Effect of anesthesia and surgery on renal function.

Area of Science:

• Nephrology
• Anesthesiology
• Surgical Physiology

Background:

• Renal function is tightly regulated by neurohormonal systems.
• Surgical stress and anesthesia can disrupt this balance, affecting renal hemodynamics and salt/water balance.
• Understanding these effects is critical for patient management.

Purpose of the Study:

• To critically evaluate the impact of anesthesia and surgical procedures on renal function.
• To highlight the importance of accurate measurement techniques and consideration of confounding factors.
• To discuss the physiological mechanisms underlying perioperative renal changes.

Main Methods:

• Review and interpretation of existing methodologies for measuring in vivo renal blood flow (RBF), favoring flow probes.
• Analysis of secondary factors influencing renal responses, including intravascular volume and ventilation.
• Discussion of neurohormonal regulation and the role of atrial natriuretic peptide.

Main Results:

• Surgical stress typically induces renal vasoconstriction and salt/water retention, potentially lasting post-operatively.
• Anesthetic agents generally decrease glomerular filtration rate (GFR) and urine output; RBF effects are variable.
• Positive pressure ventilation can impair renal function via circulatory effects, manageable with fluids or inotropes.

Conclusions:

• Accurate assessment of perioperative renal function requires robust methodology and consideration of multiple physiological variables.
• Maintenance of atrial volume may mitigate stress-induced renal changes.
• Specific procedures like controlled hypotension and bypass necessitate careful renal management.