A dosage nomogram for sodium nitroprusside-induced hypotension under anesthesia

Area of Science:

• Anesthesiology
• Pharmacology

Background:

• Deliberate hypotension is used to reduce blood loss during surgery.
• Sodium nitroprusside (SNP) is a potent vasodilator used for this purpose.

Purpose of the Study:

• To evaluate the efficacy and safety of SNP for inducing deliberate hypotension during total hip replacement.
• To develop a predictive model for SNP dosage based on patient characteristics.

Main Methods:

• SNP infusion (0.01% solution) was used to achieve a mean arterial blood pressure (MAP) of 65 torr in 30 patients undergoing total hip replacement.
• A dose-response curve was established using the age/weight ratio and SNP dosage.
• A double-blind study validated the preliminary findings.

Main Results:

• SNP effectively reduced MAP to 65 torr, creating a dry surgical field.
• SNP dosage could not be predicted by body weight alone.
• A significant dose-response curve (p < 0.001, r = -0.8939) was developed using the age/weight ratio.
• The nomogram derived from combined data improved predictability and safety.

Conclusions:

• SNP is a predictable and effective agent for reducing surgical blood loss in total hip replacement.
• The age/weight ratio nomogram enhances the safe administration of SNP.