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[ Home ](https://mdster.com) 2. [ Blog ](https://mdster.com/blog) 3. [ Medical Education ](https://mdster.com/blog?category=medical-education) 4. AKI and Renal Replacement Overview: ICU Decisions That Matter Most [ Medical Education ](https://mdster.com/blog?category=medical-education) AKI and Renal Replacement Overview: ICU Decisions That Matter Most ==================================================================== Recognize dialysis emergencies, choose the right modality, and anticipate electrolyte and anticoagulation complications. [ MDster Editorial Team ](https://mdster.com/about) · Sep 16, 2026 · 7 min read · 56 [ Reviewed by Dr. Ali Ragab, MBBCH, MSc, MCAI ](https://mdster.com/medical-reviewers/dr-ali-ragab) [Editorial Policy](https://mdster.com/editorial-policy) | [Corrections Policy](https://mdster.com/corrections) [ Anesthesiology ](https://mdster.com/blog?tag=anesthesiology) [ Critical Care ](https://mdster.com/blog?tag=critical-care) [ Board Preparation ](https://mdster.com/blog?tag=board-preparation) [ Acute Kidney Injury ](https://mdster.com/blog?tag=acute-kidney-injury) [ Renal Replacement Therapy ](https://mdster.com/blog?tag=renal-replacement-therapy) ![AKI and Renal Replacement Overview: ICU Decisions That Matter Most](https://mdster.com/storage/blog/images/aki-and-renal-replacement-overview-icu-decisions-that-matter-most.jpg) Share this article Share this post On this page 1. [ Start for Complications, Not Creatinine ](#start-for-complications-not-creatinine) 2. [ Use AEIOU as a Bedside Safety Screen ](#use-aeiou-as-a-bedside-safety-screen) 3. [ “Earlier” Is Not Automatically Better ](#earlier-is-not-automatically-better) 4. [ Choose the Modality by Physiologic Tolerance ](#choose-the-modality-by-physiologic-tolerance) 5. [ Separate Clearance From Fluid Removal ](#separate-clearance-from-fluid-removal) 6. [ Anticipate Electrolyte Shifts ](#anticipate-electrolyte-shifts) 7. [ Anticoagulate the Circuit Without Harming the Patient ](#anticoagulate-the-circuit-without-harming-the-patient) 8. [ Key Takeaways ](#key-takeaways) 9. [ Frequently Asked Questions ](#blog-faqs) 10. [ References ](#references-heading) On this page 1. [ Start for Complications, Not Creatinine ](#start-for-complications-not-creatinine) 2. [ Use AEIOU as a Bedside Safety Screen ](#use-aeiou-as-a-bedside-safety-screen) 3. [ “Earlier” Is Not Automatically Better ](#earlier-is-not-automatically-better) 4. [ Choose the Modality by Physiologic Tolerance ](#choose-the-modality-by-physiologic-tolerance) 5. [ Separate Clearance From Fluid Removal ](#separate-clearance-from-fluid-removal) 6. [ Anticipate Electrolyte Shifts ](#anticipate-electrolyte-shifts) 7. [ Anticoagulate the Circuit Without Harming the Patient ](#anticoagulate-the-circuit-without-harming-the-patient) 8. [ Key Takeaways ](#key-takeaways) 9. [ Frequently Asked Questions ](#blog-faqs) 10. [ References ](#references-heading) Your postoperative patient is oliguric, receiving norepinephrine, and developing pulmonary edema. Potassium rises despite temporizing treatment. The urgent question is not how high creatinine will climb—it is whether kidney failure now threatens survival. [\[1\]](#cite-1 "Reference [1]") For anesthesiology practice, organize renal replacement therapy (RRT) around three decisions: **when to start, how fast to treat, and what treatment might destabilize next**. RRT supports homeostasis while the underlying injury is addressed; it does not reverse AKI itself. [\[2\]](#cite-2 "Reference [2]") Start for Complications, Not Creatinine --------------------------------------- Assess perfusion, congestion, urinary obstruction, and nephrotoxic exposures while arranging support. Do not reflexively give fluid for oliguria, and do not interpret a diuretic-induced increase in urine output as restored filtration. Diuretics manage volume overload; they do not treat the kidney injury. [\[1\]](#cite-1 "Reference [1]") ### Use AEIOU as a Bedside Safety Screen The mnemonic identifies major indications, but clinical severity and response to treatment determine urgency: - **A—Acidosis:** Severe metabolic acidemia that persists despite appropriate treatment, particularly with cardiovascular compromise. - **E—Electrolytes:** Dangerous hyperkalemia, especially when persistent, recurrent, or associated with ECG changes. - **I—Intoxications:** Selected dialyzable poisons, including lithium, toxic alcohols, and salicylates; use substance-specific criteria and toxicology input. - **O—Overload:** Fluid overload causing organ dysfunction, especially pulmonary edema despite medical management. - **U—Uremia:** Complications such as pericarditis, encephalopathy, or clinically significant uremic bleeding. [\[3\]](#cite-3 "Reference [3]") Do not wait for dialysis to treat hyperkalemic cardiotoxicity. Give IV calcium for toxic ECG changes, use insulin–glucose to shift potassium intracellularly, and monitor glucose afterward. These interventions buy time; calcium does not lower potassium, and intracellular shifting does not remove it. [\[4\]](#cite-4 "Reference [4]") > **Clinical Pearl:** A temporarily improved potassium after insulin is not proof that an anuric patient is safe. Recheck potassium and establish a removal strategy. [\[4\]](#cite-4 "Reference [4]") ### “Earlier” Is Not Automatically Better There is no universal creatinine or BUN threshold that mandates RRT. Consider trends, fluid balance, metabolic demands, and whether conservative treatment can safely keep pace. [\[1\]](#cite-1 "Reference [1]") In STARRT-AKI, accelerated initiation without conventional urgent indications did not improve 90-day survival and increased adverse events. This supports close surveillance—not indefinite delay or waiting through an evolving emergency. [\[5\]](#cite-5 "Reference [5]") Choose the Modality by Physiologic Tolerance -------------------------------------------- Think of intermittent hemodialysis (IHD) as rapid correction and continuous RRT (CRRT) as slower, sustained control. Neither is universally superior; patients may transition between them as their condition changes. [\[2\]](#cite-2 "Reference [2]") Clinical considerationIHDCRRTSolute removalRapid; useful for urgent potassium or toxin clearanceSlower, sustained clearanceFluid removalConcentrated into treatment sessionsAdjustable over prolonged treatmentTypical fitHemodynamically tolerant patientHemodynamic instability or acute brain injury These differences guide selection, but local expertise and immediate availability also matter. [\[1\]](#cite-1 "Reference [1]") ### Separate Clearance From Fluid Removal A patient may urgently need potassium clearance but tolerate little net ultrafiltration. Prescribe those goals separately: excessive fluid removal can worsen hypotension even during CRRT. Sustained low-efficiency dialysis offers a prolonged intermittent alternative where available. [\[3\]](#cite-3 "Reference [3]") CRRT is generally favored with hemodynamic instability or increased intracranial pressure because fluid and osmotic changes are slower. However, randomized evidence has not established a mortality advantage over intermittent therapy. Choose physiologic fit, not an assumed survival benefit. [\[2\]](#cite-2 "Reference [2]") Anticipate Electrolyte Shifts ----------------------------- Dialysis can replace one electrolyte emergency with another. Its effects depend on treatment intensity, duration, and dialysate or replacement-fluid composition. [\[6\]](#cite-6 "Reference [6]") - Follow potassium during treatment and afterward; rebound can occur after IHD. [\[4\]](#cite-4 "Reference [4]") - Monitor phosphate and magnesium alongside potassium during CRRT; ongoing losses may require replacement or different solutions. [\[6\]](#cite-6 "Reference [6]") - Plan sodium correction explicitly in severe dysnatremia. CRRT permits controlled correction but does not automatically prevent an unsafe rate. [\[3\]](#cite-3 "Reference [3]") ### Anticoagulate the Circuit Without Harming the Patient Regional citrate anticoagulation is generally preferred for CRRT when appropriate and supported by a validated protocol. Citrate chelates calcium within the circuit; systemic calcium replacement maintains patient ionized calcium. Monitor systemic and postfilter ionized calcium according to protocol—they answer different questions. [\[7\]](#cite-7 "Reference [7]") Systemic heparin introduces bleeding and heparin-induced thrombocytopenia risks. Selected patients may receive anticoagulant-free treatment, accepting shorter circuit life; regional citrate does not replace systemic thromboprophylaxis when indicated. [\[7\]](#cite-7 "Reference [7]") Watch for two distinct citrate problems: - Citrate metabolism generates an alkali load. Excess delivery with preserved metabolism can produce metabolic alkalosis. - Impaired metabolism can cause citrate accumulation: falling systemic ionized calcium, escalating calcium requirements, and worsening metabolic acidosis. A rising total-to-ionized calcium ratio around **2.5 or higher**, using identical molar units, supports suspicion. [\[8\]](#cite-8 "Reference [8]") Severe shock and liver dysfunction warrant heightened vigilance, not simplistic assumptions about citrate safety. Suspected accumulation requires prompt protocol-guided adjustment and, if persistent, stopping citrate—not merely escalating calcium indefinitely. [\[9\]](#cite-9 "Reference [9]") Key Takeaways ------------- - Use AEIOU and clinical trajectory, not an isolated creatinine, to identify urgent RRT needs. [\[1\]](#cite-1 "Reference [1]") - Choose IHD for rapid clearance when tolerated; favor CRRT when slower shifts are needed. [\[2\]](#cite-2 "Reference [2]") - Treat electrolyte monitoring and anticoagulation surveillance as part of the prescription, not afterthoughts. [\[7\]](#cite-7 "Reference [7]") The bedside question remains: can this patient maintain safe homeostasis without extracorporeal support? Reassess that balance repeatedly, including whether recovering kidney function now permits stopping RRT. [\[2\]](#cite-2 "Reference [2]") *Evidence status, September 16, 2026: KDIGO identifies its 2026 AKI/AKD update as undergoing preparation for publication after public review; draft recommendations are not treated here as finalized guidance.* [\[10\]](#cite-10 "Reference [10]") Frequently Asked Questions ---------------------------- ### Does oliguria alone require dialysis? No. Evaluate reversible causes, fluid balance, and metabolic complications. Oliguria warrants surveillance, not automatic RRT. [\[1\]](#cite-1 "Reference [1]") ### Is CRRT always best for severe hyperkalemia? No. IHD clears potassium faster when tolerated; CRRT may better suit marked hemodynamic instability. [\[3\]](#cite-3 "Reference [3]") ### Does citrate-associated alkalosis prove citrate accumulation? No. Alkalosis commonly reflects metabolized citrate delivering excess alkali. Accumulation is suggested by calcium abnormalities and often worsening acidosis. [\[8\]](#cite-8 "Reference [8]") References (10) ------------------- 1. 1. [ KDIGO. Clinical Practice Guideline for Acute Kidney Injury. 2012. ](https://kdigo.org/wp-content/uploads/2016/10/KDIGO-2012-AKI-Guideline-English.pdf) [↩](#cite-ref-1-1 "Back to text") 2. 2. [ pmc.ncbi.nlm.nih.gov/articles/PMC8481001 ](https://pmc.ncbi.nlm.nih.gov/articles/PMC8481001/) [↩](#cite-ref-2-1 "Back to text") 3. 3. [ pmc.ncbi.nlm.nih.gov/articles/PMC9989875 ](https://pmc.ncbi.nlm.nih.gov/articles/PMC9989875/) [↩](#cite-ref-3-1 "Back to text") 4. 4. [ www.ukkidney.org/sites/renal.org/files/FINAL%20VERSION%20-%20UKKA%20CLINICAL%20PRACTICE%20GUIDELINE%20-%20MANAGEMENT%20OF%20HYPERKALAEMIA%20IN%20ADULTS%20-%20191223\_0.pdf ](https://www.ukkidney.org/sites/renal.org/files/FINAL%20VERSION%20-%20UKKA%20CLINICAL%20PRACTICE%20GUIDELINE%20-%20MANAGEMENT%20OF%20HYPERKALAEMIA%20IN%20ADULTS%20-%20191223_0.pdf) [↩](#cite-ref-4-1 "Back to text") 5. 5. [ STARRT-AKI Investigators. Timing of Initiation of Renal-Replacement Therapy in Acute Kidney Injury. NEJM. 2020. ](https://www.nejm.org/doi/full/10.1056/NEJMoa2000741) [↩](#cite-ref-5-1 "Back to text") 6. 6. [ pmc.ncbi.nlm.nih.gov/articles/PMC10914214 ](https://pmc.ncbi.nlm.nih.gov/articles/PMC10914214/) [↩](#cite-ref-6-1 "Back to text") 7. 7. [ SIAARTI-SIN Joint Commission. Regional citrate anticoagulation in critically ill patients undergoing RRT. 2023. ](https://link.springer.com/article/10.1186/s44158-023-00091-w) [↩](#cite-ref-7-1 "Back to text") 8. 8. [ pmc.ncbi.nlm.nih.gov/articles/PMC10226261 ](https://pmc.ncbi.nlm.nih.gov/articles/PMC10226261/) [↩](#cite-ref-8-1 "Back to text") 9. 9. [ pmc.ncbi.nlm.nih.gov/articles/PMC13340270 ](https://pmc.ncbi.nlm.nih.gov/articles/PMC13340270/) [↩](#cite-ref-9-1 "Back to text") 10. 10. 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