Comparison of Dexmedetomidine and Propofol for hemodynamic changes and depth of an a esthesia (using BIS monitor) during laparoscopic surgery

Research article

Comparison of Dexmedetomidine and Propofol for hemodynamic changes and depth of

an

a

esthesia (using BIS monitor) during laparoscopic surgery

*Assistant professor, **Senior resident, ***Professor

Department of anaesthesia, Smt SCL General Hospital, Smt. NHL Municipal Medical College, Ahmedabad.

Abstract:

Introduction: Laparoscopy is one of the commonest surgical procedures includes creation of pneumoperitoneum with carbon dioxide which in turns causes hemodynamic instability. To manage this instability, several drugs are tried and used. Dexmedetomidine, a selective α-2 agonist, is used for sedation and hemodynamic stability.

Aims: This study aims to compare the effect of i.v. Dexmedetomidine and propofol infusion on heart rate and blood pressure attenuation and depth of anesthesia using BIS monitor during laparoscopic surgery.

Material and Method: 50 patients of ASA grade I/II divided in to two groups. Group D (n=25) received Dexmedetomidine 1 mcg/kg/10min loading dose followed by 0.2 –0.7 mcg/kg/min infusion. Group P (n=25) received 25 -75mcg/kg/min propofol infusion. Observation: Up to 30 minutes of surgery heart rate stability was better in group D, after 30 minutes it was comparable in both the groups. Mean arterial pressure was better maintained up to 75 minutes in group D, after 75 minutes it was comparable in both the groups.

Conclusion: Dexmedetomidine infusion attenuates hemodynamic response to laryngoscopy and pneumoperitoneum with adequate depth of anesthesia better than propofol.

Key words: Laparoscopic surgery, Dexmedetomidine, Propofol, BIS Monitor.

Introduction

Laparoscopic surgery is one of the most important diagnostic and therapeutic tools in the present surgical era. Since 1987, when the first laparoscopic cholecystectomy was successfully performed by Phillipe Mouret, this has become the gold standard. The benefits of minimal access techniques include less pain, early mobilization, minimal scar and shorter hospital stay, which have further increased its applications 1.

Laparoscopic surgeries require insufflation of abdomen with some gas, usually Carbon Dioxide, called pneumoperitoneum, which induces pathophysiologic changes that complicate anesthetic management. Pneumoperitoneum affects several homeostatic systems leading to alteration in acid-base balance, cardiovascular system, pulmonary

physiology and stress response. The extent of cardiovascular changes associated with pneumoperitoneum includes an increase in mean arterial pressure, decrease in cardiac output and increase in systemic vascular resistance which in turn compromise tissue perfusion.

To prevent and counteract these effects, appropriate monitoring and pharmacological interventions are required. Such interventions include preloading with intravenous fluids, administration of general anesthesia with vasodilating anesthetics, direct vasodilators like nitroglycerine 2, high doses of opioids 3, infusion of propofol and centrally acting α2 agonists like Clonidine and Dexmedetomidine 4, xylocard 5, oral gabapentin 6.

Aims and Objectives:

1. Effects of I.V. dexmedetomidine and propofol infusion on heart rate and blood pressure attenuation during laparoscopy. 2. To study the effect of titrated I. V. infusion

of Dexmedetomidine and propofol on the depth of anaesthesia during laparoscopic surgeries using BIS monitor.

BIS MONITOR:

In 1994 BIS MONITOR was developed by Aspect Medical Systems (Newton, MA). The Bispectral Index (BIS Index) offers the anesthesia professional a direct and accurate method for continuous brain status monitoring throughout the course of anesthetic or sedative administration12.

THE BIS INDEX

The BIS Index is a numerical processed, clinically-validated EEG parameter. Unlike traditional processed EEG parameters derived from power spectral analysis, the BIS Index is derived utilizing a composite of multiple advanced EEG signal processing techniques – including bispectral analysis, power spectral analysis, and time domain analysis. A patient who is awake and alert will have a BIS reading near 100, while one with no brain activity will have a reading of 0 and a flat EEG.

Materials and Methods:

Group D: Inj. Dexmedetomidine loading dose: 1 mcg /kg over 10 minutes I.V. Maintenance dose 0.2-0.7mcg/kg/hr titrated to maintain BIS value between 40-60 and vitals. (n=25)

Group P: Inj. Propofol 50 mcg/kg/min IV was started immediately after intubation and maintained between 25-75mcg/kg/min, titrated to maintain BIS value between 40-60 and vitals. (n=25)

Patients with history of significant respiratory, cardiovascular, renal diseases, history of allergy, psychiatric illness and pregnancy were excluded from the study.

Pre-anesthetic assessment was carried out on the day before surgery and routine investigations were done. After shifting patient to the operating room and before giving premedication vital data like Pulse, BP, ECG, SPO2, were recorded. All the patients were given Inj. Glycopyrollate 0.004 mg/kg i.v., Inj.

Ondansetron 0.08 mg/kg i.v., Inj. Fentanyl 2.0 mcg/kg i.v.

Group D loading intravenous infusion of 1mcg/kg of dexmedetomidine was initiated before intubation over 10 minutes, and maintenance infusion of dexmedetomidine 0.2 -0.7mcg/kg/hr was started after intubation. The rate of infusion was titrated according to the desired BIS value (40-60) and maintaining HR >60/min and systolic blood pressure >90mmHg. Group P: Inj. Propofol 50 mcg /kg/min IV infusion was started immediately after intubation and maintained between 25-75mcg/kg/min to maintain BIS value 40-60 and HR >60/min and systolic blood pressure >90mmHg.

In case of bradycardia HR <60/min rate of maintenance dose of dexmedetomidine infusion was reduce and bolus dose of inj. atropine 0.6 mg i.v. given.

All 50 patients were induced with Inj. Sodium thiopental 5– 7mg/kg i.v. Inj. Succinylcholine 1.5-2mg/kg i.v. and intubated with cuffed endotracheal tube of appropriate size. All patients were maintained with O2+N2O+ isoflurane (0.8-1%) + Inj. Atracurium 0.4 to 0.5 mg/kg and maintenance dose of 0.08-0.10 mg/kg intermittently. Heart Rate, blood pressure, SPO2, BIS, and ETCo2 were recorded before premedication, after premedication, after bolus dose of dexmedetomidine, after intubation and at the regular intervals throughout the surgery.

Reversal of anesthesia was achieved using Inj. Glycopyrrolate 8 mcg/kg i.v. Inj. Neostigmine 0.05mg/kg i.v.

Statistical analysis:

Observations were compared and results were expressed as mean ± SD. Statistically analysis was carried out using unpaired t test and P value <0.05 was considered as significant.

Observation and Results:

Fifty patients were randomly selected and compared using infusion of inj. Dexmedetomidine (Group D n=25) and inj. Propofol (Group P n=25) in laparoscopic surgeries for their efficacy in regard to hemodynamic stability and depth of anesthesia.

TABLE 1: Demographic data

Group D (n=25) Group P (n=25)

Age(yrs.) Range 17-45 16-45

Mean ± SD 28.64 ± 8.18 31.44 ± 8.86

Sex Male 11 9

Female 14 16

Duration of anesthesia (min.) Mean±SD 84.6 ± 29.65 84.00 ± 30.00

TABLE 2: Mean heart rate/ min

Group D (n=25)

Mean ± SD

Group P (n=25) Mean ± SD

P-Value Result

BEFORE PREMEDICATION 90.60 ± 14.37 87.96 ± 15.25 0.266 NS

AFTER PREMEDICATION 94.08 ± 15.58 97.72 ± 16.68 0.214 NS

AFTER INTUBATION 97.96±14.66 104.6±14.64 0.049 S

3 min 95.28± 12.58 103.88±15.00 0.016 S

5 min 92.8 ± 12.96 99.12 ± 13.61 0.049 S

10 min 89.52 ± 12.45 95.32 ± 12.02 0.040 S

15 min 86.32 ± 11.42 92.88 ± 12.08 0.026 S

30 min 83.72 ± 11.57 89.24 ± 11.08 0.091 NS

Table 2 shows mean heart rate was not significant between two groups (p value >0.05) before and after premedication. It shows difference in mean heart rate found after intubation, 3 minutes, 5 minutes, 10 minutes, and 15 minutes of surgery which was significant (P value <0.05). Mean heart rate was not significant after 30 minutes till the end of surgery between two groups (p value >0.05).

TABLE 3: Mean Arterial Pressure

Group D (n=25) Mean±SD

Group P (n=25) Mean±SD

P-Value Result

BEFORE PREMEDICATION 95.41 ± 8.61 95.2 ± 8.27 0.465 NS

AFTER PREMEDICATION 93.95 ± 6.91 91.19 ± 8.39 0.105 NS

AFTER INTUBATION 97.12 ± 5.19 105.31 ± 9.62 0.0003 S

3 min 93.33 ± 5.90 101.12 ± 9.03 0.0004 S

5 min 91.28 ± 6.18 97.31 ± 7.76 0.0020 S

10 min 89.49 ± 5.57 94.69 ± 6.67 0.0022 S

15 min 87.30 ± 4.91 93.15 ± 5.31 < 0.0001 S

30 min 85.39 ± 5.39 90.43 ± 5.26 0.0008 S

45 min 83.97 ± 4.23 88.40 ± 5.65 0.0015 S

60 min 83.91 ± 3.56 87.63 ± 4.45 0.0018 S

75 min 78.5 ± 21.30 85.57 ± 6.07 0.1101 NS

Table 3 shows mean arterial pressure was not significant between two groups (p value >0.05) before and after premedication. It shows that there was significant difference of MAP in group D and group P after intubation , 3 minutes, 5 minutes, 10 minutes, 15 minutes and up to 60 minutes. After intubation p value between two groups was 0.0003 which was significant. There was no significant difference between MAP after 75 min up to the end of surgery (p value >0.05). None of the patients in either group showed hypotension.

GRAPH -1 CHANGE IN MEAN BIS VALUE

40 50 60 70 80 90 100

BI

S

(m

ean

)

Group D (Mean)

Graph 1 show there was no significant change in BIS value between two groups and it was maintained from 40 to 60.

Only one patient in group D had bradycardia during surgery which was treated with Inj. Atropine 0.6 mg I. V. and reduction in the infusion rate of dexmedetomidine.

Discussion:

In laparoscopic surgery CO 2 is routinely used to create pneumoperitoneum and elevation of intra-abdominal pressure with raised diaphragm cause various adverse effects on the cardiovascular system. Plasma level of catecholamines and vasopressin are increased immediately after pneumoperitoneum. Increased catecholamine level activates the renin-angiotensin-aldosterone system (RAAS) leading to characteristic hemodynamic alterations such as decreased cardiac output, elevated arterial pressure and increased systemic and pulmonary vascular resistance.

Patients with normal hearts can cope with these changes but patients with compromised cardiac function may not be able to tolerate the hemodynamic changes. Various drugs have been used to attenuate the hemodynamic responses to pneumoperitoneum during laparoscopic surgery. Beta-adrenergic blocking agents like esmolol and alpha 2 agonists like clonidineand dexmedetomidine 4 have been used to attenuate the rise in MAP and HR. In our study we compared dexmedetomidine and propofol for attenuation of cardiovascular responses in laparoscopic surgery.

In the present study 50 patients of ASA Physical status 1 and 2 were randomly selected undergoing laparoscopic cholecystectomy and appendicectomy. Mean age and mean duration of surgery was also comparable in both the groups.

Dexmedetomidine, a highly selective alpha 2 agonist, has significant sympatholytic and hemodynamic stability.

Our aim was to study the attenuating effect of dexmedetomidine and propofol for heart rate, systolic blood pressure, and diastolic blood pressure and mean arterial pressure during laparoscopic surgery. In group D dexmedetomidine slow bolus was given over 10 minutes before induction due to its pharmacokinetic characteristics of rapid distribution. Infusion of dexmedetomidine and propofol was started after intubation and maintained throughout the surgery and titrated to achieve BIS value of 40-60.

Before and after premedication there were no significant changes between mean heart rate and mean arterial pressure in both the groups (p value >0.05). There were significant differences in mean heart rate after intubation, 3 minutes, 5 minutes, 10 minutes,

and 15 minutes between two groups (p value <0.05). In group D hemodynamic attenuation was observed following laryngoscopy due to bolus infusion of dexmedetomidine.Keniya VM, Ladi S, Naphade R9 investigated dexmedetomidine attenuates sympathoadrenal response to tracheal intubation and reduces perioperative anesthetic requirement. Our study also supported this.

Mean heart rate was not significant between two groups after 30 minutes till the end of surgery (p value >0.05) which shows that infusions of sedative doses of dexmedetomidine (0.2-0.8 mcg/kg/hr) and propofol (25-75 mcg/kg/min) was effective in reduction of heart rate due to stress response of laparoscopic surgery.

Infusion of dexmedetomidine in our study showed significant attenuation of MAP after intubation, and up to 60 minutes of surgery compared with propofol infusion (p value > 0.05). Both infusions of dexmedetomidine and propofol achieved heamodyanamic attenuation in MAP after 60 min till the end of surgery. Patel Chirag, Smita R Engineer, Bharat J Shah, S Madhu11 studied effect of intravenous infusion of dexmedetomidine on perioperative heamodyanmic changes. They found dexmedetomidine significantly attenuates stress responses at intubation and during intra operative period so our study supports this study.

Alka Shah, R N Adaroja 10 studied comparison of hemodynamic changes with propofol and sevoflurane anesthesia during laparoscopic surgery and they found heart rate and blood pressure decreased more in propofol group compared to sevoflurane group but patients were hemodynamic stable in both groups. Our study also showed that HR and MAP were maintained during intraoperative period by propofol infusion.

During intra operative period End tidal CO2 was maintained in both the groups. There was no significant change between two groups.

infusion of dexmedetomidine decreased the total amount of propofol and fentanyl required to maintain anaesthesia, offered better control of intraoperative and postoperative hemodynamics, decreased postoperative pain level, decreased the total amount of morphine used and showed better recovery profile compared with placebo.

In 2010, Ferdi Menda, Koner O, Sayin M, Ture H, Imer P, Aykac B.8 used dexmedetomidine to attenuate the hemodynamic response to endotracheal intubation with low dose fentanyl and etomidate in patients undergoing myocardial revascularization receiving beta blocker treatment. Thirty patients undergoing myocardial revascularization received in a double blind manner, either a saline placebo or a dexmedetomidine infusion (1 µg/kg) before the anaesthesia induction. One minute after endotracheal intubation, HR significantly increased in PLA group while, it decreased in the DEX group. The incidence of hypertension requiring treatment was significantly greater in the PLA group. It is concluded that dexmedetomidine can safely be used to attenuate the hemodynamic response to endotracheal intubation in patients undergoing myocardial revascularization receiving beta blockers.

In our study BIS value was maintained from 40 to 60 which showed adequate depth of anesthesia achieved throughout the surgery.

Conclusion:

Different agents have been tried to minimize stress response of laparoscopic surgery with hemodynamic stability. Infusion of sedative dose of Dexmedetomidine attenuates hemodynamic response to laryngoscopy and pneumoperitoneum with adequate depth of anesthesia better than propofol. To conclude with equisedative dose of dexmedetomidine is better alternative than propofol for hemodynamic stability and depth of anesthesia (using BIS monitor) during laparoscopic surgery.

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