『Shock, Sodium, Potassium & pH: The High-Stakes NCLEX Breakdown』のカバーアート

Shock, Sodium, Potassium & pH: The High-Stakes NCLEX Breakdown

Shock, Sodium, Potassium & pH: The High-Stakes NCLEX Breakdown

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 Check out thinklikeanurse.orgComprehensive Episode NotesI. The “Critical Triangle” for NCLEXFluids, electrolytes, and acid–base interpretation form the foundation of the NCLEX physiological adaptation category.Accounts for ~11–17% of exam questions.Mastery requires recognizing patterns, sequences, and priorities.II. Fluid Volume: Absolute Loss vs DehydrationA. Absolute Volume LossFluid physically leaves the vascular space.Causes: trauma bleeding, burn plasma loss, third spacing.Third spacing = fluid shifts out of vessels into unusable spaces (e.g., pancreatitis abdomen).Treatment: volume replacement.B. Pure DehydrationLoss of free water > sodium.Hallmark: high sodium (hypernatremia).Seen in elderly, confused, poor intake.Treatment: free water replacement, not saline.III. Burn Management & The Parkland FormulaEquation: 4 mL × weight × % TBSA burns (2nd & 3rd degree).Half must be given in the first 8 hours (critical due to peak capillary leak).Preferred fluid: LR (unless potassium is high).LR contraindicated in crush injuries or pre-existing hyperkalemia → switch to normal saline.Large volumes of normal saline risk hyperchloremic metabolic acidosis.IV. Fluid Overload: Early vs Late SignsEarlyBounding pulses.Widened pulse pressure.LateCrackles.JVD.Dyspnea.Early detection prevents progression to pulmonary edema or cardiogenic complications.V. Hemodynamics & Shock DifferentiationA. Hypovolemic vs Cardiogenic ShockBoth show:Low cardiac output.High SVR.Difference:Filling pressures low in hypovolemia (tank is empty).Filling pressures high in cardiogenic (pump fails; backup into lungs).B. Early Warm Septic ShockBreaks the usual rules:Low SVR from vasodilation.High cardiac output as compensation.High mixed venous oxygen (SVO2) because tissues cannot extract oxygen.Profile: High CO + Low SVR + High SVO2 = Early sepsis.VI. Potassium: The Most Lethal ElectrolyteEmergency sequence (memorize the order):Protect the heart: IV calcium gluconate.Shift potassium into cells: Regular insulin + D50, or high-dose albuterol.Remove potassium: Binders or dialysis.Critical pearlIf potassium won’t correct → check magnesium first.Low magnesium prevents potassium retention.VII. Sodium: Emergencies & Rate of CorrectionA. Low SodiumAcute symptomatic (seizing): give 3% hypertonic saline quickly.Chronic low sodium: NEVER increase more than 8–12 per 24 hours.Risk: osmotic demyelination syndrome (ODS).B. High SodiumReplace free water slowly.Do not correct faster than ½ per hour.Risk: cerebral edema.VIII. Calcium & MagnesiumLow calcium causes neuromuscular irritability:Chvostek’s sign.Trousseau’s sign.QT prolongation.Give IV calcium gluconate slowly (10–20 minutes) to prevent bradycardia.IX. Acid–Base Interpretation (NCLEX Method)Step-by-step sequencepH (acidosis, alkalosis, or compensated).CO₂ = respiratory component (moves opposite pH).Bicarbonate = metabolic component (moves with pH).Apply ROME mnemonic:Respiratory = Opposite.Metabolic = Equal.X. Metabolic AcidosisA. Normal Gap AcidosisCauses = HARD P S (focus on):D – Diarrhea (loss of bicarbonate).S – Saline overload → hyperchloremic acidosis.B. High Gap Acidosis (MUDPILES)Focus on:D – DKA (ketone acids).L – Lactic acidosis (shock, sepsis).XI. Metabolic AlkalosisMnemonic CLU → focus on U = Upper GI losses.Vomiting, NG suction = loss of hydrochloric acid.Treatment requires:Normal saline (volume).Chloride (to exchange for bicarbonate).XII. Compensation: Winter’s FormulaExpected CO₂ ≈ 1.5 × bicarbonate + 8 (±2).Use to detect mixed disorders.Example:If expected CO₂ is 21–25 but actual is 15 → metabolic acidosis with respiratory alkalosis.XIII. Priority Actions (ABCs First)Stabilize airway/breathing before calling the provider.Emergency actions:Anaphylaxis → epinephrine IM.Tension pneumothorax → immediate needle decompression.Post-op day 2–3 SOB → assume pulmonary embolism.Red man syndrome → stop infusion, antihistamine, restart slowly.HIT → stop heparin, switch to direct thrombin inhibitor.XIV. DKA & PotassiumHigh or normal potassium on arrival is misleading.Total body potassium is low.As soon as insulin is given → potassium drops fast.Anticipate and replace aggressively.XV. Mixed Disorder Example: Aspirin ToxicityStimulates respiratory center → respiratory alkalosis.Produces organic acids → high gap metabolic acidosis.Check out thinklikeanurse.org Need to reach out? Send an email to Brooke at ThinkLikeaNursePodcast@gmail.com
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