ICU Map

Acute Severe Metabolic Acidosis Evaluation

From primary disorder confirmation and Anion Gap calculation to Winter's compensation, delta ratio, and targeted source control.

RecognizeAssessDecideDifferentialInterveneReassess
Acute Severe Acidemia (pH < 7.25 / HCO3 < 15)
Assessment StepConfirm primary metabolic acidosis on simultaneous ABG and basic chemistryExplore Topic
Verify low pH (<7.35) with low serum bicarbonate (<22 mEq/L) and elevated base deficit.
Decision PointCalculate serum Anion Gap corrected for serum albuminExplore Topic
AG = Na - (Cl + HCO3). Corrected AG = Observed AG + 2.5 * (4.0 - Albumin g/dL). Normal is 10–12 mEq/L.
Differential Branches (2)
1Branch
Assessment StepHigh Anion Gap Acidosis (HAGMA: AG > 12 mEq/L)
Unmeasured acid anions accumulating. Work up 'GOLDMARK': Glycols (toxic alcohols), Oxoproline (chronic acetaminophen), L-Lactate (shock/hypoxia), D-Lactate (short gut), Methanol, Aspirin/Salicylates, Renal failure (uremia), Ketoacidosis (DKA/starvation/alcohol).
Assessment StepCheck Winter's formula (expected PaCO2) and Delta-Delta ratio
Expected PaCO2 = 1.5 * HCO3 + 8 (+/- 2). Delta Ratio = (AG - 12) / (24 - HCO3). Ratio < 0.4–0.8 indicates mixed HAGMA + NAGMA; ratio > 2.0 indicates concurrent metabolic alkalosis.
Clinical ActionExecute targeted etiology-specific reversal
DKA: IV insulin + balanced crystalloid. Sepsis: source control + perfusion restoration. Toxic alcohols: Fomepizole + urgent hemodialysis. Uremia: Dialysis initiation.
2Branch
Assessment StepNormal Anion Gap Acidosis (NAGMA / Hyperchloremic: AG <= 12)
Direct bicarbonate loss or rapid chloride loading. Differentiate GI losses (severe diarrhea, enterocutaneous fistula) from Renal Tubular Acidosis (RTA) and large-volume 0.9% saline infusion.
Clinical ActionSwitch to balanced crystalloid & replace bicarbonate if severe
Discontinue 0.9% Normal Saline; administer isotonic sodium bicarbonate or Plasmalyte; treat GI losses.

An educational representation of clinical reasoning, not a diagnostic algorithm or personalized medical advice — always apply clinical judgment and institutional protocols.

Caution

Escalate — Red Flags & Critical Warnings

  • Profound metabolic acidemia with severe AKI (AKIN stage 2–3): BICAR-ICU reported a prespecified severe-AKI subgroup signal, but BICARICU-2 did not confirm a mortality benefit and did reduce kidney replacement therapy use. Consider IV bicarbonate selectively while treating the cause and monitoring sodium, calcium, volume status, and ventilation; 2026 SSC support in septic shock with pH ≤ 7.2 and AKIN 2–3 is conditional with very low certainty.
  • Severe unexplained high anion gap acidosis with osmolar gap > 10–15 mOsm/kg — suspect toxic alcohol poisoning (Methanol / Ethylene Glycol); administer Fomepizole and consult nephrology immediately for emergency dialysis.

Related Bedside Clinical Problems (26)

Bedside Presentations
Acute Hypercapnia & Ventilatory Failure

Triaging rising PaCO2: distinguishing acute uncompensated acidemia from chronic compensation, identifying central vs pump vs dead-space failure, and titrating noninvasive ventilation.

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Acute Hypotension & Undifferentiated Shock

Rapid bedside hemodynamic categorization: confirming MAP < 65 mmHg, assessing peripheral perfusion, POCUS cardiac/IVC profiling, and differentiating hypovolemic, distributive, cardiogenic, and obstructive etiologies.

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Refractory Shock Despite High-Dose Vasopressors

Advanced multimodal hemodynamic rescue: second-line vasopressors (vasopressin, angiotensin II), inotropic augmentation, stress-dose steroids, metabolic correction, and mechanical circulatory support evaluation.

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Linked Deep-Dive Topics (7)

Reference Knowledge
Metabolic Acidosis: HAGMA, NAGMA, & Bicarbonate Evidencerenal

Differential diagnosis (GOLD MARK vs HARDCARP), toxic alcohol osmolar gaps, Urine Anion Gap, and current sodium bicarbonate evidence including BICAR-ICU and BICARICU-2.

Explore Topic →
Acid-Base Disorders: Comprehensive Critical Care Approachrenal

Stepwise 6-step interpretation algorithm, compensation formulas, albumin-corrected anion gap, delta ratio, and Stewart physicochemical (SID) principles.

Explore Topic →
Diabetic Ketoacidosis (DKA)endocrine-metabolic

Pathophysiology, SGLT2i euglycemic DKA, balanced fluid resuscitation, potassium-before-insulin safety rules, dextrose addition kinetics, and subcutaneous transition.

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Toxicologic Emergencies in Critical Caretoxicology

Resuscitate first, identify toxidromes and ECG/acid-base threats, use toxin-specific antidotes, and escalate early to poison-center, extracorporeal, or ECLS support when physiology demands it.

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Continuous Renal Replacement Therapy (CRRT)renal

Principles of convection vs diffusion, filtration fraction, delivered effluent dosing (20–25 mL/kg/h), Regional Citrate Anticoagulation, and citrate toxicity.

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Shock: Foundational Critical Care Frameworkcardiovascular

Cellular dysoxia, DO2/VO2 physiology, the 4 shock phenotypes, dynamic fluid responsiveness (PLR/PPV) vs fluid tolerance (VExUS), and vasoactive pharmacology.

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Acute Kidney Injury in Critical Carerenal

Sepsis-AKI microcirculatory decoupling, KDIGO staging, Furosemide Stress Test (FST), urine microscopy, and the AEIOU dialysis threshold framework.

Explore Topic →

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