Giving Oxygen Can Be Harmful

Paramedics and doctors who give their patients oxygen may do more harm than good, according to an new research published in the July issue of Chest, a critical care and cardiopulmonary journal.

Giving pure oxygen to a patient can reduce the blood flow to organs and tissues by increasing ventilation, which ‘blows off' carbon dioxide and constricts blood vessels, according to co-authors Dr. Steve Iscoe, a respiratory physiologist in Kingston (Canada), and Dr. Jospeh Fisher, from the department of anesthesia at Toronto General Hospital (Canada). However, there is a simple solution. If carbon dioxide is added, the blood vessels dilate, which increases blood flow and causes more oxygen to reach tissues in such key areas as the brain and the heart.

‘It's puzzling that a simple idea like this has received so little attention from clinicians,” observed Dr. Iscoe. Although there has been concern about the possibility of patients receiving too much carbon dioxide, Dr. Iscoe points out that new designs for oxygen masks allow for precise monitoring of the levels of carbon dioxide delivered or, in fail-safe mode, prevent inhalation of carbon dioxide.

Dr. Iscoe sees particular benefits from improved oxygen delivery for patients with heart attacks, stroke, carbon monoxide poisoning, wounds, foot ulcers and for increasing cerebral blood flow to fetuses during difficult birth procedures.

"The reduction in oxygen delivery to the fetus, the brain, the heart, and other body tissues that might be induced by oxygen administration is, as this paper points out, largely unrecognized even by respirologists such as myself,” noted Dr. Peter Macklem, professor emeritus of medicine at McGill University (Montreal, Canada). "The magnitude of the risk now needs to be quantified by appropriate clinical trials.”





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