European Journal of Cardiovascular Medicine

Shivering is distressing for the patient’s undergoing surgery under both regional and after general anaesthesia. The main causes for shivering intra/post-operatively are temperature loss, decreased sympathetic tone and systemic release of pyrogens1. Shivering increases expenditure of cardiac and systemic energy2, resulting in increased oxygen consumption and carbon dioxide production, lactic acidosis and raises the intraocular and intracranial pressure. It also interferes with haemodynamic monitoring intra operatively.

Regional anaesthesia produces vasodilatation, which facilitates core to peripheral redistribution of heat. It also increases sweating threshold and decreases          vasoconstriction and shivering threshold3. Intra- and post-operative management of shivering are usually done by external heating (forced air warming, warming blankets, warmed fluids) or pharmacological interventions. Various drugs from different groups like opioids, 5-hydroxytryptamine receptor (5-HT3) antagonists, N-methyl D-aspartate (NMDA) receptor antagonists, cholinomimetics and biogenic amines have been used in the literature.4-7

There are many studies available in the literature comparing different pharmacological agents for the prevention of shivering in patients undergoing surgeries under spinal or general anaesthesia and almost all studies had shown decreased incidence of shivering in groups using pharmacological agents as compared to groups in which placebo were used but based on these studies there are no clear guidelines that which drug is best among all these commonly used agents in terms of prevention of shivering as well as hemodynamic profile.

Therefore, prospective randomized double-blind study was conducted using commonly available drugs like ketamine, clonidine and tramadol to assess their efficacy when used prophylactically to control shivering under neuraxial blockade.

AIMS-

To evaluate the effectiveness of prophylactic use of intravenous ketamine, clonidine and tramadol in control of shivering in patient undergoing elective surgeries under spinal anaesthesia.

A Prospective, Randomized, Double Blind Comparative Study, done in Tertiary Care Super speciality Hospital with in a span of 1 year. Adult patients posted for various elective surgeries under Spinal Anaesthesia.

Sample Size & Sample Technique- 

P1=Proportion of patient having intra operative grade 2 shivering in ketamine group

 =30%=0.30

Q1=1-P1=0.70

P2= Proportion of patient having intra operative grade 2 shivering in tramadol group

= 6.67%=0.0667

Q2=1-P2=0.93

Sample size Formula by Fleiss 

N= 〖( ( 1.96*√(2P^' Q^' )+0.84*(P1Q1+P2Q2)^(1/2)))/((〖P1-P2)〗^2 )〗^2  =   minimum 42 in each group

Where, P’=((P1+P2))/2     &    Q’=1-P’

Hence, minimum sample size, N=42 in each group was taken with a total of 168 patients. 168 patients were entered in the computer software SPSS 16.0 and each patient has been given serial no.1 to 168 and then patient was randomized into 4 groups comprising 42 patients each.

 Inclusion Criteria –

1. Patients scheduled for elective surgeries under spinal anaesthesia.
2. Age group of 18-60 years of both sexes.
3. ASA grades I or II.

  Exclusion Criteria-

               Patients suffering from neuromuscular disease.

               Patients with Thyroid disorders.

               Patients with History of cardiopulmonary disease.

               Patients with Psychological disease.

               Patients with Temperature >38°C or <36.5°C.

               Posted for Emergency surgeries.

               Pregnant patients.

Methodology:

A clinical comparative study of prophylactic ketamine, clonidine and tramadol

for the control of shivering under spinal anaesthesia was done on 168 randomly

selected patients posted for elective surgeries for various General Surgical,

Orthopaedic, Gynaecological or Urological procedures. An informed consent

was taken for all the patients. A thorough Pre-Anaesthetic evaluation was done a

day before surgery and all the necessary investigations were done to rule out any systemic disease.

Investigations:

Hb%, TC, DC and ESR

RBS

Blood urea and Serum creatinine

Urine routine& microscopic

ECG

Premedication:

Tab Alprazolam 0.5 mg and Tab Ranitidine 150 mg was administered to all patients on the night before surgery. Patients were maintained nil per oral for duration of 8 hours prior to surgery.

On the day of surgery intravenous line was secured with 20G cannula. On entering the OT, oxygen saturation, non-invasive blood pressure and ECG monitors were connected.  Basal heart rate, systolic and diastolic / mean arterial pressure, axillary temperature was recorded.  All patients were preloaded with ringer’s lactate 10ml/kg before giving spinal blockade.

The subjects were randomized into 4 groups by using computer generated random numbers to receive ketamine, tramadol or clonidine. To avoid participant and experimenter bias each subject was given a random number with identification of drug code in an individual sealed envelope. The study drug was coded and presented to the anaesthetist not involved in the management of the patient, to maintain the double blindness of the study and administered by intravenous (i.v) route just before giving the block. The study drug and intravenous saline were maintained at body temperature before administering them to the patient. The patients were randomized into four groups of 42 patients each as follows:

Group A: Control group. In this group 10 ml of normal saline was administered.

Group B: Ketamine group.  Here patients received 0.5mg/kg of ketamine diluted to 10ml in normal saline intravenously, 2 minutes before spinal anaesthesia.

Group C: Clonidine group. In this group, patients received 75 mcg of clonidine diluted to 10ml in normal saline intravenously, 2 minutes before spinal anaesthesia.

Group D: Tramadol group. Here patients received 1 mg/kg of tramadol diluted

to 10ml in normal saline intravenously, 2 minutes before spinal anaesthesia.

Anaesthesia technique:

The temperature of the OT was maintained at 97±1°F for all the patients. The

study drug was administered by intravenous (IV) route before giving the

block. Spinal anaesthesia instituted at either L3-4 or L4-5 interspaces using 2.8 ml (14 mg) of hyperbaric bupivacaine 0.5% (with 8.5% dextrose) using a 25gauge spinal needle. During the intraoperative period, pulse rate, non-invasive blood pressure (NIBP), oxygen saturation, continuous ECG monitoring, surface temperature and level of sensory block was assessed at 10 min intervals. The surface temperature was measured by axillary thermometer.

Shivering was graded using a scale validated by Tsai and Chu:

Grade 0=no shivering

          1=piloerection but no visible shivering

          2=muscular activity in only one muscle group

           3=muscular activity in more than one muscle group but not generalized

          4=shivering involving the whole body.

During surgery, the shivering scale was recorded at 5 minutes intervals upto 90 minutes of surgery/till the end of surgery.  The prophylaxis was regarded as ineffective if the patients exhibited grade 3 shivering any time during the study and then IV tramadol 50 mg was administered as a rescue drug.

Side effects of drug used in the study such as hypotension, sedation was also recorded at 5 mins, 10 mins and then at intervals of 10 mins upto 90 minutes of surgery/till the end of surgery. Hypotension is defined as a decrease in mean arterial pressure (MAP) of more than 20% from the baseline. Hypotension was treated with IV incremental bolus dose of mephentermine 6mg and a further IV infusion of ringer lactate.

Degree of sedation was also assessed on a 5-point scale.

1=fully awake and oriented

2=drowsy,

3=eyes closed but arousable to command

4=eyes closed but arousable to mild physical stimulation

5=eyes closed but unarousable to mild physical stimulation.

In the end of the study, grades on shivering scale were compared in all the 4 groups to know the effectiveness of clonidine, tramadol and ketamine intravenously for the prevention of shivering during intraoperative period in neuraxial blockade. Also, the side effects of the drugs like hypotension, sedation, vomiting, hallucination etc were compared in 4 groups based on standard charts.

Statistical Methods:

Continuous variable will be analysed by Mean, SD and test of significance between means by ANOVA and “t”-test. - Post hoc comparisons were performed by Tukey HSD test.

Categorical data showing relationship between age, gender, ASA grade with shivering

Grade will be analysed using Chi Square Test or Fisher Exact Test.

Statistical software SPSS 16.0 will be used for data analysis.

Statistical significance:

P<0.05 is significant

P<0.01 is highly significant                      

P>0.05 is not significant

The age range was 18-60 years for all the groups.  The mean values of age with standard deviations (SD) are 38.5±10.29 for tramadol group,36±9.74 for ketamine group, 36.17±9.15 for clonidine group, 34.1±10.53 for normal saline group.  There was no significant difference between the groups (p>0.05).

In tramadol group, 57.14% of the patients were female and 42.86% of the patients were male.  In ketamine group 54.76% of patients were female and 45.24% of the patients were male.   In clonidine group, 66.67% of patients were females 33.33% of patients were male.  In normal saline group, 50% of patients were female and 50% of patients were male.  There was no significant difference in gender wise distribution among the four groups (p=0.681).

TABLE 1: DISTRIBUTION OF DURATION (MIN) OF SURGERIES UNDER    SPINAL ANAESTHESIA IN FOUR GROUPS OF PATIENTS STUDIED

SURGICAL DURATION:

Duration range in tramadol group was 31-150 minutes with a mean value of 69.83 and standard deviation of 27.53. Duration range in ketamine group was 31-150 minutes with a mean value of 65.17 and SD of 30.07.  Duration range in clonidine group was 31-150 minutes with a mean value of 64.50 and SD of 31.88. Duration range in normal saline group was 30-180 min. with a mean value of 63.83 and SD of 31.75. There was no significant difference observed in the duration of surgery (p=0.46).

Table 2: Median sensory Level in four groups of patients studied

P=0.052

SENSORY LEVEL OF SPINAL ANAESTHESIA

In tramadol group, the sensory level in 40.48% of patients was till T8, 54.76%, till T7 and 4.76% till T6. In ketamine group, the sensory level of spinal anaesthesia in 47.62% of patients was till T8, 52.38% till T7. In clonidine group, the sensory level in 47.62% of patients was till T8, 52.38% till T7. In normal saline group, the sensory level 2.38% patient was till T10, 47.62% till T8, 47.62 till T7 and 4.17% till T6.

There was no significant difference observed in the median level of spinal anaesthesia in the four groups (p=0.052).

TABLE 3: DISTRIBUTION OF GRADE OF SHIVERING IN FOUR GROUPS OF PATIENTS STUDIED.

DISTRIBUTION OF GRADES OF SHIVERING

The above table shows the distribution of grades of shivering in tramadol, ketamine, clonidine and normal saline groups.  In tramadol group, 61.9% of patients had grade 0 shivering, 9.52% had grade 1, 4.76% had grade 2 and 23.81% had grade 3 shivering. In ketamine group, 80.95% of patients had grade 0, 2.38% had grade 1, 4.76% had grade 2, 11.9% of patients had grade 3 shivering. In both above groups no patient had grade 4 shivering.

In clonidine group, 52.38% of patients had grade 0, 11.9% had grade 1, 14.29% had grade 2, 16.67% had grade 3 shivering while 4.76% patients had grade 4 shivering.  In normal saline group 42.86% of patients had grade 0, 19.05% had grade 1, 16.67% had grade 2, 14.29% had grade 3 and 7.14% had grade 4 shivering.

There was significant difference observed in the distribution of grade of shivering in normal saline group compared to tramadol, ketamine and clonidine group (p=0.0499).

FIGURE 1: GRAPHIC REPRESENTATION SHOWING DISTRIBUTION OF GRADE OF SHIVERING AMONG FOUR GROUPS.

SURFACE TEMPERATURE

The temperature range was 36-38°C for all the groups. The mean values of temperature with standard deviation were 36.92±0.7 for tramadol group, 36.42±0.37 for ketamine group, 36.47±0.44 for clonidine group and 36.55±0.54 for normal saline group. There was no significant surface temperature difference between the groups (p=0.67).

TABLE 04: DISTRIBUTION OF SEDATION SCORE IN FOUR GROUPS OF PATIENTS STUDIED

SEDATION SCORE

In tramadol group, 88.1% of patients had sedation score of 1 and 11.9% had score of 2. In ketamine group, 26.19% of patients had sedation score of 1, 28.57% had score of 2, 30.95% had score of 3 and 14.29% of patients had sedation score of 4. In clonidine group, 100% of patients had sedation score of 1. In normal saline group 100% of patients had sedation score of 1.

There was significant difference observed in the distribution of sedation score in ketamine group compared to tramadol, clonidine and normal saline groups (p<0.001).

FIGURE 2: GRAPHIC REPRESENTATION SHOWING COMPARISON OF HEART RATE (MIN) AMONG FOUR

GROUPS

HEART RATE

Analysis of heart rate: Statistical analysis of change in the heart rate at interval of 10 min starting from administration of spinal anaesthesia till the end of surgical procedure in tramadol, ketamine, clonidine and normal saline groups was presented though it was monitored continuously.

Group T (Tramadol group)

The baseline mean heart rate and standard deviation was 74.33 and 6.21 in this group respectively. At 5 min after spinal anaesthesia, the heart rate changed minimally with a mean value of 74.17 and standard deviation (SD) of 6.81. Subsequently a decreasing trend was noted starting from 5 min to 70 min. The mean value and SD at 70 min were 69.85 and 4.93 respectively. Then there is an increase in heart rate from 70 min to 80 min then it again reduces at 90 mins. The mean value and standard deviation at 90 min were 69.42 and 5.37 respectively.

Group K (Ketamine group)

 The baseline heart rate and standard deviation was 74.95 and 4.27 in this group respectively. At 5 min after spinal anaesthesia, the heart rate increased to mean value of 79.24 and standard deviation of 6.1. Subsequently an increasing trend was noted starting from 5 min to 20 min. the mean value and standard deviation at 20 min were 89.1 and 2.58 respectively. Then there was transient decrease in the heart rate from 20 min to 60 min.  The mean value and standard deviation at 60 min were 71.77 and 3.79 respectively. Heart rate increased minimally at 70 mins then again decreases till 90 mins with mean of 69.83 and SD of 5.42 at 90 mins.

Group C (Clonidine group)

 The baseline heart rate and standard deviation was 74.14 and 5.82 in this group respectively. At 5 min till 20 mins after spinal anaesthesia, the heart rate barely changed with a mean value of 74.95 and standard deviation of 6.08 at 20 mins. Subsequently heart rate was showing decreasing trend till 70 mins. The mean value and standard deviation at 70 min were 69.68 and 5.5 respectively. Then there was minimal increase in heart rate from 70 mins to 90 mins. The mean value and standard deviation at 90 min were 70.50 and 4.12 respectively.

Group P (Normal saline)

 The baseline mean heart rate and standard deviation was 74.40 and 7.55 in this group respectively.  At 5 min after spinal anaesthesia, the heart rate barely changed with a mean value of 74.64 and standard deviation of 8.08. Subsequently heart rate was not changed much from baseline value till 20 min. The mean value and standard deviation at 20 min were 74.14 and 8.38 respectively. There was slight increase in heart rate from 20 to 30 mins. Then there was a decreasing trend noted in the heart rate from 30 min to 90 min. The mean value and standard deviation at 90 min were 68.53 and 5.68 respectively.

There was statistically significant difference observed in ketamine group

with respect to heart rate compared to tramadol, clonidine and normal saline

groups till 40min after spinal anaesthesia with p-value of <0.001 except the

baseline values (p=0.93).

After 40 min, there was no statistically significant difference observed among the groups.

MEAN ARTERIAL PRESSURE:

Analysis of mean arterial pressure (MAP):

Statistical analysis of change in the MAP at interval of 10 min starting from administration of spinal anaesthesia till the end of surgical procedure in tramadol, ketamine, clonidine and normal saline groups was presented though it was monitored continuously.

Group T (Tramadol group

The baseline mean value and standard deviation of mean arterial pressure (MAP) in this group was 81.86 and 7.27 respectively. At 5 min after spinal anaesthesia there was transient decrease in the MAP with mean value of 78.90 and SD of 6.83. Subsequently there is decrease in the MAP from 5 min till 50 min with mean value of 68.35 and SD of 4.82. Then there is transient increase in the mean arterial pressure till 90 min with mean value of 70.05 and SD of 2.14.

Group K (Ketamine group)

 The baseline mean value and standard deviation (SD) of mean arterial pressure (MAP) in this group was 81.02 and 5.53 respectively. At 5 min interval after spinal anaesthesia there was increase in MAP with mean value of 83.19 and SD of 5.85. Subsequently there was increasing trend noted in MAP from 5 min to 20 min with mean value of 89.02 and SD of 6.29.  Then there was decrease in MAP till 70 min with mean value of 73.33 and SD of 7.62. from 70 to 90 mins MAP showed minimal change with mean and SD of 73.40 and 2.60 respectively at 90 mins.

Group C (Clonidine group)

 The baseline mean value and standard deviation (SD) of mean arterial pressure (MAP) in this group was 81.10 and 4.41 respectively. At 5 min interval after spinal anaesthesia, there was a decrease in MAP with mean value of 79.45 and SD of 4.31. Subsequently there was decreasing trend noted in MAP from 5 min till 50 min with mean value of 71.09 and SD of 4.26 at 50 min. from 50 to 70 mins MAP increases which further reduces from 70 to 90 mins. Mean and SD at 90 mins were 71.12 and 1.20 respectively.

Group P (Normal saline)

The baseline mean value and standard deviation (SD) of mean arterial pressure (MAP) in this group was 81.74 and 5.56 respectively.  At 5 min interval after spinal anaesthesia, there was a decrease in MAP with mean value of 78.93 and SD of 5.44. Subsequently there was a decreasing trend in MAP from 5 min to 40 min with mean value of 70.71 and SD of 5.39.  Then there was increase in MAP from 40 min till 60 min with mean value of 73.24 and SD of 6.15 at 60 min. 60 min onwards there was minimal change in MAP noted till 90 mins in this group.

There was statistically significant difference observed in ketamine group with respect to mean blood pressure compared to tramadol, clonidine and normal saline groups till 50 min after spinal anaesthesia with p-value of <0.001 except for baseline

value (p=0.870) and value at 5 mins (p=0.0012).  After 50 min, there was no statistically significant difference observed in four groups.

TABLE 5: SURGERIES IN FOUR GROUP OF PATIENTS STUDIED PERCENTAGE WISE DISTRIBUTION.

This study evaluates the effectiveness of prophylactic use of ketamine, clonidine and tramadol in preventing shivering during neuraxial anaesthesia. The present study included 168 patients aged 18-60 years planned for elective surgeries under spinal anaesthesia. The patients were randomly allocated in to 4 groups.

Age distribution

The mean values of age with standard deviations (SD) are 38.5±10.29 for tramadol group, 36±9.74 for ketamine group, 36.17±9.15 for clonidine group, 34.1±10.53 for normal saline group.  There was no significant difference between the groups (p>0.05).

Gender distribution

In tramadol group, 57.14% of the patients were female and 42.86% of the patients were male.  In ketamine group 54.76% of patients were female and 45.24% of the patients were male.   In clonidine group, 66.67% of patients were females 33.33% of patients were male.  In normal saline group, 50% of patients were female and 50% of patients were male.  There was no significant difference in gender wise distribution among the four groups (p=0.681).

Duration of surgery, P value = 0.46, Hence no significant difference observed among 4 groups.

Median level of spinal anaesthesia, P = 0.052, Hence no significant difference observed among 4 groups.

Incidence of shivering:

Shivering can double or even triple oxygen consumption and carbon dioxide production along with marked increase in plasma catecholamine level which is associated with high-risk of cardiac complications. Shivering also increases intraocular and intracranial pressures8-11. Therefore, there is extreme need to prevent shivering in patients posted for surgeries.

In our study, in ketamine group 80.95% patients had no shivering while 2.38% cases had grade 1 shivering, 4.76% had grade 2 and 11.9% had grade 3 shivering. As compare to ketamine, in tramadol group 61.9% patients had no shivering and 23.81% had grade 3 shivering while in clonidine group 52.38% patients had no shivering, 16.67 % had grade 3 shivering and 4.76% had grade 4 shivering. There was significant difference observed in the distribution of grade of shivering in normal saline group compared to tramadol, ketamine and clonidine group (p=0.0499).

This data was comparable to study conducted by Wason R et al40, where 200 patients of ASA grade I and II who underwent lower limb or lower abdominal surgeries, were randomly allocated into four groups of 50 each and were given prophylactic i/v normal saline as placebo, ketamine, tramadol or clonidine. The demographic profile and median sensory level were comparable to our study.

Comparison Of Age Distribution:

In Wason R et al study, Twenty-eight percent (14/50) patient did not shiver at all in the control group, while 82% patients (41/50) in the ketamine group, 94% patients (47/50) in the clonidine group and 88% patients (44/50) in the tramadol group did not shiver at all, which was statistically significant (P=0.000). In the control group, 27 patients (54%) exhibited grade 3 shivering; however, only five patients (10%) in the ketaminegroup, two patients (4%) in the clonidine group and four patients (8%) in the tramadol group exhibited grade 3 shivering, which was statistically significant (P=0.001).

The incidence of grade 3 shivering showed a statistically significant difference [p=0.001] in group placebo [27/50] as compared with the other groups [group Ketamine = 5/50, group Clonidine = 2/50, group Tramadol = 4/50]. However, the drugs used for the study were equally efficacious in controlling shivering when used prophylactically, and no drug showed any significant advantage over the other.

A study, conducted by Amir Nazir et al41, with the aim to evaluate the effectiveness of prophylactic intravenous ketamine in the prevention of shivering during spinal anesthesia for elective lower limb surgery and comparing it with intravenous tramadol, 90 patients of ASA grade I and II of either sex, aged 18 to 60 years were randomized into three equal groups and all patients received prophylactic intravenous drug as either normal saline (Group S, n=30) or ketamine 0.5 mg/kg (Group K, n=30) or tramadol 0.5 mg/kg (Group T, n=30) for shivering.

Comparison Of Incidence of Grade II Shivering:

In the above study significant difference noted in shivering in drug groups as compared to control group (p value<0.05) which is comparable to our study, also the incidence of grade II shivering in ketamine and tramadol group are comparable to our study but in Amir et al study, only grade II shivering were compared as after 15 min of anaesthesia or concomitant of prophylactic dose of study drug if patient developed grade III or IV shivering study drug was considered ineffective and 25 mg of i/v tramadol was administered to the patient. Prophylactic ketamine has a similar efficacy as compared to tramadol in preventing shivering during spinal anaesthesia.

Another study conducted by Sia et al43, with 100 patients posted for knee arthroscopy under extradural block, randomly allocated into two groups of 50 each. Group I received i/v clonidine 0.1mcg/kg before giving block while Group II received a saline bolus, reported shivering in 3 (6%) patients as compared to 19(38%) in group II (p<0.001), concluded that clonidine is effective in preventing shivering as compared to placebo.

Dal et al46, witnessed significant results with ketamine 0.5 mg/kg i.v as well as with ketamine 0.25mg/kg as compared to normal saline as placebo to prevent shivering under spinal anaesthesia.

Bilotta45 and Chan et al49, found tramadol to be a promising drug in doses of 0.5 mg/kg and 0.25 mg/kg i.v. respectively in controlling shivering under neuraxial blockade.

Variation in Heart Rate and Mean Arterial Pressure: 

In our study, hemodynamic profile of study drugs was also compared as ketamine is known to cause hypertension and tachycardia whereas clonidine is known to cause bradycardia and hypotension as side effects.

Change in the Heart Rate and Mean Arterial Pressure at interval of 10 mins starting from administration of spinal anaesthesia till the end of surgical procedure in tramadol, ketamine, clonidine and normal saline groups were compared though it was monitored continuously.

When the hemodynamic parameters (heart rate and mean blood pressure) were compared, the patients in the ketamine group had a higher heart rate and mean blood pressure during the first 40 min of observation as compared with the other three groups; however, thereafter, the two were comparable in all the four groups.

The baseline heart rate at 5mins in tramadol, ketamine, clonidine and control group were 74.33±6.21, 74.95±4.27,         74.14±5.82,         74.4±7.55 respectively with p value of 0.9 which suggests non-significant difference among these groups. From 10 mins to 40 mins heart rate was significantly higher in ketamine group as compared to other group with p value of <0.001 and after 40 mins, p value was found to be >0.05 suggestive of no significant difference among groups. This variation in heart rate is in concordance with study conducted by Wason R et al40 according to which heart rate was significantly higher in ketamine group till 30 mins of surgery with no comparable difference   after 30 mins.

                                 Variations in Heart Rate

              Our study                                  

    Wason R et al study

On comparing MAP in 4 groups, we found that, in tramadol, ketamine, clonidine and normal saline group baseline MAP was 81.86±7.2, 81.02±5.53 81.1±4.41, 81.74±5.56 with p value of              0.870 which suggest non- significant difference among 4 groups. After 5 mins till 50 mins of surgery MAP was showing decreasing trend in tramadol, clonidine and control group with p value of <0.001 while in ketamine group MAP was showing increasing trend till 20 mins of surgery there after there was decrease in MAP till 50 mins after which it was similar to baseline values.

There was statistically significant difference noted in ketamine group till 20 mins after spinal anaesthesia with p-value of <0.001 except for baseline value (p=0.870) and value at 5 mins (p=0.0012).  After 50 min, there was no statistically significant difference observed in four groups.

These variation in MAP in different groups are comparable with Wason R et al40 study, according to which MAP was significantly higher in ketamine group till 30 mins of surgery with no comparable difference after 30 mins.

                       Variations in Mean Arterial Pressure

          OUR STUDY                                                  

WASON R et al STUDY

Comparison of sedation score:

Sedation as side effects of drugs used in the study were also recorded at 5 mins, 10 mins and then at intervals of 10 mins upto 90 minutes of surgery/till the end of surgery using 5-point scale.

In tramadol group, 88.1% of patients had sedation score of 1 and 11.9% had score of 2. In ketamine group, 26.19% of patients had sedation score of 1, 28.57% had score of 2, 30.95% had score of 3 and 14.29% of patients had sedation score of 4. In clonidine and normal saline group, 100% of patients had sedation score of 1.

There was significant difference observed in the distribution of sedation score in ketamine group compared to tramadol, clonidine and normal saline groups (p<0.001) found comparable with Wason R et al40 study.

Comparison of sedation score:

In our study as well as Wason R et al40 study, Ketamine causes significant grade 2, 3 and 4 sedations as compared to normal saline/placebo, clonidine and tramadol, which may be beneficial to us as it increases patient’s comfort, maintains cardiorespiratory stability; improves surgical conditions and prevents recall of unpleasant events during the surgery. Clonidine also has the potential to cause sedation, but in this study, clonidine did not cause any significant sedation as compared to placebo.

No significant untoward side-effects were seen in all the four groups. Vomiting was

only observed in the tramadol group in only 2% patients, which was not statistically

significant (P=0.389).

In our study, the incidence of side-effects was not significantly different among the

groups. Tramadol has the potential to cause nausea and vomiting, but the incidence of

nausea and vomiting in the study groups was comparable with the placebo group.

Similar results were reported in the Wason R study.

However, Gangopadhyay et al44, observed a significant number of cases (20/30) of

nausea and vomiting with tramadol; this high number of cases in the tramadol group

could be explained by the fact that they used tramadol at 1 mg/kg i.v. as compared

with 0.5 mg/kg i.v. in our study.

Ketamine is known to cause hallucinations, but none of the patients complained of

hallucination in any of the groups. Wason R et al40 study support our findings.

We conclude that giving either ketamine 0.5 mg/ kg, clonidine 75 mcg or tramadol 0.5 mg/kg i.v. prophylactically just before neuraxial blockade significantly decreases the incidence of shivering without causing any major side-effects. Using ketamine may be more beneficial as it improves the hemodynamic profile by its sympathomimetic effects and it sedates the patient effectively, which increases patient comfort during surgery, maintains cardiorespiratory stability and prevents recall of unpleasant events during the surgery.

LIMITATIONS

Core temperature was not assessed by a nasopharyngeal thermometer and only surface temperature by an axillary thermometer was assessed.

The study conducted in patients undergoing different surgical procedures, requiring different amount of fluid administration and fluid shift  which can lead to some amount of variation in results.

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