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Difficulty: MediumPhysiological Adaptation

A nurse is assessing a client who has a suspected proximal small bowel obstruction and has experienced severe, persistent vomiting for the past 24 hours. Which of the following clinical findings should the nurse identify as physiological complications associated with this condition? Select all that apply.

  1. Arterial blood pH of 7.51 and a PaCO2 of 48 mm HgAnswer
  2. Resting heart rate of 112 beats/min with a narrowing pulse pressureAnswer
  3. C
    Deep, rapid respirations at a rate of 28 breaths/min
  4. Serum potassium level of 2.8 mEq/L (2.8 mmol/L)Answer
  5. E
    Widened pulse pressure with warm, flushed extremities

Answer

The expected physiological complications include an elevated arterial blood pH with elevated PaCO2, tachycardia with a narrowing pulse pressure, and a decreased serum potassium level.
The client is experiencing severe fluid, electrolyte, and acid losses due to prolonged vomiting. This leads to metabolic alkalosis with compensatory respiratory acidosis (retained CO2), profound hypokalemia, and early hypovolemic shock characterized by tachycardia and a narrowed pulse pressure due to vasoconstriction.

Step-by-Step Solution

1
Analyze the pathophysiological effects of severe, persistent vomiting.
Vomiting causes profound loss of fluid, gastric acid (hydrochloric acid), and electrolytes, particularly potassium and sodium.
Identifying the lost substances is the first step in determining the expected systemic imbalances.
2
Determine the expected acid-base imbalance and associated compensatory mechanism.
The loss of stomach acid leads to metabolic alkalosis (pH > 7.45). The respiratory system attempts to compensate by hypoventilating to retain CO2 (PaCO2 > 45 mm Hg).
Understanding the body's compensatory mechanisms helps differentiate the expected ABG values from incorrect interpretations.
3
Evaluate the cardiovascular response to profound fluid volume loss.
The body compensates for hypovolemia via sympathetic nervous system activation, causing tachycardia and vasoconstriction, which narrows the pulse pressure.
Recognizing early physiological indicators of shock is crucial for timely intervention and prevents confusing different shock states.

Key Concept

Pathophysiological consequences of upper gastrointestinal fluid loss
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Topics

Physiological Adaptation

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