Mrs. Bush, a 70-year-old woman, is admitted to the hospital. Her history states that she has been suffering from diarrhea for three weeks. On admission, she complains of severe fatigue and muscle weakness. A blood chemistry study yields the following information: Na⁺ 142 mEq/L; K⁺ 1.5 mEq/L; Cl ⁻ 92 mEq/L; Pco₂ 32 mm Hg. Which electrolytes are within normal limits? Which are so abnormal that the patient has a medical emergency? Which of the following represents the greatest danger to Mrs. Bush? a. a fall due to her muscular weakness, b. edema, c. cardiac arrhythmia and cardiac arrest.

Verified step by step guidance

1. Step 1: Identify the normal ranges for the electrolytes and blood gas values provided. Typically, normal ranges are: Na⁺: 135-145 mEq/L, K⁺: 3.5-5.0 mEq/L, Cl⁻: 98-106 mEq/L, Pco₂: 35-45 mm Hg.
2. Step 2: Compare Mrs. Bush's electrolyte values to the normal ranges. Na⁺ is 142 mEq/L, which is within the normal range. K⁺ is 1.5 mEq/L, which is significantly below the normal range, indicating hypokalemia. Cl⁻ is 92 mEq/L, which is below the normal range, indicating hypochloremia. Pco₂ is 32 mm Hg, which is below the normal range, indicating possible respiratory alkalosis.
3. Step 3: Determine which electrolyte imbalance is most critical. Hypokalemia (low K⁺) is particularly dangerous because it can lead to cardiac arrhythmias and cardiac arrest.
4. Step 4: Evaluate the symptoms and potential risks associated with the electrolyte imbalances. Severe fatigue and muscle weakness are symptoms of hypokalemia. The greatest danger is cardiac arrhythmia and cardiac arrest due to the low potassium level.
5. Step 5: Conclude that the most immediate medical emergency is the hypokalemia, which poses a risk of cardiac arrhythmia and cardiac arrest, making option c the greatest danger to Mrs. Bush.

Key Concepts

Electrolyte Balance

Electrolyte balance refers to the proper levels of minerals in the body fluids, which are crucial for various physiological functions. Key electrolytes include sodium (Na⁺), potassium (K⁺), and chloride (Cl⁻). Abnormal levels can lead to serious health issues, such as muscle weakness, fatigue, and cardiac problems. Understanding the normal ranges for these electrolytes is essential for assessing a patient's condition.

Potassium Levels and Cardiac Function

Potassium is vital for maintaining normal heart rhythm and muscle function. Normal serum potassium levels range from 3.5 to 5.0 mEq/L, and levels below this can lead to hypokalemia, which increases the risk of cardiac arrhythmias and potentially cardiac arrest. In Mrs. Bush's case, her potassium level of 1.5 mEq/L is critically low, indicating a medical emergency that requires immediate intervention.

Clinical Signs of Electrolyte Imbalance

Clinical signs of electrolyte imbalance can manifest as muscle weakness, fatigue, and changes in heart rhythm. In Mrs. Bush's situation, her severe fatigue and muscle weakness are indicative of possible electrolyte disturbances, particularly due to her low potassium levels. Recognizing these signs is crucial for timely diagnosis and treatment to prevent complications such as falls or cardiac events.