Abstract
Relationship between pulmonary insufficiency and urinary catecholamines excretion in 34 patients with hypertensive intracerebral hemorrhage or subarachnoid hemorrhage in the acute stage was evaluated. The hypoxemia was not induced by pulmonary hypoventilation but by an increase in alveolar-arterial oxygen difference. As it was known that administration of catecholamines brought an increase in intrapulmonary shunt, the relationship between alveolar-arterial oxygen difference and urinary catecholamines excretion was investigated. Alveolar-arterial oxygen difference positively correlated with urinary catecholamines excretion. The patients with increased alveolar-arterial oxygen difference had an increased intrapulmonary shunt. Maximum diameter of hematoma in 20 patients with hypertensive intracerebral hemorrhage had a significantly positive correlation with their alveolar-arterial oxygen difference. Administration of phentolamine and propranolol decreased the intrapulmonary shunt followed by a decrease in alveolar-arterial oxygen difference through reducing pulmonary vascular resistance and cardiac output, respectively. Trimethaphan camsilate also decreased these two values without any change in pulmonary vascular resistance or cardiac output. From these facts, it can be speculated that an overactivity of the sympathetic nerves exists in the acute stage of hypertensive intracerebral hemorrhage and subarachnoid hemorrhage, and that elevated catecholamines play an important role in increasing the intrapulmonary shunt followed by hypoxemia through acting on the pulmonary vascular bed, through action on the efferent sympathetic nerves to the pulmonary vascular bed, and/or through increasing cardiac output.
