Why does a patient’s respiratory rate increase when there is an excess of carbon dioxide in the blood?

The respiratory defense mechanism most impaired by smoking is mucociliary clearance. Smoking damages the cilia lining the respiratory tract and increases mucus production, which hinders the movement of mucus and trapped particles out of the airways. This impairment allows pathogens and debris to accumulate in the lungs, increasing the risk for infections and chronic respiratory conditions such as bronchitis and COPD.

Rationale for correct answer:
3. Mucociliary clearance. The mucociliary escalator is a key respiratory defense that traps and removes inhaled particles through coordinated ciliary movement and mucus transport. Cigarette smoke paralyzes and destroys cilia, thickens mucus, and decreases its clearance efficiency. As a result, irritants and pathogens remain in the airways, leading to chronic inflammation, infection, and airway obstruction over time.

Rationale for incorrect answers:
1. Cough reflex. Although chronic smoking may eventually dull the cough reflex, its initial and most significant effect is on the cilia and mucus transport system, not the cough reflex itself.
2. Filtration of air. Filtration primarily occurs in the nasal passages through hairs and turbinates, which are less affected by smoking compared to the ciliary mechanism in the lower airways.
4. Reflex bronchoconstriction. This reflex protects the airways from irritants by narrowing the bronchi; while smoke can trigger bronchoconstriction, it does not impair this reflex as consistently as it damages cilia.

Take-home points:

• Smoking destroys cilia and thickens mucus, impairing mucociliary clearance.
• This leads to mucus retention, infection risk, and chronic airway inflammation.
• Effective defense depends on intact ciliary function to remove debris and pathogens.
• Smoking cessation is essential to allow partial recovery of ciliary function and airway defense.

The primary nursing responsibility after obtaining a blood specimen for arterial blood gases (ABGs) is to take the specimen immediately to the laboratory in an iced container. This prevents ongoing metabolism by red blood cells, which can alter gas values and lead to inaccurate results for pH, PaCO₂, and PaO₂ levels.

Rationale for correct answer:
3. Taking the specimen immediately to the laboratory in an iced container.
ABG samples must be transported on ice to slow down cellular metabolism and preserve the accuracy of gas measurements. Delays or warm temperatures can falsely lower PaO₂ and raise PaCO₂ due to ongoing cellular activity. Prompt delivery ensures valid results for accurate assessment of the patient’s respiratory and metabolic status.

Rationale for incorrect answers:
1. Adding heparin to the blood specimen.
Heparin is already present in the syringe before sampling to prevent clotting; adding more after collection is unnecessary and could dilute the specimen.
2. Applying pressure to the puncture site for 2 full minutes.
Pressure should be applied for at least 5 minutes (or longer if the patient is on anticoagulants) to prevent bleeding or hematoma formation.
4. Avoiding any changes in oxygen intervention for 20 minutes following the procedure.
Oxygen interventions should not be altered before the ABG draw, but this restriction does not apply after the sample has been collected.

Take-home points:

• ABG samples must be iced and promptly delivered to maintain accuracy.
• Heparinized syringes prevent clotting during collection.
• Firm pressure for 5 minutes reduces bleeding risk at the puncture site.
• Accurate ABG results are critical for evaluating oxygenation, ventilation, and acid–base balance.