**Question:** A child on β2 agonists for treatment of bronchial asthma may exhibit all of the following features EXCEPT:

A. Increased heart rate
B. Increased blood pressure
C. Increased body temperature
D. Hypotension

**Core Concept:** β2 agonists are a class of medications that mimic the effects of natural substances, such as adenosine monophosphate (cAMP), which are responsible for the relaxation of bronchial smooth muscles in asthma. They are used to relieve bronchoconstriction and improve lung function in patients with asthma.

**Why the Correct Answer is Right:** D. Hypotension is incorrect as β2 agonists are known to cause vasodilation and increased cardiac output, leading to a rise in blood pressure. This effect is counterproductive in asthma treatment as it would worsen bronchoconstriction and lung function.

**Why Each Wrong Option is Incorrect:**

A. Increased heart rate: While β2 agonists do increase heart rate due to their effect on central sympathetic stimulation, this is a physiological response and is not pathologically significant in asthma treatment.

B. Increased blood pressure: As explained above, increased blood pressure is counterproductive in asthma treatment as it worsens bronchoconstriction and lung function.

C. Increased body temperature: β2 agonists do not cause increased body temperature when used for asthma treatment.

**Clinical Pearl:** β2 agonists are essential in asthma management as they help to relax bronchial smooth muscles, improve lung function, and reduce symptoms of bronchoconstriction. However, it is important to monitor the patient's blood pressure and heart rate as these responses may be counterproductive in asthma treatment. Adequate management of asthma involves choosing appropriate medications, considering the patient's overall condition, and adjusting the treatment accordingly.