A comparative study between propofol and thiopentone for hemodynamic parameters during induction of general anesthesia in surgical patients

Received 24 October 2016 Revised 18 November 2016 Accepted 19 November 2016 Early online 04 January 2017 Print 31 January 2017 Hemodynamic stability is very much important during induction of general anesthesia. So, this study was planned to compare hemodynamic parameters during induction by thiopentone and propofol. This prospective study was conducted after approval from institutional ethics committee in non-hypertensive patients of ASA grade I and II aged between 18-60 yrs of either sex, admitted for different surgical procedure. The patients were randomized into group P (propofol) and group T (thiopentone). Heart rate, both systolic (SBP) and diastolic blood pressure (DBP) were recorded during induction and at 1 minutes, 2 minutes, 3 minutes and 4 minutes interval after intubation. Thirty patients in each group were included during study period. After induction, there was fall in both mean SBP and DBP after an increase during intubation which was more in group T (p˂0.05). The statistically significant difference was observed only at 1min between two groups for SBP (P value <0.05). The mean heart rate was almost similar at pre induction time in both the groups (p>0.05). There was rise in heart rate during intubation in both the groups, thereafter heart rate started decreasing. The fall was similar in both the group at any given point of observation (P value >0.05). Both propofol and thiopentone alter the blood pressure and heart rate during induction in surgical patients which are more pronounced in thiopentone but these changes return close to baseline value earlier in case of propofol. So, propofol could be the preferred inducing agent in hemodynamically unstable patients. Corresponding author

emodynamic stability is very much important during induction of general anaesthesia in surgical patients.Thus, anaesthetic agent with minimum effect on heart rate (HR) and blood pressure (BP) would be the agent of choice for general anaesthesia.Use of inhalational anaesthetics can cause progressive cardiopulmonary depression.Thus, use of non-inhalational anaesthetic agents can decrease the requirement of inhalational anaesthetics which lead to less cardiovascular depression 1 .Intravenous anaesthetics have a faster onset with minimal side effects than inhalation anaesthet-H Propofol vs Thiopentone for hemodynamic changes J Med Allied Sci 2017; 7 (1) ics and are used commonly in induction of general anaesthesia for most of the surgical procedures.The concept of intravenous anaesthesia was first established in 1920 2 .Thiopentone, the most widely used intravenous inducing agent was first administered in 1934 by Waters and Lundy.Even today thiopentone remains the gold standard against which all newer intravenous induction agents are compared.Hypertensive and hypovolemic patients are more sensitive to thiopentone, characterised by exaggerated hypotensive effects which is due to decrease in myocardial contractility as well as peripheral vasodilation 3,4 .Propofol came into use for practice in 1984.It produces rapid, smooth induction of anaesthesia and fast recovery with decrease incidence of postoperative nausea and vomiting.Thus propofol appears to be a suitable alternative induction agent.The cardiovascular depressant properties of propofol are similar or greater than those of thiopentone 5 .Propofol is likely to cause profound hypotension in hypovolemic or previously hypertensive patients and those with cardiac disease.Reduced myocardial contractility and decreased systemic vascular resistance could be the reason for decrease in blood pressure 6,7 .On literature search very few studies were found in India which compared hemodynamic parameters of thiopentone and propofol.This present study was done to compare hemodynamic parameters during induction of general anaesthesia by thiopentone and propofol in surgical patients.

Materials and methods
The present prospective study was conducted in a tertiary care teaching hospital of southern Rajasthan for a period of one year.After approval from institutional ethics committee; non-hypertensive patients of physical state ASA grade I and grade II aged between 18-60 yrs of either sex, admitted for different surgical procedure were included in the study.
The patients were randomly selected into two groups using computer generated random numbers.Informed consent was taken from all the patients.A thorough pre-anaesthetic check-up with detailed history, clinical examination and routine investigations were done in all cases before surgery.Patients were pre medicated with Inj.Glycopyrrolate 4μg/kg, Inj.Ondansetron 0.1mg/kg, Inj.Fentanyl 2μg/kg and Inj.Midazolam 0.02mg/kg intravenously 10 minutes before induction.Injection scoline 1.5 mg/kg was also given to all patients during induction and intubation.Group P received propofol 2.2 mg/kg, and Group T received thiopentone 5 mg/kg intravenously for the induction of anesthesia.All patients had continuous pulse oximeter, ECG and blood pressure monitoring.Hemodynamic parameters like pulse rate, blood pressure both systolic and diastolic were recorded during induction and at 1 minutes, 2 minutes, 3 minutes and 4 minutes interval after intubation.
All data is expressed in Mean±SD.Data was analyzed using Microsoft excel and SPSS software version 17. Suitable statistical tests like Chi square test and t test were used to analyze the data.A p value of less than 0.05 was considered statistically significant.

Result
In present study both group P and group T were comparable with respect to age, sex and weight of all patients (Table 1).
Table 2 and figure 1 show mean SBP at different time periods in both the groups.The base line values were almost similar in both the groups.(p>0.05)After induction, there was fall in mean SBP which was after an increase during intubation when compared to baseline.Rise was more in group T (p˂0.05).The statistically significant difference was observed only at 1min interval between two groups (p<0.05).There was fall in mean DBP after intubation in both groups, but fall was slightly more in T group.The mean DBP was almost similar at all time intervals in both the groups.There was no statistically significant difference at any point of observation (p >0.05).
Table 4 and figure 2 show mean heart rate at different time periods in both the groups.The mean heart rate was almost similar at pre induction time in both the groups (p>0.05).There was rise in heart rate during intubation in both the groups, thereafter heart rate started decreasing.The fall was similar in both the group.There were no significant difference at any given point of observation (p >0.05).

Discussion
Propofol and thiopental have been used routinely as inducing agents for various surgical procedures.Hemodynamic instability can occur at the time of induction in patients.Thus, anesthesiologists have been trying to use a variety of induction modes to decrease these hemodynamic changes and various studies have shown comparable results of thiopentone and propofol on hemodynamic changes during induction 8,9 . In present study we compared the hemodynamics parameter of thiopental and propofol used for induction of general anaesthesia.
There was no significant difference in blood pressure and heart rate between the two groups prior to intubation in present study.However, there was significant increase in both systolic blood pressure and diastolic blood pressure; and heart rate after 1 minute of intubation in both the groups.The reason for this could be due to the fact that we recorded blood pressure and heart rate after intubation which can cause sympathetic stimulation; often leading to release of catecholamines which manifested as an increase in systolic and diastolic blood pressures and heart rate 10,11 .Other studies had also shown more hemodynamic changes after laryngoscopy and intubation than those after the use of laryngeal mask airway 12,13 .
In present study fall of blood pressure by propofol was much greater than those seen after thiopentone after 2, 3 and 4 min of intubation.This fall could be due to decrease in myocardial contractibility, peripheral vascular resistance and sympathetic tone caused by propofol In present study after one minute of intubation rise in blood pressure was significantly more in thiopentone group.That is why propofol is more effective in preventing the increase in blood pressure after intubation than thiopentone 15 .In present study heart rate was found to be increased in both the groups after intubation and there was no significant difference at any point of observation after intubation in both the groups.Various other studies have also reported variable change in heart rate like no change, a decrease and an increase 8,16,17 .This variation could be due to depression of the baroceptor response or reflex tachycardia probably due to a central vagolytic effect 6 .

Conclusion
Both propofol and thiopentone alter the hemodynamic parameters like BP and HR during induction.These changes are more pronounced in thiopentone but these changes return close to baseline value earlier in case of propofol then with thiopentone.So, propofol could be the preferred inducing agent as compared to thiopentone.

Fig 2 .
Fig 2. Change in heart rate in both the groups

5 .
McCollum et al have also observed that propofol caused significantly more hypotension than thiopentone 14 .

Table 1 :
Characteristics of both the groups

Table 2 :
Comparision of mean systolic blood pressure at different time interval in both the groups (1)ed Allied Sci 2017; 7(1)

Table 3 :
Comparison of mean diastolic blood pressure at different time interval in both the groups Fig 1. Change in Blood pressure in both the groups

Table 4 :
Comparison of mean heart rate at different time of observation in both the groups