IV dexmedetomidine vs IV lidocaine in attenuating airway reflexes during recovery of thyroidectomy patients

The Takeaway

Following thyroid surgery, dexmedetomidine was more effective in reducing the cough reflex during the tracheal extubation period.

Study Design

• 140 participants
• ASA I or II
• Exclusion Criteria: ASA class III or IV, refusing the procedure or study participation, patients with asthma, chronic cough,or symptoms of an upper respiratory infection prior to surgery, current smokers, those taking ACE inhibitors,those with sinus bradycardia (less than 60 beats per min), and those with a history of heart block or beta-blockers were excluded.
• Precedex Arm: loading dose 0.5 μg/kg 10 min before induction, followed by infusion @0.4 μg/kg/hour until 30 min prior to completion
• Lidocaine Arm: loading dose of 1.5mg/kg lidocaine 2% 10 min before induction. Then infusion of lidocaine @1.5 mg/kg/hour until 30 min prior to completion.

Physiology Refresh

Precedex is a highly selective alpha-2 adrenergic receptor agonist that works primarily through the following mechanisms:

Primary Mechanism: Alpha-2 Adrenergic Receptor Activation

Dexmedetomidine binds with high selectivity to alpha-2 receptors (particularly the alpha-2A subtype) with an alpha-2 selectivity ratio of approximately 1600:1. This is significantly higher than clonidine, another alpha-2 agonist.

Central Nervous System Effects

1. Locus Coeruleus: The primary site of action is the locus coeruleus in the brainstem, where dexmedetomidine inhibits norepinephrine release by presynaptic activation of alpha-2 receptors.
2. Sedation: Unlike traditional sedatives (benzodiazepines, propofol), dexmedetomidine produces a unique "arousable sedation" resembling natural sleep. Patients can be easily awakened and remain cooperative even during sedation.
3. Anxiolysis: Reduces anxiety without significant respiratory depression.

Analgesic Effects

Dexmedetomidine produces analgesia through:

• Inhibition of substance P release in the dorsal horn of the spinal cord
• Activation of alpha-2 receptors in the spinal cord
• Modulation of descending noradrenergic pathways

The analgesic effect is moderate but can significantly reduce opioid requirements.

Sympatholytic Effects

1. Hemodynamic effects: Produces a biphasic cardiovascular response:
   • Initial transient hypertension (due to peripheral alpha-2B receptor activation)
   • Followed by hypotension and bradycardia (due to central sympatholytic effects)
2. Reduces plasma catecholamine levels by up to 90%

Other Physiological Effects

1. Minimal respiratory depression: Unlike opioids and other sedatives, dexmedetomidine preserves respiratory drive even at higher doses.
2. Anti-shivering properties: Useful for hypothermia management and post-anesthetic shivering.
3. Neuroprotective potential: May reduce ischemic injury through several mechanisms including modulation of apoptosis.
4. Organ-protective effects: Some evidence suggests protective effects on heart, kidney, and brain tissue, likely through anti-inflammatory and anti-oxidant properties.

Excerpts

bleeding after thyroidectomy is still a major concern and is frequently linked to serious side effects such cardiac arrest, reoperation, and cervical hematoma.

Deep extubation lowers cardiopulmonary stimulation and lowers the risk of coughing

postoperative coughing was less in the dexmedetomidine group; where only 5 patients experienced severe cough, compared to the lidocaine group where 15 patients had severe cough

dexmedetomidine also modulate the inflammatory process, responsible for airway hyperactivity by decreasing the levels of IL-6 and TNF–α and attenuating tracheal ring contraction caused by exogenous acetylcholine and the C-fiber mediated contraction

there was significant difference regarding heart rate, where 8 patients of the dexmedetomidine group had bradycardia

there were no statistically significant differences between the groups regarding the postoperative pain or analgesic intake.

Abstract

Background: Cardiac and other airway reflexes are linked to intubation and extubation processes. These hemodynamic and respiratory responses during extubation have previously been attenuated with the use of intratracheal instillation and intravenous administration of lidocaine. In surgical intensive care units, dexmedetomidine, a strong α2 receptor agonist, considered to make extubation easier. However, its effect on reducing cardiopulmonary reflexes during extubation process under general anesthesia is currently being investigated.

Objective:  To evaluate the capability of IV lidocaine or Dexmedetomidine to suppress the coughing reflex during extubation process following thyroid surgery.

Methods: This clinical trial was carried out in the operating rooms of Ain shams university hospitals. It included 140 participants, with 70 patients in each group. NCT05657028 is the clinicaltrials.gov registration number for this trial.

Results: Showed no statistically significant difference in hemodynamics in both groups regarding MAP and SpO₂. While intraoperative bradycardia has been recorded with the dexmedetomidine group in comparison with lidocaine group, also there was a decrease in the incidence of postoperative cough in dexmedetomidine group in comparison with lidocaine group and no statistically significant difference regarding the pain postoperatively.

Conclusion: Following thyroid surgery, dexmedetomidine was more effective in reducing the cough reflex during the tracheal extubation period. Both intravenous lidocaine and dexmedetomidine achieved acceptable analgesic effect. In terms of hemodynamics, intravenous infusions of dexmedetomidine caused bradycardia,

Citation

Zaher, O. N. H., Kotb, M. M., AbdelHamid, H. M., Abdelaziz, M. M., & Hafiez, R. H. A. (2025). Intravenous dexmedetomidine versus intravenous lidocaine in attenuating airway reflexes during recovery of thyroidectomy patients. Anaesthesia, Pain & Intensive Care, 29(1), 99-104.

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