Studies on autonomic blockade. II. Observations on the nature of blood pressure fall with high selective spinal anesthesia in pregnant women.

In the preceding report (p. 1354 of this issue) it was demonstrated that normal pregnant females at term respond with a striking fall in blood pressure to autonomic blockade with high selective spinal anesthesia or TEAC. With the former, severe side effects, such as nausea, vomiting, cyanosis, fatigue and other symptoms of imminent circulatory collapse, were present while with the latter, these symptoms were absent although the hypotensive levels were the same. This suggested to us the necessity for further investigation on the nature of blood pressure fall with high selective spinal anesthesia in pregnant women. Among the factors considered of importance in the genesis of spinal hypotension are the following: