Comparison of haemodynamic responses to laryngeal mask airway insertion and laryngoscopy with endotracheal intubation in adults undergoing elective surgery at Muhimbili

Abstract

Background Airway management is of utmost importance during delivery of general anaesthesia. Traditionally, laryngoscopy and endotracheal tube (ETT) insertion has been the mainstay in providing adequate airway management and delivering anaesthesia. The laryngeal mask airway (LMA) offers a much less invasive way of maintaining the airway as it does not pass through the glottis but is placed over the glottis. It does not require the use of the laryngoscope. Laryngoscopy and tracheal intubation or laryngeal mask airway insertion are noxious stimuli which provoke a transient but marked sympathetic response manifesting as hypertension and tachycardia. In susceptible patients particularly those with systemic hypertension, coronary heart disease, cerebrovascular disease and intracranial aneurysm, even these transient changes can result in potentially deleterious effects like left ventricular failure, arrhythmias, myocardial ischaemia, cerebral haemorrhage and rupture of cerebral aneurysm. Objective To determine the haemodynamic response elicited by laryngoscopy and endotracheal intubation and compare it with that elicited by laryngeal mask insertion in ASA I and ASA II patients, undergoing elective surgeries at Muhimbili national Hospital (MNH) and Muhimbili Orthopaedic Institute (MOI) in 2011. Methods A hospital based prospective randomized comparative study was conducted to determine the haemodynamic response elicited by laryngoscopy and endotracheal intubation and compare it with that elicited by laryngeal mask insertion in ASA I and ASA II patients, undergoing elective surgeries at MNH and MOI . After induction of anaesthesia either an ETT or LMA was inserted. Evaluations included measurement of blood pressure and heart rates before insertion, after insertion of device, 1 minute, 3 minutes and 5 minutes after insertion. Measuments were taken from the Drager infinity gamma XL monitor. Time and ease of insertion was also noted.Results There was an increase in HR, SBP and DBP seen after laryngoscopy and ETT insertion as well as after laryngeal mask insertion. The change in haemodynamic parameters after laryngoscopy and ETT insertion were significantly greater than those elicited by LMA insertion (p<0.0001). The increase took about 5 minutes to return to pre insertion values in the ETT group, while it took about 3 minutes for the same values to return to pre insertion values in the LMA group. It took a significantly shorter time to insert an LMA (12.63 sec) as compared to time taken to insert an ETT (22.76 sec). Insertion of an LMA was rated easy in 84% of the patients while it was rated easy in 60% of the ETT patients. Conclusion The haemodynamic changes elicited by LMA insertion are less and short lived compared to those elicited by laryngoscopy and ETT insertion. It takes a shorter time and is much easier to insert an LMA as compared to laryngoscopy and ETT insertion. These changes might be insignificant in a normotensive patient, but could be harmful in a patient with cerebrovascular or cardiovascular abnormalities. The use of an LMA is recommended in these groups of patients.