An implementation of apneustic anesthesia ventilation in the horse: comparison with conventional mechanical ventilation.

OBJECTIVE: To compare the cardiopulmonary effects of apneustic anesthesia ventilation (AAV) and conventional mechanical ventilation (CMV) in dorsally recumbent anesthetized horses. STUDY DESIGN: Randomized, crossover design. ANIMALS: A total of 10 healthy adult horses from a university-owned herd. METHODS: Following xylazine, midazolam and ketamine administration, horses were orotracheally intubated and positioned in dorsal recumbency. Anesthesia was maintained with isoflurane in oxygen [inspired oxygen fraction (FiO2) = 0.3 initially, with subsequent titration to maintain PaO2 ≥ 85 mmHg (11.3 kPa)]. Horses were instrumented and ventilated with AAV or CMV for 1 hour according to predefined criteria [10 mL kg-1 tidal volume (VT), PaCO2 of 40-45 mmHg (5.3-6.0 kPa) during CMV and <60 mmHg (8.0 kPa) during AAV]. Dobutamine was administered to maintain mean arterial pressure (MAP) >65 mmHg. Cardiopulmonary data were collected at baseline, 30 and 60 minutes. The effects of ventilation mode and time were analyzed using repeated-measures anova with significance defined as p < 0.05. RESULTS: Data from nine horses were analyzed. A significant effect of mode at one or more time points was found for respiratory rate, arterial and end-tidal CO2 tensions, arterial pH, mean airway pressure (Paw), respiratory system dynamic compliance index (CrsI), venous admixture (Q˙s/Q˙t), mean pulmonary artery pressure and systemic vascular resistance. No significant differences between modes were found for VT, FiO2, PaO2, arterial hemoglobin saturation, alveolar dead space, heart rate, MAP, cardiac index, stroke volume index, oxygen delivery index, oxygen extraction ratio and dobutamine administration. CONCLUSIONS AND CLINICAL RELEVANCE: In dorsally recumbent anesthetized horses, both ventilation modes supported adequate oxygenation with minimal supplemental oxygen. Compared with CMV, AAV resulted in higher CrsI and lower Q˙s/Q˙t. Despite higher mean Paw with AAV, the cardiovascular effects of each mode were not different. Further trials of AAV in anesthetized horses are warranted.

Clinical management of Candida albicans keratomycosis in a bottlenose dolphin (Tursiops truncatus).

OBJECTIVE: Corneal ulceration secondary to trauma commonly affects marine mammals, often with opportunistic secondary bacterial or fungal infections. This report characterizes the combined use of auriculopalpebral and ophthalmic nerve blocks, adipose-derived stem cells, and subconjunctival injections for successful treatment of corneal trauma and infection in dolphins. ANIMAL STUDIED: An 11-year-old, female bottlenose dolphin (Tursiops truncatus) presented with bilateral diffuse corneal opacities, which progressed to keratomycosis caused by Candida albicans. PROCEDURE: Aggressive medical management was employed, including the use of subconjunctival injections of adipose-derived stem cells, plasma, topical and oral antifungals and antibiotics, and anti-inflammatory and pain medications. Anesthetic block of the auriculopalpebral and ophthalmic nerves was employed to evaluate the corneas. CONCLUSION: Subconjunctival injections were employed over 52 days, followed by topical drops for 5 months. At last evaluation, there was no evidence of blepharospasm bilaterally. Only a faint superficial gray corneal opacity remained OS. A temporal paraxial corneal opacity was present OD, with receding inactive vascularization and a small amount of melanosis temporally.