Changes in heart rate and blood pressure during epidural tap
Tamura, T.; Yokoyama, K.
Masui. Japanese Journal of Anesthesiology 34(4): 477-482
1985
ISSN/ISBN: 0021-4892 PMID: 4021096 Document Number: 246288
During epidural tap, the changes of heart rate and blood pressure were monitored and recorded continuously in 60 elective surgical patients aged 21-79 yr. These patients were divided into 2 groups. The 1st group consisted of 39 patients without atropine premedication, and the 2nd group consisted of 21 patients with atropine premedication (7 patients received i.m. injection and 14 patients i.v. injection). All patients were placed on ECG monitoring and 34 patients were cannulated in radial artery for blood pressure measurement before lumbar epidural tap. Then patient was placed on right or left recumbent position and had lumbar epidural tap. During epidural tap, a transient fall in heart rate was observed in 76.9% of the 1st group and in 49.6% of the 2nd group. A transient fall in blood pressure was observed in 60.0% of the 1st group and in 44.4% of the 2nd group. From anatomical and physiological points, the cause of this heart rate and blood pressure fall is probably vagal reflex. During epidural tap, the tip of Touhy needle stretches the dura when it reaches the epidural space. Dura mater is innervated by vagal nerve and once it is stretched by a needle or a continuous epidural cateter, vagal type reflex may be observed. This vagal type of reflex was very transient and overcome uneventfully in all these cases. This reflex might be trouble in a patient who has severe coronary artery sclerosis or hypertension.