Effects of atrial natriuretic peptide at a low dose on water and electrolyte metabolism during general anesthesia.

STUDY OBJECTIVE

To assess the hemodynamic, renal, and endocrine effects of small continuous doses of atrial natriuretic peptide (ANP) in patients anesthetized with sevoflurane for gastrectomy.

DESIGN

Prospective randomized study.

SETTING

Operating room and wards of a university hospital.

PATIENTS

20 ASA physical status I and II patients scheduled for gastrectomy.

INTERVENTION

Atrial natriuretic peptide (0.05 microg/kg/min; ANP group, n = 10) or saline (control group, n = 10) was infused continuously for 2 hours beginning at the start of the operation.

MEASUREMENTS

Plasma concentrations of ANP, brain natriuretic peptide, cortisol, angiotensin II, and aldosterone; plasma renin activity; serum and urinary sodium, potassium, and chloride; and urinar output.

MAIN RESULTS

The ANP group showed much greater urine volume and sodium, potassium, and chloride excretion than the control group, although the ANP group had a lower arterial blood pressure. The infusion did not affect surgery-induced increases in hormones. No patients experienced excessive hypotension, bradycardia, or other perioperative complications.

CONCLUSIONS

Continuous intravenous infusion of ANP at 0.05 microg/kg/min during gastrectomy was associated with greater water and electrolyte excretion unaccompanied by changes in potentially interacting hormones. Low-dose infusion may be particularly safe and useful for controlling water and electrolyte metabolism intraoperatively.