Effects of intravenous dexmedetomidine on perioperative haemodynamics and quality of emergence in patients undergoing head and neck surgery following general anaesthesia—a comparative randomized, double-blind placebo-controlled study
Authors: Nair Venugopal Achuthan , Gladston Divya V. , Krishna K. M. Jagathnath , Koshy Rachel Cherian 
Published: May 2022

Abstract
Background
Dexmedetomidine is a widely used alpha-2 adrenoreceptor agonist in perioperative patient care. Its postsynaptic activation of the receptors in the central nervous system is responsible for reduced neuronal firing with resultant sedation, anxiolysis, analgesia, hypotension and bradycardia leading to effective stress response attenuation seen during laryngoscopy and orotracheal intubation. Major head and neck surgeries demand nasotracheal intubation which is more stressful than orotracheal as it traverses through the nasopharynx which is very pain-sensitive. This is to protect the airway in the immediate postoperative period from oedema or haematoma in the oral cavity or neck. Though its stress response attenuation, haemodynamic stability during the intraoperative period following orotracheal intubation has been well studied, its role in the prevention of emergence delirium and tube tolerance following nasotracheal intubation in major head and neck surgery is not found in the literature. Our aim was to evaluate whether dexmedetomidine effectively attenuates the stress response following nasotracheal intubation, perioperative haemodynamic fluctuations and quality of emergence in patients undergoing head and neck oncosurgeries.

Methods
A total of 150 patients were randomly assigned to one of the two groups; group D (dexmedetomidine group) and group S (control group with saline). Group D patients received a bolus dose of dexmedetomidine 1 μg/kg in 10 ml saline over 10 mts before induction of GA followed by an infusion at 0.4 μ/kg/h during surgery. Statistical analysis was done using SPSS version 11.0 (SPSS Ltd., Chicago, IL). Categorical data were represented using frequencies and percentages. Continuous variables were represented using mean and standard deviation. The association between categorical variables was assessed using the chi-square or Fisher’s exact test, and continuous variables following normality assumption with respect to the two groups were assessed using an independent sample t-test. P value < 0.05 was considered to be statistically significant.

Results
Patients in the D group showed statistically significant attenuation of heart rate (P < 0.05) and blood pressure (P < 0.05) throughout the surgical period compared to saline. Also, there was a significant reduction in blood loss (P = 0.042), cough score (P = 0.001) and sedation score (P = 0.001) in the D group.

Conclusions
We conclude that a bolus dose of dexmedetomidine 1 μg/kg given 10 min before induction of anaesthesia followed by an infusion at 0.4 μg/kg/h during surgery effectively attenuates the haemodynamic responses during nasotracheal intubation and provides smooth emergence as evidenced by reduced coughing, agitation and arousable sedation without respiratory depression which facilitates tube tolerance following major head and neck oncosurgeries. Blood loss was also found to be significantly reduced.