STUDIES ON AUTONOMIC BLOCKADE. I. COMPARISON BETWEEN THE EFFECTS OF TETRAETHYLAMMONIUM CHLORIDE (TEAC) AND HIGH SELECTIVE SPINAL ANESTHESIA ON BLOOD PRESSURE OF NORMAL AND TOXEMIC PREGNANCY 1

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Abstract
Comparative studies were made of the effects of autonomic blockade with TEAC and high selective spinal anesthesia on the blood pressure of 5 normotensive non-pregnant women, 12 normal pregnant women and 15 toxemic patients in the prepartum and postpartum periods. High selective spinal anesthesia with a 0.2% procaine soln. was the technic selected. This technic blocks selectively the vasoconstrictor fibers and those which mediate the pinprick sensation. In all groups studied, the effects of TEAC and high selective spinal anesthesia on the blood pressure were practically parallel. A negligible fall in blood pressure was observed in normotensive non-pregnant and toxemic subjects. Marked hypotension with bradycardia and shock-like condition was observed in the prepartum periods of normal term pregnant subjects and a return of the blood pressure responses to normotensive non-pregnant levels was observed in the postpartum period. The results obtained in normal pregnancy with high selective spinal anesthesia further substantiate the hypothesis derived from expts. with TEAC that the blood pressure of such patients is supported by increased neurogenic tone and is more sensitive to the action of autonomic blockade. The lack of blood pressure response of most toxemic patients adds more evidence to the humoral theory of toxemic hypertension. The present data tend to oppose the clinical observation reported by some authors that a considerable fall in the blood pressure can be observed in all toxemic patients treated with spinal anesthesia.