Epidural morphine decreases postoperative hypertension by attenuating sympathetic nervous system hyperactivity

Area of Science:

• Anesthesiology
• Cardiovascular Surgery
• Pharmacology

Background:

• Postoperative hypertension is a common complication after abdominal aortic surgery.
• Sympathetic nervous system hyperactivity is implicated in its development.
• Effective management strategies are needed to mitigate this risk.

Purpose of the Study:

• To evaluate the role of sympathetic nervous system hyperactivity in postoperative hypertension after abdominal aortic surgery.
• To assess the efficacy of epidural morphine sulfate in attenuating this response.

Main Methods:

• A randomized, double-blind, placebo-controlled study involving 24 adult patients undergoing abdominal aortic surgery.
• Administration of epidural morphine sulfate (6 mg) versus saline placebo.
• Monitoring of pain scores, plasma norepinephrine, epinephrine, and arginine vasopressin levels, and blood pressure.

Main Results:

• Patients receiving epidural morphine required less parenteral morphine and reported lower pain scores.
• Markedly lower plasma norepinephrine levels were observed in the epidural morphine group.
• Fewer patients in the morphine group required treatment for hypertension, with lower overall blood pressures post-surgery.

Conclusions:

• Sympathetic nervous system activity, not adrenal epinephrine or arginine vasopressin, drives hypertension post-aortic surgery.
• Epidural narcotics, specifically morphine sulfate, are effective in attenuating this sympathetic response and reducing postoperative hypertension.