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The Vagal Factor in Foetal Heart Rate Change:II.–Some Experience with Anti‐Cholinergic Drugs
Author(s) -
Bradfield Alan
Publication year - 1962
Publication title -
australian and new zealand journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.734
H-Index - 65
eISSN - 1479-828X
pISSN - 0004-8666
DOI - 10.1111/j.1479-828x.1962.tb00668.x
Subject(s) - atropine , bradycardia , heart rate , medicine , anesthesia , anticholinergic , transplacental , umbilical cord , fetus , blood pressure , pregnancy , placenta , biology , anatomy , genetics
Summary1 The commonest type of heart rate pattern in clinically detectable foetal distress appears to result from umbilical cord complications. 2 It has a primary reflex basis. The efferent arc is the foetal vagus nerve. 3 The effect on foetal heart rate of drugs with anti‐vagal activity has been investigated during labour in 61 patients about term. 4 Atropine was given intravenously to 31 mothers who showed foetal heart rate patterns of the “cord” type. Within 15 minutes it consistently increased foetal heart rate and relieved bradycardia. When this effect was delayed there was clinical and electrocardiographic evidence to suggest an unusual degree of vagotonia. 5 Atropine was also injected directly into the foetal scalp on 14 occasions. Identical changes in heart rate were seen, except that their onset was more rapid. This is additional evidence of the specificity of action of the drug itself and of its transplacental passage. 6 Scopolamine, given to 8 mothers, altered the foetal heart rate in the same way as atropine. This action should not be overlooked when the drug is used as a sedative. 7 Scopolamine n‐butyl bromide (buscopan) injected intravenously to 8 mothers was not associated with any change in foetal heart rate. 8 Foetal heart rate is a single parameter of a complex physiological situation. Hence, the demonstrable relief of “cord” bradycardia by atropine and scopolamine must not yet be taken as licence for their use in clinically detectable foetal distress.