[A.L. Lavoisier and the anesthetist]

The activity of the anesthesiologist is centered upon the respiratory organ function; therefore, the question of how the fundamental knowledge of gas exchange was gained seems justified. During the 18th century, the elegant but incorrect phlogiston theory (G.E. Stahl, 1659-1734) dominated all theoretical conceptions about combustion and respiration. Chemistry at that time was a collection of observations without any sound hypothetical background. Our knowledge about oxidation, combustion, and respiration was developed mainly by the work of A.L. Lavoisier (1743-1794). He observed that metals gain weight during their calcination (oxidation) and concluded that air is taken up during this process. In these experiments he also proved that air consists of two elastic fluids (gases), one respirable and the other nonrespirable. After experiments with a sparrow breathing in a closed vessel until it expired, Lavoisier stated that during respiration respirable air (O2) is changed into fixed air (CO2) in the lungs with the mephitic portion of the air (N2) not taking part. These were the first investigations of respiration where accurate and reproduciable methods were applied. Respirable air is also transformed into fixed air by a burning candle. After investigations by which thermochemistry was founded, respiration could be defined as a slow form of combustion. In these and other biologically oriented experiments, Lavoisier developed direct and indirect calorimetry. He named respirable gas oxygen and explained the composition of water. In refuting the phlogiston theory, he established modern chemistry. His fate was sealed during the French revolution: in 1794 he was executed as a consequence of his activities as a farmer.(ABSTRACT TRUNCATED AT 250 WORDS)