Sign up to save your podcasts
Or
Share Shock, Sodium, Potassium & pH: The High-Stakes NCLEX Breakdown
Share to email
Share to Facebook
Share to X
Share to email
Share to Facebook
Share to X
Or
Shock, Sodium, Potassium & pH: The High-Stakes NCLEX Breakdown
Check out thinklikeanurse.org
Comprehensive Episode Notes
I. 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 [email protected]
View all episodes
By Brooke WallaceCheck out thinklikeanurse.org
Comprehensive Episode Notes
I. 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 [email protected]