| Bronchospasm | |
|---|---|
 | |
| Inflamed airways and bronchoconstriction in asthma. Airways narrowed as a result of the inflammatory response cause wheezing. | |
| Specialty | Pulmonology |
Bronchospasm or abronchial spasm is a suddenconstriction of the muscles in the walls of thebronchioles. It is caused by the release (degranulation) of substances frommast cells orbasophils under the influence ofanaphylatoxins. It causes difficulty in breathing which ranges from mild to severe.
Bronchospasms occur inasthma, chronicbronchitis andanaphylaxis. Bronchospasms are a possible side effect of some drugs:pilocarpine,beta blockers (used to treat hypertension), a paradoxical result of usingLABA drugs (to treatCOPD), and other drugs. Bronchospasms can present as a sign ofgiardiasis.
Some factors that contribute to bronchospasm include consuming certain foods, taking certain medicines, allergic responses to insects, and fluctuating hormone levels, particularly in women.[1][2]Bronchospasms are one of several conditions associated with cold housing.[3]
The overactivity of the bronchioles' muscle is a result of exposure to a stimulus which under normal circumstances would cause little or no response. The resulting constriction and inflammation causes a narrowing of the airways and an increase inmucus production; this reduces the amount ofoxygen that is available to the individual causing breathlessness, coughing andhypoxia.
Bronchospasms are a serious potential complication of placing abreathing tube duringgeneral anesthesia. When the airways spasm or constrict in response to the irritating stimulus of the breathing tube, it is difficult to maintain the airway and the patient can becomeapneic. During general anesthesia, signs of bronchospasm include wheezing, high peak inspiratory pressures, increased intrinsicPEEP, decreased expiratory tidal volumes, and an upsloping capnograph (obstructive pattern). In severe cases, there may be complete inability to ventilate and loss ofETCO2 as well as hypoxia and desaturation.
Bronchospasms can occur for a number of reasons. Lower respiratory tract conditions such asasthma,chronic obstructive pulmonary disease (COPD), andemphysema can result in contraction of the airways. Other causes are side effects of topical decongestants such asoxymetazoline andphenylephrine. Both of these medications activate alpha-1 adrenergic receptors that result in smooth muscle constriction. Non-selectivebeta blockers are known to facilitate bronchospasm as well. Beta blockers bind to the β2 receptors and block the action of epinephrine and norepinephrine causing shortness of breath.[4]
Additionally, the pediatric population is more susceptible to disease and complications from bronchospasm due to their airway diameter being smaller; applyingPoiseuille's Law to the airways it is clear that airflow resistance through a tube is inversely related to the radius of the tube to the fourth power, therefore, decreases in airway results in significant flow impediments.[5]
Signs and symptoms:
Beta2-adrenergic agonists are recommended for bronchospasm.
Theneurotransmitteracetylcholine is known to decrease sympathetic response by slowing the heart rate and constricting thesmooth muscle tissue. Ongoing research and successful clinical trials have shown that agents such asdiphenhydramine,atropine andipratropium bromide (all of which act asreceptor antagonists ofmuscarinic acetylcholine receptors) are effective for treating asthma and COPD-related symptoms.[6]