• A N Akbar, M Muzi, C W Lopatka, and T J Ebert.
• Department of Anesthesiology, VA Medical Center, Milwaukee, Wisconsin, USA.
• J Clin Anesth. 1996 May 1;8(3):194-7.

Study ObjectiveTo compare the sympathetic and hemodynamic responses to intubation with either an endotracheal tube (ETT) or laryngeal mask airway (LMA).DesignProspective, randomized, single-blinded study.SettingThe in vivo study was carried out in an experimental laboratory.Patients16 healthy male consenting volunteers, ages 20 to 31 years, were studied.InterventionsAfter placement of a radial artery catheter, ECG electrodes, and a recording needle in the peroneal nerve, subjects were anesthetized with propofol 2.5 mg/kg, paralyzed with vecuronium 0.15 mg/kg, and ventilated via mask for 5 minutes with oxygen and 0.5 MAC desflurane or 0.5 MAC isoflurane. A LMA or ETT was inserted and neurocirculatory responses were continuously recorded.Measurements And Main ResultsMeasurements of heart rate (HR), mean arterial pressure (MAP), and sympathetic nerve activity (SNA) were made at preintubation baseline and at the peak response after airway manipulation. The time to recovery to 20% and 10% of baseline MAP and HR also was measured. Neurocirculatory variables did not differ in either the LMA (n = 7) or ETT (n = 9) groups immediately prior to intubation. The ETT group demonstrated a 27% HR increase and a 42% MAP increase compared with a 12% HR increase and a 23% MAP increase in the LMA group. Muscle SNA increased 600% in the ETT group versus 66% in the LMA group (p < 0.01). The time to return MAP and HR to 20% and 10% of perintubation baseline was significantly longer in the ETT than the LMA group (p < 0.01).ConclusionsBecause of the substantial reduction in the neurocirculatory responses to the LMA versus ETT, the LMA may prove advantageous in patients in whom HR and MAP increases may predispose to adverse cardiac or cerebrovascular events.

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