Fluid, Electrolyte And Acid-Base Homeostasis
Fluid, Electrolyte and Acid-Base Homeostasis:
Ms. Brown is a 70-year-old woman with type 2 diabetes mellitus who has been too ill to get out of bed for 2 days. She has had a severe cough and has been unable to eat or drink during this time. On admission, her laboratory values show the following:
Serum glucose 412 mg/dL
Serum sodium (Na+) 156 mEq/L
Serum potassium (K+) 5.6 mEq/L
Serum chloride (Cl–) 115 mEq/L
Arterial blood gases (ABGs): pH 7.30; PaCO2 32 mmHg; PaO2 70 mmHg; HCO3– 20 mEq/L
Case Study Questions
Based on Ms. Brown admission’s laboratory values, could you determine what type of water and electrolyte imbalance does she has?
Describe the signs and symptoms to the different types of water imbalance and described clinical manifestation she might exhibit with the potassium level she has.
In the specific case presented which would be the most appropriate treatment for Ms. Brown and why?
What the ABGs from Ms. Brown indicate regarding her acid-base imbalance?
Based on your readings and your research define and describe Anion Gaps and its clinical significance
Sample Solution
1. Ms. Brown's Water and Electrolyte Imbalance:
Based on her laboratory values, Ms. Brown likely has a mixed water and electrolyte imbalance with elements of:
- Hyponatremia (low sodium): Serum Na+ of 156 mEq/L is below the normal range of 135-145 mEq/L.
- Dehydration: Inability to eat or drink for 2 days suggests hypovolemia, a decrease in total body fluid volume. This can contribute to her low sodium and other imbalances.
- Hyperkalemia (high potassium): Serum K+ of 5.6 mEq/L is above the normal range of 3.5-5.0 mEq/L.
2. Water Imbalance and Potassium Level Manifestations:
Full Answer Section
Types of Water Imbalance:- Hyponatremia: Can cause confusion, nausea, muscle weakness, lethargy, and seizures in severe cases.
- Hypernatremia: Less common in this case, but can cause thirst, drowsiness, muscle cramps, and coma in severe cases.
- Hypotonic dehydration: Caused by fluid loss exceeding electrolyte loss, leading to swelling of cells. Symptoms include fatigue, muscle cramps, nausea, and dizziness.
- Hypertonic dehydration: Caused by electrolyte loss exceeding fluid loss, leading to cell shrinkage. Symptoms include thirst, confusion, and rapid heartbeat.
- Muscle weakness: This is the most common symptom and can range from mild fatigue to paralysis.
- Cardiac arrhythmias: High potassium can disrupt heart rhythm, potentially leading to serious complications.
- Tingling/numbness: Potassium imbalances can affect nerve function, causing tingling or numbness in extremities.
- Weakness and fatigue
- Nausea and vomiting
- Muscle cramps
- Dizziness or lightheadedness
- Confusion or delirium
- Irregular heartbeat
- Treatment for Ms. Brown:
- Fluid resuscitation: Intravenous fluids with appropriate electrolytes, considering her hyponatremia and hypovolemia.
- Potassium monitoring: Closely monitoring her K+ levels and potentially administering insulin or glucose to drive potassium back into cells.
- Addressing the underlying cause: Treating the cough and any other contributing factors, such as infection or metabolic issues.
- Acid-Base Imbalance on ABGs:
- Mild metabolic acidosis: pH of 7.30 is slightly below the normal range of 7.35-7.45.
- Normal respiratory status: PaCO2 of 32 mmHg and PaO2 of 70 mmHg are within normal ranges.
- Compensatory metabolic response: HCO3– of 20 mEq/L is slightly elevated, indicating her body is trying to buffer the acidosis.
- Anion Gap:
- Definition: The anion gap is the difference between the measured cations (Na+ and K+) and the main measured anions (Cl– and HCO3–). It normally ranges from 8-16 mEq/L.
- Clinical significance: A widened anion gap (>16 mEq/L) indicates the presence of unmeasured negatively charged molecules (anions) in the blood. This can be due to various conditions, including diabetic ketoacidosis, lactic acidosis, and renal failure.