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Difficulty: HardPhysiological Adaptation

An emergency department nurse receives a client with end-stage renal disease who has missed three consecutive hemodialysis sessions. The client is profoundly lethargic and reports severe, generalized muscle weakness. Assessment reveals a blood pressure of 110/60 mm Hg, heart rate of 48 bpm, and respiratory rate of 24 bpm. Telemetry monitoring shows sinus bradycardia with tall, peaked T waves and significantly widened QRS complexes. Arterial blood gas (ABG) analysis indicates a pH of 7.26, PaCO2 of 31 mm Hg, PaO2 of 94 mm Hg, and HCO3 of 15 mEq/L. Which prescribed intervention should the nurse implement FIRST?

  1. Administer intravenous calcium gluconate.Answer
  2. B
    Administer intravenous regular insulin and 50% dextrose.
  3. C
    Infuse an intravenous bolus of sodium bicarbonate.
  4. D
    Prepare the client for emergent hemodialysis access insertion.

Answer

The correct intervention is to administer intravenous calcium gluconate to immediately stabilize the myocardial resting membrane potential.
Intravenous calcium gluconate is the absolute priority intervention for a client with severe hyperkalemia manifesting with significant electrocardiogram (ECG) changes, such as widened QRS complexes or a sine wave pattern. Calcium does not lower the serum potassium level; instead, it immediately raises the threshold potential of cardiac myocytes. This stabilizes the resting membrane potential and antagonizes the cardiotoxic effects of hyperkalemia, thereby preventing lethal arrhythmias like ventricular fibrillation or asystole. Once the myocardium is protected, the nurse can subsequently administer potassium-shifting agents (like insulin and dextrose) and prepare for potassium-removing therapies (like hemodialysis).

Step-by-Step Solution

1
Analyze the client's clinical presentation and laboratory data.
The client exhibits signs of severe hyperkalemia (missed dialysis, muscle weakness, bradycardia, peaked T waves, and widened QRS complexes) alongside a partially compensated metabolic acidosis.
Recognizing the underlying physiological disturbances is essential for prioritizing care in an emergency.
2
Identify the most immediate life-threatening condition.
The significantly widened QRS complexes indicate that the hyperkalemia has progressed to a state of severe myocardial instability, risking imminent ventricular fibrillation or asystole.
According to prioritization principles, imminent threats to circulation and cardiac function must be addressed before correcting other physiological imbalances.
3
Determine the primary mechanism and onset of action for the available interventions.
Calcium gluconate acts immediately to stabilize the cardiac membrane, whereas insulin/dextrose and sodium bicarbonate shift potassium intracellularly over a longer period, and hemodialysis requires significant preparation time.
Pharmacological intervention must match the extreme urgency of the physiological threat.
4
Select the priority intervention.
Intravenous calcium gluconate is administered first to protect the heart.
Myocardial stabilization is a strict prerequisite to allow time for subsequent potassium-lowering therapies to take effect.

Key Concept

Prioritization of care in severe hyperkalemia: Immediate myocardial stabilization with calcium gluconate precedes potassium-lowering therapies when severe electrocardiogram changes are present.
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Topics

Physiological Adaptation

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