ABSTRACT
The first detection of a combustible gas in the blood was made in 1894 by Haldane (1). This gas was supposed by de Saint Martin and Nicloux to be carbon monoxide (2,3). Nicloux and others attempted to show that CO was formed in the body and first asserted that the origins of CO in the body arose via carbohydrate metabolism (4). The proof should have been the determination of the CO in inspired and expired air simultaneously, combined with measurement of carboxyhemoglobin (COHb) in the blood. Unfortunately, these measurements were not possible with the methods available before 1940. With the onset of the industrial revolution and the invention of the combustion engine, it became urgent to work out methods to measure and determine COHb because it was rapidly discerned that CO levels in the atmosphere were dangerous. It was discovered very early that the COHb levels in the blood reflected the CO concentration in the alveolar air determined using rebreathing techniques. It was not until 1949, however, that Sjorstrand and later Coburn discovered that endogenously produced CO arose from the degradation of hemoglobin released from senescing erythrocytes. CO measurements via COHb or by rebreathing techniques in the 1970s were used by clinicians to deter-
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mine the life span of erythrocytes and the rate of heme turnover in their patients. Greater than 75% of CO produced in normal humans arises from erythrocyte turnover generated as a by-product of heme metabolism.
