Acute pre-kidney kidney damage: caused by decreased blood flow to the kidneys

Normally, the kidneys receive a plentiful amount of blood with about 1100ml per minute or 20-25% of the cardiac output.

The main purpose of delivering large amounts of blood to the kidneys is to provide sufficient plasma with the fluid and solute concentrations required for effective glomerular filtration. Therefore, a decrease in blood flow to the kidneys is usually accompanied by a decrease in the level of glomerular filtration (GFR) and a decrease in the amount of water and solutes in the urine. As a result, an acute decrease in blood flow to the kidneys causes oliguria, or in other words, the amount of urine excreted decreased in comparison to the amount of water and solutes ingested. This condition leads to fluid retention and body fluids. If the amount of blood to the kidneys is reduced significantly, with absolutely no urine to be excreted, it is called anuria.

When the amount of blood to the kidney has not dropped below 20-25% of normal, acute kidney damage can be reversed if the cause of kidney ischemia is treated before the kidney cells are damaged. love. Unlike other tissues, the kidney can tolerate a relatively large decrease in the amount of blood reaching the kidney before the physical damage to kidney cells occurs. The reason for this phenomenon is that when blood flow to the kidneys decreases, the GFR and the amount of NaCl filtered by the glomeruli (as well as the rate of filtration of water and other electrolytes) decrease. This reduces the amount of NaCl that should have been absorbed by the renal tubule, and which uses up most of the normal kidney's energy and oxygen.

Therefore, when blood flow to the kidney and GFR decreases, so does the kidney's need for oxygen. When the GFR reaches zero, the kidney's oxygen demand approaches a level sufficient to sustain the tubular cells even without sodium reabsorption.

When the blood flow to the kidney is lower than the baseline need, usually less than 20-25% of the blood flow to the normal kidney, the kidney cells become hypoxic, and a further decrease in blood flow to the kidney, if prolonged, causes damage or even death of kidney cells, especially tubular epithelial cells.

If the cause of the acute renal damage to the kidney is not corrected and the ischemia in the kidney persists for longer than a few hours, this type of renal failure may progress to acute renal damage, which should be discussed. comment later. Acute reduction in blood flow to the kidneys is the most common cause of acute kidney damage in hospitalized patients, especially in patients with severe kidney injury. The table lists several causes of decreased blood flow to the kidneys and causes acute pre-kidney damage to the kidneys.

Board. Several causes of acute pre-kidney kidney damage

* Reduced circulating volume

Haemorrhage (trauma, surgery, postpartum, gastrointestinal bleeding)

Diarrhoea or vomiting

Burn

Heart failure

Heart attack

Heart valve damage

Peripheral vasodilation and hypotension

Anaphylaxis

Anaesthesia

Infections, acute infections

Renal vascular abnormalities

Renal artery stenosis, embolism or thrombosis of the renal artery or vein.