RUHS, Jaipur, PB B.Sc Nursing Entrance-2022
Medical & Surgical Nursing
Hard

What type of acid base imbalance occur in chronic obstructive pulmonary disease?

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2022

Explanation

  • In Chronic Obstructive Pulmonary Disease (COPD), airflow obstruction and poor gas exchange lead to alveolar hypoventilation.
  • Hypoventilation causes the retention of carbon dioxide (CO2), a condition known as hypercapnia.
  • CO2 combines with water in the blood to form carbonic acid (H2CO3), which increases the concentration of hydrogen ions (H+).
  • This increase in H+ ions lowers the blood pH to a level below 7.35, resulting in acidosis.
  • Because the primary cause is a failure of the respiratory system to eliminate CO2, the imbalance is classified as respiratory acidosis.

Why Other Options Were Wrong

  • Option B: Respiratory alkalosis is caused by hyperventilation, where too much CO2 is expelled. This is the opposite of the gas exchange impairment seen in COPD.
  • Option C: Metabolic acidosis results from an excess of metabolic acids or a loss of bicarbonate, which is not the primary problem in COPD. The issue in COPD is respiratory, not metabolic.
  • Option D: Metabolic alkalosis is caused by a loss of metabolic acids (e.g., from vomiting) or an excess of bicarbonate. This is unrelated to the pathophysiology of COPD.

Related Visual

Visual explanation — Related Visual
Clinical Relevance
  • Nursing practice connection: Knowing Pathophysiology of acid-base imbalances in chronic respiratory conditions helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
  • Nurses must recognize that for patients with chronic COPD, the body's primary stimulus to breathe may be hypoxia (low oxygen) rather than high CO2 levels. Administering high-flow oxygen can suppress this hypoxic drive, leading to respiratory arrest.
  • Monitoring for changes in level of consciousness (e.g., confusion, lethargy) is critical, as these can be early signs of worsening respiratory acidosis and CO2 narcosis.
  • Patient education on techniques like pursed-lip breathing is a key nursing intervention to help patients manage dyspnea and improve CO2 elimination.
How to Approach the Question
  • First, identify the core condition mentioned in the question: Chronic Obstructive Pulmonary Disease (COPD).
  • Recall the primary pathophysiological effect of COPD on the respiratory system. COPD involves airflow limitation, which impairs the lungs' ability to perform gas exchange effectively.
  • Consider how impaired gas exchange affects carbon dioxide (CO2) levels. The lungs are unable to blow off CO2 efficiently, leading to its accumulation in the blood (hypercapnia).
  • Relate the change in CO2 to blood pH. Carbon dioxide is an acid-forming substance in the blood (CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3−). Therefore, retaining CO2 makes the blood more acidic, lowering the pH.
  • Determine the origin of the imbalance. Since the problem originates from lung dysfunction, it is a 'respiratory' issue.
  • Combine these points: a respiratory problem causing a decrease in pH (acidosis) leads to the diagnosis of 'Respiratory acidosis'.
Concept Tested & Keywords
  • Concept Tested: Pathophysiology of acid-base imbalances in chronic respiratory conditions.
  • Stem keywords: acid base imbalance, chronic obstructive pulmonary disease, COPD
  • Lead-in keywords: What type
  • Negative lead-in flag: false

Question ID

Q2ZtZLJ_OUsODZS8Y4DMJ3

Reference Book

E6 Nursing Fundamentals Potter Perry 12e Part 5 pp. 56-58, 55-57

E6 Biochemistry U Satyanarayana— Part 2 (pp 421-820 of 840) p. 99-101

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