Carbon monoxide poisoning is like a tragic love story, a biological version of the body's fatal attraction.
The doughnut-shaped hemoglobin molecule - the molecule that makes our red-blood cells - is a precision instrument. It's made to easily bind the oxygen we breathe and to release easily that oxygen when blood reaches hungry tissue, Dr. Jeffrey Hammersley, a pulmonologist at the Medical College of Ohio, said.
This easy pickup and delivery runs into trouble in the presence of carbon monoxide. It turns out the poison gas is picked up even more easily than oxygen. Carbon monoxide binds to hemoglobin 200 times better than oxygen does, Dr. Hammersley said.
“It jumps on quicker, binds, and doesn't want to get off.''
With this kind of attraction/attachment going on, we're always taking in carbon monoxide. Smokers give themselves regular doses, carrying carbon monoxide levels up to 8 percent. We get a dose of the gas in heavy traffic, especially in the summer.
But once the rate reaches 10 to 30 percent, symptoms follow. Unfortunately, the symptoms feel a lot like the onset of flu, and they tend to occur at times when we expect to suffer from influenza, said Dr. Donato Borrillo, a specialist in the treatment of carbon monoxide poisoning in Toledo Hospital. So headaches and nausea in all the members of a single family may raise no alarms.
Gas-fueled space heaters, gas-fueled furnaces, charcoal grills, gas-fueled ranges, portable kerosene heaters, and wood stoves are major culprits in carbon monoxide fatalities, according to the National Fire Protection Association.
“By the time somebody starts putting things together that everybody's sick, nobody's thinking clearly anymore,'' Dr. Borrillo said. At 30 to 40 percent carbon monoxide saturation, there is vomiting, vision changes, and confusion, eventually leading to collapse, coma, and eventually death.
For moderate to severe cases of carbon monoxide poisoning, Toledo Hospital puts patients into a high-pressure oxygen unit known as a hyperbaric chamber. One hundred percent oxygen is supplied at two to three times the pressure of the air we breathe in one or two 90-minute sessions.
Dr. Borrillo said pure oxygen delivered at high pressure “stacks the deck'' in favor of oxygen, forcing carbon monoxide out of the blood and muscle. When oxygen is delivered at normal air pressure, carbon monoxide-tainted hemoglobin has a half life of five hours. At oxygen three times the normal air pressure, the tainted hemoglobin has a half-life of 23 minutes.
But at MCO, doctors use pure oxygen, delivered at normal pressure as long as the patient is conscious. Dr. Hammersley cites an Australian study that he said demonstrates that hyperbaric treatment offers no advantage.