Evaluation of sheep sinonasal endoscopic anatomy as a model for rhinologic research.

OBJECTIVES: Despite many publications describing sheep models for functional endoscopic sinus surgery (FESS) procedures, accurate endoscopic anatomical studies are lacking. There are no publications correlating computed tomography (CT) and 3D models with endoscopic anatomical descriptions. This study evaluates and describes the endoscopic anatomy of a sheep model. METHODS: Ten live sheep (20-sides) were included. Two cadaveric specimens, imaged using thin slice CT for 3D reconstruction correlation were also included. Using endoscopy, anatomical structures were measured and described. Measurement of the same structures was carried out using the 3D imaging model. RESULTS: Three sets of turbinates were identified at 2.3, 5.1 and 8.5 cm from the anterior nasal sill. Frontal recess and uncinate process were identified at 12.7 cm. The septum has a bony and cartilaginous component and measures 10.5 cm. The sphenopalatine foramen was measured at 12.1 cm. All anatomical measurements were correlated with the measurements on the CT scan 3D volume-rendering model, thereby allowing for an accurate description of the sheep sinonasal anatomy. CONCLUSION: This study describes the endoscopic sinonasal anatomical measurements of the adult sheep. It is the first study to evaluate the sheep CT and endoscopic anatomy in order to determine its feasibility as an animal model for research in FESS.

Rapid hemostasis in a sheep model using particles that propel thrombin and tranexamic acid.

OBJECTIVES/HYPOTHESIS: Bleeding during endoscopic sinus surgery and open surgeries can easily obstruct the surgeons' field of view and increase morbidity and risk of intraoperative complications. Intraoperative bleeding could potentially be addressed by a hemostatic agent that safely disperses itself through the escaping blood. We tested the safety and efficacy of a self-propelling formulation of thrombin and tranexamic acid (SPTT) in stopping bleeding in a paranasal sinus injury and in an open surgical carotid injury sheep model. STUDY DESIGN: Interventional animal study. METHODS: SPTT was tested in the sinonasal space following endoscopic injury to the inferior turbinate of six sheep, and to the common carotid artery following open surgical injury in eight sheep. In the nasal cavity, bleeding time and local inflammation were measured and compared to plain gauze. Following carotid arteriotomy, successful hemostasis and markers of thrombosis and coagulopathy were compared to Floseal. RESULTS: SPTT significantly decreased bleeding times in the sinonasal space compared to plain gauze (mean difference = 3.8 minutes, P = .002). All of the carotid bleeds (100%) were successfully controlled with SPTT after 10 minutes of application under pressure, compared to 25% with Floseal. No adverse events were noted, and there was no evidence of thromboembolism. CONCLUSIONS: SPTT significantly reduced bleeding time in a sheep model of surgical sinus bleeding and successfully stopped bleeding following catastrophic carotid artery injury, with no adverse events observed. LEVEL OF EVIDENCE: NA Laryngoscope, 127:787-793, 2017.