Should hyperbaric oxygen be used to treat the pregnant patient for acute carbon monoxide poisoning? A case report and literature review

Abstract

Carbon monoxide (CO) is the leading cause of death due to poisoning. Although uncommon, CO poisoning does occur during pregnancy and can result in fetal mortality and neurological malformations in fetuses who survive to term. Uncertainty arises regarding the use of hyperbaric oxygen (HBO) as a treatment for the pregnant patient because of possible adverse effects on the fetus that could be induced by oxygen at high partial pressures. While the dangers of hyperoxia to the fetus have been demonstrated in animal models, careful review of animal studies and human clinical experience indicates that the short duration of hyperoxic exposure attained during HBO therapy for CO poisoning can be tolerated by the fetus in all stages of pregnancy and reduces the risk of death or deformity to the mother and fetus. A case is presented of acute CO poisoning during pregnancy that was successfully treated with HBO. Recommendations are suggested for the use of HBO during pregnancy.

Carbon monoxide poisoning

“…In the setting of smoke inhalation, concomitant cyanide toxicity may be seen with CO poisoning [111,159]. Fetal monitoring and other tests of fetal wellbeing may help to detect fetal compromise in a CO-poisoned pregnant patient [160].…”

“…The safety of HBOT in pregnancy has been questioned, but many authors recommend HBOT for pregnant patients with CO poisoning because of the potential benefit to the mother and fetus and the difficulty of assessing intrauterine hypoxia [122,124,127,160,229,230]. A maternal CO-Hgb level greater than 15% to 20%, evidence of fetal distress, and other standard criteria for HBOT in CO poisoning often are cited as indications for HBOT in CO-poisoned pregnant patients [2,160,221]. Pregnant women may require longer treatment with oxygen than nonpregnant patients [118,119,123,229,231].…”

Acute Poisoning During Pregnancy: Observations from the Toxicology Investigators Consortium

“…Although short hyperoxic exposure during HBO therapy is tolerated by the fetus and had been shown to reduce fetal risk of death in some reports [32], its efficacy in carbon monoxide poisoning is controversial and it is unknown if the elevated fetal carboxyhemoglobin fraction has a role in the toxicity of carbon monoxide to the fetus. Despite the uncertainty, many medical toxicologists tend to administer HBO therapy to treat pregnant patients with carbon monoxide poisoning.…”

Carbon Monoxide Poisoning

“…In the setting of chronic CO poisoning, polycythemia may be seen as a response to chronic hypoxia. Fetal monitoring may be helpful to detect fetal compromise in the COpoisoned pregnant patient [171]. Most recently, the role of biochemical markers of brain damage (neuron-specific enolase, S-100 beta) after CO poisoning has been investigated [172][173][174].…”

“…The safety of HBOT in pregnancy has been questioned, but many authors recommend HBOT for the pregnant patient in the setting of CO poisoning, because of the potential benefit to both mother and fetus and the difficulty of assessing intrauterine hypoxia [118,120,123,171,242,243]. A maternal CO-Hgb level greater than 15% to 20%, evidence of fetal distress, or other standard criteria for HBOT in CO poisoning are often cited as indications for HBOT in the CO-poisoned pregnant patient [1,171,234]. Pregnant women may require longer treatment with oxygen than the nonpregnant patient [114,115,119,242,244].…”