If a Nurse/CHO is creating a Care plan for a COPD patient, what type of Acid-base Imbalance will be most commonly observed?

Appeared in: Uttarakhand CHO - 2021

Explanation

Chronic Obstructive Pulmonary Disease (COPD) is characterized by airflow limitation, which impairs the body's ability to exhale carbon dioxide (CO₂) effectively.
This retention of CO₂, a condition known as hypercapnia, leads to an increase in the formation of carbonic acid (H₂CO₃) in the blood.
The accumulation of carbonic acid lowers the blood's pH, resulting in a state of respiratory acidosis.
Over time, the kidneys compensate by retaining bicarbonate (HCO₃⁻) to buffer the acid, but the primary, underlying imbalance is respiratory acidosis.

Option B: Respiratory alkalosis is caused by hyperventilation, where too much CO₂ is exhaled. This is the opposite of the gas exchange problem in advanced COPD, which involves CO₂ retention (hypoventilation).
Option C: Metabolic acidosis is caused by an increase in metabolic acids (e.g., lactic acid, ketones) or a loss of bicarbonate. The primary problem in COPD is respiratory, not metabolic.
Option D: Metabolic alkalosis is caused by a loss of acid (e.g., from vomiting) or an excess of bicarbonate. This is not directly related to the pulmonary pathology of COPD.

Clinical Relevance

Nursing practice connection: Use the key finding related to Acid-base imbalance in COPD to guide bedside assessment, documentation, and the next nursing action.
A nurse's primary role in managing a COPD patient with respiratory acidosis is to improve ventilation and maintain a safe oxygen level. This involves monitoring respiratory status, ABGs, and mental status.
A critical safety consideration is the cautious administration of oxygen. In patients with chronic hypercapnia, the respiratory drive may be dependent on hypoxia. High-flow oxygen can suppress this 'hypoxic drive,' leading to respiratory depression. The target SpO₂ is usually 88-92%.
Nurses must educate patients on energy conservation techniques, pursed-lip breathing, and effective coughing to help clear secretions and improve gas exchange.

How to Approach the Question

First, identify the core pathophysiology of the disease mentioned in the question. The question is about COPD.
Recall that COPD is a chronic lung disease that makes it hard to breathe out (airflow obstruction).
Consider the effect of this pathophysiology on gas exchange. Difficulty exhaling means the patient retains carbon dioxide (CO₂).
Relate the retained substance (CO₂) to its effect on blood pH. Remember that CO₂ acts as an acid in the body.
An accumulation of acid due to a respiratory problem is called respiratory acidosis.
Eliminate the other options. Alkalosis involves losing too much acid or having too much base. Metabolic imbalances are primarily caused by kidney or metabolic issues, not lung function.

Concept Tested & Keywords

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E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 56-58

E6 Nursing Fundamentals Taylor p. 780-782

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