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To compare two protocols of combined parenteral general anesthesia, the authors analyzed electrocardiographic changes in anesthetized rats undergoing left pneumonectomy. One group of rats was anesthetized with a combination of medetomidine and ketamine (group 1, n = 10), and the other was injected with diazepam and ketamine (group 2, n = 10). Investigators obtained two electrocardiograms from each rat, one before surgery (5 min after anesthesia) and one after surgery (60 min after anesthesia). Anesthetic induction was quick for all rats, though four rats in group 2 died before surgery. Mean cardiac frequency and R-wave amplitude were significantly lower in rats in group 1 than in rats in group 2. Rats in group 1 received injections of atipamezole about 60 min after surgery, which reversed the effects of medetomidine; these rats regained voluntary respiratory movement more quickly than did rats in group 2. Two additional rats in group 2 died during postsurgical recovery. These results suggest that for thoracic surgery in rats, medetomidine-ketamine is an appropriate anesthetic combination, may be safer than diazepam-ketamine and yields a shorter recovery time.

Objetivo Valorar la lesion de isquemia-reperfusion y el rechazo agudo precoz del pulmon sometido a un tiempo de isquemia de 10 h. Material y metodos Se han utilizado 30 ratas Sprague-Dawley, en 15 de las cuales se realizo un trasplante pulmonary izquierdo con tiempos de isquemia de 4 h (n = 5), 6 h (n = 5) y 10 h (n = 5). Del donante se extrajo el bloque cardiopulmonar, se diseco el pulmon izquierdo y se efectuo el implante con la tecnica de manguitos (cuffs) . A las 48 h se extrajo el bloque cardiopulmonar. Se valoraron la evolucion postoperatoria, la lesion de isquemia-reperfusion y el rechazo agudo del χ 2 pulmon trasplantado y del contralateral. El analisis estadistico se realizo con el test de la χ 2 y el test exacto de Fisher para el calculo de probabilidades. Resultados Los animales trasplantados con un tiempo de isquemia de 10 h no tuvieron peor evolucion clinica (p = 0,711). No se observaron diferencias significativas entre los parametros histologicos de lesion de isquemia-reperfusion y de rechazo agudo con los distintos tiempos de isquemia, ni en la evolucion clinica por la presencia y gravedad de estos. Tampoco se observo que el rechazo agudo se relacionara con la lesion de isquemia-reperfusion (p > 0,05). Conclusiones En nuestro estudio, el tiempo de isquemia pulmonar prolongado de 10 h no se asocia ni a lesiones de isquemia-reperfusion y rechazo agudo mas graves ni a una peor evolucion clinica. El rechazo agudo no se relaciona con la presencia ni con la gravedad de la lesion de isquemia-reperfusion.

OBJECTIVE To assess ischemia–reperfusion injury and early acute rejection of the lung subjected to ischemia for 10 hours. MATERIAL AND METHODS Fifteen of 30 Sprague–Dawley rats underwent transplantation of a left lung that had been subjected to ischemic times of 4 (n=5), 6 (n=5), or 10 hours (n=5). The cardiopulmonary block was removed from the donor, the left lung was dissected, and the transplant was carried out using the cuff technique. The cardiopulmonary block was extracted after 48 hours. We assessed postoperative progress, ischemia–reperfusion injury and acute rejection of the transplanted and contralateral lungs. Statistical probabilities were analyzed using the χ 2 and Fisher exact tests. RESULTS Clinical course was not worse after an ischemic time of 10 hours (=.711). No significant differences were observed in histological markers of ischemia–reperfusion injury and acute rejection or in clinical course in relation to the different ischemic times; nor was clinical course related to the presence or severity of lesions or rejection. Similarly, acute rejection was unrelated to ischemia–reperfusion injury (>.05). CONCLUSIONS In this study, a prolonged ischemic time of 10 hours was not associated with ischemia–reperfusion injuries, with more severe acute rejection, or with a worse clinical course. Acute rejection was also unrelated to the presence or severity of ischemia–reperfusion injury.