What is the main risk when using sodium nitroprusside in surgery?

Sodium nitroprusside is a potent vasodilator often used in surgical settings to rapidly decrease blood pressure. One of the main risks associated with its use is cyanide toxicity. This occurs because sodium nitroprusside, upon metabolism, releases cyanide ions, particularly when used in high doses or over prolonged periods. The body can detoxify small amounts of cyanide, but excessive amounts can overwhelm this capacity, leading to serious metabolic disturbances and potentially life-threatening conditions.

While hypotension, metabolic acidosis, and rebound hypertension are also concerns when using sodium nitroprusside, they are less directly tied to the drug's metabolism and its toxicological effects. The risk of cyanide toxicity therefore stands out as a critical point of caution during its administration, emphasizing the importance of careful dosing and monitoring in surgical procedures.