This single blind randomized clinical trial study was performed in 66 pregnant women who experienced shivering following spinal anesthesia for elective cesarean section and were referred to obstetrics and gynecology department of Ayatollah Mousavi Hospital in Zanjan city affiliated Zanjan University of medical science, from December 2011 to November 2012. All participants who have ASA physical status (ASA-PS) scale I-II and do not have any disorder or disease were enrolled in this study and randomly divided into three groups (n=22) (Figure 1). The drugs were intravenously injected to the patients. We randomly allocated our cases by Excel software using Rand between order. Allocation into each group was based on opening sealed and opaque envelopes indicating the drug name. Clinicians were not blinded to the treatment allocation.

Group 1: Dexamethasone, 0.6 mg/kg (10 mL)

Group 2: Pethidine, 0.5 mg/kg (10 mL)

Group 3: Normal Saline (10 mL)

Figure 1

The temperature was measured and recorded for all patients at the entrance to the operating room. Prescription serum temperature was about 30 to 35 °C and the operation temperature was about 23 to 25 °C. The outcome variables are core temperature, nausea, headache, and shivering that were recorded before, and after surgery in the recovery room. Core temperature was measured by mercury thermometer. The frequency of nausea, headache, and shivering was measured through visual signs by physicians.

In this study, data were analyzed using SPSS software version 16. Descriptive analyses were performed including means and standard deviations (SD). Also, in this study, independent T test and One Way ANOVA were used to statistically test mean differences between groups and variables. Logistic Regression model was used to predict the adjusted odds ratio (OR). The level of significance was set at p < 0.05 for all analyses.

The results showed, mean and SD of age, BMI, body temperature, heart rate, systolic and diastolic blood pressure, and bleeding in all patients (n=66) were 28.80 ± 5.82, 31.90 ± 2.09, 36.83 ± 0.56, 80.88 ± 6.80, 10.87 ± 1.55, 7.07 ± 0.72, and 930.76 ± 111.385 respectively (Table 1). At the same time, in Table 1, the mean and SD of age, BMI, and bleeding in groups treated with Dexamethasone, Pethidine, and normal saline were 28 ± 6.27, 31.70 ± 1.90, and 772.73 ± 132.49, 29.36 ± 5.05, 31.79 ± 2.04, and 740.00 ± 117.14, 29.41 ± 6.24, 32.22 ± 2.37, and 1279.55 ± 1955.37, respectively. Those are not statistically different.

Table 2 introduced frequency of shivering, nausea and headache in the three groups. 16 (72.7%) patients in the Dexamethasone group, 10 (45.5%) patients in the Pethidine group, and 11 (50%) patients in the Normal saline group had to shivering (P = 0.149). Also, 45.5% patients in the Dexamethasone group, 40.9% patients in the Pethidine group, and 50% patients in the Normal saline group experienced nausea, which is not statistically different (P = 0.832) (Figure 2).

Figure 2

Previous studies showed some drugs can reduce the body core and skin temperature gradient and decrease the skin temperature 3. On the other hand, Dexamethasone is effective in reducing shivering in patients by regulating immune responses 12. Most studies showed that Dexamethasone is effective in preventing postoperative shivering with spinal anesthesia 1516. The mechanism of post-anesthetic shivering can be established as a thermo-regulatory reaction to low body temperature that occurs during surgeries, which leads to clonic and tonic patterns 3416.

Our results showed that there was no significant difference between the three groups receiving Pethidine, Dexamethasone, and normal saline in headache complication. However, Dexamethasone prophylaxis was reported to have positive effects on headache after spinal anesthesia for cesarean section 17. In this study, we showed that there was no significant difference between the three groups in nausea complication. Pethidine was shown to be more effective in reducing postoperative shivering after the cesarean section 18. In some of the studies showed the efficacy of Pethidine in reduce and prevention of shivering after surgeries 1017. In the some studies, Dexamethasone and Pethidine were also reported to be equally effective in reducing and preventing postoperative shivering after surgeries 17.

In our study, no significant differences between the three groups were observed in vital signs. However, diastolic pressure was slightly lower in patients receiving Pethidine. The anti-shivering action of pethidine was inhibited by high dose of naloxone, which blocks both μ and k receptors, but not by low dose of naloxone which block only μ receptors 19. A disadvantage of Pethidine is that it can cause respiratory depression in the presence of previously administered opioids or anesthetics. Moreover, nausea and vomiting are also important side effects of Pethidine 20.

The limitation of this study is small sample size. Hence, further studies with a larger sample size is recommended.

Although statistically there was no significant difference between the three groups of Dexamethasone, Pethidine and Normal Saline receivers regarding the reduction of shivering 13141516; because Pethidine is an opioid analgesic, it may interact with another drugs and lead to respiratory depression 16, and clinical complication rate in Dexamethasone group was lower comparing to Pethidine and Normal Saline groups. Hence, Dexamethasone prophylaxis is recommended.

The authors declare no conflict of interest.

All authors contributed to the design of the research. HGH, YM, and ST collected the data. ZKH, YM conducted analysis and interpretation of data. All authors drafted the first version. HGH, ZKH, YM, and ST edited the first draft. All authors reviewed, commented and approved the final draft.

Zanjan University of medical science, Zanjan, Iran.

RCT: Randomized, Controlled Trial