Magnesium Sulfate Versus Lidocaine as Additives to Dexmedetomidine for Cough Suppression After Functional Endoscopic Sinus Surgery

Functional Endoscopic Sinus Surgery (FESS) is a widely performed procedure for the management of chronic rhinosinusitis and nasal polyposis. Despite being minimally invasive(1).Postoperative coughing, in particular, is a frequent complication that can increase venous pressure, disrupt the surgical site, cause bleeding, and prolong recovery(2).

Coughing and other airway reflexes during extubation are largely mediated by the stimulation of rapidly adapting stretch receptors (RARs) in the trachea, often aggravated by the presence of an endotracheal tube(3). Although these reflexes are suppressed under deep anesthesia, they become prominent as the patient regains consciousness. A smooth and controlled emergence from anesthesia is especially important in sinonasal procedures where postoperative bleeding can have serious consequences(4).

Postoperative sore throat (POST) is considered a minor complication of general anesthesia. POST complaints can range in severity from slight throat irritation to incapacitating discomfort that prevents swallowing, and transitory voice alterations are frequently noticed during the postoperative visit. The identified risk factors for POST following tracheal intubation include female gender, younger age, preexisting lung disease, longer anesthesia duration, and blood-stained endotracheal tube (ETT) at extubation. The ETT size, intubation techniques, and muscle relaxant use are also associated with POST development(5).

Dexmedetomidine, a highly selective alpha-2 adrenergic agonist, has emerged as another promising agent for attenuating airway reflexes. It provides sedative, anxiolytic, and sympatholytic effects without significant respiratory depression(6). Dexmedetomidine reduces central sympathetic output and modulates the arousal pathways, leading to smoother emergence and decreased airway hyperreactivity. Its ability to suppress extubation-related coughing has been demonstrated in several clinical studies, along with favorable effects on hemodynamic stability and postoperative analgesia(7).

Among the strategies employed to reduce this airway reactivity is intravenous (IV) lidocaine, it has been used effectively to blunt airway reflexes(8). It exerts its action by stabilizing neuronal membranes and inhibiting sodium channel activity, thereby decreasing the excitability of afferent airway nerves(9). IV lidocaine also reduces mucus secretion and limits tracheal irritation, resulting in fewer instances of coughing and sore throat. Its safety profile, rapid onset, and ease of administration make it a practical choice in a variety of surgical settings.

Magnesium sulfate, which acts as an NMDA receptor antagonist, is currently recognized as one of the most effective agents for the prevention and management of POST by peripheral NMDA receptors. Local application of magnesium can mitigate nociceptive stimuli caused by mucosal inflammation triggered by endotracheal intubation. Magnesium sulfate also exhibits, anti-inflammatory, and anti-edema properties for traumatic edema and inflammation(10).

Despite the individual benefits of lidocaine, Magnesium sulfate and dexmedetomidine, there is limited direct comparative data regarding their relative efficacy in preventing postoperative cough following FESS.