Alleviating Stress Response to Tracheal Extubation in Neurosurgical Patients: A Comparative Study of Two Infusion Doses of Dexmedetomidine

Abstract

Background: Tracheal extubation is almost always associated with increase in sympathoadrenal activity may result in hypertension, tachycardia, and arrhythmias. Attempts have been made to oppose the pressor response by the use of various drugs. Dexmedetomidine decreases norepinephrine which reduces the blood pressure and the heart rate (HR). We hypothesize that the infusion of dexmedetomidine may produce more stable hemodynamics during extubation as compared to boluses.

Materials and methods: Ninety adult patients aged 18-65 years, the American Society of Anesthesiologists Grade I-II undergoing intracranial surgeries for various neurologic problem at All India Institute of Medical Sciences were enrolled in this randomized controlled trial. Primary.

Objectives: (1) To observe the hemodynamic changes (HR and mean arterial pressure [MAP]) and airway responses during tracheal extubation following two infusion doses of dexmedetomidine.

Secondary objectives: (1) Time to emergence and time to tracheal extubation, (2) Early postoperative complications such as laryngospasm and bronchospasm, and (3) adverse effects of the study drug. Patients were assigned into three groups - (1) Group D_0.2 - 0.2 μg/kg/h diluted to 50 ml, (2) Group D_0.4 - 0.4 μg/kg/h diluted to 50 ml and Group P (Placebo) - 0.9% NS 50 ml. The hemodynamics including the HR and MAP were recorded just before the loading dose of the study drug and then were recorded every 5 min till the infusion was stopped at tracheal extubation and every 1 min till 10 min postextubation. In addition, the airway, respiratory and cardiovascular complications along with postoperative nausea and vomiting, shivering, cough grading, Aldrete score, Ramsay sedation scale, and intraoperative awareness were recorded.

Statistical analysis: Continuous variables such as HR and MAP were analyzed using analysis of variance and categorical variables were analyzed using the Chi-square test.

Results: Patient demographics were comparable between the three groups. There was a significant reduction in HR and MAP just before extubation and up to 10 min post extubation in the D_0.2 and D_0.4 groups as compared to placebo (P < 0.001) but the difference among the dexmedetomidine groups were not significant. Patients belonging to D_0.2 group emerged faster than D_0.4 group, however, the results were comparable with placebo group. 73.3% patients of the placebo group had tachycardia and hypertension at emergence as compared to only 3.3% patients in the D_0.4 group (P < 0.001). Eighty percentage patients of D_0.2 and 100% patients of D_0.4 group had a significant reduction in cough as compared to placebo (P < 0.001). No patient in either groups had intraoperative awareness, any respiratory complications, or allergic reactions to the study drug. Modified Aldrete scoring and Ramsay sedation scale were comparable in all the three groups.

Conclusion: Dexmedetomidine suppresses cough and hemodynamic responses (HR and MAP) to tracheal extubation significantly without delaying emergence.

Keywords: Comparative; dexmedetomidine; extubation; infusion; neurosurgical; stress.

Figure 1

Perioperative trend of heart rate in the 3 study groups expressed as mean standard deviation. HR: Heart rate, HR_BL: Baseline heart rate, HR 5, HR 10, HR 15, HR 20, HR 25, HR 30, HR 35, HR 40, HR 45, HR 50, HR 55, HR 60: Heart rates at 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 min from the start of drug administration, HR_BE: Heart rate just before tracheal extubation, HR PE: Heart rate immediately posttracheal extubation, HR PE1, HR PE2, HR PE3, HR PE4, HR PE5, HR PE6, HR PE7, HR PE8, HR PE9, HR PE10: Heart rates postextubation at 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 min, respectively, Group D_0.2 – dexmedetomidine 0.2 μg/kg/h infusion group, Group D_0.4 – dexmedetomidine 0.4 μg/kg/h infusion group, Group P – Placebo group

Figure 2

Perioperative trend of mean arterial pressure in the 3 study groups expressed as Mean standard deviation. MAP: Mean arterial pressure, MAP_BL: Baseline MAP, MAP 5, MAP 10, MAP 15, MAP 20, MAP 25, MAP 30, MAP 35, MAP 40, MAP 45, MAP 50, MAP 55, MAP 60: Mean arterial pressures at 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 min from the start of drug administration, MAP_BE: MAP just before tracheal extubation, MAP PE: MAP immediately post tracheal extubation, MAPPE1, MAPPE2, MAPPE3, MAPPE4, MAPPE5, MAPPE6, MAPPE7, MAPPE8, MAPPE9, MAPPE10: MAP postextubation at 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 min, respectively, Group D_0.2 – dexmedetomidine 0.2 μg/kg/h infusion group, Group D_0.4 – dexmedetomidine 0.4 μg/kg/h infusion group, Group P – Placebo group

Figure 3

Cardiovascular complications in the 3 study groups expressed as n (%). Group D_0.2 – dexmedetomidine 0.2 μg/kg/h infusion group, Group D_0.4 – dexmedetomidine 0.4 μg/kg/h infusion group, Group P – Placebo group

Figure 4

Cough grade in patients in the 3 study groups expressed as n (%). Group D_0.2 – dexmedetomidine 0.2 μg/kg/h infusion group, Group D_0.4 – dexmedetomidine 0.4 μg/kg/h infusion group, Group P – Placebo group