β2-adrenergic agonists remain the first-line drugs for acute asthma attacks. These drugs, inhaled four to six times daily, rapidly relax smooth muscle in the airways and are effective for up to 6 hours. Studies of beta2 agonists in chronic asthma failed to show any inﬂuence of these agents on the inﬂammatory component of asthma. β2 agonists are recommended for short-term relief of bronchospasm (“rescue inhalers”) or as first-line treatment for patients with very infrequent symptoms or symptoms provoked solely by exercise (239).
Anticholinergic agents are weak bronchodilators that work via inhibition of muscarinic receptors in the smooth muscle of the airways. The quaternary derivatives such as ipratropium bromide (Atrovent) are available in an inhaled form that is not absorbed systemically. Anticholinergic drugs may provide additional benefit in conjunction with standard steroid and bronchodilator therapy but should not be used as single-agent therapy because they do not inhibit mast cell degranulation, do not have any effect on the late response to allergens, and do not have an anti-inﬂammatory effect (239).
Perioperative Management of Asthma
In patients with asthma, elective surgery should be postponed whenever possible until pulmonary function and pharmacotherapeutic management are optimized. The most recent guidelines of the American Academy of Allergy, Asthma and Immunology’s recommend three interventions to reduce perioperative pulmonary complications related to asthma (239): 1.
Review the patient’s asthmatic control, including the need for oral steroids.
2.
Optimize the patient’s symptomatic control through the use of long-acting pharmacotherapy, including oral steroids if needed.
3.
For patients on oral steroid therapy within 6 months of therapy or for patients using large doses of inhaled corticosteroids, consider perioperative stress dose steroids.
For mild asthma, the use of inhaled beta-adrenergic agonists preoperatively may be all that is required. For chronic asthma, optimization of steroid therapy will greatly decrease alveolar inﬂammation and bronchiolar hyperresponsiveness. Inhaled beta2-agonists should be added to therapy as needed for further control of asthma. Each drug prescribed should be used in maximal dosage before adding an additional agent. Preoperative treatment with combined corticosteroids and an inhaled beta2-adrenergic agonist for a 5-day period may decrease the risk of postoperative bronchospasm in patients with asthma (240). For patients undergoing emergent surgery who have significant bronchoconstriction, a multimodal approach should be instituted, including aggressive bronchodilator inhalation therapy and intravenous steroid therapy. The role of spirometry, outside of cardiothoracic procedures, has limited value in predicting postoperative pulmonary complications and should be limited to the confirmation of undiagnosed obstructive pulmonary disease (241).