There are four manifestations of COPD that can be (and are often recommended by textbooks to be) treated preoperatively – atelectasis, bronchospasm, pulmonary edema, and respiratory tract infections. Keep in mind, however, that there are no controlled trials which support the use of preoperative β–agonists, aminophylline, antibiotics, hydration, or chest physiotherapy in the COPD population. [Kesten S. Clin Chest Med 18: 173, 1997; Warner D. Anesthesiology 92: 1467, 2000], thus many of the “advantages” mentioned below remain theoretical in nature.
May predispose to infection by impairing lung lymphocyte and macrophage function.
Wheezing and Bronchodilation
Elective surgery should be postponed for acute wheezing (chronic wheezing, by contrast, is a known component of COPD). All patients with wheezing should have had a bronchodilator trial at some point – therapy is considered successful if pulmonary function tests improve by 15% or more. Bronchodilators available to treat acute wheezing include sympathomimetics (ex. most commonly the selective β2–agonists albuterol, terbutaline, metaproterenol), all of which increase the ratio of cAMP (dilator) to cGMP (constrictor), i.e. the cAMP/cGMP ratio; parasympatholytics (inhaled atropine at 0.025 mg/kg [Marini JJ et al. Chest 80: 285, 1981] and ipratropium); possibly steroids. Aminophylline is no longer used because of its potential for causing ventricular fibrillation.
Fluid Status and Secretions
Hypovolemia is particularly dangerous in thoracotomy patients because volume is needed in order to reduce the viscosity of secretions. Additional modalities (besides liberal use of fluids) include the use of humidified inhalate, acetylcysteine (Mucomyst), potassium iodide (an oral expectorant), postural drainage, coughing, chest percussion, deep breathing, incentive spirometry, and other means of pulmonary toilet.
Preoperative pulmonary infections should be aggressively treated, although the optimal waiting period prior to operation has not been defined.