Biomaterial Database

Magnesium sulfate, maternal hypothermia, and fetal bradycardia with loss of heart rate variability. 1998

R J Cardosi, and R A Chez

Department of Obstetrics and Gynecology, University of South Florida, Tampa, USA.

BACKGROUND Fetal bradycardia and decreased heart rate variability can indicate a nonreassuring fetal status. However, there can be iatrogenic, physiologic, or pathologic causes. METHODS A patient in premature labor received toxic levels of magnesium sulfate for tocolysis. Elevated maternal serum magnesium levels correlated inversely with maternal temperature and both fetal heart rate and fetal heart rate variability. There was also a relative decrease of the maternal heart rate from baseline. When the magnesium levels returned to normal, these vital signs returned to normal. CONCLUSIONS Magnesium sulfate therapy can result in maternal hypothermia and a decrease in fetal heart rate and heart rate variability. Maternal hypothermia might be the cause of fetal bradycardia. A direct action of magnesium on the fetal heart might be the cause of heart rate variability.

UI	MeSH Term	Description	Entries
D007035	Hypothermia	Lower than normal body temperature, especially in warm-blooded animals.	Hypothermia, Accidental,Accidental Hypothermia,Accidental Hypothermias,Hypothermias,Hypothermias, Accidental
D008278	Magnesium Sulfate	A small colorless crystal used as an anticonvulsant, a cathartic, and an electrolyte replenisher in the treatment of pre-eclampsia and eclampsia. It causes direct inhibition of action potentials in myometrial muscle cells. Excitation and contraction are uncoupled, which decreases the frequency and force of contractions. (From AMA Drug Evaluations Annual, 1992, p1083)	Magnesium Sulfate, Heptahydrate,Heptahydrate Magnesium Sulfate,Sulfate, Magnesium
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011248	Pregnancy Complications	Conditions or pathological processes associated with pregnancy. They can occur during or after pregnancy, and range from minor discomforts to serious diseases that require medical interventions. They include diseases in pregnant females, and pregnancies in females with diseases.	Adverse Birth Outcomes,Complications, Pregnancy,Adverse Birth Outcome,Birth Outcome, Adverse,Complication, Pregnancy,Outcome, Adverse Birth,Pregnancy Complication
D001919	Bradycardia	Cardiac arrhythmias that are characterized by excessively slow HEART RATE, usually below 50 beats per minute in human adults. They can be classified broadly into SINOATRIAL NODE dysfunction and ATRIOVENTRICULAR BLOCK.	Bradyarrhythmia,Bradyarrhythmias,Bradycardias
D005260	Female		Females
D006340	Heart Rate, Fetal	The heart rate of the FETUS. The normal range at term is between 120 and 160 beats per minute.	Fetal Heart Rate,Fetal Heart Rates,Heart Rates, Fetal,Rate, Fetal Heart,Rates, Fetal Heart
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D015149	Tocolytic Agents	Drugs that prevent preterm labor and immature birth by suppressing uterine contractions (TOCOLYSIS). Agents used to delay premature uterine activity include magnesium sulfate, beta-mimetics, oxytocin antagonists, calcium channel inhibitors, and adrenergic beta-receptor agonists. The use of intravenous alcohol as a tocolytic is now obsolete.	Tocolytic,Tocolytic Agent,Tocolytic Effect,Tocolytic Effects,Tocolytics,Agent, Tocolytic,Agents, Tocolytic,Effect, Tocolytic,Effects, Tocolytic