Influence of carbon monoxide poisoning on the fetal heart monitor tracing: a report of 3 cases.
BACKGROUND
The diagnosis of carbon monoxide poisoning in the third trimester of pregnancy requires an index of suspicion, and the appearance of the fetal heart monitor tracing may help in this regard.


METHODS
Three cases of third-trimester acute carbon monoxide poisoning occurred. In each pregnancy, the fetal heart monitor tracing on admission was correlated with the maternal carboxyhemoglobin level, and how the pattern changed following the institution of therapy was analyzed.


CONCLUSIONS
In all 3 cases, the initial fetal heart rate pattern demonstrated decreased variability with an elevated baseline and an absence of accelerations and decelerations. Within 45-90 minutes of treatment onset, the baseline fetal heart rate dropped by 20-40 beats per minute, the variability became moderate, and accelerations occurred. Absent accelerations with minimal variability, if caused by uteroplacental insufficiency, are usually preceded by recurrent decelerations. Absent accelerations with minimal variability in the absence of recurrent decelerations may suggest another cause, of which carbon monoxide intoxication can be added to the differential, especially since this disorder often has nonspecific clinical symptoms.
Towers
Craig V
CV
Department of Obstetrics and Gynecology, Long Beach Memorial Women's Hospital, Long Beach, California, USA. drtowers@rbcpress.com
Corcoran
Vincent A
VA
D002249:Carbon Monoxide Poisoning / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D005260:Female; D005311:Fetal Hypoxia / Q000175:diagnosis* / Q000628:therapy; D005323:Fetal Monitoring / Q000379:methods*; D006340:Heart Rate, Fetal / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010100:Oxygen / Q000627:therapeutic use*; D011247:Pregnancy; D011256:Pregnancy Outcome
D010100:Oxygen