Dexmedetomidine for Improved Quality of Emergence From General Anesthesia

A Dose-Finding Study

Marie T. Aouad, MD; Carine Zeeni, MD; Rony Al Nawwar, MD; Sahar M. Siddik-Sayyid, MD, MHPE; Hanane B. Barakat, MD; Sandra Elias, MD; Vanda G. Yazbeck Karam, MD, MHPE


Anesth Analg. 2019;129(6):1504-1511. 

In This Article

Abstract and Introduction


Background: Dexmedetomidine provides smooth and hemodynamically stable emergence at the expense of hypotension, delayed recovery, and sedation. We investigated the optimal dose of dexmedetomidine for prevention of cough, agitation, hypertension, tachycardia, and shivering, with minimal side effects.

Methods: In this prospective, randomized, double-blind trial, 216 adult patients were randomly assigned to dexmedetomidine 1 μg/kg (D 1), 0.5 μg/kg (D 0.5), 0.25 μg/kg (D 0.25), or control (C). During emergence, cough, agitation, hemodynamic parameters, shivering, time to extubation, and sedation scores were recorded.

Results: A total of 190 patients were analyzed. The respective incidences for the groups D 1, D 0.5, and D 0.25 versus group C were 48%, 64%, and 64% vs 84% for cough—corrected P < .003 between groups D 1 and C; 33%, 34%, and 33% vs 72% for agitation—corrected P < .003 between group C and each of the study groups; and 4%, 2%, and 7% vs 22% for shivering—corrected P = .03 and corrected P = .009 between groups D 1 and D 0.5 versus group C, respectively. The percent increase from baseline blood pressure on extubation for the 3 treatment groups was significantly lower than group C. Percent increase in heart rate was lower than control in groups D 1 and D 0.5 but not in group D 0.25. Time to extubation and sedation scores were comparable. However, more hypotension was recorded during the emergence phase in the 3 treatment groups versus group C.

Conclusions: D 1 at the end of surgery provides the best quality of emergence from general anesthesia including the control of cough, agitation, hypertension, tachycardia, and shivering. D 0.5 also controls emergence phenomena but is less effective in controlling cough. The 3 doses do not delay extubation. However, they cause dose-dependent hypotension.


Emergence from general anesthesia may be accompanied by cough, agitation, hypertension, tachycardia, and shivering. These changes may be detrimental to patients, in particular those with impaired cardiac and pulmonary reserves. Also, they may prolong postanesthesia care unit (PACU) stay.[1] Although coughing during anesthetic recovery may not be life threatening, periextubation cough might lead to undesirable postoperative events, especially in patients at risk for complications related to increases in intracranial[2] or intraocular pressure[3] or detrimental hemodynamic changes. Therefore, there may be valid reasons to adopt measures to prevent cough, at least in certain situations. The compression phase of coughing is a forced expiration against a closed glottis that can generate intrathoracic pressures as high as 40 kPa,[4] which can be detrimental in patients at risk for bleeding, such as posttonsillectomy, patients with spontaneous pneumothorax,[5] bullae or severe emphysema, or posttracheal reconstruction. In addition, coughing might be associated with respiratory complications, such as laryngospasm, oxygen desaturation, upper airway obstruction, pulmonary edema,[6] and vocal cord injury.[7,8] In extreme situations, it might favor airway rupture.[9] Various drugs have been investigated for the prevention or treatment of these undesirable effects including opioids, lidocaine, ketamine, tramadol, and dexmedetomidine.[10–12]

Dexmedetomidine is a selective α2-receptor agonist that has sympatholytic, analgesic, sedative, anxiolytic, amnestic, antishivering, and opioid-sparing properties without respiratory depression.[13] Its intraoperative use decreases opioid consumption and pain intensity.[13] Dexmedetomidine has a favorable side effect profile with significantly less impact on the respiratory drive whether used as a single agent or in combination with opioids.[7]

Previous research has shown that dexmedetomidine given as an intraoperative continuous infusion or a bolus at the end of surgery may improve recovery profiles with a variable impact on extubation times and sedation scores.[14–16] In addition, its efficacy in controlling cough and other emergence phenomena is not consistent across the studies. Therefore, some controversies regarding its efficacy and optimal dose still need to be clarified. Our hypothesis is that dexmedetomidine will prevent the occurrence of cough and other emergence phenomena. The aim of this prospective, multicenter, randomized, double-blind, placebo-controlled study is to investigate the optimal dose of dexmedetomidine for prevention of cough (primary outcome) and for a better quality of emergence from general anesthesia as evidenced by stable systolic blood pressure (SBP), heart rate (HR), and absence of agitation and shivering (secondary outcomes) without hypotension, delayed recovery, and excessive sedation.