Viral respiratory infections are a common trigger for acute asthma episodes. Viruses like rhinovirus can damage the airway and impair its defenses, making it more susceptible to inflammation. Early life wheezing from viruses is a risk factor for developing asthma. The sympathetic nervous system response to asthma involves adrenaline release and bronchodilation, but fails to fully reverse bronchoconstriction. James' symptoms relate to this sympathetic response. Salbutamol acts as a sympathomimetic drug by directly stimulating beta-2 receptors, mimicking the effects of adrenaline to induce bronchodilation. It was administered to James to help reverse bronchoconstriction from the asthma episode.

1. Asthma Case Study
1. An upper respiratory virus is a common trigger for acute episodes of asthma. Discuss how a viral
infection might trigger an acute episode of asthma.
Viral respiratory tract infections are commonand cause illnesses. For patients at danger for
asthma, or with prevailing asthma, viral respiratory tract infections can have aintense effect on
the expression of disease or loss of control. A scientific study shows that the wheezing episodes
early in life with the human rhinovirus or common cold virus, is a chief risk factor for the future
diagnosis of asthma at age six years. Viral respiratory tract infections, most commonly with
rhinovirus, are the major microorganisms associated with acute asthma. A deficiency in antiviral
activity and the lack in integrity of the airway epithelial barrier might make individuals with
asthma more potent to have severe viral respiratory infections of the lower airway, and thus raise
the risk of acute asthma.
Wheezing illnesses are thoroughlyrelated with viral respiratory infections in patients of all
ages.The connection of wheezing episodes with respiratory infections in early stage of life has
also provided achance to define the potential connection of these events to the ultimate
development of asthma. This link has been best studied with RSV and HRV respiratory
infections.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2972660/
http://bmb.oxfordjournals.org/content/61/1/29.full
2. Describe the sympathetic nervous system (SNS) response during a moderate to severe episode
of asthma and explain how this relates to James' presenting sign and symptoms.
Asthma patients also have the capability to trigger the sympathetic nervous system (SNS). SNS
stimulation results in general release of epinephrine from the adrenal medulla, as well as
triggering of noradrenergic fibres that stimulate pulmonary and lymphoid tissues. In the lungs
sympathetic stimulation assists the dilation of bronchi, performing through smooth muscle in
blood vessels and submucosal glands. Sympathetic activity rises to fightbronchodilationbut, fails
to control bronchoconstriction due to insignificant innervations of the airway smooth muscles
even though; it results in vasoconstriction of blood vessels and signs/syptoms appears to james
are relate to the response of SNS as explain above.

2. http://www.mbschachter.com/asthma.htm
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2077080/
http://www.jmedsoc.org/temp/JMedSoc263159-2298845_062308.pdf
3. Describe the mechanismof action(orbiological action) of salbutamol and explain the rationale for
administering this drug given its effect on the SNS.
Sympathomimetic drugs are stimulating compounds which mimic the properties of agonists of
the sympathetic nervous system such as the catecholamines,
epinephrine (adrenaline),norepinephrine(noradrenaline),dopamine, etc. Salbutamol is example of
Sympathomimetic drugs. This drugfunction through several mechanisms, postsynaptic
receptorsstimulating production and release of catecholamine, blocking breakdown
and reuptake of certain neurotransmitters. The direct stimulation of the α- and β-adrenergic
receptors can triggers sympathomimetic effects. Salbutamol is an extensively used direct-
acting β2-agonist. Other examples include phenylephrine, isoproterenol, and dobutamine.
http://salbutamol.org/
Longmore,Murray; Wilkinson,IanB.;Davidson,EdwardH.; Foulkes,Alexander;Mafi,AhmadR.(2008).
OxfordHandbookof Clinical Medicine (8thed.).OUPOxford.