to the number of sample size plus attrition (144). Group T0.5 received 0.5 mg/kg of tramadol intravenously, Group T0.25 received 0.25 mg/kg tramadol and Group TNS received 0.05 ml/kg of normal saline intravenously. This was revealed to the researcher at the end of the study. These doses (4 ml volume) were prepared by a pharmacist in syringes and the anaesthetist (researcher) who administered the drug was blinded to the treatment allocation. The drugs were administered by intravenous bolus by the researcher to the parturients who developed Grade 2 or 3 shivering and met the inclusion criteria for the study. The intensity of shivering was graded on a scale 0–3 as: 0 = no shivering, 1 = mild fasciculations of face or neck, 2 = visible muscle activity confined to one muscle group, 3 = visible muscle activity in more than one muscle group. Treatment efficacy was evaluated subjectively by the parturient as no improvement, slight improvement or marked improvement 5 min after the injection. The patients were given oxygen by face mask at 5 L/min, reassured and covered with extra warmed sterile drapes during shivering. The anaesthetist recorded the severity of the shivering, time to disappearance of shivering (in min) and response rate (shivering ceased after treatment in 15 min). If shivering did not subside after 15 min, the treatment was considered not effective. Tramadol 0.5 mg/kg was then administered intravenously as rescue treatment. Recurrence of the shivering, if any (after rescue treatment), was also recorded and treated with 0.5 mg/kg of tramadol.
Adverse effects such as nausea and vomiting were documented. As soon as the baby was extracted, oxytocin 5–10 IU was given intravenously, followed by 30 IU oxytocin in 500 ml infusion given slowly to the patient's response. The Apgar scores of the babies were recorded at 1 and 5 min. The neonatologist was always in attendance to resuscitate the baby if the need arises. The maternal vital signs and SpO2 were continuously monitored. Also monitored were intraoperative blood loss and urine output. The patients were also followed up to the recovery room and monitored for recurrence of shivering for 30 min.
Statistical analysis was done using SPSS Version 17.0. (Chicago, USA: SPSS Inc.). The statistical association was done using Student's t-test and analysis of variance for continuous variables. Pearson's correlation coefficient was used to show a linear correlation between two continuous variables. Values in tables are presented in means and standard deviations, percentages and numbers. P < 0.05 was considered statistically significant.
| Results|| |
The total number of patients who had caesarean section during the study period was 341, and the incidence of shivering was 42.2%. Of the 144 parturients entered for the study, 140 were analysed. Four were excluded due to incomplete data. Forty-seven each for groups T0.5 and T0.25, and 46 for TNS (control) were analysed. The patients' demographic variables are presented in [Table 1]. There were no significant differences between the groups with regard to age, weight and duration of surgery.
|Table 1: Patients' demographics and duration of surgery (mean/standard deviation)|
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[Table 2] shows the perioperative temperature data of the different groups. When the mean tympanic temperature recorded at various times in the three groups during pre-operative, intraoperatve and the post-operative periods were compared, there were no statistically significant differences (P = 0.759). The temperature changes at various times in each group during the pre-operative, intraoperatve and the post-operative periods were compared [Table 3]. The result showed that in Group T0.5, there was no significant change in tympanic temperature pre-operatively up to the onset of shivering, but there was a significant reduction in temperature after the onset of shivering for up to 15 min (P = 0.000). The same result was recorded in Group TNS. In Group T0.25, a significant reduction in tympanic temperature from the onset of shivering was recorded for up to 10 min [Table 3].
|Table 2: Perioperative temperature variations (°C) (mean/standard deviation)|
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[Table 4] shows the post-anaesthetic shivering (PAS) record and response profile. In the treatment Group T0.5, 59.6% of parturients had Grade 2 shivering and 40.4% had Grade 3 shivering. There was no statistically significant difference in severity of shivering among the different groups. There was a significant difference in the time of cessation of shivering after the treatment for various groups (P = 0.000). 80.1% of the parturients had marked improvement in response to shivering treatment in Group T0.5 while 80.4% of the control group recorded no response [Figure 1].
Recurrence rates of shivering were 4.2% (n = 2), 10.6% (n = 5) and 32.6% (n = 15) for groups T0.5, T0.25 and TNS, respectively. There was a statistically significant difference between the groups (P = 0.000). The incidence of side effects such as nausea and vomiting was low for all the groups. Four patients in Group T0.5 had nausea, three and two in Groups T0.25 and TNS, respectively. One patient in Group T0.5 vomited. These patients were promptly treated with intravenous metoclopramide 10 mg and were reassured. One patient complained of headache in Group T0.5, and she was treated with intravenous paracetamol 600 mg.
There was no significant difference in the Apgar scores of the babies at 1 and 5 min in the treatment groups and the control [Table 5]. More parturient had shivering after the extraction of their babies in all the groups [Figure 2]. The number of patients who had shivering before delivery in Group T0.5 was 16 (34%), T0.25 was 19 (41.3%) and TNS was 18 (40%); while after delivery, in Group T0.5 was 31 (66%), T 0.25 was 28 (58.7%) and TNS was 28 (60%).
| Discussion|| |
This study showed that tramadol was significantly more effective compared to placebo in the treatment of shivering in parturients undergoing spinal anaesthesia for caesarean section. The results showed that there was a statistically significant difference in the time of cessation of shivering between the different treatment groups (P = 0.000). The cessation of shivering was faster in the group treated with tramadol 0.5 mg/kg (3.1 ± 1.1 min). This is in agreement with the study by Chan et al. and Shukla et al., where cessation of shivering with tramadol took more than 2 min using the same dose of tramadol (0.5 mg/kg). This, however, was not in agreement with studies by Bahaarat et al., where shivering stopped within 2 min of treatment with tramadol, and Bansal and Jain, who recorded cessation of shivering in 1.8 min with tramadol. This is probably so because Bansal and Jain  used a higher dose of an intravenous bolus of 50 mg tramadol in their study.
Marked response to treatment was 80.1% in the group that had treatment with tramadol 0.5 mg/kg while marked response for Group T0.25 and TNS was 44.7% and 4.3%, respectively. Better response to treatment was observed in Group T0.5 probably due to higher plasma concentration, compared to Group T0.25. The response for Groups T0.25 and TNS does not agree with the study by Chan et al., where 92% and 27% response were reported for tramadol 0.25 mg/kg and normal saline, respectively. This may be due to the use of different regional anaesthetic techniques (epidural, spinal and combined spinal epidural) in their study. In this study, a single anaesthetic technique was used for uniformity.
In the present study, the factors that could influence the occurrence of shivering, such as temperature of intravenous fluids, drugs and operating room ambient temperature, were not tightly controlled but this may not affect the validity of this study since the study was focused on the response to treatment rather than the incidence of shivering. By randomisation, the three groups were subjected to a similar degree of influence of these factors. Pharmacological agents have been used successfully to reduce the incidence of shivering following spinal anaesthesia for caesarean section. The incidence of shivering in this study was 42.2% as compared to 30% observed by Ejiro et al., when ondansetron and tramadol were used as prophylaxis against post-anaesthesia shivering.
In this study, core temperature was measured using the tympanic membrane temperature. Tympanic membrane probe which would have been more convenient, more reliable and would have measured core temperature continuously was not used because it was unavailable. Shivering occurs commonly as a protective response to core hypothermia though it can occur in normothermia. There was a significant fall in the tympanic membrane temperature in all the groups during shivering and post-treatment compared with their baseline values. This could be explained by the spinal anaesthesia-induced sympathetic block which causes core to peripheral redistribution of heat and also cold operating room temperature which can lead to hypothermia.,, There was no significant temperature difference from pre-operative value to the onset of shivering in the Group T0.5, which indicates that shivering can occur even in normothermic patients. Furthermore, there was no significant difference in Group T0.25 between pre-operative value and 15 min after the onset of shivering, suggesting that cessation of shivering was not related to modulation of temperature but probably due to resetting of thermoregulation to a lower threshold by the studied drug. Pharmacological intervention does not raise body temperature but resets the threshold to a lower level, thereby decreasing shivering and its episode.
Talakoub and Noorimeshkati  reported a 97.2% response rate when 0.5 mg/kg of tramadol was used in the treatment of shivering. This is high when compared to our study; the difference may be because they did not differentiate between partial and marked response. In Group T0.5, about 20% had a partial response to the treatment. This was a significant number; perhaps using a higher dose of tramadol will improve the response. However, this may be at the risk of increased side effects. Some researchers have, however, reported effective control of shivering using 1 mg/kg with no unpleasant effects., Recurrence of shivering was highest with normal saline group probably due to its lack of anti-shivering property or that shivering never completely stopped. The probable reason for recurrence of shivering in the tramadol group could be as a result of low plasma concentration of the active drug, when hypothermia is still persisting, and individual variations in the core temperatures.
The Apgar scores of the babies at 1 and 5 min were not significantly different in the groups indicating that tramadol, as an agent for controlling PAS, did not affect the babies since it does not cause much respiratory depression like other opioids, and the research doses were low., Moreover, in most patients, shivering started after delivery of the baby. This is in keeping with the study by Chan et al., where the number of patients who had shivering before delivery of baby was smaller 11 (30.5%) compared to after delivery 25 (69.5%). Sadegh et al. also observed that the rate of shivering, especially in the second 30 min after induction of spinal anaesthesia for caesarean section, was higher than th first 30 min in their study groups. The reason for this is not fully understood; however, there are several possible mechanisms for shivering associated with spinal anaesthesia. Internal redistribution of core temperature, loss of thermoregulatory vasoconstriction below the level of the blockade and decrease of vasoconstriction threshold have been suggested to explain shivering under spinal anaesthesia, especially in parturients.,
Tramadol is effective in control of shivering during spinal anaesthesia in obstetric patients. A dose of 0.5 mg/kg controlled shivering better than 0.25 mg/kg without significant side effects. Therefore, 0.5 mg/kg of tramadol can be used to manage shivering following caesarean section under spinal anaesthesia. Management of PAS should be given adequate attention in anaesthetic practice because of the discomfort and adverse effects on the patients.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]