Circulatory Factors in Adrenal Crisis in the Dog

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Abstract
Arterial pressure, heart rate, cardiac index and resistance were followed simultaneously in adrenalectomized dogs in terminal adrenal insufficiency, acute crisis produced by minor amounts of trauma or hemorrhage in dogs still apparently healthy, and acute crisis following a bilateral adrenal removal at a single operation. In all, the development of circulatory crisis was initiated by a sharp fall in resistance and in blood pressure. Unlike the normolemic intact dog, a rise in cardiac index did not follow this resistance fall. The available reserve blood volume, as measured by the response to Isuprel, was subnormal before the resistance decline, and fell progressively during the crisis. The pressor response to epinephrine was probably not normal before crisis, but did not obviously diminish until shortly before death. Pressor responses to more weakly active pressor agents were progressively reduced in early crisis. The pressor response to efferent nerve stimulation was lost early, although respiratory response was still present. An exaggerated, or a prominent because unopposed, vagal reflex was common. All animals showed a marked sensitivity to anesthesia. Heart size was not only small but fixed as the filling time was altered. It is argued that a reasonable explanation of these findings may lie in a metabolic failure of the nervous system, one characteristic of which is a loss of sympathetic function.
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