Life-Saving Chamber

February 1, 2005
By WILLIAM HATHAWAY, Courant Staff Writer

In two separate incidents after the Jan. 22 snowstorm, three Boston-area residents were poisoned by carbon monoxide as they sat in cars warming up in the frigid weather. Snow had clogged the tailpipes of the vehicles, and the odorless, colorless and potentially deadly gas backed up inside the idling cars.

Instead of being rushed to one of Boston's many hospitals, the victims were sent to Hartford Hospital, one of the few institutions in New England with a hyperbaric chamber big enough to care for more than one person at a time. Using the same technology that saves the lives of deep-sea divers who decompress too rapidly, the chamber fills with 100 percent oxygen pressurized to 2.5 atmospheres.

A 90-minute treatment, repeated three times in the next 24 hours, helps flush toxic gas from the bloodstream of poisoning victims and prevent brain damage, said Dr. George A. Perdrizet, director of the Hartford Hospital Center for Wound Healing and Hyperbaric Medicine.

The incident serves as a reminder about the potential danger of carbon monoxide poisoning from inefficient burning or ventilation of fossil fuel. It also illustrates the peculiar and as-yet not fully understood healing properties of oxygen under pressure.

Hartford's hyperbaric chamber looks like a mini-submarine, a steel cylinder about 6 feet wide and 20 feet long. Several hospitals in Connecticut have at least one mono-place chamber; these look more like coffins and can treat only one patient at a time. The multiplex chamber in Hartford makes it a common destination in cases of multiple poisonings by carbon monoxide.

Carbon monoxide poisoning cases were not the reason Hartford Hospital in the summer of 2003 entered into a lease-purchase agreement for the chamber, which is valued at $900,000. In the past year, staffers at the wound center have treated about 50 carbon monoxide cases. They also have used the chamber to treat wounds of about 500 people, most of them suffering from diabetic ulcers.

Use of hyberbaric chambers to treat wounds has not been widely accepted until recently and still is considered "fringe medicine" by many, Perdrizet said.

"Historically, the treatment had been misused" to treat diseases that compressed oxygen did nothing to help, he said.

Perdrizet said his experience five years ago working with investigators at the University of California, San Francisco, convinced him that pressurized chambers helped cure wounds.

Perdrizet said he lobbied Hartford Hospital officials for a wound center with "all the bells and whistles," including the hyberbaric oxygen chamber. He said on average 10 percent to 15 percent of wound patients met criteria for hyberbaric oxygen treatment. The patients usually suffer from diabetes or are recovering from radiation treatments for a variety of cancers. Their wounds have failed to heal after six weeks of standard care. The treatment also seems to benefit patients who suffer from infection by flesh-eating bacteria, a rare but grisly infection.

Studies have shown treatment in hyperbaric chambers can reduce the amputation rate for diabetic foot ulcers by 40 percent, Perdrizet said. And since the chamber was installed at Hartford Hospital, the federal government approved reimbursement for the treatment of diabetic foot ulcers.

Scientists still are not sure exactly how the therapy helps heal wounds, although one recent study has shown that compressed oxygen seems to trigger angiogenesis, or the growth of new blood vessels in wounds, Perdrizet said.

The way hyperbaric chambers treat carbon monoxide poisoning patients is much better understood, however. For more than a century, medical science has known that when mining tunnels were cleared of water with compressed air, the miners who worked in those tunnels tended to get sick after they moved to areas without compressed air. And since the early part of the 20th century, they have also known that decompression in divers can cause the formation of potentially lethal nitrogen gas bubbles in the bloodstream.

Workers on the Hudson River tunnel in New York who suffered what later would be known to deep-sea divers as "the bends" were treated in 1889 with compressed air. Increased pressure from the hyperbaric chamber forces potentially dangerous bubbles of nitrogen to dissolve in the bloodstream. A gradual reduction of pressure allows gases to be safely absorbed and exhaled through the lungs. Compressed oxygen allows carbon monoxide patients to absorb and eliminate the dangerous gas.

Officials at the wound center say they are plenty busy treating wounds and hope that education decreases their need to treat carbon monoxide poisoning cases.

Everybody should install carbon monoxide detectors for their homes with audible alarms, urged Dr. Charles McKay, director of medical toxicology at Hartford Hospital and associate medical director at the Connecticut Poison Control Center.

He stressed that any source of fossil fuel - if it burns inefficiently or is not properly ventilated - can cause carbon monoxide poisoning. That means people should not run generators indoors or use alternative heating sources such as charcoal grills. One local man was treated for carbon monoxide poisoning this year after working on a snow blower in an enclosed area.

The symptoms of carbon monoxide poisoning can be subtle, with victims suffering mild headaches, nausea and lightheadedness. Poisoning victims should be immediately given fresh air and taken to the hospital, where a blood test can confirm carbon monoxide poisoning, he said.