Smoke Inhalation Injury in a Pregnant Patient

Abstract

For smoke inhalation injury of a pregnant woman, one must treat two patients and be aware of the potential effects of carbon monoxide (CO) and cyanide (CN) poisoning on both the mother and the fetus. In a pregnant woman, the size and age of the fetus and the degree of poisoning allow for tremendous variability in the toxicity of CO and CN and their respective treatment options. The authors will review a case of a 32-year-old woman who was at 37 weeks of gestation and admitted to the Evans-Haynes Burn Center after a house fire and received hydroxocobalamin (Cyanokit) for suspected CN poisoning. In addition, a review of the literature, current guidelines, and treatment options of inhalation injury during pregnancy will be discussed. The authors will focus only on the toxic components of smoke inhalation injury rather than the mechanical components from heat and particulate damage. Literature review clearly identifies that the treatment of pregnant women with inhalation injury remains a controversial subject. The use of hydroxocobalamin (Cyanokit) as a treatment modality for potential CN poisoning in a pregnant patient has not been reported in the literature. Animal studies have shown that combined CO and CN poisoning are more lethal than either one alone and at lower concentrations. Due to the synergistic effects of CO and CN, and because these two toxins concentrate at even higher levels in the fetus than the mother, the authors will clarify the urgent seriousness of prompt administration of hydroxocobalamin in a pregnant patient with suspected smoke inhalation injury. This case review details the treatment of a 32-year-old woman who was at 36 weeks of gestation on admission to the Evans-Haynes Burn Center. The authors will report her injuries and the course of treatment. Although burned and presenting with concomitant smoke inhalation injury, both the woman and her child fared well with no significant complications due to the smoke inhalation at 6 months of follow-up. Smoke inhaled from modern structural fires potentially contains both CN and CO gases. This makes the prompt recognition of this injury and selection of appropriate therapy an emergent priority. In October 2010, the Food and Drug Administration approved hydroxocobalamin for use in pregnant patients in the acute setting when CN toxicity is suspected. Because CO and CN have additive effects when both are present in the body, the prompt administration of hydroxocobalamin not only eliminates the effects of CN but also potentially attenuates its synergistic effects on CO. It is only through a better understanding of the details of smoke inhalation injury, the current treatment options, and the considerations regarding their use that new research and strong guidelines can be developed to better serve our patients.

Carbon Monoxide Poisoning during Pregnancy: Presentation of a Rare Severe Case with Fetal Bladder Complications

“…No reports of the use of hydroxocobalamin in pregnant women describe any teratogenic effects [ 8 ], nor have we found any case describing bladder lesions secondary to fetal hypoxia in the context of cardiac arrest.…”

“…During the embryonic phase, CO can cause a variety of birth defects. During the fetal stage, congenital anomalies are less common, but death or permanent neurological damage may occur [ 8 ]. Studies of monkeys and of cats after inhalation of carbon monoxide found that the most vulnerable areas of the brain are those containing white matter (periventricular, especially) and the brainstem, followed by the thalamus and the cerebral cortex [ 9 ].…”

A modern literature review of carbon monoxide poisoning theories, therapies, and potential targets for therapy advancement.

“…HBO is currently available only in select centers, mostly large tertiary care facilities in first world countries, and there is no strong consensus on guidelines for its use or requirements for transferring high-risk patients to a facility that possesses HBO capabilities (Brent, 2005;Roderique et al, 2012).…”

Carbon Monoxide and Cyanide Poisoning in the Burned Pregnant Patient

“…51 The classic treatment consists of 100% normobaric oxygen (NBO 2 ) administered via a tightly fitting, non-rebreather mask for a minimum of 6 hours. 18,54,66 When breathing normal ambient air, the half-life of maternal COHb is 4–6 hours. In contrast, the half-life of maternal COHb is reduced to 40–75 minutes when 100% NBO 2 is administered.…”

“…As the best method to treat the fetus is to treat the mother, in the setting of the burned pregnant patient with significant CO poisoning, HBO 2 therapy may be indicated once the mother is stabilized to optimally eliminate CO potentially fatal to both mother and child. 2,16,17,24,28,38,41,44,49,51,54,56,66,68,71,83,89,93…”