One of the reasons for impaired gas exchange is?

KPSC Staff Nurse - 2017

Medical Surgical Nursing

Hard

Appeared in: KPSC Staff Nurse - 2017

Explanation

Impaired gas exchange refers to a disruption in the normal transfer of oxygen into the blood and carbon dioxide out of the blood at the alveolar-capillary level.
Low tidal volume (shallow breathing) causes hypoventilation, which reduces the amount of fresh air reaching the alveoli, thus impairing the diffusion gradients for O2 and CO2.
Increased mucous production can physically obstruct airways, leading to a ventilation-perfusion (V/Q) mismatch. In this state, blood flows past alveoli that are not receiving air, so gas exchange cannot occur.
Because both low tidal volume and increased mucus are direct physiological causes, the option that includes both is the most complete and accurate answer.

Option A: This option is incomplete. While low tidal volume is a correct cause of impaired gas exchange, it is not the only correct cause listed among the options.
Option B: This option is also incomplete. Increased mucous production is a valid cause, but another correct cause is also provided, making the 'Both' option superior.
Option C: Decreased air entry is a clinical sign or a consequence of an underlying problem, not a primary physiological cause itself. It is what a nurse might observe or auscultate as a result of low tidal volume or mucus plugging.

Clinical Relevance

Nursing practice connection: Knowing Pathophysiology of Impaired Gas Exchange helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must assess for impaired gas exchange by monitoring respiratory rate, depth, use of accessory muscles, breath sounds (for decreased air entry or adventitious sounds), and pulse oximetry (SpO2).
Interventions are targeted at the underlying cause: encouraging deep breathing and using an incentive spirometer can help correct low tidal volume, while airway clearance techniques (e.g., coughing, suctioning, chest physiotherapy) are used for increased mucus.
What if? If a patient with increased mucus production also has a weak cough reflex, the risk of airway obstruction and subsequent atelectasis is much higher. The nursing priority becomes aggressive airway clearance, possibly including nasotracheal suctioning, to prevent respiratory failure.

How to Approach the Question

First, understand the question. It asks for a reason or cause of impaired gas exchange.
Evaluate each option to determine if it is a primary cause or a resulting sign/symptom.
Analyze Option A (Low tidal volume): This leads to hypoventilation, which is a direct cause of poor gas exchange.
Analyze Option B (Increased mucous production): This leads to airway obstruction and V/Q mismatch, another direct cause.
Analyze Option C (Decreased air entry): Recognize this as a clinical finding or sign that results from an underlying cause, rather than the cause itself.
Since both A and B are correct primary causes, evaluate Option D. It correctly combines both valid causes, making it the most comprehensive and best answer.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 2A p. 59-61

E6 Nursing Fundamentals Potter Perry 12e Part 4 p. 241-243