Response to Injury, Fluids, and Nutrition

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Questions and Answers

What is the primary cause of hypernatremia?

Gain of water

Increased extracellular volume

Loss of free water or gain of sodium (correct)

Loss of sodium

What symptoms are most commonly associated with hypernatremia when serum sodium concentration exceeds 160 mEq/L?

Skin rashes

Central nervous system symptoms (correct)

Muscle spasms

Gastrointestinal distress

What is the first step in treating hypernatremia in hypovolemic patients?

Use diuretics to increase urine output

Restore volume with normal saline (correct)

Administer oral potassium supplements

Monitor serum sodium levels

Which of the following treatments is appropriate for mild, asymptomatic hypokalemia?

KCl 40 mEq per enteral access as a single dose Signup and view all the answers

What rate of intravenous potassium supplementation is generally advisable in an unmonitored setting?

No more than 10 mEq/h Signup and view all the answers

Under which condition can potassium supplementation be increased to 40 mEq/h?

When accompanied by continuous ECG monitoring Signup and view all the answers

What could be a severe complication of hypernatremia?

Subarachnoid hemorrhage Signup and view all the answers

What is a caution that must be considered when treating hypernatremia in patients with oliguria or impaired renal function?

Careful monitoring of potassium levels is essential Signup and view all the answers

What is the common cause of extracellular volume deficit in surgical patients?

Loss of GI fluids from nasogastric suction Signup and view all the answers

Which symptom is associated with severe dehydration?

Severe thirst Signup and view all the answers

What is the primary physiological change in chronic volume deficit?

Decreased skin turgor Signup and view all the answers

In which situation would extracellular volume excess most likely occur?

Secondary to renal dysfunction Signup and view all the answers

Which is a sign of severe dehydration?

Dry axilla and groin Signup and view all the answers

Which fluid disorder is the most common among surgical patients?

Extracellular volume deficit Signup and view all the answers

What characterizes the acute volume deficit?

Cardiovascular and central nervous system signs Signup and view all the answers

What might indicate the presence of third-space fluid losses?

Massive volume deficits from infections Signup and view all the answers

What is a potential consequence of severe extracellular volume deficit?

Cardiovascular shock Signup and view all the answers

What indicates a hemoconcentration in the context of fluid volume disturbances?

Concentration of solutes in the blood Signup and view all the answers

Which of the following electrolytes is recognized as the principal cation of extracellular fluid?

Na+ Signup and view all the answers

What is the normal serum potassium concentration range?

3.5-5.0 mEq/L Signup and view all the answers

What are the common cardiac symptoms associated with hyperkalemia?

Arrhythmia and arrest Signup and view all the answers

Which of the following contributes to hyperkalemia?

Excessive potassium intake Signup and view all the answers

What symptom typically does NOT appear until the ionized calcium fraction falls below 2.5 mg/dL?

Neuromuscular symptoms Signup and view all the answers

Which ECG change is commonly associated with hyperkalemia?

T-wave inversion Signup and view all the answers

What treatment is recommended for managing hyperkalemia?

Calcium supplementation Signup and view all the answers

What factor does NOT typically trigger an increase in serum potassium levels?

Increased potassium excretion by kidneys Signup and view all the answers

Study Notes

Fluid Balance

Normal Fluid Balance: The normal fluid balance in a 70 kg man is comprised of 140 liters of total body water. This includes 28 liters of extracellular fluid (ECF) and 42 liters of intracellular fluid (ICF). The principal ECF cation is sodium (Na+). Potassium (K+), and magnesium (Mg2+) are the principal cations of the ICF.
Stages of Dehydration:
- Mild Dehydration (2-5% BW lost as water): Thirst, low urine volume, reduced sweating, and dry axilla and groin are common symptoms.
- Moderate Dehydration (6-10% BW lost as water): These symptoms include severe thirst, nausea, tachycardia, orthostatic hypotension, severe oliguria, and thready pulse.
- Severe Dehydration (11-15% BW lost as water): Stupor, severe oliguria, hypotension, shock, coma, and death are potential consequences.

Extracellular Volume Deficit vs. Excess

Extracellular Volume Deficit:
- The most common fluid disorder in surgical patients.
- Acute volume deficit can lead to cardiovascular and central nervous system complications.
- Chronic volume deficit is characterized by tissue signs such as decreased skin turgor and sunken eyes.
- The most common cause of volume deficit in surgical patients is loss of GI fluids due to nasogastric suction, vomiting, diarrhea, or enterocutaneous fistula.
- Third-space fluid losses can also contribute to massive volume deficits.
Extracellular Volume Excess:
- May be iatrogenic or secondary to renal dysfunction, congestive heart failure, or cirrhosis.
- Results in an increase in both plasma and interstitial volumes.

Hypokalemia

A serum potassium concentration below the normal range of 3.5-5 mEq/L.
The severity of symptoms depends on the level of hypokalemia and the rate of decline.
Mild cases typically present with minimal symptoms.
Moderate to severe hypokalemia often manifests with fatigue, weakness, muscle cramps, and arrhythmias.
Treatment: Potassium repletion, with the rate guided by the severity of symptoms.
- Mild, asymptomatic hypokalemia: oral repletion is sufficient.
- Moderate to severe hypokalemia: IV repletion is often necessary, with careful monitoring to avoid complications.

Hyperkalemia

Serum potassium concentration above the normal range of 3.5-5 mEq/L.
Can occur due to excessive K+ intake, increased release of K+ from cells, or impaired renal excretion.
Clinical manifestations:
- Primarily GI (nausea/vomiting, diarrhea), neuromuscular (weakness, paralysis), and cardiovascular (arrhythmia, arrest).
Treatment: Calcium supplementation and correction of other contributing factors.

Hypocalcemia

A serum ionized calcium level below 2.5 mg/dL.
Can be caused by a variety of factors, including vitamin D deficiency, parathyroid disorders, chronic kidney disease, and certain medications.
Neuromuscular symptoms and decreased cardiac contractility often present when the ionized calcium level is low.
Treatment: Calcium supplementation and addressing the underlying cause of hypocalcemia.

Hypercalcemia

A serum calcium concentration above the normal range (8.5-10.5 mg/dL).
Often associated with hyperparathyroidism due to parathyroid adenoma.
It can lead to:
- Bone remineralization
- Decreased bone density
- Neuromuscular symptoms
Treatment: Focused on managing the underlying condition (such as parathyroid adenoma removal).

Nutritional Assessment Criteria

Nutritional Status:
- BMI (Body Mass Index): Used to assess body weight relative to height.
- WHO (World Health Organization) criteria:
  - Underweight: BMI ≤ 18.5 kg/m²
- Asian criteria:
  - Underweight: BMI ≤ 18.5 kg/m²

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Description

Test your knowledge on fluid balance, normal hydration levels, and the stages of dehydration. This quiz will cover essential concepts related to extracellular and intracellular fluids, their roles, and symptoms of volume deficits. Prepare to explore critical information that is vital for understanding fluid management in health care.