Retinal artery air embolism in dogs: Fluorescein angiographic evaluation of effects of hypotension and hemodilution

Cerebral air embolism can cause cerebral complications after open heart sur gery. The duration of cerebral artery occlusion by air embolism is thought to vary depending on the conditions. However, no study has evaluated factor s affecting the duration of occlusion. Ln this study, we examined the effec ts of blood pressure and hemodilution on the duration of retinal artery occ lusion caused by air embolism in dogs. The duration of retinal artery occlu sion caused by the injection of 0.6 mt of air into the common carotid arter y was measured by fluorescein angiography and compared among the following three periods: a control period, during which the mean blood pressure (MBP) was maintained at 80 mm Hg; a hypotension period, during which MBP was dec reased to 60 mm Hg by exsanguination; and a hypotension plus hemodilution p eriod, during which an additional exchange of blood with hydroxethyl starch solution was performed and MBP was maintained at 60 mm Hg. When MBP was lo wered from 80 to 60 mm Hg, the duration of retinal artery occlusion was pro longed from 34 +/- 39 to 166 +/- 30 s (P < 0.01). Ln dogs with MBP of 60 mm Hg, hemodilution (12.0 +/- 0.9 to 7.3 +/- 0.5 g/dL hemoglobin concentratio n) shortened the duration from 166 +/- 90 to 75 +/- 50 s (P < 0.05). Our re sults demonstrate that hypotension prolongs and hemodilution shortens the d uration of retinal artery occlusion caused by air embolism. Implications: W e evaluated the effects of blood pressure and hemodilution on the duration of retinal artery occlusion caused by air embolism by retinal fluorescein a ngiography. Hypotension prolonged and hemodilution shortened the duration o f retinal artery occlusion caused by air embolism.