CHAPTER 45 PULMONARY DISORDERS
Practice of Geriatrics
CHAPTER 45 PULMONARY DISORDERS
William John Hall, M.D., F.A.C.P.
Age-Related Changes in Immune Response
Physiologic and Anatomic Changes in the Lung with Aging
Pulmonary Assessment of Older Persons
Obstructive Airways Syndromes in Older Patients
Smoking Cessation in the Older Patient
Interstitial Pulmonary Fibrosis
Critical Care Management of the Older Patient
All primary care physicians are aware on a daily basis of the impact of respiratory illnesses on the care of older adults. National studies confirm that acute respiratory symptoms are among the most common reasons for older persons to seek medical attention. In addition, the clinical manifestations of the more chronic respiratory diseases play a major role in the reduced function, acute hospitalizations, and increased mortality seen in older persons.1 In this chapter the prognostic and clinical significance of age-related changes in respiratory function itself is emphasized, and some of the altered clinical manifestations of common acute and chronic respiratory diseases that are especially pertinent to the modern and effective primary care of older persons are selectively reviewed.
AGE-RELATED CHANGES IN IMMUNE RESPONSE
Definite but not well understood alterations in host defense are associated with aging. Mucociliary clearance in both the upper and lower airways is probably diminished, but the effect of aging is hard to isolate from other age-related changes such as swallowing difficulties and relative malnutrition. Age-related changes in immune function represent a complex series of events that lead to imbalances in the immune system.2 Thymic involution and loss of thymic hormones are thought to be important primary events in age-related changes in immunity. Lymphocyte function declines with age, as evidenced by diminished proliferative responses to a variety of mitogens and antigens. Other changes include alterations in lymphocyte subpopulations, decreased secretion of interleukin-2, and functional alterations in cytotoxic lymphocytes and natural killer cells.
While the most dramatic changes occur in cellular immunity, aging also affects humoral immunity. Immunoglobulin levels generally do not change with age, although antibody levels to specific pathogens may decline. Response to immunization is diminished in aging individuals. From a practical standpoint, age-related changes in the immune system predispose the lung to attack from respiratory viral infections, while at the same time, reliable responses to protective measures, such as influenza vaccine administration, are blunted.
PHYSIOLOGIC AND ANATOMIC CHANGES IN THE LUNG WITH AGING
Despite decades of research in the fields of respiratory physiology and lung biology, there is still difficulty in isolating age-related changes in lung structure and function from the many other confounding risk factors encountered by most individuals during 70 or more years of living. These uncertainties should perhaps not be surprising. The current cohort of persons over age 65 was born and raised in the preantibiotic era, when the devastating effects on lung development of then common childhood respiratory viral infections such as pertussis and measles were rampant. Tuberculosis was the most common cause of death during the teens and early adulthood of this cohort, and exposure as measured by tuberculin testing was nearly 100%. As a whole, there has probably been a higher prevalence of cigarette smoking in the generation born between 1910 and 1930 than at any time in the history of the human race. As adults in the post-World War II era, they have had the longest potential exposure to ambient levels of air pollution ever experienced. Finally, until recent decades, studies intended to develop normative standards for lung function have been largely cross-sectional in design and predominantly excluded persons older than 65 on the flawed assumption that projections from regression equations accurately reflect the aging effects on lung function.
However, accurate characterization of the age-related changes in respiratory function is more important clinically now than ever before. From a variety of epidemiologic studies it is now known that evidence of impaired lung function, especially diminution in expiratory flow rates, is predictive of higher mortality rates, not only from lung disease but also from heart disease and most of the other leading causes of death in both men and women.3 Impaired lung function may even be predictive of cognitive disorders in aging adults. As the population of older persons increases, and older individuals seek permission and guidelines from their physicians to pursue a more active lifestyle, measurement of respiratory function has even been suggested as an important global “biomarker” of successful aging and quality of life. The subsequent discussion briefly summarizes the available data pertinent to age-related changes in the mechanics of lung function, gas exchange, control of ventilation, and exercise capacity.
Age-Related Changes in the Lung and Chest Wall
A common observation made on physical examination of older persons is that the chest configuration often appears “abnormal,” a finding that is actually far more attributable to changes in muscle mass and thoracic spine configuration than to actual changes in the physical properties of the lung. The actual changes in lung capacity instead represent a redistribution of the classic subdivisions of lung volume. Both the lung and the chest wall have rubber band-like elastic properties. Thus, the lung at the end of inspiration has a natural tendency to collapse, while the chest wall has a tendency to recoil outward, thus serving as an opposing force to the retractive properties of the lung itself. This elastic recoil pressure for the lung decreases with age, the classic assumption being that changes occur in the amount and composition of the lung connective tissue components (elastin, collagen, proteoglycans), although more recent data have questioned this assumption. Simultaneously, the chest wall itself stiffens with age. The net effect of these changes is a decrease in compliance (change in volume, change in pressure) of the total respiratory system, which in turn increases the work of breathing. Simultaneously, there is a diminution in the mass and efficiency of the respiratory muscles. The net result is that a 70-year-old has to work nearly twice as hard to compensate for age-related compliance changes as he or she did at the age of 20. The age-related changes in lung volumes follow from these alterations in compliance.4
Static Lung Volumes
While the total lung capacity (TLC) remains constant with age, some of the lung subdivisions demonstrate age-related changes. One of the most reliable measures of lung volume, the so-called functional residual capacity (FRC), is slightly elevated as a function of age. The FRC is determined by the balance between the natural tendency of the lung to collapse and the opposing tendency of the chest wall to expand outward, forces that are fairly evenly matched with aging. The vital capacity is slightly reduced owing to an increase in the residual volume (RV), the amount of air remaining in the lungs after maximum expiration. The increase in RV is a reflection of the changes in the elastic properties of the lung. In summary, these so-called static lung volumes do not change appreciably with age, and any alterations suggest a pathologic process. Accurate documentation of lung volumes is important to avoid mislabeling older persons as having lung disease when none is present, particularly in overreading a chest radiograph. For example, the combined changes in lung and chest wall properties and the increased kyphotic curve of the spine with aging may result in a clinical and radiologic appearance of an increased antero-posterior (AP) diameter, sometimes referred to as “senile emphysema.” This is certainly a misnomer from the physiologic point of view. There is some degree of airspace enlargement with aging, and possibly some decline in the absolute number of alveoli, but the other more progressive and destructive aspects of emphysema are not seen solely as a function of advanced age. These individuals have normal lung volumes.
Expiratory Flow Rates
Both respiratory muscle function and the elastic recoil of the lung contribute to flow rates as measured by the classic forced expiratory maneuver, which is the basis of the commonly used clinical spirometry measurement. During the forced flow maneuver, assuming maximum expiratory effort, expiratory flow rates are determined mainly by the elastic recoil of the lung. Since recoil is diminished with age, compression of the airways occurs earlier during the expiratory maneuver in older persons. In addition to explaining the age-associated reduction in forced flow rates, this decrease of flow in smaller airways has several important implications. First, diminished expiratory flow rates may result in a less effective cough, and the premature closure of small airways may lead to gas exchange abnormalities, most notably hypoxemia. As a general approximation, males experience a drop of 14 to 30 mL/year in forced vital capacity (FVC), and a drop of 23 to 32 mL/year in 1-second forced vital capacity (FEV1). Comparable values for women are 14 to 24 mL/year (FVC) and 19 to 26 mL/year (FEV1).5 Recent longitudinal studies of older persons strongly indicate that decline in expiratory flow rates is a nonlinear phenomenon characterized by accelerated decline after age 50.6 Also, there is in all studies tremendous variability, reflecting the heterogeneous nature of aging effects in the lung as in virtually all other organs. The reasons for this variability is not known. European studies comparing lung function in sets of older identical twins living together or separated at an early age suggest that between a half and two thirds of the variability seen in pulmonary function can be attributed to genetic factors.7
Many studies have documented a linear age-related drop in PaO2 with no change in PAO2 or PaCO2. (Throughout this chapter the subscript A refers to alveolar gas partial pressures, while the subscript a designates partial pressures of respiratory gases in arterial blood.) In absolute terms, there is a linear deterioration of about 0.3% PaO2/year, or a drop of about 4 mmHg per decade.8 The most likely reason for these changes is increased heterogeneity in ventilation-perfusion matching throughout the lung and premature airway closure.
Control of Ventilation
Classic teaching suggests that rather remarkable age-related changes occur in the ventilatory response to both hypoxia and hypercapnia, both responses decreasing with age. Sophisticated studies using mouth occlusion pressure techniques have documented a decrease of approximately 50% as measured by P100 in response to isocapneic hypoxia and hyperoxic hypercapnia compared to young subjects. These changes are almost certainly due to central neural mechanisms and possibly diminished muscle strength and coordination rather than to any alteration in the lungs.9 The obvious clinical implication of these age-related blunted responses is that in selected situations, symptoms of breathlessness will be lacking despite clinically significant alterations in arterial blood gases.
Maximum oxygen capacity (VO2max) is influenced by age, but any substantial diminution is much more a reflection of reduced muscle mass, cardiac function, and overall level of conditioning. It is very unlikely that age-related changes in pulmonary function play a major role in exercise limitation in older age groups.
Pulmonary Function Tests
For clinical purposes, pulmonary function data obtained through clinical spirometry are the mainstay of clinical practice, and a working knowledge of testing and age-related changes is of practical importance. Two important principles bear emphasis. First, given normal levels of comprehension and adequate neuromuscular coordination, spirometric measures, including evaluation of bronchodilator responsiveness, have the same degree of accuracy in older persons as in younger ones. Adequacy of testing is usually verified by the direct observations made at the time of pulmonary function testing and by establishing the reproducibility of repeated measurements. Consequently, serial comparisons in the same individual are highly predictive in older persons, just as they are in younger cohorts. Second, caution must be exercised in the use of “normal” standards for the various spirometric indices. The usual way to describe normative values is to construct regression equations based on spirometric results from cross-sectional surveys of nonsmoking individuals. These equations are usually expressed as a function of height and age for males and females. The major applicability of these normal values, of course, is to identify individuals outside the normal range and, in the case of older subjects, to differentiate age-related changes from disease states. As is true with many other normative standards, the populations tested to derive the standards include a paucity of older persons and may not reflect the actual age-related changes that would be evident from longitudinal measurements made over years in the same subjects. Recently, a number of longitudinal studies on lung function have been done, and regression equations derived from these studies are probably more representative of the aging process.5 In general, these studies indicate a more substantial effect of age on lung function than was previously predicted from cross-sectional data. Moreover, they demonstrate a nonlinear, accelerated decline in function after the fifth decade. These data are replacing the older cross-sectional normals used in most software programs and commercially available prediction charts.
Even when the most contemporary normal values are available, the primary care physician must still interpret the clinical significance of any change in pulmonary function. By convention, individual values within 80% of predictive values have been considered “normal” in younger populations. Given the tremendous individual variability in most volume and flow rate changes with age, use of the 80% range may give spurious results. Most experts recommend using the 95% confidence intervals in applying normal ranges.
PULMONARY ASSESSMENT OF OLDER PERSONS
Evaluation of respiratory symptoms can be difficult and frustrating in older patients. The presence of co-morbidity in the form of cardiovascular and arthritic disease is confusing. Patients at times cannot reliably perform pulmonary function and exercise studies. There is some information about respiratory sensation and aging that is relevant to an accurate clinical evaluation. Studies examining psychological recognition of increasing resistive and elastic loads have demonstrated that older subjects have decreased sensation of these loads, which seems to occur at the level of central nervous system (CNS) processing.10 The authors have already commented on the decreased perception of chemical stimuli (hypoxia, hypercapnia). Putting all this together, there is suggestive evidence that older persons may not develop dyspnea or breathlessness until a substantially later stage of their clinical illness compared to younger people. This phenomenon is surely apparent to anyone who cares for older persons with pneumonia, who present with subtle symptoms and very abnormal arterial blood gas measurements. A very common response of the older patient who experiences dyspnea with exertion is to simply become less active, often under the mistaken impression that the complaints are an expected concomitant of age. Thus, when questioned by the physician about dyspnea, these patients legitimately answer in the negative. Evaluation of older persons with pulmonary disease should always include some assessment of change in activity. Conversely, complaints of breathlessness should always be taken very seriously in the older patient, since this symptom may indicate a more advanced stage of disease. Some practical suggestions: In the great majority of cases, these evaluations are no different from those in younger adults. However, when the diagnosis is more perplexing, the physician should try to quantitate the symptoms of dyspnea and breathlessness. One of the most reliable ways to do this is by using a variety of quantitative scales (e.g., Borg’s scale), which have demonstrated remarkable validity in older persons. Second, one can be more imaginative in “testing.” For example, taking an older patient for a walk up a flight of stairs accompanied by a pulse oximeter almost invariably allows the astute clinician to characterize the disorder. This maneuver cannot be delegated to a lab technician or a nurse.
The well-described blunting of the immune system may also mask some of the more commonly observed signs and symptoms of respiratory disease, especially acute respiratory tract infections. Thus, blunted febrile response and diminished sputum production are common manifestations of pneumonia in older patients.
OBSTRUCTIVE AIRWAYS SYNDROMES IN OLDER PATIENTS
Chronic Obstructive Pulmonary Disease
The health impact of chronic obstructive pulmonary disease (COPD) in elderly patients is enormous. Compared with the general population, older patients with COPD are twice as likely to rate their health as fair or poor, nearly twice as likely to report limitations in their usual activities, and visit physicians for medical care more frequently. For at least the past 25 years, there has been a steady increase in age-adjusted office visits, hospitalizations, and mortality for COPD in both men and women. Several factors may explain why COPD is increasing as a health problem for the elderly. First, as previously mentioned, the current generation of older persons were the generation with the highest prevalence of heavy cigarette smoking in the history of the world. Even people who have previously smoked but have now stopped may experience an accelerated decline in respiratory function late in life.11 This decline, combined with the age-related decline in expiratory flow rates, may lead to signs and symptoms of COPD at an advanced age. As previously emphasized, these patients are often not detected early, since the development of breathlessness is considered by the patient to be due to “old age.” Standard physiologic measures used to evaluate older patients with COPD (e.g., spirometry, arterial blood gases, pulse oximetry) have the same validity as in younger cohorts. Increasingly, however, it has been realized that various clinical parameters may be of more value in assessing the severity of COPD and the response to treatment in older persons. Use of the previously cited Borg scale and the baseline dyspnea index score predict general health status to a greater extent than physiologic measurements in older patients with COPD.
Reversible Airways Obstruction
Although the previous literature describes asthma as a disease of childhood or early adult life, more current data strongly suggest that asthma is a very common and especially serious disease in older persons. Various studies cite an asthma prevalence rate of 4% to 8% in persons over age 65. Rates of hospitalization for asthma are highest in the age groups over age 65. Asthma death rates also rise dramatically with advancing age. Although many older patients with asthma have a clear lifelong clinical history of symptomatic bronchospasm, there is growing appreciation that asthma may commonly become manifest after age 65. In a recent report of older asthmatics attending a pulmonary referral clinic, 48% had developed asthma after age 65. Early-and late-onset asthmatics had similar clinical manifestations of wheeze and cough and notable paroxysms of dyspnea at night.12 There are at least two reasonable conclusions from these studies. First, individuals with asthma can survive to an older age. In these studies, asthma did not “burn out” with age as folk wisdom suggests. Second, reversible airways obstruction can develop in older persons, in which case certain less common causes should be evaluated. In particular, when elderly patients present with new symptoms of wheeze and cough, a diagnosis of gastroesophageal reflux should be considered. Failure to do this may lead to a potentially dangerous course of therapy for “asthma” with little likelihood of causing anything other than (occasionally fatal) side effects. Typical symptoms of gastroesophageal reflux in older persons are more often respiratory symptoms than heartburn. In the acute hospital setting, it has been noted that patients who have a fall in oxyhemoglobin saturation as measured by pulse oximetry when swallowing water are often experiencing occult aspiration.13 Respiratory viral infections, especially those due to influenza and respiratory syncytial virus, are the most common precipitating agents of new asthma in older persons and regularly produce by far the most serious and prolonged episodes of bronchospasm.14 Subsequent episodes can be substantially prevented with the use of influenza vaccination each fall. Presently, less than 50% of eligible persons over age 54 receive a yearly flu shot.
Special Therapeutic Considerations in Obstructive Airways Syndromes
The pharmacologic management of obstructive airways disease does not differ substantially in principle from standard treatment regimens. However, older persons are unequivocally more prone to the side effects of these agents, most of which can be avoided or attenuated if they are anticipated by the primary care physician. In addition, it is increasingly important to maintain vigilance against the untoward effects of various drug combinations. Some of these considerations are outlined in the following section.
Inhaled beta-2 agonists are the most important class of drugs for the treatment of bronchospasm in all age groups. Their rapid onset of action, relatively low incidence of side effects, and lack of interaction with other agents make them ideal for use in older patients as well. These agents are not without drawbacks. Studies of older COPD patients who underwent 24-hour Holter monitoring during nebulized beta-agonist therapy have reported an increase in asymptomatic arrhythmias. Metered-dose inhaler (MDI) administration can often “fail” because of the inherent difficulties many older persons encounter in using these devices. At a minimum, patients must have adequate comprehension, hand-eye coordination, and use of wrist and fingers, and must be able to perform a sustained vital capacity maneuver for 5 to 10 seconds.15 A major reason for the failure of MDI administration in older persons is a lack of proper instruction in their use. When MDIs cannot be used, several “user friendly” mechanical aids can be tried that, along with spacers, improve the feasibility and efficacy of this form of treatment. When older patients cannot successfully use MDIs, a traditional nebulizer powered by a small air compressor can often be used very effectively instead. Anticholinergic therapy, usually with quaternary ammonium compounds such as ipratropium bromide, are effective in the treatment of COPD.16 These compounds have the advantage of being poorly absorbed and tend not to produce anticholinergic side effects such as confusion, thickened secretions, and urinary retention, even when used improperly. While no specific studies of the clinical use of these agents in older patients have been done, most reported series do include substantial numbers of patients in their seventies and eighties. There have been a few case reports of precipitation of acute angle-closure glaucoma related to improper use of ipratropium by MDI.
Given the sometimes unrelenting clinical course of bronchospastic disease in older persons, the use of corticosteroids is a necessity at times. Specific guidelines for the use of systemic steroids are not available. However, as with many other medications, steroid use carries special hazards for older persons. There is a higher incidence of the familiar complications of chronic steroid use, including cataracts, hypertension, glucose metabolism, muscle wasting, and osteoporosis. In particular, older persons are much more prone to the adverse effects of steroid administration on bone metabolism. All older persons (the majority of whom are women) should take ample calcium supplementation (2 g/day) and vitamin D (800 IU/day), and, in most instances, women should take estrogen replacement. Newer bisphosphonate preparations (e.g., alendronate) should often be prescribed. Aerosolized steroids are probably effective for the modulation of bronchospasm in older patients. Although some of the more serious side effects of systemic steroid therapy can be avoided by the use of aerosolized steroids, the same issues previously described in connection with the use of beta-agonists by MDI are relevant. If used improperly, substantial steroid absorption can take place through the oral mucous membranes. In addition, older persons are probably more prone to develop oral thrush, given the fact of age-related immune suppression.
THE USE OF METHYLXANTHINES
Theophylline clearance is not altered by age, but clinical confounders that do alter clearance (e.g., congestive heart failure [CHF], liver disease, erythromycin, ciprofloxacin, cimetidine administration) are all much more common in the elderly. Chronic theophylline toxicity, as opposed to acute theophylline intoxication, is associated with clinical differences, including a lower frequency of vomiting and a greater frequency of seizures and cardiac arrhythmias. Moreover, there is a striking lack of correlation of the peak serum theophylline concentrations with the clinical course. Recent studies have confirmed that chronologic age is a greater influence than peak theophylline concentration on the likelihood that clinical manifestations of theophylline poisoning will occur. The influence of advancing age is perhaps not surprising. The elderly patient with airway obstruction often has secondary cardiac disease that may be subclinical. Longstanding cardiovascular disease compounded by the vasoconstrictive effect of theophylline on the cerebral vasculature may lead to impaired cerebral blood flow. In summary, elderly patients have an inordinately greater risk of experiencing a life-threatening event with theophylline toxicity than younger persons. Peak serum theophylline concentration cannot predict which patients with chronic theophylline intoxication will experience one of these events.17 Given the many other therapeutic choices, there is very little reason to use this class of agents in the management of older persons with obstructive airways syndromes.
Most older patients with obstructive airways disease have substantial co-morbidity because of the increased prevalence of other chronic illnesses such as cardiovascular disease, hypertension, musculoskeletal disorders, cataracts, urinary retention, and osteoporosis. At times, treatment options for disease in one organ system are restricted or contraindicated because of a concomitant disorder in another organ system. For example, beta-blockers are commonly used for the treatment of coronary artery disease and hypertension, but they exacerbate bronchospasm in older patients. Likewise, cough induced by ACE inhibitors may be confusing in patients undergoing therapy for asthma because cough is such a dominant symptom in older persons with asthma. Eye drops often contain beta-blockers and nonsteroidal anti-inflammatory drugs (NSAIDs), which may exacerbate asthma. The use of some H2 blockers prolongs the metabolism of theophylline preparations. In summary, the recognition and therapy of obstructive airways disease in older persons is an important aspect of medical management. Proper selection of drugs is challenging and is a very good test of a physician’s clinical skills.
Lung cancer is responsible for 18% of all cases of cancer in men and 12% in women. Of all deaths related to cancer, approximately 34% in men and 22% in women are attributable to lung cancer. Half of all cases of lung cancer occur in patients 65 years of age and older, the peak incidence occurring at about age 75.18 The increased importance of this neoplasm with age in both sexes is attributable mainly to cigarette smoking and possibly to an age-related diminution in immunologic surveillance. The approach to diagnosis does not differ in older persons. Tissue confirmation and evidence of metastases can usually be obtained relatively noninvasively by the use of sputum cytology, fiberoptic bronchoscopy, and computed tomographic (CT) imaging. Decisions about treatment must take life expectancy and the presence of co-morbid conditions into careful consideration. However, age per se is not a contraindication to resectional surgery or participation in chemotherapy and radiation therapy protocols.
SMOKING CESSATION IN THE OLDER PATIENT
The current generation of older persons grew up in an era when there was far more societal approval of smoking than is currently the case in the United States. In fact, national surveys have documented that the highest prevalence of smoking in men occurs in the cohort born between 1910 and 1930, that is, those individuals currently between the ages of 65 and 85. Given the well-known reduced life expectancy of smokers, there are fewer smokers in the ranks of the elderly, and there has been some speculation that these individuals are relatively “immune” from the adverse effects of smoking. In fact, continued cigarette smoking after age 65 remains a major risk factor for death and a reduced quality of life. A male smoker in the age range of 60 to 64 who can stop smoking reduces his risk of dying of a smoking-related illness in the next 15 years by 10%. The relative risk of death from all causes in both older males and females is approximately double that of individuals who have never smoked. Rates of life-threatening influenza and pneumonia are reduced in former smokers. Recent studies have documented an improvement in expiratory flow rates and markedly reduced prevalence of respiratory symptoms in cohorts over age 65.11 In addition, smoking cessation has well-documented beneficial effects on the morbidity and mortality of many of the chronic diseases most closely associated with aging (e.g., cardiovascular disease, cancer, and osteoporosis). Given these data, it is puzzling that efforts at smoking cessation seem to play such a minor role in the primary care of older persons. The key to successful intervention hinges very much on the role of the primary care physician. Older persons tend to be much more respectful and adherent to strong advice given by their physicians than younger cohorts. Perhaps the most important factor in the success of smoking cessation is the advice and encouragement given by the primary care provider. As in younger cohorts, nicotine gum and transdermal nicotine patches can be successful adjuncts to a program centered around strong physician advocacy and group support through a variety of community agencies.
Pulmonary embolization is a major cause of morbidity in older persons, especially among the more sedentary and bedbound. A number of factors predispose older persons to deep venous thrombosis. There is a higher frequency of factors contributing to venous stasis, such as congestive heart failure and general immobility. There is also increasing evidence that older persons frequently have a hypercoagulable state, as evidenced by increased fibrinogen concentrations and other clotting factors, and a decrease in the activity of the fibrinolytic system. Hypercoagulable states, such as those following myocardial infarction or even viral respiratory illnesses, may be transient. Pulmonary embolism has been thought to be particularly difficult to diagnose because its common symptoms, such as dyspnea and hemoptysis, may be absent. Angiography has been avoided in older patients and has been thought by some to be relatively contraindicated in this age group. When the diagnostic features of acute pulmonary embolism are evaluated and the characteristics among younger and older patients are compared, surprisingly few differences are observed.19 Clinical syndromes characterized by either pleuritic pain or hemoptysis, isolated dyspnea, or circulatory collapse are observed with comparable frequency in all age groups. Furthermore, these nonspecific manifestations are quite frequent in patients over the age of 70. Among these patients with documented pulmonary embolism, dyspnea or tachypnea occurs in 92%, dyspnea, tachycardia, or pleuritic pain in 94%, and dyspnea, tachypnea, or radiographic evidence of atelectasis or parenchymal abnormality in 100%. In various trials, complications of pulmonary angiography were not more frequent in patients over age 70.
CHAPTER 45 PULMONARY DISORDERS
CHAPTER 45 PULMONARY DISORDERS