Carbon Monoxide poisoning in children - Toxicology
Table of Content
- Pathophysiology • Mechanism
- Clinical features Severity wise • Exposure wise
- Diagnosis Confirmation • Imaging • Supportive
- Treatment Acute • Specific
- Long term effect • Outcomes
- Further Reading
Pathophysiology ,clinical presentations and management of carbon monoxide poisoning (Dec/14) and (Dec/15) Marks - 3+3+4
Carbon monoxide is a colorless, odorless, and tasteless toxic gas, that can be produced from the combustion of any carbon-containing fuel.
CO is the most commonly involved gas in poisonous exposure in children.
It's a medical emergency and needs treatment right away.
Etiology - Common Sources involved in Pediatric CO poisoning
- wood-burning stoves and fireplaces
- kerosine generators
- Old furnaces
- Hot water heaters
The majority of effects of CO poisoning are due to systemic toxicity than local.
Carbon monoxide has a much higher affinity for Hb than oxygen. Gets rapidly attached to hemoglobin displacing oxygen molecule from its sites. You are talking about the affinity that is 210 times that of oxygen that of oxygen. [Yildiz, 2018]
The mechanisms involved are
1. Reduction in Oxygen carrying capacity and thus oxygen delivery
CO combines with Hemoglobin and reduces oxygen-carrying capacity and tissue hypoxia ensues afterward.
2. Disruption of Cellular respiratory chain
Carbon monoxide combines with Cyt. Oxidase making it unavailable for respiratory chain cycle at cellular levels
3. Promoting Inflammation
Results in triggering inflammatory cascade at high-oxygen demand organs such as the heart, brain (AAP 2011)
4. Displacing NO
Clinical Features - What are the common symptoms of CO poisoning in children?
Symptoms of CO poisoning are variable and non-specific.
Children are specifically susceptible to CO poisoning due to relatively high metabolic and oxygen demands than adults.
Often the early mild symptoms can be easily confused with ‘flu-like’
illness and lead to the wrong diagnosis as a viral infection or Gastroenteritis especially if no specific history of exposure.
- Mental status changes like Confusion, irritability, and irrational behavior
- Cherry Red skin(very typical sign)
- cardiovascular collapse
Acute exposure to very high CO levels will rapidly result in brain injury, cerebral edema, coma, and death without going through initial symptoms.
The normal level of carbon monoxide is 0.5%
Symptoms of Carbon monoxide exposure in children based on the extent of exposure
Diagnosis is based on
History of exposure + Clinical findings + Confirmatory testing
Even at significant carboxyhemoglobin levels, the patient can have normal oxygen saturation on pulse oxymeters. Therefore the confirmatory testing must include...
- The levels of Carboxyhemoglobin should be obtained by Direct measurement of blood carboxyhemoglobin
- Measurement of carboxyhemoglobin using a co-oximetry.
A CO-oximeter is a device that measures oxygen-carrying hemoglobin as well as the other non-normal hemoglobins such as carboxyhemoglobin and methemoglobin.
It is essential to rule out methemoglobinemia where history is not clear.
- Pa02 - Will essentially show normal PaO2 level.
- Lactate - High lactate will support the findings of tissue hypoxia
Creatinine Kinase (Ck)
Ck is a useful indicator of Tissue Breakdown from hypoxia and Rhabdomyolysis
To rule out dysrhythmias
- CXR: To rule out pulmonary edema. Pulmonary edema due to CO poisoning is rare in children. Rather the pulmonary edema is caused due to LVF resulting from myocardail injury and secondory aspirations (more about aspiration syndromes) due to altered sensorium and loss of cough reflex.
- CT/MRI brain: may conclude cerebral edema acutely and cerebral atrophy demyelination in later stages
Differentials - What are other exposure which can cause similar symptoms
The mild symptoms of CO poisoning can mimic exposure to
- Indoor air pollutants
- Tobacco smoke
- Volatile organic compounds
How to differentiate Exposure to CO for others
CO typically does not irritate the eyes and lungs, which is usually the case with other masqueraders.
- Move the child to a safe place with fresh air.
- Try to eliminate the source of exposure.
Specific Treatment of CO poisoning in Children
Mainstay of Treatment
How to administer oxygen?
100% oxygen through a non-rebreathing mask to achieve a highest possible concentration of alveolar oxygen concentration PAo2 in the beginning This can be later reduced to 60 to 90% as per the situation
Indication of Hyperbaric oxygen in CO poisoning
- HbCO levels less than 25%
- Abnormal cerebellar examination
- acute coronary syndrome
- altered mental status
What are the Outcomes/Sequelae of CO poisoning in children?
CO poisoning is a predictable cause of mortality and morbidity in post-disaster situations when widespread power cut occur CDC-MMWR 2012.
Persistent and delayed cognitive and cerebellar effects.
Dive Deep If you would like to
- Carbon monoxide poisoning in children – own observations - Jackowska, T. et al. Carbon monoxide poisoning in children – own observations. (2013). Source - [Image 1 ]
- Practice Recommendations in the Diagnosis, Management, and Prevention of Carbon Monoxide Poisoning
- Hyperbaric oxygen for carbon monoxide poisoning - Life in the fast lane
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Shama Sowdagar | DNB (Pediatrics)
Shama has completed residency from Kanchi kamakoti Child Trust Hospital, Chennai and works as a Pediatrician