[Direct potentiometric determination of the level of cyanide in plasma following an infusion of sodium nitroprusside].

Plasma cyanide concentrations were measured potentiometrically in 12 patients before and after infusion of sodium nitroprusside (SNP). A close correlation was found between the increase in plasma cyanide level and the total dose of SNP and between the increase and the mean rate of SNP infusion. After a total dose of 3.