Haemodynamic responses to the intubating laryngeal mask and timing of removal

We determined (a) the haemodynamic responses to intubating laryngeal mask ( ILM) airway insertion/intubation and removal in anaesthetized patients, and (b) whether the timing of ILM removal influences these responses. One-hund red and twenty patients without cardiovascular disease were studied. ILM ai rway insertion/intubation was 5 min after induction with propofol 2 mg kg(- 1) and maintenance of anaesthesia with sevoflurane 2% in oxygen 33% and nit rous oxide. Patients were randomly assigned for removal of the intubating l aryngeal mask airway at 1, 3 and 5 min after successful intubation. Systoli c and diastolic arterial pressures and heart rate were recorded preinductio n (baseline), before ILM airway insertion/intubation, at 1-min intervals af ter insertion/intubation, and at 1-min intervals for 5 min after ILM remova l. ILM insertion was successful at the first attempt in all patients, but 4 6 patients required more than one intubation attempt. Compared with baselin e values, there were no increases in systolic or diastolic arterial pressur e, but there was an increase in heart rate 1 min after ILM insertion/intuba tion (9%, P < 0.001) and 1 min after ILM removal (8%, P < 0.01). There was a significant increase in systolic and diastolic pressures and heart rate 1 min after ILM insertion/intubation (30%, 31% and 15%; all: P < 0.002) comp ared with before ILM insertion/intubation values and 1 min after ILM remova l (9%, 8% and 7%; all P < 0.05) compared with 1 min after ILM insertion/int ubation values. Removal of the ILM 1 min after successful intubation result ed in higher arterial pressure compared with removal at 3 min (systolic art erial pressure 10% higher for 1 min, P = 0.01) and 5 min (systolic arterial pressure 10-23% higher for 3 min, P < 0.01; diastolic arterial pressure 10 -20% higher for 4 min, P > 0.02), but there were no differences in heart ra te between groups. Systolic and diastolic arterial pressures were greater i f more than one intubation attempt was required. Early removal or multiple intubation attempts did not exceed baseline haemodynamic values. We conclud e that ILM insertion/intubation and removal in anaesthetized patients produ ces little or no haemodynamic response, even if multiple intubation attempt s are required. The timing of removal exerts a small, but clinically unimpo rtant influence on these responses.