Can renal afferent arteriolar vasoconstriction cause anuria in the setting of severe renal (kidney) ischemia?

From the Guidelines

Renal afferent arteriolar vasoconstriction can indeed cause anuria in the setting of severe renal ischemia, as it dramatically reduces glomerular filtration pressure, which is already compromised during renal ischemia. This occurs because, when blood flow to the kidneys is severely restricted due to ischemia, the body initially attempts to maintain glomerular filtration rate (GFR) through autoregulatory mechanisms. However, if afferent arterioles constrict (which can happen due to increased sympathetic tone, angiotensin II activation, or endothelin release during shock states), this creates a "double hit" on renal perfusion. The combination of systemic hypoperfusion and local vasoconstriction can reduce GFR to essentially zero, resulting in anuria (urine output less than 50-100 mL/day) 1.

Key points to consider in this context include:

• The pathophysiology of renal ischemia and its impact on renal function, as outlined in the acc/aha 2005 practice guidelines for the management of patients with peripheral arterial disease 1.
• The role of angiotensin II-induced efferent arteriolar vasoconstriction in maintaining glomerular filtration rate, and how agents that cause efferent arteriolar dilation, such as ACE inhibitors or angiotensin II receptor blockers, can cause acute renal failure in certain situations 1.
• The importance of maintaining adequate renal perfusion pressure and avoiding nephrotoxic medications that cause afferent arteriolar constriction, such as NSAIDs or ACE inhibitors/ARBs, in the management of acute kidney injury.

In clinical practice, it is crucial to prioritize the maintenance of renal perfusion and avoid medications that can exacerbate renal ischemia, in order to prevent anuria and other complications of acute kidney injury. This approach is supported by the most recent and highest quality evidence, including the guidelines outlined in 1.

From the Research

Renal Afferent Arteriolar Vasoconstriction and Anuria

• Renal afferent arteriolar vasoconstriction can lead to a decrease in renal blood flow and glomerular filtration rate (GFR) 2.
• Severe renal ischemia can cause anuria, which is characterized by a significant reduction in urine output 3, 2.
• The pathophysiology of ischemic acute renal failure involves an interplay of haemodynamic and tubular abnormalities, including renal vasoconstriction and loss of blood flow and GFR autoregulation 2.

Mechanisms of Renal Ischemia

• Renal ischemia can lead to impaired renal autoregulatory capability, resulting in decreased renal blood flow and GFR 4.
• Reactive oxygen species (ROS) accumulation, likely involving superoxide and/or hydrogen peroxide, can impair renal autoregulation in ischemic conditions 4.
• Atherosclerotic renal artery disease is a progressive disorder that can lead to bilateral renal ischemia and anuria 3.

Clinical Implications

• Identification of ischemic renal disease (IRD) is crucial, as it is a potentially reversible cause of chronic renal failure in hypertensive patients 3.
• Treatment methods, including percutaneous transluminal angioplasty, endovascular stenting, and surgical revascularization, can improve outcomes in patients with IRD 3.
• Antioxidant treatment may improve renovascular autoregulatory function and prevent the progression to chronic kidney disease after acute kidney injury 4.