Carbon monoxide (CO) is a colorless, odorless, and tasteless gas, making it impossible for humans to detect. It is produced by the incomplete burning of carbon-containing fuels, such as wood, gasoline, or natural gas. When inhaled, CO causes sudden illness and death by preventing the body from properly utilizing oxygen. This article explores the clinical link between carbon monoxide poisoning and gastrointestinal disturbances, specifically diarrhea.
Gastrointestinal Distress as a Symptom
Carbon monoxide poisoning can manifest with various gastrointestinal (GI) symptoms, including nausea, vomiting, and, less frequently, diarrhea. Because these initial symptoms are non-specific, they often lead to a misdiagnosis of common illnesses like the flu or food poisoning. One study found that approximately 17% of patients diagnosed with CO poisoning reported experiencing diarrhea during their acute clinical picture.
While neurological signs are the most common, GI distress suggests a systemic toxic effect impacting multiple organ systems. These symptoms are secondary manifestations arising from the body’s response to oxygen deprivation, not a direct irritant effect. The involvement of the digestive tract indicates the poisoning affects more than just the brain and heart.
The Cellular Mechanism of Carbon Monoxide Toxicity
The danger of carbon monoxide lies in its ability to bind to hemoglobin in red blood cells with an affinity more than 200 times greater than oxygen. When CO binds to hemoglobin, it forms carboxyhemoglobin (HbCO), which blocks the sites where oxygen normally attaches. This process drastically reduces the blood’s capacity to transport oxygen, leading to systemic cellular hypoxia, or oxygen starvation in the tissues.
Organs and tissues requiring the most oxygen, such as the brain and heart, are the first to show signs of distress. However, the gastrointestinal tract lining is also highly sensitive to this lack of oxygen. The resulting systemic hypoxia can cause intestinal ischemia—a reduced blood flow and oxygen supply to the gut tissue. This tissue injury disrupts the normal function and integrity of the intestinal lining, leading to symptoms like inflammation, increased fluid secretion, and ultimately, diarrhea.
Primary Acute Symptoms of CO Poisoning
The symptoms most commonly associated with acute carbon monoxide poisoning are often described as “flu-like.” The most frequent complaint is a headache, often described as dull and continuous, followed closely by dizziness and generalized weakness. These neurological symptoms reflect the brain’s high demand for oxygen and its immediate sensitivity to HbCO.
Nausea and vomiting are common presentations, reflecting oxygen deprivation’s impact on the central nervous system and the GI tract. As exposure levels increase, the patient may experience confusion, chest pain, and a rapid heart rate, indicating strain on the cardiovascular system. Severe exposure signs progress rapidly to include seizures, loss of consciousness, and potentially death.
The severity of symptoms relates directly to both the concentration of CO in the air and the duration of exposure. People who are sleeping or intoxicated may succumb to the poisoning before experiencing any warning signs. Recognizing these classic symptoms, and the possibility of accompanying GI issues, is the first step in seeking immediate help.
Immediate Steps and Medical Confirmation
If carbon monoxide poisoning is suspected, the immediate response is simple and life-saving: evacuate the area and get to fresh air immediately. After moving affected individuals away from the suspected source, emergency medical services should be called without delay. Do not attempt to re-enter the building until emergency personnel confirm it is safe.
Medical professionals confirm the diagnosis by measuring the level of carboxyhemoglobin (COHgb) in the blood. This is done using a specialized blood test, often a CO-oximeter, which determines the percentage of hemoglobin bound to carbon monoxide. For non-smokers, a COHgb level above 2% supports a diagnosis of poisoning.
Although this diagnostic test is necessary for confirmation, treatment with 100% oxygen is often started immediately upon suspicion, as delay can cause permanent damage. Breathing pure oxygen accelerates the dissociation of carbon monoxide from the hemoglobin molecule. Leaving the environment and seeking emergency treatment rapidly is the most important factor in limiting toxic effects on the entire body, including the gastrointestinal tract.