“A comparative study between the efficacy of a combination of dexmedetomidine with propofol versus fentanyl with propofol for insertion of ProSeal laryngeal mask airway.â€

Supraglottic airways have become a standard device for airway management filling a gap between the face mask and the tracheal tube. It allows spontaneous ventilation as well as positive pressure ventilation. A Laryngeal Mask Airway (LMA) is one of such devices which can be safely used in general anaesthesia allowing spontaneous ventilation in place of facemask without a leak. LMA insertion also has an advantage of being less stimulating to the airways than the tracheal intubation. Therefore, lesser hemodynamic changes occur in response to LMA insertion as compared to those found during tracheal intubation. ProSeal LMA is a modification of classic LMA which provides a better seal and facilitates passage of oro-gastric tube for gastric suction.

Smooth insertion of LMA needs sufficient depth of anesthesia to suppress the airway reflexes and relax the jaw muscles. Inadequate depth of anesthesia may provoke coughing, gagging, laryngospasm and may lead to adverse hemodynamic changes. Therefore, optimal conditions for LMA insertion necessitate generous use of anesthetic agents.

 Inhalational and Intravenous agents; both have been used for providing the satisfactory conditions for insertion of LMA. The intravenous (IV) anaesthetic agents are preferred over inhalational agents for insertion of LMA. Among the intravenous agents, propofol is the induction agent of choice, because of its potential suppressor effects on upper airway reflexes. Propofol when used alone often fails to provide satisfactory condition for insertion of LMA. This may lead to coughing, gagging, and even laryngospasm. In addition the higher doses of propofol required to produce adequate condition for insertion, may lead to undesirable cardiorespiratory depression. ProSeal LMA requires greater degree of anaesthetic depth for insertion as compared to classic LMA. The effective concentration of propofol (EC50 Prof LMA) required for ProSeal LMA insertion is 38% greater as compared to Classic LMA. To reduce the dose of propofol and maintain satisfactory insertion conditions various adjuvants have been combined with it in routine anaesthesia practice.

 The most commonly used adjuvant for this purpose are; muscle relaxants, benzodiazepines, opioids, ketamine and α2 receptor agonists.The adjuvants reduce the EC50 of propofol for LMA insertion; thus decreasing the absolute dose of propofol and reducing the associated side effects. Amongst the adjuvants, fentanyl is commonly combined with propofol. Fentanyl is a short acting opioid agonist commonly used in combination with propofol. It depresses the airway reflex responses in a dose related manner and potentiates the effect of propofol.

 Dexmedetomidine is a highly selective α2 receptor agonist. It produces sedative, anxiolytic and analgesic effects without causing clinically significant respiratory depression. It reduces the dose of propofol required to attain adequate depth of anaesthesia. It has also shown to diminish airway and circulatory responses during intubation and extubation.

On the basis of above observations we propose this study to compare the efficacy  of a combination of propofol and dexmedetomidine with that of propofol and fentanyl for successful ProSeal LMA insertion during general anesthesia.