OBJECTIVETo explore the substantial resection limits of CO2 laser surgery for hypopharynx and the course of wound healing in animals, for the purpose of evaluating the clinic usefulness of transoral CO2 laser surgery in the treatment of selected hypopharyngeal carcinomas.

METHODSTwenty-three dogs were randomly assigned to two groups. Group one (11 dogs) received left piriform sinus resection, group two (12 dogs) received the resection of posterior wall of the hypopharynx. Six dogs in group one were killed immediately or 4, 8, 12, 16, 20 d post-operatively. Seven dogs in group two were killed immediately or 7, 14, 21, 28, 35, 42 d post-operatively. The whole larynx and hypopharynx were taken out and the specimens were examined by naked eyes and under microscope. The other 5 dogs in each group were fed until the wound healed, the duration were observed.

RESULTSAll the operations were successful and the results were satisfactory. In group one, the dogs could take food the day after operation; two dogs had slight cough during eating and recovered after five days. In group two, the dogs could take food the next day after operation, eight dogs had slight cough during eating and recovered after ten days. The excision dimension was satisfactory. In group one (resection of the lateral wall of piriform sinus), the size of raw surface was (7.5 +/- 0.8) cm2 (x +/- s) and the healing time was (18.4 +/- 1.5) d. In group two (resection of the posterior wall of the hypopharynx), the wound surface was (7.0 +/- 0.5) cm2 and the healing time was (39.8 +/- 1.9) d. The healing time in group two was significantly longer than that in group one (t = 19.535, P <0. 01). The post-operative healing process were observed, including cellulose membrane coverage, granulation filling and epithelization.

CONCLUSIONSTransoral CO2 laser was suitable for partial hypopharynx resection. Animals can recuperate well with little complications. Although the course of wound healing was delayed, wound surface can recover with good laryngeal and deglutition functions.