Final answer:
Pursed-lip breathing helps patients with emphysema by decreasing small airway collapse during expiration. It prevents airway collapse by increasing airway pressure and improves gas exchange without necessarily strengthening accessory respiratory muscles or prolonging inspiration.
Step-by-step explanation:
Your question asks why patients with emphysema commonly use pursed-lip breathing. Pursed-lip breathing is a technique that can help manage the shortness of breath and improve ventilation. When a patient with emphysema purses their lips to breathe, it creates a smaller exit for the air and slows down the exhalation phase. This action helps them in several ways, one of which is significantly relevant to the condition of emphysema.
Decreases small airway collapse during expiration is the correct answer. In emphysema, the elasticity of the alveoli is compromised, which can cause the airways to collapse, trapping air in the lungs and making it difficult to breathe. By pursing their lips, patients with emphysema are able to increase the airway pressure and keep the airways open longer during expiration, reducing the likelihood of collapse. This also helps optimize the V/Q ratio by improving the ventilation of the lungs, reducing the trapped air, and hence improving gas exchange.
Pursed-lip breathing is not associated with strengthening accessory respiratory muscles nor does it prolong inspiration. It specifically acts on the expiration phase by providing back pressure which keeps the air passages open.