Explained: What is carbon monoxide poisoning and how it manifests

New Delhi: Carbon monoxide (CO) poisoning is a serious and potentially fatal condition resulting from the inhalation of CO gas. Often referred to as a “silent killer,” CO is colorless, odorless, and tasteless, making it difficult to detect without proper equipment. It is produced by the incomplete combustion of carbon-based fuels, such as gas, wood, coal, and oil. From a doctor’s perspective, timely diagnosis and treatment are critical to prevent severe complications, including permanent neurological damage and death.

In an interaction with News9Live, Dr. Anil Thakwani, Consultant and Senior oncologist, at Shardacare-Health City, explained how carbon monoxide poisoning can affect health.

Pathophysiology

Carbon monoxide has a significantly higher affinity for hemoglobin (about 200-250 times) compared to oxygen. When inhaled, CO binds with hemoglobin to form carboxyhemoglobin (COHb), reducing the oxygen-carrying capacity of the blood. This results in tissue hypoxia, particularly affecting organs with high oxygen demand, such as the brain and heart. Additionally, CO impairs mitochondrial function, further exacerbating cellular hypoxia and leading to oxidative stress and tissue damage.

Clinical Presentation

Patients with CO poisoning present with non-specific symptoms, which often mimic other conditions like viral infections or food poisoning. Early symptoms include headache, dizziness, nausea, vomiting, fatigue, and confusion. As exposure continues, neurological symptoms such as memory loss, ataxia, and altered mental status may occur. Severe cases may result in seizures, loss of consciousness, arrhythmias, myocardial infarction, and death. Children, pregnant women, and individuals with preexisting heart or lung conditions are particularly vulnerable.

Diagnosis

Diagnosis of CO poisoning is challenging due to its non-specific symptoms. A high index of suspicion is required, especially when multiple individuals in the same environment present with similar complaints. Measurement of carboxyhemoglobin (COHb) levels in the blood is the definitive diagnostic test. Pulse oximetry is unreliable in detecting CO poisoning as it cannot differentiate between oxyhemoglobin and carboxyhemoglobin. Arterial blood gas analysis and CO-oximetry are preferred for accurate diagnosis.

Treatment

The primary goal of treatment is to restore oxygen delivery to tissues by displacing CO from hemoglobin. Immediate removal of the patient from the CO-exposed environment is essential. Administering 100% oxygen via a non-rebreather mask significantly reduces the half-life of carboxyhemoglobin from approximately 4-6 hours in room air to 40-80 minutes. For severe poisoning or patients with neurological symptoms, hyperbaric oxygen (HBO) therapy is recommended. HBO therapy reduces the half-life of COHb to 15-30 minutes, promotes oxygen delivery to ischemic tissues, and minimizes the risk of long-term neurological damage.

Complications

Delayed neurological sequelae (DNS) can occur days to weeks after the initial exposure, even in patients who initially appeared to recover. Symptoms include cognitive dysfunction, mood changes, memory loss, and movement disorders. Cardiac complications, such as arrhythmias and myocardial injury, are also common, especially in elderly or high-risk patients.

Prevention

Prevention of CO poisoning is a public health priority. Households and workplaces should install CO detectors, regularly maintain fuel-burning appliances, and ensure adequate ventilation. Public education campaigns on CO safety and early symptom recognition are essential.

Conclusion

From a doctor’s perspective, carbon monoxide poisoning is a medical emergency requiring prompt diagnosis and intervention. Recognizing the subtle signs, initiating rapid treatment with oxygen therapy, and preventing delayed complications are essential in reducing mortality and morbidity. Public awareness and the use of CO detectors play a crucial role in preventing CO poisoning.