Pulmonary Disease
4.1 Chronic Obstructive Pulmonary Disease
Florin Costescu
Peter Slinger
The Global Initiative for Chronic Obstructive Lung Disease (GOLD) defines chronic obstructive pulmonary disease (COPD) as a common preventable and treatable disease, characterized by persistent airflow limitation that is usually progressive and that is associated with an enhanced chronic inflammatory response in the airways and the lung. It is associated with chronic inflammation, parenchymal destruction, and enhanced airway reactivity that is not fully reversible (1). COPD is a major cause of morbidity and mortality worldwide, affecting 5% to 8% of the population and expected to become the third leading cause of death by 2020. By far the most important risk factor associated with COPD is the amount and duration of cigarette smoking. Other risk factors include environmental or occupational exposures (noxious particles, fumes, gases, or dusts), genetic causes (α-1 antitrypsin deficiency, various gene polymorphisms) and childhood illnesses (neonatal bronchopulmonary dysplasia, asthma).
COPD encompasses a broad spectrum of pathophysiologic mechanisms, disease severity, and clinical manifestations including chronic bronchitis and emphysema. Chronic bronchitis is defined as chronic productive cough for 3 months in each of 2 successive years and not attributed to others causes. It is the result of mucous gland hyperactivity and chronic inflammation of the airways causing excessive bronchial secretions, luminal plugging, and increased airway resistance. Emphysema is a term describing the pathologic structural changes associated with COPD and characterized by nonuniform parenchymal destruction, loss of alveolar attachments and reduced elastic recoil. Many patients will manifest with overlapping features of chronic bronchitis and emphysema, as well as features usually associated with asthma (i.e., asthma-COPD overlap syndrome).
The diagnosis of COPD is considered in any patient with a history of risk factors or symptoms of cough, dyspnea, or sputum production. The diagnosis requires spirometry demonstrating a postbronchodilator forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ratio of less than 0.7, confirming airflow limitation that is not fully reversible. The GOLD classification describes severity of disease based on postbronchodilator FEV1 (Table 4.1) (1).
The differential diagnosis of COPD includes asthma, chronic bronchitis without airflow limitation, heart failure, bronchiectasis, bronchiolitis obliterans, and tuberculosis.
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The general management of COPD includes a combination of nonpharmacologic interventions, pharmacotherapy, and surgical options. Table 4.2 summarizes the nonpharmacologic management strategies.
Pharmacotherapy for stable COPD is used to reduce symptoms, improve exercise tolerance, minimize frequency and severity of exacerbations and improve mortality. Levels of therapy are based on spirometry parameters as well as future risk of exacerbations as described in Table 4.3. Patients can be categorized based on symptoms (Medical Research Council dyspnea scale or COPD Assessment Test, see reference 1), severity of airflow limitation (FEV1% predicted) and risk of exacerbations. In general, treatment options include short- and long-acting inhaled bronchodilators (anticholinergics and β2 agonists), oral bronchodilators (theophylline), inhaled glucocorticoids and/or oral phosphodiesterase-4 inhibitors (e.g., roflumilast). Less well-established therapies may include mucolytics such as N-acetylcysteine or longterm antibiotics.
COPD exacerbations are acute deteriorations in the patient’s respiratory condition beyond normal daily variations and represent a significant burden to the health
care system. Typical features of such exacerbations include worsening of cough, changes in character and volume of sputum and increase in dyspnea. The most common triggers of exacerbations are infectious (viral and bacterial respiratory infections) but environmental pollution, pulmonary embolism, and others can contribute. Management of exacerbations includes short-acting bronchodilators, antibiotics, or antivirals targeting likely pathogens and short courses of systemic glucocorticoids. Some patients may need hospitalization, oxygen therapy, and further supportive management including mechanical ventilation.
care system. Typical features of such exacerbations include worsening of cough, changes in character and volume of sputum and increase in dyspnea. The most common triggers of exacerbations are infectious (viral and bacterial respiratory infections) but environmental pollution, pulmonary embolism, and others can contribute. Management of exacerbations includes short-acting bronchodilators, antibiotics, or antivirals targeting likely pathogens and short courses of systemic glucocorticoids. Some patients may need hospitalization, oxygen therapy, and further supportive management including mechanical ventilation.
TABLE 4.2 Nonpharmacologic Nonsurgical Therapy for Stable COPD | ||||||||
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TABLE 4.3 Pharmacologic Therapy for Stable COPD | ||||||||||||||||||||||||
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COPD patients with disease progression despite optimal pharmacologic and nonpharmacologic therapy, with significant hypoxia or hypercapnia, with high mortality risk or with very severe airflow limitation should be referred for evaluation for lung transplantation at a specialized center.
The goals of the preoperative assessment of COPD are:
To assess the severity of the disease and other comorbidities;
To evaluate the perioperative pulmonary risk;
To optimize the patient’s medical management before surgery;
To plan perioperative care;
To educate the patient regarding perioperative care; and
To obtain informed consent for perioperative procedures, as needed.
Clinical history and physical examination evaluate the patient’s baseline symptoms and functional capacity and assess current respiratory status (2). Signs and symptoms of COPD exacerbation or active respiratory infection are sought. Reports of new or worsening dyspnea not previously investigated, changes in cough and sputum volume or character, symptoms of upper respiratory tract infection, low oxygen saturation, systemic signs of infection (e.g., fever, chills), active wheezing, or use of accessory respiratory muscles require further investigation. In these cases, strong consideration is made to postponing elective surgery, referring the patient to his primary care physician or pulmonologist or even directing the patient toward an emergency department for further evaluation and management.
Recent pulmonary function testing is warranted in patients with changes from baseline symptoms and patients undergoing intrathoracic surgery (see Chapter 4.12). Preoperative ABG analysis will not change perioperative management in the majority of COPD patients but may be useful in patients with known or suspected hypoxemia or hypercapnia. We typically obtain an ABG for any patient with moderate or worse COPD to identify chronic CO2 retainers, in particular if there is increased risk of postoperative pulmonary complications (PPCs) and if postoperative ventilation may be required (see Chapter 4.10). This helps establish a safe perioperative management plan that may include mechanical ventilation management with maintenance of PaCO2 levels close to baseline, targeted oxygen therapy, and intensive postoperative monitoring. Other laboratory investigations are based on specific indications related to comorbidities, medications, and planned surgical procedure.
Current evidence does not support the routine use of preoperative chest x-rays. However, it is reasonable to obtain a chest x-ray in COPD patients exhibiting changes from baseline status, those with other known cardiorespiratory comorbidities and
those over the age of 50 years old undergoing intrathoracic or major intra-abdominal surgery. Chest radiologic examinations should be reviewed and features with specific perioperative concerns such as bullae noted.
those over the age of 50 years old undergoing intrathoracic or major intra-abdominal surgery. Chest radiologic examinations should be reviewed and features with specific perioperative concerns such as bullae noted.
Another important aspect of preoperative assessment of the COPD patient is evaluation of the risk of PPCs (3,4). Observational studies have consistently described COPD as a strong independent predictor of PPCs (see Chapter 4.10).
Even in patients with very severe COPD and/or increased risk of PPCs, the perioperative risk must be weighed against the potential benefits of surgery and no level of respiratory dysfunction has been identified as an absolute contraindication to surgery.
The preoperative assessment of a COPD patient should lead to a clear strategy to optimize the patient’s respiratory status as time permits and to reduce the perioperative risk.
Both preoperative patients with stable COPD and those presenting with exacerbations or active respiratory tract infections should be optimally managed as previously described. We typically delay elective surgery for 6 weeks after a respiratory tract infection. For patients with a recent or prolonged course of glucocorticoids, perioperative supplementation may be indicated (see Chapter 18.6).
The preoperative consultation offers an excellent opportunity to promote smoking cessation. The current literature does not provide evidence of harm related to preoperative short-term smoking cessation. In fact, intensive smoking cessation interventions with counseling and nicotine replacement therapy have been associated with decreased pulmonary and wound healing complications and should be implemented as early as possible (5) (see Chapter 4.9).
Intraoperative strategies to be considered to reduce pulmonary complications include avoidance of general anesthesia (when appropriate) (6), judicious titration of short- or intermediate-acting neuromuscular blockers, complete reversal of neuromuscular blockade at the end of the surgery and lung-protective ventilation (particularly for intermediate- to high-risk patients undergoing abdominal surgery) (7).
In the postoperative period, adequate pain control with epidural analgesia (when appropriate) (8,9), chest physiotherapy, and incentive spirometry may contribute to improved respiratory outcomes.
REFERENCES
1. Global Initiative for Chronic Obstructive Lung Disease—Global Strategy for the Diagnosis, Management and Prevention of Chronic Obstructive Pulmonary Disease—Updated 2016. www.goldcopd.org. Accessed on August 30, 2016.
2. Bapoje SR, Whitaker, JF, Schulz T, et al. Preoperative evaluation of the patient with pulmonary disease. Chest. 2007;132:1637-1645.
3. Qaseem T. Risk assessment for and strategies to reduce perioperative pulmonary complications for patients undergoing noncardiothoracic surgery: A guideline from the American College of Physicians. Ann Intern Med. 2006;144:575-580.
4. Smetana GW, Lawrence VA, Cornell JE; American College of Physicians. Preoperative pulmonary risk stratification for noncardiothoracic surgery: Systematic review for the American College of Physicians. Ann Intern Med. 2006;144:581-595.
5. Thomsen T, Tønnesen H, Møller AM, et al. Effect of preoperative smoking cessation interventions on postoperative complications and smoking cessation. Brit J Surg. 2009;96:451.
6. Hausman MS Jr, Jewell ES, Engoren M. Regional versus general anesthesia in surgical patients with chronic obstructive pulmonary disease: Does avoiding general anesthesia reduce the risk of postoperative complications? Anesth Analg. 2015;120: 1405-1412.
7. Futier E, Constantin JM, Paugam-Burtz C, et al. A trial of intraoperative low-tidal-volume ventilation in abdominal surgery. N Engl J Med. 2013;369:428-437.
8. Pöpping DM, Elia N, Marret E, et al. Protective effects of epidural analgesia on pulmonary complications after abdominal and thoracic surgery—A meta-analysis. Arch Surg. 2008;143:990-999; discussion 1000.
9. Rigg JR, Jamrozik K, Myles PS, et al. Epidural anaesthesia and analgesia and outcome of major surgery: A randomised trial. Lancet. 2002;359:1276-1282.
4.2 Asthma
Florin Costescu
Peter Slinger
Asthma is a chronic inflammatory disease affecting the airways characterized by bronchial hyperresponsiveness and airflow obstruction (1,2). As of 2004, the prevalence of the disease has been estimated around 300 million and is expected to rise to 400 million by 2025. It is believed that asthma accounts for 1 out of every 250 deaths worldwide. Pathologically, the disease is characterized by chronic airway inflammation, increased bronchial smooth muscle mass, mucus hypersecretion, and luminal narrowing. Clinically, it most commonly presents before age 20 with waxing and waning symptoms of bronchoconstriction such as intermittent cough, wheezing, chest tightness, and shortness of breath. Symptoms typically vary from day to day and may be precipitated by specific triggers such as exercise, emotional stress, exposure to irritants (e.g., allergens, smoke, dust), medications (e.g., aspirin, nonsteroidal anti-inflammatories, β blockers), respiratory tract infections or iatrogenic airway manipulation. Spirometry is the primary method for confirming the diagnosis and will usually show variable airflow limitation with expiratory obstruction and significant improvement (>12% and 200 mL increase) in FEV1 with bronchodilators. However, normal spirometry does not exclude the diagnosis of asthma and bronchoprovocation testing (e.g., methacholine challenge) may be needed for confirmation, particularly in patients with atypical presentation. Recent evidence also suggests that patients with persistent childhood asthma are at risk for abnormal development of lung function and fixed airflow obstruction in adulthood similar to a COPD pattern (3).
The differential diagnosis of asthma or wheezing includes other pulmonary obstructive conditions (COPD, asthma-COPD overlap syndrome, bronchiolitis, bronchiectasis, cystic fibrosis (CF)), nonrespiratory diseases (heart failure, gastroesophageal reflux disease, panic disorder) and other respiratory diseases (postviral cough, vocal cord dysfunction, tracheal stenosis).
Optimal management of asthma includes:
Routine monitoring of symptoms and lung function to optimize asthma control through a preventative approach;
Controlling factors and comorbidities such as smoking and reflux disease; and
Pharmacotherapy for control of persistent asthma and treatment of acute exacerbations.
 Figure 4.1 Stepwise approach for asthma pharmacotherapy. EIB, exercise-induced bronchospasm; ICS, inhaled corticosteroid; LABA, inhaled long-acting β2 agonist; LTRA, leukotriene receptor antagonist; SABA, inhaled short-acting β2 agonist. (Source: National Heart, Lung, and Blood Institute; National Institutes of Health; U.S. Department of Health and Human Services. National Asthma Education and Prevention Program: Expert panel report III: Guidelines for the diagnosis and management of asthma 2007.) |
The goals of asthma therapy are to reduce impairment from chronic disease and minimize risk of exacerbation and need for emergency care. Chronic pharmacotherapy is tailored to severity of disease. Asthma severity is classified into either intermittent or persistent (mild, moderate, or severe) disease based on symptoms, need for short-acting β2 agonists, spirometry values and number of exacerbations requiring oral glucocorticoids per year (see reference 2). Pharmacologic options for management of chronic asthma include short- and long-acting β2 agonists, inhaled and oral corticosteroids, oral bronchodilators (e.g., theophylline), leukotriene modifiers, anti-IgE therapy (i.e., omalizumab) for patients with allergic sensitivity and anti-IL-5 antibodies for patients with eosinophilic asthma. A stepwise approach for the pharmacotherapy of asthma is recommended, as described in Figure 4.1.
In patients with chronic asthma, the perioperative period can be associated with life-threatening bronchospasm and status asthmaticus. Management of these acute exacerbations include short-acting inhaled β2 agonists, short-acting inhaled anticholinergics, systemic and inhaled glucocorticoids, inhalational anesthetics, ketamine, magnesium sulfate, intravenous β2 agonists, intravenous aminophylline or theophylline and supportive therapy with oxygen, mechanical ventilation and/or extracorporeal membrane oxygenation as needed (4,5).
Preoperative assessment and optimization is essential. Well-controlled asthma does not seem to confer additional risk of postoperative pulmonary complications. However, perioperative bronchospasm, in particular during airway instrumentation, is still a major, potentially life-threatening concern. Therefore, achieving optimal asthma control before surgery is still key.
Even patients with severe asthma can present to the preoperative clinic with few to no symptoms. It is essential to elicit a thorough history of the disease, with particular attention to specific triggering factors, previous exacerbations, need for hospitalizations, and mechanical ventilation as well as previous history of perioperative acute bronchospasm. The patient’s current pharmacotherapy, recent use of systemic glucocorticoids and frequency of need for short-acting bronchodilators are noted. Recent respiratory tract infections should be ruled out. Current and best pulmonary function tests are reviewed. Clues to poorly controlled asthma potentially benefitting from referral to a pulmonologist for further optimization are listed in Table 4.4. Specific validated asthma questionnaires exist to help assess asthma control (see reference 2).
Physical examination focuses on signs of ongoing bronchoconstriction or respiratory tract infection. Careful pulmonary auscultation will identify signs of active bronchoconstriction such as prolonged expiration, wheezing or even diminished or absent breath sounds in severe bronchospasm. Evidence of right heart failure from longstanding pulmonary disease is sought. Respiratory rate, pulse oximetry, and use of accessory respiratory muscles are noted.
Recent pulmonary function testing may be indicated if there is doubt about the degree of asthma control or if the patient will undergo lung resection surgery. A chest radiograph is not useful unless indicated by concerns of pulmonary infection or other comorbidities such as heart failure. Further investigations are guided by history and physical examination.
For elective surgery, asthmatic patients with active wheezing or clues to poorly controlled asthma need to be optimized or referred to an asthma specialist for further optimization. A short course of systemic glucocorticoids (e.g., methylprednisolone 40 mg per day orally for 5 days) may be beneficial in noncompliant patients or those with newly diagnosed asthma and has been shown to decrease the risk of postintubation wheezing (6). For patients with recent respiratory tract infection, we typically
delay elective surgery for 6 weeks. Otherwise, current asthma therapy is maintained up to the time of surgery. Some authors have expressed concerns regarding the perioperative use of xanthine derivatives such as theophylline due to the risk of ventricular arrhythmias and hypotension. However, this is much less of a concern with the advent of newer inhalational anesthetic agents that have replaced the arrhythmogenic halothane. The need for perioperative steroid supplementation in the context of hypothalamo-pituitary-adrenal suppression is considered (see Chapter 18.6). Additionally, an aggressive preoperative smoking cessation plan should be implemented as early as possible.
delay elective surgery for 6 weeks. Otherwise, current asthma therapy is maintained up to the time of surgery. Some authors have expressed concerns regarding the perioperative use of xanthine derivatives such as theophylline due to the risk of ventricular arrhythmias and hypotension. However, this is much less of a concern with the advent of newer inhalational anesthetic agents that have replaced the arrhythmogenic halothane. The need for perioperative steroid supplementation in the context of hypothalamo-pituitary-adrenal suppression is considered (see Chapter 18.6). Additionally, an aggressive preoperative smoking cessation plan should be implemented as early as possible.
TABLE 4.4 Clues to Poorly Controlled Asthma Potentially Requiring Optimization (2) | |||||||
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Asthmatic patients may benefit from judicious anxiolytic premedication, as painful procedures before anesthesia induction may potentially trigger bronchospasm. Additionally, we routinely administer 2 to 4 puffs of short-acting β2 agonists before induction of general anesthesia and airway manipulation.
REFERENCES
1. Global Initiative for Asthma—Diagnosis of Diseases of Chronic Airflow Limitation: Asthma, COPD and Asthma-COPD Overlap Syndrome—Updated 2015. www.ginasthma.org. Accessed on September 20, 2016.
2. National Asthma Education and Prevention Program: Expert panel report III: Guidelines for the diagnosis and management of asthma. National Heart, Lung, and Blood Institute—2007. www.nhlbi.nih.gov/health-pro/guidelines/current/asthma-guidelines/full-report. Accessed on September 20, 2016.
3. McGeachie MJ, Yates KP, Zhou X, et al. Patterns of growth and decline in lung function in persistent childhood asthma. N Engl J Med. 2016;374:1842.
4. Sellers WF. Inhaled and intravenous treatment in acute severe and life-threatening asthma. Br J Anaesth. 2013;110:183-190.
5. Woods BD, Sladen RN. Perioperative considerations for the patient with asthma and bronchospasm. Br J Anaesth. 2009;103:I57-I65.
6. Silvanus MT, Groeben H, Peters J. Corticosteroids and inhaled salbutamol in patients with reversible airway obstruction markedly decrease the incidence of bronchospasm after tracheal Intubation. Anesthesiology. 2004;100:1052-1057.
4.3 Restrictive and Interstitial Lung Diseases
Florin Costescu
Peter Slinger
A restrictive pattern of lung disease is characterized on pulmonary function testing (PFT) by decreased total lung capacity (TLC), FEV1 and FVC but with normal or increased FEV1/FVC ratio. This pattern can be caused by any pathophysiologic process causing restriction of the respiratory system including:
Intrinsic lung parenchymal diseases, referred to as interstitial lung diseases (ILDs);
Extrinsic diseases involving the pleura, pleural cavity, diaphragm, or chest wall (e.g., pleural effusions, ankylosing spondylitis, kyphoscoliosis, obesity); and
Neuromuscular disorders causing respiratory muscle weakness (e.g., myasthenia gravis, Guillain-Barré syndrome, muscular dystrophies).
This chapter will focus on ILDs. Please refer to the other chapters of this textbook for the preoperative assessment and management of extrapulmonary disorders.
TABLE 4.5 Causes of Interstitial Lung Disease (Nonexhaustive List) | ||||||
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ILDs are a heterogeneous group of disorders characterized by a restrictive physiology associated with inflammation and/or fibrosis of the lung parenchyma. As compared to extrapulmonary restrictive lung diseases, ILDs are usually associated with impaired diffusing capacity for carbon monoxide (DLCO) on PFTs. They are classified into those with known pathophysiologic processes and those that are idiopathic, as detailed in Table 4.5 (1). The most common identifiable causes are related to exposure to occupational or environmental agents, drug-related toxicity or radiation-induced lung injury.
Common to all ILDs are pathophysiologic processes of pulmonary parenchymal fibrosis and inflammation causing decreased distensibility and increased recoil of the lungs, with a resulting contraction of lung volumes. Maximal voluntary ventilation decreases but alveolar hypoventilation and CO2 retention is typically seen only in end-stage disease as the patient compensates for low tidal volumes (TV) with increased respiratory rate. Heterogeneous alterations in the alveolar-capillary unit can cause significant ventilation perfusion mismatching and chronic hypoxemia, with resultant pulmonary hypertension and eventually cor pulmonale.
TABLE 4.6 Therapeutic Strategies for ILDs and Perioperative Considerations | ||||||||||||||
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Patients with ILDs typically present with progressive dyspnea on exertion or nonproductive cough. A history of occupational or environmental exposure or signs and symptoms associated with connective tissue diseases may be elicited. Physical findings may include fine crackles on lung auscultation or clubbing of the fingers but are usually nonspecific. Confirmation of diagnosis can be challenging and is usually made from a combination of clinical, radiologic (reticular pattern on chest radiography, disease-specific interstitial opacities on computed tomography [CT]), physiologic (restrictive lung function, impaired DLCO) and pathologic (lung biopsy, bronchoalveolar lavage) evidence by a multidisciplinary team involving experienced pulmonologists, radiologists, and pathologists (2,3).
Management strategies of ILDs and specific perioperative considerations are described in Table 4.6 (3).
The goals of the preoperative visit are to assess the severity of the disease, to optimize medical management before surgery, and to plan ahead for the perioperative care. It is useful to involve the patient’s pulmonologist in this process.
Clinical history and physical examination evaluates the patient’s baseline symptoms and functional capacity, as well as any signs or symptoms of exacerbations requiring further investigations. Particular attention is paid to evidence of pulmonary hypertension and cor pulmonale such as exertional syncope, dyspnea out of proportion to pulmonary function or physical signs of right ventricular failure. A high index of suspicion is necessary in patients with advanced disease and longstanding hypoxemia. If in doubt, an electrocardiogram and echocardiography can assess right ventricular function and estimate pulmonary artery pressures. Some ILDs may be associated with cardiac, renal and hepatic dysfunction (e.g., sarcoidosis, systemic
lupus erythematosus, rheumatoid arthritis) and involvement of these organs should be assessed. Recent PFTs and chest radiologic examinations are reviewed. ABG analysis is useful in evaluating the need or adequacy of long-term oxygen therapy and the baseline PaCO2 in cases of advanced disease.
lupus erythematosus, rheumatoid arthritis) and involvement of these organs should be assessed. Recent PFTs and chest radiologic examinations are reviewed. ABG analysis is useful in evaluating the need or adequacy of long-term oxygen therapy and the baseline PaCO2 in cases of advanced disease.
There is no strong evidence for any preoperative interventions to improve perioperative outcomes in patients with ILDs specifically (4). Nevertheless, certain recommendations can be applied. Elective surgery is delayed for treatment of reversible exacerbations such as those related to respiratory infections. Preoperative smoking cessation must be strongly encouraged with effective interventions such as counseling, nicotine replacement, bupropion, and varenicline (see Chapter 4.9). Pulmonary rehabilitation has been shown to provide significant improvement in exercise capacity, dyspnea, and quality of life in ILD patients although its benefits on perioperative outcomes have not been demonstrated (7). General measures of prevention of postoperative pulmonary complications such as avoidance of general anesthesia (when adequate), lung protective mechanical ventilation, restrictive fluid management strategy, optimal pain control with opioid-sparing therapies (e.g., epidural analgesia), postoperative chest physiotherapy, and incentive spirometry may be beneficial (see Chapter 4.10). Preoperative nutritional support may be indicated in patients with severe malnutrition (pulmonary cachexia syndrome) but specific nutritional interventions in this patient population still need to be further investigated (see Chapter 8.19).
One of the most common reasons for patients with ILDs to present for preoperative evaluation is for surgical lung biopsy for diagnostic confirmation. The procedure can be performed via thoracotomy or video-assisted thoracoscopic surgery under general anesthesia and most commonly requires one-lung ventilation. Overall perioperative mortality in elective surgical biopsies has been reported to be less than 2%. However, it is important to understand that risk factors such as preoperative hypoxemia, nonelective surgery in acute exacerbation or rapidly progressing ILD, male sex, advanced age, provisional diagnosis of idiopathic pulmonary fibrosis, or connective tissue disease-related ILD and other comorbidities have been associated with significantly high perioperative mortality rates (8).
Patients with ILD having lung resection surgery also pose a particular challenge as they have a significantly increased risk of postoperative pulmonary complications including acute lung injury and prolonged hospital stay as well as increased mortality rates (9,10). Those undergoing larger resections (i.e., pneumonectomy vs. lobectomy vs. wedge) are at particular risk.
REFERENCES
1. Travis WD, Costabel U, Hansell DM, et al. An official ATS/ERS statement: Update of the international multidisciplinary classification of the idiopathic interstitial pneumonias. Am J Respir Crit Care Med. 2013;188:733-748.
2. King Jr., Pardo A, Selman M. Idiopathic pulmonary fibrosis. Lancet. 2011;378:1949-1961.
3. Raghu G, Rochwerg B, Zhang Y, et al. An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline: Treatment of idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 2015;192:e3.
4. Ma M, Slinger P. Anesthesia for patients with end stage lung disease. In Slinger P, et al. Principles and Practice of Anesthesia for Thoracic Surgery. Springer; 2011:p360-361.
5. Richeldi L, du Bois RM, Raghu G, et al. Efficacy and safety of nintedanib in idiopathic pulmonary fibrosis. N Engl J Med. 2014;370:2071-2082.
6. King Jr, Bradford WZ, Castro-Bernardini S, et al. A phase 3 trial of pirfenidone in patients with idiopathic pulmonary fibrosis. N Engl J Med. 2014;370:2083-2092.
7. Dowman L, Hill CJ, Holland AE. Pulmonary rehabilitation for interstitial lung disease. Cochrane Dat Syst Rev. 2014;(10):CD006322.
8. Hutchinson JP, Fogarty AW, McKeever TM, et al. In-hospital mortality after surgical lung biopsy for interstitial lung disease in the United States. Am J Respir Crit Care Med. 2016; 193(10):1161-1167.
9. Kumar P, Goldstraw P, Yamada K, et al. Pulmonary fibrosis and lung cancer: risk and benefit analysis of pulmonary resection. J Thorac Cardiovasc Surg. 2003;125:1321-1317.
10. Sato T, Teramukai S, Kondo H, et al. Impact and predictors of acute exacerbation of interstitial lung diseases after pulmonary resection for lung cancer. J Thorac Cardiovasc Surg. 2014;147:1604-1611. e3.
4.4 Cystic Fibrosis
Florin Costescu
Peter Slinger
Cystic fibrosis (CF) is an autosomal recessive disorder caused by a mutation of the gene encoding the CF transmembrane conductance regulator (CFTR) protein on chromosome 7. CFTR functions as a chloride channel found at the apical border of epithelial cells lining most exocrine glands. Its mutation causes changes in cellular electrolytes and water transport, resulting in abnormal and thickened secretions affecting multiple organs including sinuses, lungs, pancreas, hepatobiliary system, gastrointestinal tract, and reproductive organs (1,2). CF is a chronic, progressive, and life-shortening disease most commonly seen in the Caucasian population (1 in 3,000 incidence) although Hispanics, African Americans, and other populations can be affected. Significant advances in medical care over the last half-century have dramatically improved outcomes and the median predicted survival in the United States is around 40 years, according to the Cystic Fibrosis Foundation 2014 Registry Report (3).
The diagnosis is made in a patient with clinical symptoms of CF in at least one organ system and evidence of CFTR dysfunction such as elevated sweat chloride >60 mmol/L or two CF-causing CFTR mutations (4).
In CF, abnormal viscous secretions cause luminal obstruction and specific organ dysfunction eventually leading to manifestations such as obstructive airway disease and recurrent infections in the lungs, pancreatic insufficiency and diabetes mellitus, hepatobiliary obstructive disease and liver failure, intestinal obstruction, obstructive azoospermia, and male infertility. Clinical manifestations of CF with perioperative concerns are summarized in Table 4.7 along with some common management strategies (2). The vast majority of morbidity and mortality is related to pulmonary complications including pneumothorax, severe lung infections (in particular Burkholderia cepacia colonization), massive hemoptysis, and respiratory failure.
It is important to understand that CF patients and their families can be significantly involved in their own medical care and demonstrate an impressive understanding of their disease and the medical options available to them. It is therefore essential for the perioperative physician to have a clear and exhaustive understanding of the different aspects of the disease and respect the experience and concerns of each patient. It is also particularly useful to involve the patient’s primary CF specialist in the preoperative evaluation and management, as they often have a well-established long-term relationship with the patient.
TABLE 4.7 Cystic Fibrosis Clinical Manifestations and Common Management | ||||||||||||||
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Each patient should undergo a thorough preoperative history and physical examination. In particular, the pulmonary evaluation is critical and focuses on disease progression and impact on exercise tolerance. Progression of respiratory symptoms of cough, sputum secretion, wheezing, and shortness of breath should be investigated. Worsening of exercise capacity may indicate an acute respiratory exacerbation,
progression of baseline lung disease or worsening pulmonary hypertension and right heart failure. Previous history of hospitalization, antibiotic therapy, intensive care admission, need for mechanical ventilation, and respiratory complications such as pneumothorax or hemoptysis are noted. Past anesthetic and perioperative history should also be reviewed. History determines other CF-related comorbidities of particular concern to the perioperative period such as diabetes, liver disease, gastroesophageal reflux, and confirms the adequacy of their management.
progression of baseline lung disease or worsening pulmonary hypertension and right heart failure. Previous history of hospitalization, antibiotic therapy, intensive care admission, need for mechanical ventilation, and respiratory complications such as pneumothorax or hemoptysis are noted. Past anesthetic and perioperative history should also be reviewed. History determines other CF-related comorbidities of particular concern to the perioperative period such as diabetes, liver disease, gastroesophageal reflux, and confirms the adequacy of their management.
The physical examination is essential in determining the patient’s respiratory status. Lung auscultation may reveal wheezing and adventitious sounds consistent with upper airway secretions. Any signs of acute respiratory infection or respiratory failure such as fever, chills, oxygen saturation lower than baseline, tachypnea or use of accessory muscles warrant further investigations. Evidence of right-sided heart failure should be sought for by examining the jugular venous pulse and the lower extremities. Stigmata of pancreatic or liver dysfunction may be present.
Recent pulmonary function testing should be obtained and will typically reveal an obstructive pattern, with decreased FEV1 and FEV1 to FVC ratio as well as evidence of gas trapping with an increased residual volume to TLC ratio. ABG analysis is indicated if there is suspicion of CO2 retention or to assess level of hypoxemia and need for long-term oxygen therapy. Other laboratory investigations of specific importance include a complete blood count, electrolytes, renal function tests, fasting glucose, coagulation tests, liver enzymes, bilirubin, and albumin levels to assess nutritional status and renal, hepatobiliary, and pancreatic function. Recent sputum cultures and sensitivities should be reviewed. Electrocardiogram and echocardiography may be indicated based on history and physical examination.
Recent chest radiologic examinations may reveal findings of particular perioperative concern such as bullae, atelectasis, or consolidations.
As mentioned previously, the preoperative evaluation and management should consist of a multidisciplinary approach involving the patient’s primary CF specialist(s) and may include a pulmonologist, an endocrinologist, a gastroenterologist, a dietitian, a surgeon, and an anesthesiologist. Unless surgery is urgently or emergently indicated, preoperative optimization ensures that the patient’s respiratory function is at baseline, that optimal nutritional support is provided and that diabetes is well controlled. The patient’s routine respiratory medications (including chronic antibiotherapy) are continued throughout the perioperative period and a clear plan for glucose control is established. Sputum clearance techniques and chest physiotherapy are continued up until induction of anesthesia (5).
REFERENCES
1. Stoltz DA, Meyerholz DK, Welsh MJ. Origins of cystic fibrosis lung disease. N Engl J Med. 2015;372:351-362.
2. Huffmyer JL, Littlewood KE, Nemergut EC. Perioperative management of the adult with cystic fibrosis. Anesth Analg. 2009;109:1949-1961.
3. Cystic Fibrosis Foundation Patient Registry—Annual Data Report 2014. www.cff.org. Accessed on September 22, 2016.
4. Farrell PM, Rosenstein BJ, White TB, et al. Guidelines for diagnosis of cystic fibrosis in newborns through older adults: Cystic fibrosis consensus report. J Pediatr. 2008;153:S4-S14.
5. Della Rocca G. Anaesthesia in patients with cystic fibrosis. Curr Opin Anaesthesiol. 2002; 15:95.
4.5 Adult Respiratory Distress Syndrome
Christopher Potestio
Cortessa Russell
Acute respiratory distress syndrome (ARDS) is a rare clinical syndrome characterized by acute-onset hypoxic respiratory failure. Mortality in ARDS is estimated anywhere from 20% to 50% despite advancement in therapy (1,2,3). While the hallmark of ARDS is rapidonset hypoxemia with PaO2/FiO2 ratio <300, the syndrome may include other characteristic findings such as poor pulmonary compliance and bilateral pulmonary infiltrates on chest radiograph despite preserved left ventricular function. ARDS remains difficult to anticipate and manage. It is often part of a wider picture of multiorgan dysfunction syndrome (MODS) and continues to challenge intensivists and perioperative physicians.
DEFINITION
A panel of experts from the European Society of Intensive Care Medicine endorsed by the American Thoracic Society and the Society of Critical Care Medicine established the Berlin definition of ARDS (4):
“ARDS is an acute diffuse, inflammatory lung injury, leading to increased pulmonary vascular permeability, increased lung weight, and loss of aerated lung tissue… [with] hypoxemia and bilateral radiographic opacities, associated with increased venous admixture, increased physiological dead space and decreased lung compliance.”
Key Components (Tables 4.8 and 4.9)
Acute onset, with symptoms developing in <1 week
Bilateral opacities consistent with pulmonary edema on imaging studies
Category
Criteria for Diagnosis
Oxygenation
MILD: PaO2/FiO2 ≤300 with PEEP or CPAP ≥5 cm H2O MODERATE: PaO2/FiO2 ≤200 with PEEP ≥5 cm H2O SEVERE: PaO2/FiO2 ≤100 with PEEP ≥5 cm H2O
Timing
Within 1 week of known clinical insult or new or worsening respiratory symptoms
Chest imaging
Bilateral opacities not fully explained by effusions, lung collapse, or pulmonary nodules
Origin of edema
Respiratory failure must not be fully explained by cardiac failure or fluid overload
Need objective assessment (e.g., echocardiography) to exclude hydrostatic edema if risk factors present
CPAP, continuous positive airway pressure; FiO2, fraction of inspired oxygen; PaO2, partial pressure of arterial oxygen, PEEP, positive end expiratory pressure
Severity of ARDS
Mortalitya (95% CI)
Mild
27% (24-30%)
Moderate
32% (29-34%)
Severe
45% (42-48%)
a In this meta-analysis, studies provided data on hospital mortality or 90-day mortality.
Pulmonary edema “must not be fully explained by cardiac failure or fluid overload” in the best estimation of the physician using available information (i.e., echocardiography)
Changes from the 1994 American-European Consensus Conference (AECC) include:
The term “Acute Lung Injury” was removed from the definition; replaced by the designations of mild, moderate, or severe ARDS based on PaO2/FiO2 ratio
“Acute” was further defined as “onset within 7 days of an inciting event or worsening respiratory function”
PaO2/FiO2 ratio requires a minimum PEEP of 5 cm H2O. Of note, noninvasive positive pressure ventilation (NIPPV) may be used to manage patients with mild ARDS. In these cases, the PaO2/FiO2 ratio requires CPAP of 5 cm H2O. NIPPV is unreliable when delivering high airway pressures and is therefore inadequate respiratory support for patients with moderate or severe ARDS.
CT scan was added as an option for evaluating radiographic criteria to improve interrater reliability
No need to exclude heart failure with PCWP <18 cm H2O, as both diseases can co-exist
Additional Information About the Berlin Definition
Four ancillary variables were studied
Radiographic severity
Respiratory system compliance (≤40 mL/cm H2O)
Ventilator management with PEEP ≥10 cm H2O
Corrected expired volume per minute (≥10 L/min)
Low sensitivity (54.6%) in identifying patients with diffuse alveolar damage on lung biopsy (5).
PaO2/FiO2 ratios change based on ventilator settings, and no standard ventilator settings are specified. The Berlin definition can aid a clinician in diagnosis of the disease. It does not address underlying etiology, risk factors, or ways to further quantify lung injury.
PATHOPHYSIOLOGY
ARDS manifests as diffuse alveolar injury resulting from an insult to either side of the alveolar-capillary membrane (Table 4.10). Injury may occur to the
vascular or the alveolar epithelium. Development of ARDS may be exacerbated by mechanical ventilation due to either barotrauma (injury to alveoli from increased pressure) or volutrauma (injury to alveoli resulting from increased stretching of alveolar tissue). Because ARDS is a heterogeneous process involving dependent lung segments, normal alveoli may be over distended by TVs. Affected alveoli are worsened by shearing forces of expansion and collapse during positive pressure ventilation from inadequate recruitment, a condition known as atelectrauma.
vascular or the alveolar epithelium. Development of ARDS may be exacerbated by mechanical ventilation due to either barotrauma (injury to alveoli from increased pressure) or volutrauma (injury to alveoli resulting from increased stretching of alveolar tissue). Because ARDS is a heterogeneous process involving dependent lung segments, normal alveoli may be over distended by TVs. Affected alveoli are worsened by shearing forces of expansion and collapse during positive pressure ventilation from inadequate recruitment, a condition known as atelectrauma.
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The phases of ARDS are:
Injury
Exudative (days 0 to 7): infiltration of protein-rich neutrophilic edema and formation of hyaline membranes
Proliferative (days 7 to 21): proliferation of type II pneumocytes along the basement membrane and initiation of lung repair. Patients may be weaned from mechanical ventilation
Fibrotic (3 to 4 weeks): some patients require long-term support, exudates convert to fibrosis with normal architecture disruption. Increased morbidity and mortality
Resolution
RISK FACTORS FOR THE DEVELOPMENT OF ARDS
Several patient variables are associated with the development of ARDS at the time of surgery (3). Intraoperative management as shown in Table 4.11 is associated with ARDS.
Lung protective strategies targeting TV between 6 and 8 mL/kg ideal body weight have been associated with survival benefit for patients with ARDS (7). These strategies focus on minimizing trauma caused by increased pressure in the alveoli (barotrauma) and also overdistention of alveoli (volutrauma). Driving pressure is a ratio that accounts for the functional size of the lung in ARDS patients. An easy way to calculate this value in the clinical setting is plateau pressure minus PEEP. Decreases in driving pressure have also been associated with increased survival (8). A reasonable target for driving pressure is below 20 cm H2O.
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