Efficacy and safety of dexmedetomidine infusion for patients undergoing awake craniotomy: An observational study

Dexmedetomidine and Perioperative Arrhythmias

The highly selective α2-adrenoceptor agonist dexmedetomidine is a commonly used sedative drug for patients undergoing anesthesia and intensive care treatment. Several studies have indicated that dexmedetomidine may have a potential role in preventing and treating perioperative tachyarrhythmias. However, the specific effect and mechanism of action of dexmedetomidine in this context remain unclear. Dexmedetomidine is known to regulate the electrophysiologic function of the myocardium by inhibiting the function of the sinus node and atrioventricular node, as well as affecting myocardial repolarization. This paper aims to provide a theoretical basis for the prevention and treatment of perioperative arrhythmias by summarizing the effects of dexmedetomidine on myocardial electrophysiologic function and its impact on different types of arrhythmias.

Recent Advances in the Clinical Value and Potential of Dexmedetomidine

Dexmedetomidine, a highly selective α2-adrenoceptor agonist, has sedative, anxiolytic, analgesic, sympatholytic, and opioid-sparing properties and induces a unique sedative response which shows an easy transition from sleep to wakefulness, thus allowing a patient to be cooperative and communicative when stimulated. Recent studies indicate several emerging clinical applications via different routes. We review recent data on dexmedetomidine studies, particularly exploring the varying routes of administration, experimental implications, clinical effects, and comparative advantages over other drugs. A search was conducted on the PubMed and Web of Science libraries for recent studies using different combinations of the words “dexmedetomidine”, “route of administration”, and pharmacological effect. The current routes, pharmacological effects, and application categories of dexmedetomidine are presented. It functions by stimulating pre- and post-synaptic α2-adrenoreceptors within the central nervous system, leading to hyperpolarization of noradrenergic neurons, induction of an inhibitory feedback loop, and reduction of norepinephrine secretion, causing a sympatholytic effect, in addition to its anti-inflammation, sleep induction, bowel recovery, and sore throat reduction effects. Compared with similar α2-adrenoceptor agonists, dexmedetomidine has both pharmacodynamics advantage of a significantly greater α2:α1-adrenoceptor affinity ratio and a pharmacokinetic advantage of having a significantly shorter elimination half-life. In its clinical application, dexmedetomidine has been reported to present a significant number of benefits including safe sedation for various surgical interventions, improvement of intraoperative and postoperative analgesia, sedation for compromised airways without respiratory depression, nephroprotection and stability of hypotensive hemodynamics, reduction of postoperative nausea and vomiting and postoperative shivering incidence, and decrease of intraoperative blood loss. Although the clinical application of dexmedetomidine is promising, it is still limited and further research is required to enhance understanding of its pharmacological properties, patient selection, dosage, and adverse effects.

Awake craniotomy with dexmedetomidine during resection of brain tumours located in eloquent regions

INTRODUCTION

An awake craniotomy (AC) is the gold standard for the resection of supra-tentorial brain tumours in eloquent areas. Intraoperative monitoring "on-demand" of essential eloquent brain functions and the increasing need to preserve higher intellectual functions during surgery requires a unique anaesthetic approach during AC. Dexmedetomidine is considered the first-choice pharmacological agent for sedation during AC.

MATERIAL AND METHODS

Twenty-six patients with a single brain tumour located in areas of eloquent brain function were enrolled in this prospective study. The patients underwent AC under conscious sedation. Motor-evoked potentials and brainstem-evoked auditory potentials were measured using neurophysiological tests during surgery to assess brain potentials. Intraoperative brain relaxation was reached using a modified Bristow scale. Neuromonitoring and psychological tests were maintained until meningeal closure.

RESULTS

All operations were carried out successfully, and no reoperations were needed. No significant impact on circulatory and respiratory parameters was observed during conscious sedation based on dexmedetomidine. Neither instrumental airway support nor conversion to general anaesthesia was necessary. Brain relaxation was good in 84% of cases. Intraoperative epileptic episodes were observed in 15% of the patients. Neuro-logical and psychological monitoring was satisfactory. Unaltered muscle force was observed postoperatively in 88% of the patients.

CONCLUSIONS

AC performed under conscious sedation, and dexmedetomidine infusion without instrumental airway support, was safe and well-tolerated by patients with comfortable physiological sleep for most of the procedure. This approach to AC was associated with minimal risk of perioperative adverse events and may be particularly beneficial in patients with severe comorbidities.

Effect of dexmedetomidine sedation on swallowing reflex: A pilot study

Background/purpose

Swallowing reflex depression during dental treatment or oral surgery may cause water to enter the lower respiratory tract, leading to coughing, thus hindering these procedures. Based on the hypothesis that dexmedetomidine (DEX) sedation may depress swallowing reflex, we aimed to characterize its effects on swallowing reflex and elucidate the affected functions.

Materials and methods

Swallowing reflex was induced in 9 young healthy male volunteers using a 5 mL-distilled water bolus injection over 3 s through a polyethylene catheter 3 times, both under wakefulness and DEX sedation. Swallowing EMG burst duration, pre-swallow EMG activity value, swallowing EMG burst peak value, latency time, and swallowing reflex timing in relation to the respiratory cycle were analyzed.

Results

The EMG burst duration was significantly prolonged with DEX sedation [206.9 ± 90.3% (1.20 ± 0.98 s)] compared to that with wakefulness [100 ± 00% (0.53 ± 0.28 s), P = 0.007]. No significant differences in the pre-swallow EMG activity value (P = 0.343), swallowing EMG burst peak value (P = 0.218), and latency times were apparent between wakefulness and DEX sedation (P = 0.793). Distributions of timing of the swallows in relation to the respiratory cycle did not significantly differ between the two conditions (P = 0.860).

Conclusion

Our data demonstrate that DEX sedation carries a potential risk of aspiration due to swallowing reflex depression during elevation of the larynx; therefore, suctioning of water and saliva should be rigorously performed. However, peripheral muscle contraction of the submental muscle complex, neural organization function, and timing of the swallowing reflex in relation to the respiratory cycle are not affected.