[Plasma and red blood cell cyanide concentrations during hypotension induced by sodium nitroprusside or by a nitroprusside-trimetaphan mixture in rabbits].

Plasma and red blood cells cyanide concentrations during hypotension induced by sodium nitroprusside and a nitroprusside-trimetaphan mixture were studied in 29 male rabbits under halothane anesthesia. They were randomly divided into three groups; Nitroprusside (group N; n = 10), A nitroprusside-trimetaphan mixture (group M; n = 10), Controls (group C; n = 9). No changes were noted in plasma and red blood cells cyanide concentrations in group C throughout the experiment. During and after induced hypotension, in group N, plasma cyanide concentration was significantly higher than the control value. The maximum increase occurred 60min after induction of hypotension and the highest concentration of plasma cyanide was six times the control value. In contrast, in group M, plasma cyanide concentration was unchanged from the control value. However, during and after induced hypotension, red blood cells cyanide concentrations of group N and group M were significantly higher compared with the control values. Red blood cells concentrations of cyanide increased for 30 and 60 min during induced hypotension in group N (27.11 +/- 3.9 micrograms.ml-1, P less than 0.001, 46, 73 +/- 4.7 micrograms.ml-1, P less than 0.001, respectively) and in group M (0.31 +/- 0.05 micrograms.ml-1, P less than 0.05, 0.29 +/- 0.03 micrograms.ml-1, P less than 0.05, respectively). In conclusion, the data suggest that a nitroprusside-trimetaphan mixture is a safe method for hypotensive anesthesia.