|Year : 2019 | Volume
| Issue : 2 | Page : 76-81
Comparison of three different doses of dexmedetomidine for prevention of postspinal anesthesia shivering in transurethral resection of prostate surgery
Fahd Hossain, Swati Singh
Department of Anaesthesia, Indira Gandhi Institute of Medical Sciences, Patna, Bihar, India
|Date of Submission||02-Mar-2019|
|Date of Acceptance||22-May-2019|
|Date of Web Publication||28-Aug-2019|
Dr. Fahd Hossain
49C, Shamsul Huda Road, Kolkata, West Bengal
Source of Support: None, Conflict of Interest: None
Background and Aims: Postanesthetic shivering (PAS) is an unpleasant and potentially serious complication. It is often neglected, and no universal protocols are established for its prevention. The efficacy of dexmedetomidine for the treatment and prevention of PAS is well demonstrated. Very few studies have been done regarding the optimal effective dose of dexmedetomidine for the prevention of postspinal anesthesia (SA) shivering. Thus, we aimed to compare and evaluate three different doses of intravenous dexmedetomidine and to investigate the optimum dose of dexmedetomidine that effectively prevents shivering in patients undergoing transurethral resection of the prostate (TURP).
Methods: In this randomized, double-blind, prospective study, 150 patients of the American Society of Anesthesiologists I and II scheduled for elective TURP under SA were enrolled. Patients were randomly allocated into one of the three groups receiving dexmedetomidine: Group P: 0.5 μg/kg, Group Q: 0.75 μg/kg, and Group R: 1.0 μg/kg. The primary outcome of the study was intraoperative incidence of shivering. The secondary outcomes, such as hemodynamic parameters and adverse reactions, were also noted.
Results: Shivering score of different groups revealed statistically significant lower incidence and severity of shivering in Group Q and Group R when compared to Group P(P = 0.0395). Incidences of nausea/vomiting, bradycardia, and hypotension were more in Group R when compared to Group P and Group Q. Axillary temperature and sedation scores were comparable among different groups (P > 0.05).
Conclusion: Dexmedetomidine in the dose of 0.75 μg/kg provides adequate antishivering effect with added benefit of sedation and less hemodynamic instability.
Keywords: Dexmedetomidine, shivering, spinal anesthesia, transurethral resection of prostate
|How to cite this article:|
Hossain F, Singh S. Comparison of three different doses of dexmedetomidine for prevention of postspinal anesthesia shivering in transurethral resection of prostate surgery. Indian Anaesth Forum 2019;20:76-81
|How to cite this URL:|
Hossain F, Singh S. Comparison of three different doses of dexmedetomidine for prevention of postspinal anesthesia shivering in transurethral resection of prostate surgery. Indian Anaesth Forum [serial online] 2019 [cited 2020 Jan 21];20:76-81. Available from: http://www.theiaforum.org/text.asp?2019/20/2/76/265637
| Introduction|| |
Shivering is a very distressing experience for postoperative patient in postanesthesia care unit (PACU) similar to pain and nausea and vomiting. The incidence of shivering is estimated to be as high as 50%–60% in the normal population undergoing general anesthesia (GA). Shivering is also a common problem encountered after neuraxial (spinal and epidural) anesthesia as well. An incidence of shivering of up to 55% has been reported. It can result in increased oxygen demand up to 400% of normal and induce metabolic derangements such as hypoxemia, hypercarbia, and lactic acidosis. Therefore, shivering may be detrimental in patients with low cardiac and pulmonary reserves. It also increases intraocular and intracranial pressure and may contribute to increased wound pain, delayed wound healing, and delayed discharge from PACU. Shivering is more common in transurethral resection of the prostate (TURP) that may be due to absorption of a large amount of irrigating fluid at room temperature. Rapid reduction in core temperature starts with bladder irrigation during TURP as unheated irrigation fluid is used and could be a significant etiological factor in the production of the hemodynamic responses. Thus, patients undergoing TURP are more prone to develop shivering which could be discomforting as well as deleterious to them.
Considering these undesirable consequences of shivering, measures required to prevent it in the perioperative period are important. Trials have been conducted that have compared dexmedetomidine with various drugs and also demonstrated the efficacy of dexmedetomidine for treatment as well as prevention of postanesthesia shivering., Very few studies have evaluated the optimal effective dose of dexmedetomidine for the prevention of postspinal anesthesia (SA) shivering. We aimed to investigate the dose of dexmedetomidine that effectively prevents shivering without significant side effects in patients undergoing TURP under SA who have a high incidence of perioperative shivering.
| Methods|| |
This study was conducted after being approved by the Institute Ethics Committee and was registered with the Clinical Trials Registry of India (CTRI/2014/11/005220). Patients belonging to the American Society of Anesthesiologists-Physical Status I and II and aged between 40 and 75 years undergoing elective TURP were selected for this prospective, randomized, double-blind study. Patients with a history of cardiopulmonary diseases, cerebrovascular accident, uncontrolled diabetes mellitus, and hepatic and renal dysfunction, were excluded from the study. Patients having initial body temperature >38°C or <36°C and who received blood transfusion intraoperatively were also excluded from the study.
One hundred and fifty patients were randomly allocated into three groups (Groups P, Q, and R were given dexmedetomidine 0.5 μg/kg, 0.75 μg/kg, and 1.0 μg/kg of body weight, respectively) by computer-generated randomization. The study drug was diluted with normal saline and volume made to 50 ml and given intravenously over 10 min just after administration of SA. The patients were subjected to detailed clinical examination and routine investigations to exclude any systemic disorder. The study protocol was explained to the patient and written informed consent was obtained from each participant. No premedication was given. On arrival of the patient in the operating room, intravenous access was established (either hand or forearm) and standard monitors – noninvasive blood pressure (NIBP), electrocardiogram, peripheral arterial oxygen saturation (SpO2), and axillary surface temperature probe were attached; and resuscitation facilities were made available. The baseline heart rate (HR), NIBP, respiration rate, SpO2, and temperature were recorded. The operation theater was maintained at a constant humidity 50%–55% and temperature of 21°C–23°C. Irrigation and intravenous fluids were administered at room temperature. Before performing SA, 10 ml/kg/h of lactated Ringers' fluid was administered that was reduced to 6 ml/kg/h after giving SA. Following guidelines for asepsis and antisepsis, SA was instituted at L 3–4 or L 4–5 interspace. After eliciting free flow of the cerebrospinal fluid, 3 ml of 0.5% hyperbaric bupivacaine was injected using an appropriate needle. The study drug was prepared by an independent clinician not involved in the study. The anesthesiologist performing the block and observing the patient was blinded to the treatment group. Neither the patient nor the attending anesthesiologist who also collected the data were aware of the group allocation. HR, respiratory rate, and SpO2 were recorded every 5 min (after SA was given) for 1 h and then every 15 min till discharge from PACU. Body temperature was noted every 15 min. Sedation was assessed every 10 min as per Ramsay Sedation Score: (1) Anxious and agitated or restless or both; (2) Cooperative, oriented, and calm; (3) Responsive to commands only; (4) Brisk response to light glabellar tap or loud auditory stimulus; (5) Sluggish response to light glabellar tap or loud auditory stimulus; and (6) Unresponsive. Shivering was assessed every 5 min on a scale similar to that validated by Tsai and Chu: 0: No shivering; 1: Piloerection or peripheral vasoconstriction but no visible shivering; 2: Muscular activity in only one muscle group; 3: Muscular activity in more than one muscle group but not generalized; and 4: Shivering involving the whole body.
If the shivering score was 3 or above at 15 min after SA, the prophylaxis was regarded as ineffective and 25 mg pethidine was given intravenously slowly. If a patient developed symptomatic bradycardia (<60/min) or HR <50/min, 0.5 mg intravenous atropine was given. Hypotension was defined as decrease in mean arterial pressure (MAP) of <25% from the baseline. Hypotension was treated with 6 mg mephentermine as an intravenous bolus and then with further intravenous infusion of lactated Ringers' solution as required. In case of nausea and vomiting, 10 mg intravenous metoclopramide was given. Any adverse effects such as hypotension, bradycardia, allergy, and nausea and vomiting were treated and recorded.
The incidence of shivering related to SA from a previous report was 55% in patients receiving no intervention to prevent it. Thus, the sample size required to achieve 30% absolute reduction in the incidence of postanesthesia shivering in association with dexmedetomidine was minimum 42 patients in each group with a power of 80%, α error of 0.05, and β error of 0.2. Thus, 50 patients in each group (total 150) were included to allow for dropouts and withdrawals from the study. Descriptive statistics were used to describe the baseline characteristics. Dichotomous outcomes were compared by Fisher's exact test/Chi-square test as applicable. Numerical data were expressed as mean and standard deviation. Qualitative data were expressed as frequency and percentage. Chi-square test (Fisher's exact test) was used to examine the relation between qualitative variables. One-way analysis of variance followed by Tukey's test was used to analyze the differences among the groups in demographic profiles, temperature changes, HRs, and MAPs. The within-group data were analyzed using repeated-measures analysis of variance followed by Bonferroni's test. P < 0.05 was considered statistically significant. All patients who were randomized were included in the analysis. The analysis was performed using GraphPad InStat version 3.1 (Graphpad Software Inc. San Diego, CA, USA).
| Results|| |
One hundred and seventy-five patients were assessed for eligibility, among them nine patients refused to participate and 16 patients did not meet inclusion criteria. All 150 patients randomized into different groups completed the study as shown in consort diagram [Figure 1]. The demographic data of the three groups were comparable (P > 0.05) [Table 1]. The analysis of shivering score of different groups in the present study revealed statistically significant lower incidence and severity of shivering in Group Q and Group R when compared to GroupP(P = 0.0395) [Table 2] and [Figure 2]. Baseline SpO2 and respiratory rate of different groups were comparable (P > 0.05). Significant intragroup variation in MAP and HR was seen in all groups when compared to baseline (P < 0.001) [Table 3] and [Figure 3], [Figure 4]. The intergroup comparison of hemodynamics showed a significant decrease in HR at 45 min between Group R andP(P < 0.05).
|Table 3: Comparison of mean arterial pressure (mmHg) of different groups|
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Comparison of axillary temperature of different groups revealed no significant differences among groups (P > 0.05), but significant differences were noted within groups when compared to baseline values (P < 0.001) [Table 4]. Comparison of sedation score of different groups in the current study did not reveal any significant variation (P > 0.05) [Table 5]. In the present study, the incidence of nausea/vomiting, bradycardia, and hypotension was more in Group R when compared to GroupPand Group Q. However, only the incidence of hypotension was statistically significant (P < 0.05) [Table 6] and [Figure 5].
|Table 4: Comparison of axillary temperature (°C) of different groups at different time intervals|
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|Table 5: Sedation score of patients at different time intervals (number of patients expressed as per sedation score 1/2/3/4/5/6)|
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| Discussion|| |
The human temperature regulating mechanism is complex that normally maintains the body temperature within a tight range (36.5°C–37.5°C) known as “interthreshold range.” If the core temperature falls below this range, the body responds by vasoconstriction and shivering which increases heat production two to five folds. The exact mechanism of shivering during SA is not known. The possible mechanisms include disruption of central thermoregulation, internal redistribution of body heat, and heat loss to the environment. Risk factors for hypothermia in SA are aging, level of sensory block, temperatures of the local anesthetic used, operating room, and intravenous solutions. The present study revealed that in Group P, 28% of patients shivered, whereas corresponding figures in Group Q and Group R were 10% each. Among those who shivered, majority had Grade 2 shivering: 22% in GroupPand 8% each in Group Q and Group R. One patient in GroupPhad Grade 3 shivering and needed treatment, whereas none required treatment in Group Q and Group R. In our study, comparison of shivering score of different groups revealed statistically significant lower incidence and severity of shivering in Group Q and Group R when compared to GroupP(P = 0.0395).
In a previous study comparing meperidine to dexmedetomidine, incidence of shivering in meperidine group was 10%, in the placebo group was 55%, whereas in dexmedetomidine group was 15% which is similar to that observed in Group Q and Group R of our study. In yet another study, the incidence of shivering was 18% in dexmedetomidine group (1 μg/kg followed by 0.4 μg/kg/h infusion) compared to placebo (53% incidence).
Dexmedetomidine (1 μg/kg over 10 min followed by infusion of 0.4 μg/kg/h) was compared with saline in a trial for prevention of post-SA shivering. The authors found that 56.7% patients of saline group shivered, whereas only 10% of patients receiving dexmedetomidine had shivering. These results very much corroborate our findings. In our study, 10% of patients of each Group Q and Group R had shivering.
In a previous trial, patients scheduled for elective laparoscopic total hysterectomy under GA, received dexmedetomidine or normal saline and were allocated in four different groups. It was concluded that 0.75 or 1.0 μg/kg body weight of dexmedetomidine provided effective prophylaxis against postoperative shivering as well as analgesic effect although potential for intraoperative requirement for atropine, sedation in immediate recovery period, and delayed extubation time with dexmedetomidine were noted.
In a previous study, the authors found 0.5 μg/kg of dexmedetomidine effective for prevention of post SA shivering in patients undergoing arthroscopic surgery. However, in contrast to this trial, in our study, the incidence of shivering was 28% in GroupP(dexmedetomidine 0.5 μg/kg). This was significantly higher than the incidence in Group Q (10%) and Group R (10%). Authors in another tria compared dexmedetomidine with pethidine and tramadol for the treatment of postneuraxial anesthesia shivering, concluded 0.5 μg/kg of dexmedetomidine to be effective. In a study, the investigators compared dexmedetomidine 0.5 μg/kg, 0.3 μg/kg, or 0.2 μg/kg. They found that among the three doses investigated, dexmedetomidine 0.3 μg/kg effectively treated shivering associated with SA with modest hemodynamic and sedation effects. However, in our trial, we did not find dexmedetomidine in the dose of 0.5 μg/kg to be as effective in the prevention of postanesthesia shivering. This difference may be attributed to the patient selection and type of surgery. The latter study was conducted in minor surgeries such as herniorrhaphy with minimal blood loss/fluid shift. Our study was performed on patients undergoing TURP who were more prone to develop shivering.
Another study compared placebo (saline) with dexmedetomidine (1.0 μg/kg followed by 0.5 μg/kg/h infusion) for prevention of shivering in patients undergoing laparoscopic gynecologic surgeries under GA. Investigators reported the incidence of shivering to be 46.6% in placebo group and 10% in dexmedetomidine group. This matches with the incidence of shivering in Group Q and Group R of our study. However, in this study, GA was given; our study was done under SA. However, when dexmedetomidine was used at 1 μg/kg body weight (Group R), significant lowering of HR was observed at 45 min when compared to dexmedetomidine at dose 0.5 μg/kg body weight. Same finding was observed in a few previous studies.,
Dexmedetomidine used in any dose (0.5/0.75/1 μg/kg) had no effect on SpO2 and respiratory rate. This finding highlights that dexmedetomidine has limited respiratory effects in therapeutic doses. Comparison of axillary temperature of different groups revealed no significant differences among groups, but significant differences were noted within groups when compared to baseline values. This finding was corroborated by previous trials.,, There was no significant variation in sedation at all the three doses which were again in tandem with few previous trials.,,
There are a few limitations in our study. We conducted this study only in patients undergoing elective TURP. It is to be seen whether our findings can be extrapolated to other group of patients and surgical procedures.
| Conclusion|| |
We found that both 0.75 μg/kg and 1 μg/kg dose of dexmedetomidine were equally effective for prevention of post-SA shivering. The higher dose of 1 μg/kg was associated with higher incidence of side effects such as bradycardia and hypotension making 0.75 μg/kg dose most ideal dose for the purpose.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]