Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Vet J. 2013 Jun;196(3):325-31. doi: 10.1016/j.tvjl.2012.12.018. Epub 2013 Feb 8.
The mouth-gag is a common tool used in veterinary medicine during oral and transoral procedures in cats but its use has recently been associated with the development of blindness. The goal of this study was to investigate whether maximal opening of the mouth affects maxillary artery blood flow in six anesthetized cats. To assess blood flow, the electroretinogram (ERG), brainstem auditory evoked response (BAER) and magnetic resonance angiography (MRA) were evaluated qualitatively with the mouth closed and open. During dynamic computer tomography (CT) examinations, detection of contrast medium in the maxillary artery was quantified by measuring the Hounsfield units (HUs). The peak HU, time to peak and mean HU were determined. Changes ⩾10% of these parameters were considered indicative of altered blood flow. ERG and BAER were normal with the mouth closed in all cats, but was abnormal with the mouth opened maximally in two cats and one cat, respectively. During MRA, blood flow was undetected in either maxillary artery in one cat and reduced in the right maxillary artery in two cats, when the mouth was open. During CT, the peak HU decreased ⩾10% in three cats, the time to peak was ⩾10% longer in two cats, and the mean HU was ⩾10% lower in one cat when the mouth was open. No cat developed apparent blindness or deafness. Maximal opening of the mouth caused alterations in several indicators of blood flow in some individual cats.
口塞是兽医在猫进行口腔和经口腔手术时常用的工具，但最近其使用与失明的发生有关。本研究的目的是调查口部最大张开是否会影响麻醉状态下 6 只猫的上颌动脉血流。为了评估血流，通过闭眼和张口时评估视网膜电图（ERG）、脑干听觉诱发电位（BAER）和磁共振血管造影（MRA）定性。在动态计算机断层扫描（CT）检查期间，通过测量亨氏单位（HU）来定量检测上颌动脉中的造影剂。确定峰值 HU、达到峰值的时间和平均 HU。这些参数的变化≥10%被认为表明血流发生改变。在所有猫中，口部紧闭时 ERG 和 BAER 均正常，但在 2 只猫和 1 只猫中，口部最大张开时异常。在 MRA 中，当口部张开时，1 只猫的左右上颌动脉均未检测到血流，2 只猫的右侧上颌动脉血流减少。在 CT 中，3 只猫的峰值 HU 下降≥10%，2 只猫的达到峰值的时间延长≥10%，1 只猫的平均 HU 下降≥10%。没有猫出现明显的失明或耳聋。口部最大张开会导致一些个体猫的一些血流指标发生变化。
