Examkin

Question

Difficulty: MediumPhysiological Adaptation

A client is receiving intravenous antibiotics for acute pyelonephritis. During hourly rounding, the client appears restless and mildly confused. The physical examination reveals warm, flushed skin. Current vital signs demonstrate a blood pressure of 104/62 mm Hg104/62 \text{ mm Hg}, a heart rate of 114 bpm114 \text{ bpm}, a respiratory rate of 28 breaths/min28 \text{ breaths/min}, and a temperature of 38.8∘C38.8^\circ\text{C} (101.8∘F101.8^\circ\text{F}). Based on this early stage of physiological decompensation, which of the following arterial blood gas (ABG) profiles is most likely present?

  1. pH=7.48\text{pH} = 7.48, PaCO2=28 mm Hg\text{PaCO}_2 = 28 \text{ mm Hg}, HCO3−=23 mEq/L\text{HCO}_3^- = 23 \text{ mEq/L}Answer
  2. B
    pH=7.28\text{pH} = 7.28, PaCO2=38 mm Hg\text{PaCO}_2 = 38 \text{ mm Hg}, HCO3−=15 mEq/L\text{HCO}_3^- = 15 \text{ mEq/L}
  3. C
    pH=7.31\text{pH} = 7.31, PaCO2=54 mm Hg\text{PaCO}_2 = 54 \text{ mm Hg}, HCO3−=24 mEq/L\text{HCO}_3^- = 24 \text{ mEq/L}
  4. D
    pH=7.47\text{pH} = 7.47, PaCO2=42 mm Hg\text{PaCO}_2 = 42 \text{ mm Hg}, HCO3−=31 mEq/L\text{HCO}_3^- = 31 \text{ mEq/L}

Answer

The profile demonstrating uncompensated respiratory alkalosis: pH=7.48\text{pH} = 7.48, PaCO2=28 mm Hg\text{PaCO}_2 = 28 \text{ mm Hg}, HCO3−=23 mEq/L\text{HCO}_3^- = 23 \text{ mEq/L}.
The correct answer demonstrates uncompensated respiratory alkalosis (pH>7.45\text{pH} > 7.45, PaCO2<35 mm Hg\text{PaCO}_2 < 35 \text{ mm Hg}, normal HCO3−\text{HCO}_3^-). In the early (warm) phase of septic shock, inflammatory mediators and endotoxins stimulate the respiratory center in the medulla, leading to an increased respiratory rate (tachypnea). This hyperventilation causes the client to rapidly exhale carbon dioxide (CO2\text{CO}_2), resulting in a primary respiratory alkalosis. The client's documented respiratory rate of 28 breaths/min28 \text{ breaths/min} aligns with this expected physiological shift.

Step-by-Step Solution

1
Analyze the client's clinical presentation and vital sign trends.
The client exhibits fever, tachycardia, tachypnea (28 breaths/min28 \text{ breaths/min}), warm/flushed skin, and altered mental status.
These findings represent the classic manifestations of the early (hyperdynamic or 'warm') phase of systemic inflammatory response syndrome (SIRS) and early septic shock.
2
Determine the physiological effect of the altered vital signs on acid-base balance.
A respiratory rate of 28 breaths/min28 \text{ breaths/min} causes the excessive elimination of carbon dioxide (CO2\text{CO}_2), which is an acidic compound.
Hyperventilation in early sepsis is a compensatory and inflammatory response that directly lowers PaCO2\text{PaCO}_2 levels in the blood.
3
Match the physiological effect to the corresponding ABG profile.
A low PaCO2\text{PaCO}_2 (<35 mm Hg< 35 \text{ mm Hg}) leads to an elevated pH (>7.45> 7.45), classifying the imbalance as respiratory alkalosis.
Accurately identifying the acid-base disturbance helps the nurse confirm the client's current stage of physiological decompensation and prioritize interventions.

Key Concept

Early septic shock triggers systemic inflammation that stimulates the respiratory center, leading to hyperventilation and a resulting respiratory alkalosis.
Estimated Time:1m 30s
Rate this question

Topics

Physiological Adaptation

More questions from this topic