- How do you explain the sputum cytologic findings?
There is an outpouring of mucus into the airways, some of which becomes inspissated and can further block expiration, exacerbating the air-trapping from the bronchoconstriction. The mucus forms the Curschman spirals. The Charcot-Leyden crystals are the conglomerates of the reddish granules released from eosinophils.
- Why do you seen the inflammatory cell type that predominates in image 9.3?
Asthma in children is most often an allergic phenomenon, and many asthmatics will demonstrate other forms of atopy. This is a form of type I hypersensitivity response. The offending allergen reacts with IgE coating mast cells lining the airways, resulting in release of mast cell granules containing cytokines such as histamine that lead to bronchoconstriction and edema. Eosinophil chemotactic factor is also released.
- How is this disease likely to differ in adults?
In adults, asthma is typically the "intrinsic" variety in which the reaction occurs to stimuli such as exercise or cold, not an external allergen. However, the end result is the same.
- What are the consequences of this disease? What is the functional effect on the lung? How does it differ from emphysema
The acute episodes can be severe--status asthmaticus--which is life-threatening and requires immediate treatment with bronchodilators. There is a chronic component to this disease, since over time there is bronchial smooth muscle hypertrophy and submucosal glandular hyperplasia. Since this disease is typically episodic, chronic obstructive pulmonary disease is unlikely to be a result.
The functional effect is increased airway resistance due to the bronchiolar smooth muscle contraction, increased abnormal airway secretions, and edema with inflammation in the walls of airways.
Emphysema is a chronic process with destruction of lung tissue and enlargement of air spaces distal to the terminal bronchioles.
- What lung disorder(s) may result in an increase in the functional residual capacity (FRC)?
The FRC is increased with acute asthma and with emphysema. It also increases gradually with normal aging.
- What pharmacologic therapies are available this disease?
Drugs used to treat asthma include fast-acting medications for symptomatic relief such as the beta-adrenergic agonists, methylxanthines, and anticholinergics. The short-acting beta-adrenergic agonists effect relief via stimulation of beta-adrenergic receptors and activation of G proteins to form cyclic adenosine monophosphate (cAMP). Such drugs include epinephrine and isoproterenol. The resorcinols including metaproterenol and terbutaline, and the saligenin albuterol, work similarly but do not have the serious inotropic cardiac side effects of the catecholamines. Theophylline, a methylxanthine, promotes bronchodilation by increasing cAMP by the inhibition of phosphodiesterase. Anticholinergics such as atropine sulfate also produce bronchodilation but with significant systemic side effects.
To control asthma over the long-term, pharmacologic agents include glucocorticoids, leukotriene inhibitors and receptor antagonists, and mast cell-stabilizing agents. Glucocorticoids are potent anti-inflammatory drugs with serious long-term side effects from prolonged oral use. Inhaled glucocorticoids such as beclomethasone have lessened systemic effects. Leukotrienes generated by the lipo-oxygenase pathway of arachidonic acid metabolism mediate many of the features of asthma. Zileuton is a 5-lipoxygenase synthesis inhibitor. Montelukast is a leukotriene receptor antagonist. Cromolyn sodium is an agent inhibits the degranulation of mast cells and release of mediators.
- What consent process is required to treat this child?
If the child is able to talk, and tell you the name and address of her parent(s), you can call to obtain consent. That is reasonable because the ability to talk means there is probably no life-threatening situation. But if you perceive the child to be in immanent danger of either death or permanent injury, you do not need to wait to get consent. And it is important to remember that asthma can indeed lead to death. So if you believe there is not time to call her parent(s) first, you are justified in treating her. This is sometimes called the "emergency exception" to informed consent, and sometimes called "presumed consent." But it is important to know that it only applies to life-threatening cases, not anything that happens in the emergency department, or elsewhere in a health care setting. As always, it helps to tell her what you are going to do before you do it--that lessens the anxiety and actually decreases the amount of pain and discomfort that a patient experiences from procedures.
