2024, Number 3
Cyanide poisoning treated with high doses of hydroxocobalamin. Case report and review of this complication
Full text
10.35366/116174
Language: English
References: 5
Page: 202-204
PDF size: 204.06 Kb.
ABSTRACT
Cyanide poisoning frequently complicates major burn injuries with inhalation syndrome. The established treatment protocol recommends a standard dose of 70 mg/kg of hydroxocobalamin for adults, with the option to administer a second dose, not exceeding a maximum of 140 mg/kg. Our objective is to chronicle the case of a patient for whom an escalated dosage, exceeding the approved limit, was imperative to reverse the intoxication. The unconventional decision to administer such high doses proved life-saving, albeit not conforming to the medication's technical specifications. Notably, side effects observed were not markedly worse than those associated with the standard dose, except for the occurrence of moderate kidney failure. It is worth noting that this renal complication is also documented with standard doses and did not necessitate renal replacement therapy.INTRODUCTION
Cyanide poisoning frequently complicates major burn injuries accompanied by inhalation syndrome. Recognizing cyanide toxicity as a component of inhalational injury is crucial for effective management. Early administration of treatment with accurate doses increases the likelihood of successfully overcoming intoxication. However, the evidence supporting the use of hydroxocobalamin as a cyanide antidote is limited, primarily due to a lack of randomized controlled trials in humans. The standard validated dose for hydroxocobalamin treatment in adults is 70 mg/kg, with the possibility of repeating a second dose up to a maximum of 140 mg/kg.
CASE REPORT
A 44-year-old male admitted to the burn unit following a house fire presented confusion and mild deterioration of consciousness. Pre-hospital care included orotracheal intubation and the administration of 5 g of hydroxocobalamin. The in-hospital assessment revealed 4% body surface burns, mainly on the face, with second-degree burns. Inhalation syndrome was suspected, leading to the prescription of 100% FiO2, fibrobronchoscopy, and monitoring with serial arterial blood gases and portable X-Ray (Figure 1).
Initial blood gases indicated lactic acidosis (pH 7.29, lactate 1.5 mmol/L). Over the next six hours, it increased to 5.3, prompting a second dose of 5 grams of hydroxocobalamin. Continuous monitoring showed rising lactate levels until 8.2 mmol/L after 12 hours (Table 1), leading to the administration of a third dose (15 grams total in the first 24 hours). Lactic acid levels progressively decreased to 3 mmol/L after the third dose (Table 2). The patient developed acute renal failure with a creatinine increase from 0.85 mg/dL to 1.12 mg/dL, which resolved without the need for pharmacological or replacement therapy. The patient was discharged ten days later with excellent renal and respiratory function and partial recovery of normal lung anatomy (Figure 2).
DISCUSSION
Hydroxocobalamin is a hydroxylated active form of vitamin B12, precursor of methylmalonyl CoA mutase cofactors and homocysteine remethylation(1). It is essential for cell reproduction and growth, metabolism of some amino acids, myelin synthesis and the integrity of the nervous system and maintenance of normal erythropoiesis. Its use in medicine is wide, being mainly used to treat malabsorptive or deficient syndromes such as occurs with resections of the digestive tract or in pernicious anemia, or in the pediatric population for patients with methylmalonic acidemia with or without homocystinuria(1). However, it has acquired special relevance in burn patients due to its potential capacity for the treatment of cyanide poisoning, whose main origin is the combustion of materials such as wool, nylon, polyurethanes, polyacrylonitriles or resins. Cyanide, due to its high affinity for iron, causes the inhibition of enzymes such as cytochrome oxidase, blocking ATP production and inducing cellular hypoxia(2).
The mechanism of action of hydroxocobalamin consists of its ability to bind 1:1 to circulating cyanide in the blood to form cyanocobalamin, a stable and non-toxic compound that is eliminated in the urine(3). The standard validated dose is 70 mg/kg, simplified as 5 grams for the adult population, and a second dose can be repeated up to a maximum of 140 mg/kg or 10 grams(3). However, some cases have been reported of administration of higher doses up to 370 mg/kg(4) without relevant consequences in patients as in this case where the prescription of a third dose (15 grams in total or 250 mg/kg) was able to reverse the cyanide intoxication and save the patient's life. Renal alterations secondary to high doses should be highlighted due to their importance in burn patients. Cases of acute renal failure with acute tubular necrosis, renal failure and presence of calcium oxalate crystals have been reported(5). Therefore, regular monitoring of renal function should be carried out up to seven days after initiation of treatment.
CONCLUSIONS
The comprehensive understanding and timely use of hydroxocobalamin is transcendental for any physician who deals with burn patients and, due to its excellent safety profile, its use should not be delayed whenever there is suspicion of a possible cyanide poisoning(5), taking into consideration the renal complications that are added to those already characteristic of severe burns. However, it cannot be asserted that it is safe to administer up to 250 mg/kg of hydroxocobalamin in a patient with cyanide poisoning because it is a single patient. On the other hand, thanks to this clinical case together with others reported in the literature, there are more and more indications of the safety of this compound and its scarce side effects, so it is essential to carry out studies with a larger sample size in order to prove this hypothesis.
REFERENCES
AFFILIATIONS
1 MD, Anesthesiology and critical care in Hospital La Fe, Valencia, Spain.
2 MD, Anesthesiology and critical care in Hospital La Ribera, Alzira, Spain.
3 MD, Orthopedic Trauma physician in Hospital La Fe, Valencia, Spain.
4 ORCID: 0000-0003-0136-0246
CORRESPONDENCE
Daniel Pérez-Ajami. E-mail: daniajami1995@gmail.comReceived: 12-11-2023. Accepted: 04-03-2024.