Final answer:
Mechanical ventilation is primarily used in this case to manage respiratory failure. It helps increase lung volume and decrease the work of breathing, which is crucial in patients with COVID-19 and asthma who are struggling to breathe effectively.
Step-by-step explanation:
The primary reason for mechanical ventilation in the case of a 27-year-old patient with COVID-19 and asthma is c) Respiratory failure. This is because COVID-19 can cause severe respiratory distress, which may be exacerbated in patients with pre-existing respiratory conditions like asthma. Mechanical ventilation is used to support or replace the patient's natural breathing process when they are unable to do so effectively on their own. It helps to increase lung volume and decrease the work of breathing, allowing for adequate exchange of oxygen and carbon dioxide and helping to prevent respiratory arrest.
An allergic reaction causing the airways to swell would most likely increase the resistance of the respiratory system because swollen airways make it harder for air to flow through. Increased resistance can lead to breathing difficulties, particularly in patients with asthma, as it exacerbates the obstruction of the airways.