[Preferential delivery of emulsified isoflurane to peripheral nerves in goats]

To develop a new model for preferential delivery of isoflurane to peripheral nerves in goats, and to identify preliminarily volatile anesthetic action sites.

Eighteen goats were randomly and equally divided into arterial group, control group and venous group. In the arterial group, emulsified isoflurane was infused into the femoral artery of the goats to deliver isoflurane to the peripheral nerves. In the control group, 30% Intralipid which used as a solvent of emulsified isoflurane was infused via the femoral artery of the goats with the same infusing speed as that of the arterial group. In the venous group, emulsified isoflurane was infused via an ear peripheral vein. Minimum partial pressure (MPP), the partial pressure (Piso) of isoflurane in blood producing immobility in 50% of the goats exposed to noxious stimuli, was determined with an up-and-down method and a noxious stimulus by clamping the dew-claw of the hindlimbs of the goats in the arterial group and the control group, or the dew-claw of the hindlimb of the goats in the venous group.

No isoflurane was found in the jugular and femoral veins of the goats in the control group, and normal nociceptive reflexeswere maintained. The MPP of the femoral vein of the goats from the control group did not differ from the MPP of the jugular vein of the goats from the arterial and venous groups. The MPP of femoral vein p was 7 times of that of jugular vein ](38.45 +/- 17. 01) mmHg vs. (5.82 +/- 2.32) mmHg, 1 mmHg = 0.1333 kPa, P < 0.05] in the goats from the arterial group, and 4 times of that of jugular vein in the goats from the venous group [(9.41 +/- 1.61) mmHg, P < 0.05]. The MPP of jugular vein in the goats from the arterial group was about half of that of the goats in the venous group.

A new model of preferential delivery of isoflurane to the peripheral nerves in goats has been developed. Only Piso higher than that used in clinical anesthetic range has a significant anesthetic effect on peripheral nerves.