Renal AKI, CKD, Dialysis, and Fluid Balance
Key Takeaways
- Renal questions often test early recognition of fluid overload, hypovolemia, electrolyte danger, and medication accumulation.
- Urine output trends, daily weight, creatinine change, potassium, acid-base status, and mental status are more useful than one isolated value.
- Dialysis access assessment is a safety check: protect fistulas and grafts from blood pressure cuffs, venipuncture, and compression.
- Hyperkalemia with ECG changes, pulmonary edema, uremic symptoms, and severe acidosis require urgent escalation.
- Patient teaching should translate renal restrictions into practical choices about fluids, sodium, potassium, phosphorus, and medications.
Renal AKI, CKD, Dialysis, and Fluid Balance
Case anchor
A 72-year-old adult is admitted after vomiting and taking ibuprofen for back pain. Baseline creatinine is 0.9 mg/dL; today it is 2.4 mg/dL. Blood pressure is 92/54 mm Hg, urine output is 20 mL/hr, potassium is 5.2 mEq/L, and the patient reports weakness. The CMSRN nurse thinks in categories: prerenal hypoperfusion, intrinsic injury from nephrotoxins, obstruction, and complications that can become life-threatening before the exact cause is confirmed.
Assessment priorities
Start with volume and perfusion. Compare current and baseline creatinine, urine output, daily weight, lung sounds, edema, mucous membranes, orthostatic symptoms, jugular venous distention, and blood pressure response to fluids or diuretics. Ask about contrast, NSAIDs, ACE inhibitors, ARBs, diuretics, antibiotics, herbal products, urinary retention, flank pain, and recent infection. A bladder scan is useful when output is low because obstruction is fixable and easy to miss.
AKI versus CKD patterns
| Finding | AKI focus | CKD focus |
|---|---|---|
| Creatinine | Rapid rise from baseline | Long-standing elevation or low eGFR |
| Fluid status | May be dry, overloaded, or shifting | Often sodium and water sensitive |
| Electrolytes | Hyperkalemia can change quickly | Phosphorus, calcium, anemia, acidosis concerns |
| Nursing goal | Reverse cause and prevent complications | Slow progression and support self-management |
In AKI, trending is essential. A creatinine of 1.5 mg/dL may be severe if yesterday was 0.6, while 3.0 mg/dL may be near baseline for some dialysis patients. CMSRN questions often reward the nurse who recognizes trend plus symptoms rather than memorizing a single number.
Fluid balance interventions
Strict intake and output, daily weights at the same time, renal-dose medication review, and avoidance of nephrotoxins are core interventions. Report urine output less than 0.5 mL/kg/hr in an unstable patient, new crackles, escalating oxygen need, sudden weight gain, hypotension, confusion, or potassium increase. If fluid resuscitation is ordered, reassess lungs and perfusion frequently. If diuretics are ordered, monitor response, potassium, magnesium, blood pressure, and renal function.
Fluid overload can be subtle before it is dramatic. A patient with CKD who gains 3 kg over two days, has rising blood pressure, decreasing oxygen saturation, and new crackles is not just noncompliant; the patient may need urgent diuresis, dialysis evaluation, or respiratory support. Keep the patient upright, apply oxygen per protocol, notify the provider, and prepare for additional labs, ECG, chest imaging, or dialysis.
Electrolyte and medication risks
Hyperkalemia is a priority because it can cause fatal dysrhythmias. Watch for muscle weakness, paresthesias, peaked T waves, widened QRS, bradycardia, or ventricular rhythms. Anticipate ECG monitoring, calcium for membrane stabilization, insulin with dextrose to shift potassium intracellularly, beta agonist therapy, bicarbonate if acidotic, potassium binders, diuretics, or dialysis depending on severity and orders.
Renal impairment increases medication toxicity. Opioids, gabapentin, digoxin, lithium, certain antibiotics, metformin, anticoagulants, and magnesium or phosphorus products may accumulate. Before giving scheduled medications, check current renal function, hold parameters, sedation level, heart rate, and drug levels when applicable. A CMSRN-safe action is to question a nephrotoxic or renally cleared drug when kidney function has worsened.
Dialysis access and treatment safety
For an arteriovenous fistula or graft, assess bruit and thrill, distal circulation, bleeding, infection, and skin integrity. Do not use that arm for blood pressure, venipuncture, IV starts, or tight clothing. For central dialysis catheters, maintain sterile dressing care and do not access unless trained and permitted by policy.
Before dialysis, review weight, vital signs, potassium, access status, and medications that may be held because dialysis can cause hypotension. After dialysis, reassess vital signs, mental status, access bleeding, cramps, dizziness, and weight change. Disequilibrium syndrome is uncommon but important: headache, nausea, restlessness, confusion, or seizure after rapid solute shifts should be escalated.
Patient education
Teaching should be specific. Instead of saying avoid potassium, name high-potassium foods the patient actually eats and explain the dietitian plan. Discuss sodium restriction, fluid limits, daily weight log, blood pressure monitoring, phosphate binders with meals, anemia treatment, and avoiding NSAIDs unless specifically approved. Teach dialysis patients to report fever, access redness, loss of thrill, shortness of breath, chest pain, missed dialysis, or uncontrolled bleeding from access.
Escalation cues
Call promptly for hyperkalemia with ECG changes, pulmonary edema, severe hypertension with symptoms, hypotension with oliguria, new confusion, pericarditis symptoms, seizure, severe acidosis, rapidly rising creatinine, suspected obstruction, access infection, or access bleeding that does not stop. On exam questions, choose actions that protect cardiac rhythm, oxygenation, perfusion, and dialysis access.
A patient with AKI has potassium 6.4 mEq/L and new peaked T waves. What is the nurse's priority?
A patient with vomiting has creatinine increased from 0.8 to 2.1 mg/dL and urine output 18 mL/hr. Which provider order should the nurse question first?
Which assignment should the nurse avoid for the arm with a mature arteriovenous fistula?