CHRONIC OBSTRUCTIVE PULMONARY DISEASE Listen to Audio -most common respiratory disorder within the anesthetic practice -increased prevelance with age COPD prevelance may increase with: -increasing age -cigarette smoking -male predominace Emphysema Pathophysiology Treatment Preoperative management Intraoperative management Emergence/postoperative management Chronic Bronchitis Pathophysiology Treatment Preoperative management Intraoperative management Emergence postoperative management Emphysema PATHOPHYSIOLOGY -irreversible enlargement of airways distal to the terminal bronchioles -destruction occurs within the alveoli septa -destruction of alveoli septa also include damage to the pulmonary capillaries -destruction of the pulmonary capillaries decreases the carbon monoxide diffusion capacity -loss of elastic recoil creates premature collapse of airways during exhalation -loss of elastic recoil is due to lack of supporting radial traction of the small airways -generally increased: RV, FRC, TLC -bullae: large cystic areas within some portions of the lung -characteristic feature is dead space -Pa02 is usually normal or slightly decreased -PaC02 is usually normal TREATMENT -primarily supportive -important intervention is smoking cessation -long term bronchodilator therapy should be started for patients who have a reversible element to airway obstruction -inhaled beta2 agonist, glucocorticoids, ipratropium are very beneficial in treatment -antibiotics are often useful -oxygen supplementation cautiously given to treat hypoxemia *low flow oxygen therapy (1-2 L/min) for chronic hypoxic patients with Pa02<55mmHg ANESTHETIC MANGEMENT Preoperative Mangement: Inquire into any recent changes in the following: -dyspnea -sputum production -wheezing dyspnea can often be ascertained by FEV1 measurements: -FEV1 < 50% predicted = 1.2 -1.5 L often correlated with dyspnea on exertion -FEV1 < 25% predicted approx: 1 L often correlated with dyspnea with minimal activity carefully evaluate the following preoperatively: -pulmonary function tests -chest xrays: take notice of presence/absense of bullous changes -arterial blood gas Factors which may help to reduce postoperative pulmonary complications include: -correcting hypoxemia (ex. oxygen supplementation cautiously) -alleviating bronchospasm (ex. bronchodilators) -reducing and clearing pulmonary secretions (ex. smoking cessation, chest physiotherapy, and antibiotics) -treating any underlying pulmonary infections (ex. antibiotics) Patients with great risk of postoperative pulmonary complications involve : -preoperative predicted PFTs < 50% -therefore may postoperative mechanical ventilation Intraoperative Mangement -regional anesthesia may be more beneficial in comparison to general anesthesia in COPD patients regional anesthesia may also involve negative attributes such as: -decreased lung volumes -accessory respiratory muscle restriction due to high spinal -ineffective cough due to inhibited accessory muscle use and decreased lung volumes (ex. VC) -retention of secretions due to ineffective cough -resultant hypoxemia may occur General anesthesia in patients with COPD should incorporate: -careful preoxygenation: fill FRC with 100% O2 to prevent rapid oxygen desaturation (common in COPD) -controlled ventilation with decreased tidal volumes and increased respiratory rate ( avoid air-trapping) -humidified gas to prevent bronchospasm and for prolonged cases x > 2hrs -avoid N20 in patients with bullae and preexisting pulmonary hypertension -monitor fequent ABG samples in prolonged cases, extensive abdominal cases, and all thoracic cases Intraoperative ABG: -used to guide venilation settings -as dead space increases (with general anesthesia) less accurate the ETCO2 becomes to monitor PaC02 -therefore ABG PaC02 becomes more essential in monitoring ventilation status -ventilation should be focused more on normalizing the pH opposed to correcting and normalizing PaC02 -normalizing PaC02 in preoperative C02 retainers may lead to alkalosis and invite electrolyes imbalances Emergence/Postoperative Management: Timing of extubation should consider two opposing potential dreaded complications: -risk of bronchospasm due to waiting longer to extubate (ex. fully awake extubation) -risk of pulmonary insufficiency due to earlier extubation (ex. deep extubation) -evidence supports the earlier extubation in the operating room may be beneficial if criteria are met Patients who most likely require postoperative mechanical ventilation include: -preoperative predicted FEV1 <50% -upper abdominal incision -thoracic incision -prolonged duration of anesthesia Chronic Bronchitis PATHOPHYSIOLOGY -productive cough on most days of three consecutive months for at least two consecutive years factors which may be responsible for chronic bronchitis: -cigarette smoking -air pollutants -exposure to dust -recurrent pulmonary infections -familial factors Airway obstruction may occur to due: -hypertrophied bronchial mucosal glands leading to increased secretions -inflammation leading to mucous edema -increased bronchial secretions, inflammation, and edema lead to airway obstruction bronchospasm may be associated with: -recurrent pulmonary infections -ex. bacterial and viral infections with increased secretions leads to hyperactive airway hypoxemia may occur due to: -increased bronchial secretions with mucous plugging -increased residual volume amidst a normal total lung capacity -results in increased intrapulmonary right to left shunt -intrapulmonary shunting ultimately causes hypoxemia physiological changes that occur in response to chronic hypoxemia include: -erythrocytosis -pulmonary hypertension -cor pulmonale (right ventricular failure) “chronic blue bloater syndrome” TREATMENT -primarily supportive -important intervention is smoking cessation -long term bronchodilator therapy should be started for patients who have a reversible element to airway obstruction -inhaled beta2 agonist, glucocorticoids, ipratropium are very beneficial in treatment -antibiotics are often useful -oxygen supplementation cautiously given to treat hypoxemia *low flow oxygen therapy (1-2 L/min) for chronic hypoxic patients with Pa02<55mmHg ANESTHETIC MANGEMENT Preoperative Mangement: Inquire into any recent changes in the following: -dyspnea -sputum production -wheezing Dyspnea can often be ascertained by FEV1 measurements: -FEV1 < 50% predicted = 1.2 -1.5 L often correlated with dyspnea on exertion -FEV1 < 25% predicted approx: 1 L often correlated with dyspnea with minimal activity carefully evaluate the following preoperatively: -pulmonary function tests -chest xrays: take notice of presence/absense of bullous changes -arterial blood gas Factors which may help to reduce postoperative pulmonary complications include: -correcting hypoxemia (ex. oxygen supplementation cautiously) -alleviating bronchospasm (ex. bronchodilators) -reducing and clearing pulmonary secretions (ex. smoking cessation, chest physiotherapy, and antibiotics) -treating any underlying pulmonary infections (ex. antibiotics) Patients with great risk of postoperative pulmonary complications involve: -preoperative predicted PFTs < 50% -therefore may postoperative mechanical ventilation Intraoperative Mangement -regional anesthesia may be more beneficial in comparison to general anesthesia in COPD patients regional anesthesia may also involve negative attributes such as: -decreased lung volumes -accessory respiratory muscle restriction due to high spinal -ineffective cough due to inhibited accessory muscle use and decreased lung volumes (ex. VC) -retention of secretions due to ineffective cough -resultant hypoxemia may occur General anesthesia in patients with COPD should incorporate: -careful preoxygenation: fill FRC with 100% O2 to prevent rapid oxygen desaturation (common in COPD) -controlled ventilation with decreased tidal volumes and increased respiratory rate ( avoid air-trapping) -humidified gas to prevent bronchospasm and for prolonged cases x > 2hrs -avoid N20 in patients with bullae and preexisting pulmonary hypertension -monitor fequent ABG samples in prolonged cases, extensive abdominal cases, and all thoracic cases Intraoperative ABG: -used to guide venilation settings -as dead space increases (with general anesthesia) less accurate the ETCO2 becomes to monitor PaC02 -therefore ABG PaC02 becomes more essential in monitoring ventilation status -ventilation should be focused more on normalizing the pH opposed to correcting and normalizing PaC02 -normalizing PaC02 in preoperative C02 retainers may lead to alkalosis and invite electrolyes imbalances Emergence/Postoperative Management: Timing of extubation should consider two opposing potential dreaded complications: -risk of bronchospasm due to waiting longer to extubate (ex. fully awake extubation) -risk of pulmonary insufficiency due to earlier extubation (ex. deep extubation) -evidence supports the earlier extubation in the operating room may be beneficial if criteria are met Patients who most likely require postoperative mechanical ventilation include: -preoperative predicted FEV1 <50% -upper abdominal incision -thoracic incision -prolonged duration of anesthesia