A client with hypoventilation is prone to develop?

SCTIMST Staff Nurse - 2015 (Set-A)

Medical & Surgical Nursing

Medium

Appeared in: SCTIMST Staff Nurse - 2015 (Set-A)

Explanation

Hypoventilation is inadequate breathing, which fails to remove carbon dioxide (CO₂) effectively from the body.
This leads to the accumulation of CO₂ in the blood, a condition known as hypercapnia.
In the blood, CO₂ combines with water to form carbonic acid (H₂CO₃), which increases the concentration of hydrogen ions (H⁺), making the blood more acidic.
This decrease in blood pH due to a primary respiratory problem is defined as respiratory acidosis.
The characteristic arterial blood gas (ABG) findings are a pH below 7.35 and a PaCO₂ level above 45 mmHg.

Option A: Metabolic acidosis is caused by a primary decrease in bicarbonate (HCO₃⁻) or an accumulation of non-volatile acids (like ketones or lactic acid), not by CO₂ retention from breathing.
Option C: Respiratory alkalosis is the direct opposite of the correct answer. It is caused by hyperventilation (breathing too fast or too deep), which leads to excessive elimination of CO₂, raising the blood pH.
Option D: Metabolic alkalosis results from a loss of acid (e.g., from severe vomiting) or an excess of bicarbonate. The body may try to compensate for this by hypoventilating, but hypoventilation is the compensation, not the primary cause.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Acid-Base Imbalance due to Hypoventilation as background academic context rather than a clinical decision trigger.
Nurses must be able to recognize the signs of hypoventilation (e.g., shallow breathing, decreased respiratory rate, altered mental status) to prevent severe respiratory acidosis and potential respiratory failure.
Early intervention, such as encouraging deep breathing, administering naloxone for an opioid overdose, or applying non-invasive ventilation, can be life-saving.
What if? - What if the patient was hyperventilating due to anxiety? In that case, they would be blowing off too much CO₂, leading to the opposite condition: respiratory alkalosis (high pH, low PaCO₂).

How to Approach the Question

First, analyze the term 'hypoventilation'. 'Hypo-' means low or decreased, and 'ventilation' refers to breathing. So, it means decreased breathing.
Next, consider the primary function of breathing: to take in oxygen and remove carbon dioxide (CO₂).
Reason what happens if breathing is decreased: CO₂ is not removed effectively and builds up in the blood.
Recall the chemical nature of CO₂ in the body. CO₂ acts as an acid because it forms carbonic acid in the blood.
Connect the dots: Increased CO₂ (an acid) will lower the blood pH, causing acidosis. Since the root cause is respiratory, the condition is respiratory acidosis.
Finally, evaluate the options to confirm your choice and eliminate the others based on their definitions (alkalosis means high pH, metabolic refers to bicarbonate issues).

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 1 p. 416-418

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