The effect of light chloralose and pentobarbitone anaesthesia on the acid-base state and oxygenation of arterial blood in dogs.

1. The effects of light anaesthesia of approximately 8 hr duration using either pentobarbitone or chloralose on the acid-base balance and oxygenation of arterial blood were determined in dogs breathing spontaneously.2. With pentobarbitone anaesthesia there was a slight initial respiratory acidaemia.3. With chloralose there was a non-respiratory acidaemia which was probably the result of using an unbuffered solvent.4. Changes in the acid-base balance and the oxygen concentration of the arterial blood over the course of each experiment were minimal.5. In one animal a pH of 7.07 was recorded; in others the oxygen tension on occasion was between 50 and 60 mm Hg. The value of monitoring the acid-base state and the oxygenation of blood in experimental preparations is discussed.