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Titolo:
THE EFFECTS OF HALOTHANE, ISOFLURANE, AND ENFLURANE ON THERMOREGULATORY RESPONSES IN THE NEURAXIS OF CATS
Autore:
FARBER NE; POTERACK KA; KAMPINE JP; SCHMELING WT;
Indirizzi:
MED COLL WISCONSIN,DEPT ANESTHESIOL,MED EDUC BLDG,ROOM 462C,8701 W WATERTOWN PLANK RD MILWAUKEE WI 53226 MED COLL WISCONSIN,DEPT ANESTHESIOL MILWAUKEE WI 53226 ZABLOCKI VET AFFAIRS MED CTR,ANESTHESIOL SERV MILWAUKEE WI 00000 MED COLL WISCONSIN,DEPT PHARMACOL & TOXICOL MILWAUKEE WI 53226
Titolo Testata:
Anesthesiology
fascicolo: 4, volume: 80, anno: 1994,
pagine: 879 - 891
SICI:
0003-3022(1994)80:4<879:TEOHIA>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
THERMAL-STIMULATION; PREOPTIC REGION; ANESTHESIA; SLEEP; HYPOTHERMIA; HUMANS; HYPOTHALAMUS; WAKEFULNESS; THRESHOLD; NEURONS;
Keywords:
ANESTHETICS, VOLATILE, ENFLURANE HALOTHANE ISOFLURANE; MEASUREMENT TECHNIQUES, ELECTROMYOGRAPHY; TEMPERATURE, THERMOREGULATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
46
Recensione:
Indirizzi per estratti:
Citazione:
N.E. Farber et al., "THE EFFECTS OF HALOTHANE, ISOFLURANE, AND ENFLURANE ON THERMOREGULATORY RESPONSES IN THE NEURAXIS OF CATS", Anesthesiology, 80(4), 1994, pp. 879-891

Abstract

Background: Normal thermoregulatory function is believed to be modulated by thermosensitive neurons in the preoptic region of the anterior hypothalamus and other sites within the central nervous system including the spinal cord. Previous evidence has demonstrated modulation of segmental spinal cord thermoregulatory mechanisms from more rostral central nervous system sites. The ability of the volatile anesthetics to disrupt normal thermoregulatory function and produce shivering-like activity during emergence is well documented. The purpose of the currentinvestigation was to examine the action of the volatile anesthetics halothane, isoflurane, and enflurane on thermoregulatory responses produced at the preoptic region and spinal cord. Methods: Cats were chronically instrumented with bilateral cannulas allowing selective heating and cooling of the preoptic region. Electrodes were implanted in hindlimb and forelimb muscles for electromyographic (EMG) analysis. Animalsunderwent selective heating and cooling of the preoptic region in theawake state, during volatile agent anesthesia and during emergence. In a separate series of animals, pontine-transected cats with epidural thermodes and a thermocouple underwent alternate heating and cooling of the spinal cord. Heating and cooling was performed in the nonanesthetized state, at graded concentrations of halothane, and during emergence. In all animals, deep core peritoneal temperature, epidural spinal cord temperature, forelimb and hindlimb EMG activity were continuouslyrecorded and digitally processed. EMG responses in both experiments were quantitated and analyzed for power spectral density. Results: In the chronically prepared animals, heating and cooling of the preoptic region in the conscious state resulted in appropriate thermoregulatory responses, including shivering-like activity and increased EMG power with preoptic region cooling. Halothane, isoflurane, and enflurane eachabolished these thermoregulatory responses. During emergence from anesthesia, however, the typical spontaneous increases in EMG power observed at normothermia were significantly attenuated by heating of the preoptic region and augmented by cooling of the preoptic region. In the acutely prepared animals, cooling of the spinal cord produced graded increases in EMG activity. Increased concentrations of halothane dose-dependently diminished this response to cooling of the spinal cord. During emergence, cooling of the spinal cord resulted in a shivering response similar to those observed during control conditions. Conclusions:The ability of preoptic region heating and cooling to modulate postanesthetic shivering implies that while thermoregulatory pathways remainintact, volatile anesthetics produce an imprecision in the control ofthermoregulatory responses at the level of the anterior hypothalamus. Attenuation of shivering-like responses generated at spinal cord levels in pontine-transected cats implies a significant blunting action ofthermoregulatory response mechanisms at the level of the spinal cord or lower brain stem.

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Documento generato il 30/09/20 alle ore 09:45:20