Neuroscience Letters 373 (2005) 165–170 Importance of anesthesia for the genesis of neurogenic pulmonary edema in spinal cord injury Manoel Baldoino Leal Filho a , Rosana Celestina Morandin b , Amanda Roberta de Almeida b , Elizabeth Cristina Cambiucci b , Guilherme Borges c , Jose Antonio Rocha Gontijo b,d , Konradin Metze b,e,* a Curso de P ´ osgradua¸ c˜ ao em Ciˆ encias M´ edicas, Faculdade de Ciˆ encias M´ edicas, Universidade Estadual de Campinas, P.O. Box 6111, 13084-971 Campinas, SP, Brazil b N´ ucleo de medicina e Cirurgia Experimental, Faculdade de Ciˆ encias M´ edicas, Universidade Estadual de Campinas, P.O. Box 6111, 13084-971 Campinas, SP, Brazil c Disciplina de Neurocirurgia, Faculdade de Ciˆ encias M´ edicas, Universidade Estadual de Campinas, P.O. Box 6111, 13084-971 Campinas, SP, Brazil d Departamento de Clinica M´ edica, Faculdade de Ciˆ encias M´ edicas, Universidade Estadual de Campinas, P.O. Box 6111, 13084-971 Campinas, SP, Brazil e Departamento de Anatomia Patol´ ogica, Faculdade de Ciˆ encias M´ edicas, Universidade Estadual de Campinas, P.O. Box 6111, 13084-971 Campinas, SP, Brazil Received 25 June 2004; received in revised form 29 September 2004; accepted 2 October 2004 Abstract There are reports describing both provocation and inhibition of neurogenic pulmonary edema by anesthetic drugs. Therefore, we compared the effect of two types of anesthesia on the formation of neurogenic pulmonary edema in rats with balloon-induced acute spinal cord injury. Animals with sham procedure (group 1) were anesthesized by intraperitoneal sodium pentobarbital. In the experimental groups, rats were submitted to acute spinal cord lesion by insufflations of a balloon in the epidural space at T8 for 1 min (group 3 under i.p. sodium pentobarbital and group 2 under i.p. xylazine–ketamine anesthesia). In rats with pentobarbital anesthesia, systolic blood pressure doubled the baseline value during compression, whereas this effect was less pronounced in the ketamine–xylazine group. The pulmonary index (100 × wet lung weight/body weight) was 0.395 (±0.018) in sham-operated rats, rose to 0.499 (±0.060) in group 2, and was maximum under pentobarbital anesthesia (0.639 ± 0.14; p = 0.0018). Histologic examination of the spinal cord showed parenchymal ruptures and acute hemorrhage. Comparison of the pulmonary index with histologic slides of lung parenchyma revealed that relevant intra-alveolar edema occurred only for index values above 0.55. On electron microscopy, endothelial alterations, and damage of the alveolar lining cells were found. Our study indicates that neurogenic pulmonary edema caused by spinal cord injury is less pronounced in rats under xylazine–ketamine anesthesia, when compared with pentobarbital. © 2004 Elsevier Ireland Ltd. All rights reserved. Keywords: Spinal cord injury; Neurogenic pulmonary edema; Pentobarbital; Xylazine; Ketamine In patients with spinal cord injuries respiratory complications are still an important cofactor of morbidity and mortality [32]. Pulmonary edema has been described after spinal cord injury in man [2–3,24,29]. Yet, the pathogenetic mechanisms pro- voking neurogenic edema are still under debate [6,30,32]. Both the release of vasoactive substances and a rapid tran- * Corresponding author. Tel.: +55 19 32893897; fax: +55 19 32893897. E-mail address: kmetze@fcm.unicamp.br (K. Metze). sient severe sympathetic discharge are thought to participate in this process [30,32]. Different experimental models in ro- dents, which simulate the traumatic spinal lesions seen in humans, have been described [30]. There is not only a consid- erable variation in the experimental way to induce spinal le- sions, but also in the anesthetic protocols. Pharmacologically different substances, such as pentobarbital [11,16,25,31] or ketamine [14,28,33] are used for anesthesia in experimental neurosurgical procedures. The type of anesthesia might be 0304-3940/$ – see front matter © 2004 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2004.10.019