Obstructive Pulmonary Diseases Dr. Beyer

Anesthesia & Obstructive Pulmonary Diseases Jerry Beyer, M.D. Wilford Hall Medical Center TOPICS • • • • Pre-operative PFTs Asthma/bronchospasm Chronic bronchitis/emphysema OSA Why? • COPD affects 10 million people • OSA can predispose patients to multiple problems to include airway misadventures • Intra-operative bronchospasm is relatively common and rapid treatment is essential • Several of the pulmonary diseases which will be discussed can result in bad outcomes if not understood and treated correctly Normal Lung Volumes & Capacities IRV IC VC TV TLC ERV FRC RV Normal Lung Volumes & Capacities Normal vs. Obstructive Spirometry Restrictive vs. Obstructive Pre-Op PFTs • Who? – Lung resection – Hx of tobacco use/SOB undergoing CABG or upper abdominal surgery – Hx of unexplained SOB Pre-Op PFTs II • Clinical findings & functional status are generally considered more predicative than PFTs • Spirometry may be helpful as a baseline in someone with COPD/asthma • PFTs may be useful in determining responsiveness to b2-agonists ASTHMA Asthma-Definition • Three characteristics: – Chronic inflammatory changes in the submucosa of the airways – Increased responsiveness of airways to various stimuli – Reversible expiratory airflow obstruction Asthma-Pathogenesis Asthma-Definition • “…a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role…. In susceptible individuals, this inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness and coughing particularly at night or in the early morning.” NEJM 345(17):1257 Asthma: Intra-Op Risk • Bronchodilator use in previous 30d, had a 1.7% incidence of bronchospasm – Anes 1996;85:460-7 • Surgical site most important predictor of pulmonary risk. – NEJM 340(12):937-44 • Increased risk for procedures >3 hours – Chest 1997;111:564-71 • Reg vs. GA: mixed data but most feel a good epidural results in fewer pulm. complications Asthma-Diagnosis • Hx of wheezing/SOB/cough • Hx of triggers: exercise, smoke, allergens, URIs • Decreased FEV1/FEF25-75% • Normal to increased FVC • “Scooped” appearance of the flow-volume loop Asthma-PFTs • Schematic diagram of forced exhaled volume in normal individuals (A) and in individuals with obstructive airway disease (B). A normal individual can exhale approximately 80% of the vital capacity in 1 s (FEV1) compared with approximately 50% in 1 s in individuals with obstructive airway disease. Asthma-PFTs Asthma-Severity • Probably the best indicatory of severity is the peak exp. flow rate and frequency of symptoms. • Ask about ER visits, hospitalizations, oral steroid use, and intubations Asthma-Severity Classification Of Asthma Severity Symptoms Nighttime Symptoms Lung Function Step 1: mild, intermittent Symptoms 2x/week; asymptomatic, normal peak flows between exacerbations; exacerbations brief (hours to days) Symptoms > 2x/week, but <1x/day; exacerbations possibly affecting activity Daily symptoms, daily use of inhaled short-acting b2-agonist, exacerbations affecting activity, exacerbations > 2x/week Continual symptoms, limited physical activity, frequent exacerbations 2x/month FEV1 or peak flow >80% predicted, peak flow variability <20% Step 2: mild, persistent Step 3: moderate, persistent >2x/month FEV1 or peak flow 80% predicted, peak flow variability 20–30% FEV1 or peak flow between 60% and 80% predicted, peak flow variability >30% >1x/week Step 4: severe, persistent Frequent FEV1 or peak flow <60% predicted, peak flow variability >30% FEV1, forced expiratory volume in 1 second. Evidence Level: A. Reference: National Asthma Education and Prevention Program. Expert Panel Report II: Guidelines for the diagnosis and management of asthma. National Heart, Lung, and Blood Institute 1997;146. DDx of Intra-Operative wheezing • • • • • • • Asthma/COPD/ airway hyper-reactivity Induced bronchospasm during anesthesia Conditions mimicking bronchospasm Pulmonary edema PTX Foreign body Upper airway obstruction Perioperative DDx for Anesthesiologist by Steve Venticinque, M.D. Asthma: Pre-Operative Evaluation • Functional Status & number of exacerbations/rescue medications • PFT/PEF-May be of value in helping determine pre-operative treatment • ABGs measurement usually are unnecessary • CXR-may be helpful as a baseline but should be based on clinical S/S. Perioperative Tx of Asthma • Determine severity. Should be free of wheezing, PEF>80% or personal best J Allergy Clin Immunol 1991;88: Suppl:523-34 • Continue all pre-op asthma medication - b2-agonists-keep in mind clinical duration of action vs. duration of surgery • If patient has more severe asthma an IV steroids should be considered. Asthma & Anesthesia • Regional may be more preferable than GA in patients with more severe forms of asthma. • A smooth GA may be preferable than a rocky/failed regional technique. • Be prepared to treat intra-operative bronchospasm Asthma & GA • Induction – Deep plane of anesthesia prior to Intub. • • • • IV induction agents (Ketamine?) Opioids Inhalational augmentation of IV induction Lidocaine-IV/LTA • Induction Controversies – Full stomach, GERD, difficult airway, LMA vs. ETT Asthma & GA-II • Maintenance – Volatile anesthetic-all are bronchodilators although some differences may exist (e.g. desflurane) • Emergence – Deep extubation vs. awake extubation Asthma & GA-III • Post-operative – Good pain control-Reg. Anesthesia probably decreases Post-op Pulmonary Complications (PPC) particularly in upper abdominal surgery – Maneuvers to increase mean lung volumes help prevent PPC Intra-op bronchospasm • • • • • • • R/O mimics-auscultate, check ETT position/FOB FiO2 100% Deepen anesthetic β2-agonists (Atrovent in patients with COPD) Steroids-do not work right away IV b2 agonists-terbutaline/epinephrine Aminophylline IV-5 mg/kg load over 5 min then 0.5-1.0 mg/kg/hour COPD-Definition • “Chronic obstructive pulmonary disease (COPD) is characterized by the progressive development of airflow limitation that is not fully reversible.” – NEJM 2000;343(4):269-280 • Chronic bronchitis: productive cough for more than 3 months over 2 years • Emphysema: enlargement of airspaces, destruction of lung parenchyma, loss of lung elasticity and closure of small airways Chronic Bronchitis vs. Emphysema Chronic Bronchitis Mechanism of Airway Obstruction Dyspnea FEV1 PaO2 PaCO2 Diffusing Capacity Hematocrit Cor Pulmonale Prognosis Decreased airway lumen due to mucus and inflammation Moderate Decreased Marked decreased (“Blue Bloater”) Increased Normal Increased Marked Poor Emphysema Loss of elastic recoil Severe Decreased Modest decrease (“Pink Puffer”) Decreased Decreased Normal Mild Good COPD-Risk factors • Tobacco abuse to include second hand smoke • Protease-antiprotease imbalance - a1-antitrypsin deficiency • Environmental pollutants Cessation of Cigarette Smoking Cost of COPD COPD & Severity COPD & Pre-op • Patients with COPD have an increased risk of post-operative pulmonary complications (RR 2.7-4.7) – NEJM 1999;340(12):937-944 • Aggressively treat patients pre-op who do not have adequate control of S/S. • Delay elective cases during acute exacerbation COPD & Pre-op II • Treatment is multimodal to include Inhaled anticholinergics, b2-agonists, pulmonary rehab, smoking cessation, corticosteroids, appropriate treatment of pulmonary infections • Intermittent positive pressure ventilation? • Avoid H2 antagonists? OSA-Definition • The intermittent cessation of breathing for a period of 10 seconds to more than one (1) minute, wherein the chest and abdomen expand in unsuccessful effort to fill the lungs with air. • Historic clues: Hypersomnolence, snoring with periods of apnea, obesity OSA & Perioperative concerns • Many patients with OSA are morbidly obese • Must suspect the patient will have a difficult airway. • Minimal use of pre-operative sedation • May have increased gastric contents & lower gastric pH OSA & Post-Op Concerns • Increased risk of upper airway obstruction with attendant risk of hypoxemia (CC>FRC). • A functioning regional anesthetic may be desirable to minimize systemic opioids. • Dysrhythmias are more common in patients with OSA Conclusion • Correct identification of a patient with severe asthma/COPD is imperative in the perioperative period. • Must know how to recognize and treat intraoperative bronchospasm • OSA is often underappreciated for its role in postoperative complications • PFTs are frequently ordered but seldom understood