The blood acid-base changes in acute cyanide poisoning in the rat in comparison with those in acute anoxic anoxia: with special reference to the relation with the time to death.

Rats were given orally various doses of NaCN (20,15,10, and 7 mg of CN per kg). When respiration stopped, the chest was opened and heart blood was taken anaerobically, and blood acid-base, lactate, and glucose determinations were made. As a control to chemical anoxia by cyanide, indentical determinations were made in the rat acutely made anoxic by exposure to N2. The time to the cessation of respiration ranged 2,4 to 14 and 2.3 to 9.3 minutes in cyanide and N2 experiments, respectively. The Po2 at the time of the sampling was much higher in cyanide experiments than in N2 experiments. the Pco2 became lower as the time to the cessation of respiration became longer in cyanide group, and it was considered to diffusion of CO2 into extravascular spae method, described by Oya and coworkers was modified. In this way, venous blood from pregnant and nonpregnant women in blood stains can be reliably differentiated up to at least 19 months storage although as a qualitative test only. 1--3 cm2 of cloth stained with blood is needed and even less from placental blood stains.