Emergency medical personnel transport a 72-year-old woman to the hospital after she experi… — USMLE Step 2 CK

Emergency medical personnel transport a 72-year-old woman to the hospital after she experienced a witnessed generalized tonic-clonic seizure at her home. Her husband states that she was recently prescribed hydrochlorothiazide for essential hypertension and has been constantly drinking water due to a severe dry mouth.

Upon triage evaluation, the patient is stuporous and withdraws from painful stimuli but does not open her eyes. Her mucous membranes are moist. Vital signs demonstrate a blood pressure of $142/88 \text{ mm Hg}$ and a heart rate of $84/\text{min}$ . A rapid metabolic panel reveals a critically low serum sodium concentration of $111 \text{ mEq/L}$ with a serum osmolality of $232 \text{ mOsm/kg}$ . The critical care team initiates an algorithmic protocol to stabilize her condition and manage her electrolytes.

Arrange the following management steps in the most appropriate chronological sequence for this patient.

1Infuse a $100 \text{ mL}$ bolus of $3\%$ hypertonic saline
2Recheck serum sodium concentration and assess for resolution of neurologic symptoms
3Discontinue hypertonic saline and address the underlying cause of hyponatremia
4Administer intravenous desmopressin if the sodium correction rate exceeds $8 \text{ mEq/L}$ over $24$ hours

Cevap

The correct sequence begins with the immediate infusion of a 3% hypertonic saline bolus to reverse cerebral edema, followed by rapid reassessment of serum sodium and symptoms. Once the patient is neurologically stable, hypertonic saline is discontinued in favor of cause-specific management. Finally, desmopressin is administered as a rescue therapy only if the subsequent correction rate exceeds the safe limit of 8 mEq/L over 24 hours.

The algorithmic management of severe, symptomatic hyponatremia (presenting with seizures or coma) requires a biphasic approach: immediate, targeted reversal of cerebral edema, followed by strict limitation of the 24-hour correction rate to prevent osmotic demyelination syndrome (ODS). The chronological sequence dictates that a

3\%

hypertonic saline bolus must be administered first to acutely raise the serum sodium by

1-2 \text{ mEq/L}

, halting seizures. This is immediately followed by rapid re-evaluation of serum sodium and clinical status to determine if further boluses are necessary. Once severe symptoms resolve, hypertonic saline must be ceased to prevent overshooting, transitioning to cause-specific management (e.g., stopping hydrochlorothiazide and enforcing fluid restriction). Finally, the physician must monitor the 24-hour trajectory; if the sodium rises by more than

8 \text{ mEq/L}

(a common complication when thiazide-induced hyponatremia undergoes auto-diuresis), desmopressin (dDAVP) and free water are administered as a late-stage rescue strategy to re-lower the sodium.

Adım Adım Çözüm

Identify the acute life-threatening emergency.

The patient has severe symptomatic hyponatremia (seizures, stupor) requiring immediate reversal of cerebral edema.

Seizures from hyponatremia can lead to permanent brain damage or brain herniation if not rapidly treated with hypertonic saline.

Determine the immediate follow-up to the acute intervention.

Serum sodium and clinical status must be rechecked shortly after the initial bolus.

To verify if the sodium has increased by the target

1-2 \text{ mEq/L}

and to decide if a repeat bolus is clinically necessary.

Transition from acute rescue to maintenance management.

Discontinue hypertonic saline once severe symptoms resolve, and address the underlying cause.

Continued administration of hypertonic saline poses a massive risk for overcorrection once the initial neurological crisis is stabilized.

Plan for potential complications during the 24-hour correction window.

Prepare to administer desmopressin (dDAVP) if the sodium level rises too rapidly.

Stopping thiazides and restoring volume can trigger profound auto-diuresis. Desmopressin is used as a reactive rescue agent if the correction rate breaches the safe limit of

8 \text{ mEq/L}

per day.

Anahtar Kavram

Algorithmic management of severe symptomatic hyponatremia prioritizing immediate cerebral edema reversal followed by strict prevention of overcorrection.

Tahmini Süre:1m 30s

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

Sık Yapılan Hatalar

Konular

Bu konudan daha fazla soru