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Experimental total ear canal ablation with lateral tympanic bulla osteotomy (TECA-LBO) was performed in 13 normal dogs to evaluate healing and retention of brain stem auditory evoked potentials (BSAEP) after surgery. Healing was evaluated by gross and microscopic examination of the surgery sites after 1 (n = 2), 4 (n = 8), 5 (n = 1), and 6 (n = 1) weeks. One dog was eliminated from the study. Brain stem auditory evoked potentials were measured using an air-conducted sound stimulus before and after surgery and before killing. Two dogs had nearly complete obliteration of the tympanic cavity by immature fibrous connective tissue. Eight dogs responded to surgery by either complete or partial re-formation of the tympanic cavity. Retention of the tympanic membrane in three dogs promoted re-formation of the tympanic cavity and blind epithelialized pockets in the surgery site with accumulation of keratinized debris. Granulation tissue formation and extensive proliferation of new bone on the internal surface of the tympanic bulla was seen in 10 dogs. Proliferative bone completely obliterated the tympanic cavity in two of these dogs. Eleven of 13 dogs had no detectable air-conducted BSAEP after surgery. There was no change in BSAEP measurements before killing compared with postoperative measurements in any dog. Two dogs with retained tympanic membranes had measurable BSAEP after surgery. This study shows that healing after TECA-LBO may be highly variable. Retention of the tympanic membrane and small osteotomies appeared to promote reformation of tympanic cavities and prevent ingrowth of granulation tissue. New bone proliferation was frequently observed in response to curettage of the epithelium lining the tympanic bulla. Hearing, as determined by BSAEP measurements, was lost except when the tympanic membrane and ossicles were retained. Retained tympanic membranes promoted accumulation of keratinized cellular debris that could become a nidus for infection or late abscessation in some dogs. These results indicate that resection of as much of the lateral and ventral tympanic bulla as possible and removal of the tympanic membrane may provide consistently improved results after TECA-LBO.  相似文献   
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Objective —The purpose of this study was to determine the effects of phosphate-buffered saline (PBS), sterile tap water, normal saline, and Ringer's lactate on wound healing in an in vitro model.
Study Design —The effects of PBS, sterile tap water, normal saline, and Ringer's lactate on a primary line of canine embryonic fibroblasts were determined.
Animals or Sample Population —A primary line of canine embryonic fibroblasts.
Methods —The effects of the various lavage solutions were determined by (1) vital staining of the treated cells with a 0.5% trypan blue solution, (2) evaluation of the amount of lactate dehydrogenase released by the treated cells, and (3) cytopathologic evaluation of hematoxylin and eosin-stained monolayers of treated canine fibroblasts. The cells were exposed to the lavage treatments for the following time intervals: 0.5 minute, 1 minute, 2.5 minutes, 5 minutes, and 10 minutes. PBS was used as the control.
Results —Sterile tap water significantly damaged canine fibroblasts at all time intervals ( P = .05). This was attributed to the alkaline pH, hypotonicity, and presence of numerous cytotoxic trace elements in the tap water used. Cytotoxic effects were noted in fibroblasts after 10 minutes' exposure to normal saline; this may be because of the acidic pH of normal saline and lack of a buffering system. Ringer's lactate did not induce any significant fibroblast injury.
Conclusions —PBS and Ringer's lactate do not induce any significant fibroblast injury, whereas normal saline and sterile tap water cause mild and severe cytotoxic effects in vitro.
Clinical Relevance —Further clinical investigation is indicated to establish whether Ringer's lactate is the wound lavage solution of choice compared with normal saline. Sterile tap water may cause considerable fibroblast injury.  相似文献   
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Ventral tympanic bulla osteotomy was performed in 13 normal dogs to evaluate healing and retention of brain stem auditory evoked potentials (BSAEP). Healing was evaluated by gross and microscopic examination of the middle ears after 1 (n = 2), 4 (n = 8), 5 (n = 1), and 6 (n = 1) weeks. One dog was eliminated from the study. Brain stem auditory evoked potentials were measured using an air-conducted sound stimulus before and after surgery and before killing. Nine of 12 dogs re-formed the tympanic bulla by formation of fibrous connective tissue lined with cuboidal epithelium in the osteotomy site. Four of the nine dogs had a reduced tympanic bulla volume (estimated 20% to 40% volume reduction) caused by soft tissue ingrowth through the osteotomy. Nine of 12 dogs had proliferation of subperiosteal new bone from the inner surface of the tympanic bulla that varied in severity. Three of these nine dogs had nearly complete obliteration of the tympanic cavity by proliferating subperiosteal new bone. Eight dogs had nodules of granulation tissue containing new bone and mineralization diffusely distributed on the surfaces of the middle ear. The measured BSAEP sensitivity before killing was equivalent to preoperative levels in 11 dogs. The remaining dog had no change in auditory sensitivity after surgery but had a markedly reduced BSAEP detection threshold before killing. This appeared to be attributable to mechanical impingement on the ossicles and tympanic membrane by proliferating bone within the tympanic cavity. This study showed that after ventral tympanic bulla osteotomy the tympanic bulla rapidly re-forms with no deleterious effect on hearing in most dogs treated. However, the internal surfaces of the middle ear appear to be sensitive to surgical trauma, and extensive new bone proliferation is easily induced. This response may be extreme, resulting in middle ear obliteration and reduced auditory sensitivity.  相似文献   
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