Which irritant is often used during the CRT to assess cough sensitivity?

Cough sensitivity is typically assessed during the Cough Reflex Test (CRT) using irritants that are known to stimulate the cough reflex. Cough-inducing agents such as capsaicin or citric acid are effective for this purpose because they directly activate sensory nerve fibers in the airways that trigger the cough response. Capsaicin, for example, is derived from chili peppers and is known to provoke a strong cough when inhaled due to its action on transient receptor potential (TRP) channels in the respiratory tract. Similarly, citric acid can also elicit coughing by irritating the airway mucosa.

In contrast, bronchodilators are primarily used to relieve bronchospasm in conditions like asthma and do not function as cough stimulants. Antihistamines are involved in reducing allergic responses and do not provoke a cough response; rather, they can sometimes suppress it. Steroid inhalers are typically used to reduce inflammation in chronic respiratory conditions, and they do not trigger the cough reflex either. Thus, the use of cough-inducing agents is essential in evaluating the cough reflex and sensitivity effectively.