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Zorluk: OrtaPhysiological Adaptation

A nurse is caring for a client who has been receiving continuous nasogastric (NG) tube suctioning for three days to treat a paralytic ileus. The client's most recent arterial blood gas (ABG) values are: pH=7.53\text{pH} = 7.53, PaCO2=47 mm Hg\text{PaCO}_2 = 47 \text{ mm Hg}, and HCO3−=33 mEq/L\text{HCO}_3^- = 33 \text{ mEq/L}. Which clinical manifestation is a direct physiological consequence of the client's current acid-base imbalance?

  1. Muscle twitching and a positive Trousseau signCevap
  2. B
    Deep, rapid respirations with a fruity breath odor
  3. C
    Warm, flushed skin and bounding peripheral pulses
  4. D
    Mild tachycardia and a progressively narrowing pulse pressure

Cevap

The correct answer is muscle twitching and a positive Trousseau sign, which indicate hypocalcemia resulting from metabolic alkalosis.
Prolonged nasogastric suctioning removes hydrochloric acid from the stomach, leading to metabolic alkalosis (indicated by the pH of 7.53 and bicarbonate of 33 mEq/L). In an alkalotic state, hydrogen ions detach from plasma proteins (like albumin) to act as a buffer. This frees up negatively charged binding sites on the proteins, which rapidly bind to free ionized calcium in the blood. The resulting drop in free ionized calcium (relative hypocalcemia) leads to heightened neuromuscular excitability. This manifests clinically as muscle twitching, cramping, hyperreflexia, and a positive Trousseau sign (carpopedal spasm).

Adım Adım Çözüm

1
Analyze the arterial blood gas (ABG) values to determine the primary acid-base imbalance.
The elevated pH (7.53) indicates alkalemia. The elevated HCO3−\text{HCO}_3^- (33 mEq/L) matches the alkaline pH, identifying primary metabolic alkalosis. The slightly elevated PaCO2\text{PaCO}_2 (47 mm Hg) shows partial respiratory compensation.
Establishing the correct acid-base disturbance is required to anticipate the physiological manifestations.
2
Determine how metabolic alkalosis affects serum electrolytes, specifically calcium.
In an alkaline environment, hydrogen ions dissociate from plasma proteins like albumin to buffer the blood. This leaves more binding sites available on albumin, which then bind free calcium, causing a rapid decrease in ionized (active) serum calcium.
Electrolyte shifts are the primary cause of symptoms during acute acid-base imbalances.
3
Identify the clinical signs associated with decreased ionized calcium (hypocalcemia).
Hypocalcemia causes increased neuromuscular excitability, which presents clinically as muscle twitching, numbness, tingling, hyperactive deep tendon reflexes, and a positive Trousseau or Chvostek sign.
This answers the question by linking the ABG interpretation to the anticipated physical assessment finding.

Anahtar Kavram

Metabolic alkalosis resulting in symptomatic hypocalcemia
Tahmini Süre:1m 30s
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Physiological Adaptation

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