Neurocirculatory responses to intubation with either an endotracheal tube or laryngeal mask airway in humans.
OBJECTIVE
To compare the sympathetic and hemodynamic responses to intubation with either an endotracheal tube (ETT) or laryngeal mask airway (LMA).


METHODS
Prospective, randomized, single-blinded study.


METHODS
The in vivo study was carried out in an experimental laboratory.


METHODS
16 healthy male consenting volunteers, ages 20 to 31 years, were studied.


METHODS
After 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.


RESULTS
Measurements 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).


CONCLUSIONS
Because 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.
Akbar
A N
AN
Department of Anesthesiology, VA Medical Center, Milwaukee, Wisconsin, USA.
Muzi
M
M
Lopatka
C W
CW
Ebert
T J
TJ
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D001808:Blood Vessels / Q000294:innervation*; D006801:Humans; D007442:Intubation, Intratracheal; D017214:Laryngeal Masks; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply*; D011446:Prospective Studies; D012016:Reference Values; D016037:Single-Blind Method; D013564:Sympathetic Nervous System / Q000187:drug effects*