Kidney Map: Acute vs. Chronic Failure, Dialysis, and Fluid Balance

Acute kidney injury vs. chronic kidney disease

The three causes of AKI, grouped by where the problem is:

• Before the kidney — not enough blood reaching it. Dehydration, blood loss, shock, heart failure. Most common.
• In the kidney — direct damage. Contrast dye, some antibiotics, NSAIDs.
• After the kidney — something blocking outflow. Enlarged prostate, stones, tumor.

The phases of AKI:

• Onset — the injury happens
• Oliguric — low urine output, usually under 400 mL a day. This is when potassium rises and becomes dangerous.
• Diuretic — urine output increases a lot. Now the risk is dehydration and losing too much electrolyte.
• Recovery — function gradually improves

The exam tests the direction of the risk: low output phase = fluid overload and high potassium. High output phase = dehydration and low electrolytes.

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What kidney failure does to labs

The single biggest danger is high potassium, because it causes fatal heart rhythms. Any question about a client in kidney failure should make you think about potassium and the heart.

Nursing care

• Strict intake and output
• Daily weight — the best measure of fluid status
• Monitor potassium and the heart rhythm
• Fluid restriction as ordered
• Diet: usually low potassium, low phosphorus, low sodium, with protein adjusted to the stage and whether the client is on dialysis
• Check every medication — many drugs are cleared by the kidneys and need dose changes
• Avoid NSAIDs and contrast dye where possible

Hemodialysis

The access site is the most tested topic.

An arteriovenous fistula or graft is a surgically created connection in the arm.

Check it every shift:

• Feel for a thrill — a buzzing vibration
• Listen for a bruit — a whooshing sound

Both present = the access is working. Either missing = report immediately.

In that arm, NEVER:

• Take blood pressure
• Draw blood
• Start an IV
• Apply anything tight

Put a sign above the bed. Teach the client to protect it.

Before dialysis: weigh the client, check vital signs, and hold medications that would be removed by dialysis or would drop blood pressure, as ordered. Blood pressure medications are commonly held.

After dialysis: weigh again, check vital signs, watch for low blood pressure, check the site for bleeding, assess for headache or confusion.

The weight difference before and after shows how much fluid was removed.

Complications: low blood pressure during treatment, muscle cramps, bleeding, infection.

Peritoneal dialysis

Fluid goes into the abdomen, sits, and drains out.

The most tested point: the drained fluid should be clear.

Cloudy drainage means infection of the abdominal lining (peritonitis). Report it immediately. Other signs: abdominal pain, fever, tenderness.

Other points:

• Use strict sterile technique with every exchange
• Warm the fluid before instilling — cold fluid causes cramping
• If the fluid does not drain well: reposition the client, check for kinks, check for constipation
• Record the amount in and the amount out
• Weigh the client with the abdomen empty for consistency

Fluid balance

Signs of too much fluid:

• Weight gain
• Swelling
• Distended neck veins
• Crackles in the lungs
• Shortness of breath
• High blood pressure
• Bounding pulse

Signs of too little fluid:

• Weight loss
• Dry mouth and skin
• Poor skin turgor
• Fast heart rate
• Low blood pressure
• Concentrated, dark urine
• Low urine output
• Dizziness on standing

Daily weight is the most reliable measure of fluid change. One kilogram of weight is about one liter of fluid.

The short version

• AKI is sudden and often reversible. CKD is gradual and permanent.
• Low urine output phase = high potassium and fluid overload
• High potassium is the main killer in kidney failure
• Fistula: feel for a thrill, listen for a bruit, no BP or blood draws in that arm
• Peritoneal dialysis: cloudy drainage = peritonitis = report
• Daily weight is the best fluid measure