And although there's a simple solution adding carbon dioxide to the mix it isn't being used by most Canadian hospitals and emergency services networks, says Dr. Steve Iscoe, a respiratory physiologist. This has implications for treating a number of serious health conditions, including heart disease, stroke, diabetes, difficult labour and delivery, and wound healing.
Dr. Iscoe's commentary, based on his own and other researchers' findings, is published in the July issue of CHEST, the Cardiopulmonary and Critical Care Journal. Co-author of the article is Dr. Joseph Fisher, from the Toronto General Hospital's Department of Anesthesia.
"Pure oxygen can reduce blood flow to organs and tissues by increasing ventilation," Dr. Iscoe explains. "The increase in ventilation, which is almost never considered, 'blows off' carbon dioxide, and this fall constricts blood vessels. When carbon dioxide is added, however, the blood vessels dilate, increasing blood flow and causing more oxygen to reach tissues in key areas like the brain and heart."
Researchers in the early 1900s observed that breathing pure oxygen increased ventilation and lowered carbon dioxide levels. Based on their observations, several tried adding carbon dioxide and claimed success in resuscitating people and infants and treating carbon monoxide poisoning.
But the practice of using expired air even before it was known to contain carbon dioxide dates back much further. The use of mouth-to-mouth resuscitation on infants was recorded in a 1754 book by Benjamin Pugh, A Treatise of Midwifery, and there are biblical references to the custom. Yet modern medical texts do not mention that inhalation of oxygen decreases carbon dioxide levels and the effects on blood flow; consequ
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Contact: Nancy Dorrane
dorrance@post.queensu.ca
613-533-2869
Queen's University
11-Jul-2005