The symptoms that derive from pulmonary disease processes account for a large percentage of referrals to palliative care practices. Although most of these cases involve malignant lung disease, more than 7% of palliative care referrals are for primary pulmonary diseases such as chronic obstructive pulmonary disease (COPD), interstitial lung diseases, and acute respiratory distress syndrome. These diseases are uniformly chronic, progressive, and debilitating, thus mandating that comprehensive care of these patients includes a solid understanding of palliative methods.
This chapter outlines how palliative care can be applied to patients who suffer from a primary pulmonary disease. COPD receives the most attention because of its relatively high prevalence.
Pathophysiology of Dyspnea
The symptoms of dyspnea are comprehensively addressed elsewhere in this text. However, for the purposes of discussing COPD disease and other primary pulmonary disease processes here, a brief description is given of the pathophysiology of dyspnea as encountered in the palliative care of the patient with pulmonary disease. A common definition of dyspnea is an unpleasant or uncomfortable sensation of breathing or a sensation of breathlessness.
As a qualitative symptom, characterizations of dyspnea may vary widely among patients with different disease processes or even among individuals with similar, underlying cardiopulmonary diseases. In a manner similar to generating a differential diagnosis for chest pain, the clinician may find that different adjectives help to uncover the origin of the patient’s dyspnea. Several studies that examined patients’ descriptors of dyspnea have demonstrated that feelings of “chest tightness” and “increased work of breathing” may be more strongly associated with asthma, whereas “suffocation” and “air hunger” are more consistent with COPD or congestive heart failure.
The origins of dyspnea are complex at best. Many details of the underlying pathophysiology have yet to be described, particularly the neural pathways that contribute to generating a sensation of breathlessness. Additionally, correlating the symptom onset with a specific underlying stimulus can be quite difficult for both clinician and researcher. For example, in a given patient with metastatic lung cancer, is the dyspnea the result of tumor compression of the bronchi, the malignant pleural effusion, the pulmonary embolism, existential anxiety, or a combination thereof? Chapter 15 provides a more detailed discussion of the pathophysiology of dyspnea. Here, we consider three major mechanisms through which dyspnea manifests itself in COPD: chemoreceptors, mechanoreceptors, and the sensation of respiratory effort.
Both peripheral and central chemoreceptors are thought to play a role in evoking dyspnea, although it is not always clear exactly how this occurs. Normal subjects and patients suffering from pulmonary diseases complain of dyspnea while breathing carbon dioxide (CO 2 ). Conversely, many patients, especially those suffering from COPD, have baseline elevations of the partial arterial pressure of CO 2 (PaCO 2 ) at rest without experiencing breathlessness. Similarly, although hypoxia is commonly thought to contribute to dyspnea (it is known to stimulate respiration via chemoreceptors), many dyspneic patients are not hypoxic. Furthermore, in those who are hypoxic, correction often only partially alleviates the symptom.
Mechanoreceptors in the upper airways may explain the benefit that many pulmonary patients receive when they sit next to an open window or a fan. Several studies have suggested that vibration of mechanoreceptors in the chest wall may improve dyspnea in normal subjects and in patients with COPD. In the lung, epithelial irritant receptors contribute to bronchospasm, whereas unmyelinated C-fibers in the alveolar walls respond to pulmonary congestion. Interestingly, many patients with COPD exhibit dynamic airway compression, as evidenced by an improvement in breathlessness from pursed-lip breathing. One study described such an improvement when patients with COPD who did not normally breathe in such a manner were taught how to do so. However, the degree to which each of these mechanisms contributes to dyspnea is unclear and is likely relatively specific to the individual patient.
Finally, one’s sense of respiratory effort—the conscious awareness of the activity of the skeletal muscles—seems to play a part as well. This effort is related to the ratio of pressure generated by the respiratory muscles to the maximum pressure generated by the muscles. Evidence indicates that most of this sense derives from simultaneous activation of the sensory cortex at the initiation of the motor cortex to breathe. A stimulus that increases the neural drive to breathe (either when the respiratory muscle load is increased or when the muscles become fatigued) will increase this ratio and therefore the sense of effort, as seen in patients with neuromuscular disorders such as amyotrophic lateral sclerosis or myasthenia gravis.
Unfortunately, although we understand many of the mechanisms that contribute to dyspnea, no one mechanism has been linked to a single disease process. It is more likely that dyspnea in a patient with pulmonary disease is multifactorial. For example, a patient with COPD may experience breathlessness from airway hyperinflation leading to weakened diaphragmatic muscle curvature and inspiratory muscle fibers, acute or chronic hypoxia, hypercarbia, mechanical compression of the airway, or increased dead space requiring increased minute ventilation. The clinician must bear in mind such pathophysiologic complexity when caring for the patient with advanced pulmonary disease processes because effective palliative management usually requires multiple approaches, both pharmacologic and nonpharmacologic. The next section introduces possible interventions for symptom palliation in the patient with COPD. As yet, no published data describe when to begin palliation of COPD with opioids or benzodiazepines. Traditional primary care and pulmonary specialty practice tend to begin these agents when the disease is far advanced and more “conservative” therapies have proven to be of only marginal benefit. Concern about opioid and benzodiazepine side effects is often cited as the primary reason for the delay in initiation of these therapies.
Primary Disease Management
Representing the majority of pulmonary diseases for which many data are available regarding palliative management and referrals to hospice and palliative care, the major focus of this chapter is palliative management of COPD. In 1997, COPD affected 10.2 million U.S. residents; in 1998, it accounted for between 15% and 19% of hospitalizations in the United States. It is the fourth leading cause of death in the world. This section reviews approaches to primary disease treatment, as well as emerging pharmacologic and nonpharmacologic palliative techniques for managing the symptoms of COPD (primarily dyspnea).
It is important to underscore the distinction between the goals of treating the primary disease (“curative” or “disease modifying”) and relieving symptoms associated with a given disease, so-called palliative therapy. The Merriam-Webster Dictionary suggests that palliation is “treatment aimed at lessening the violence of a disease when cure is no longer possible”.
Primary disease management of COPD includes prescribed combinations of short- and long-acting bronchodilators, corticosteroids, and oxygen, as well as nonpharmacologic interventions such as pulmonary rehabilitation and preventive measures such as influenza and pneumococcal vaccinations. Treatment regimens must be designed specifically for each patient based on responses to medications. No drug or drug combination has been shown to modify the progressive decline of the disease process itself. Therefore, although the foregoing framework is often useful, in the management of COPD the distinctions between disease modifying and palliative are particularly blurred or overlapping. Generally, the success of pharmacologic and nonpharmacologic management strategies has been evaluated in terms of improvement in pulmonary function tests, exercise capacity, and symptoms. Established guidelines are readily available. A summary of interventions is provided in Table 33-1 . The primary focus here is on symptom control and a review of the evidence surrounding various traditional pharmacologic and nonpharmacologic interventions.
| Drug/Intervention | Curative | Disease Modifying | Longevity Modifying | Palliative |
|---|---|---|---|---|
| Lung transplant | X | |||
| β 2 -Agonists | X | X | ||
| Anticholinergics | X | X | ||
| Methylxanthines | X | |||
| Corticosteroids | X | |||
| Oxygen | X | X | ||
| Opiates (systemic) | X | |||
| Opiates (nebulized) | (Unclear if any benefit) | |||
| Benzodiazepines | X |
Bronchodilators
Bronchodilators (ß 2 -agonists, anticholinergics, methylxanthines) tend to be the first-line interventions in attempts to improve dyspnea in the patient with COPD. The ß 2 -agonists and anticholinergics may be delivered in short- or long-acting compounds and in inhaled forms (ß 2 -agonists are also manufactured in oral formulations, but these are not frequently used in adults). Short-acting bronchodilators can improve symptoms rapidly and can be administered on a scheduled basis for consistent control. For stable disease (i.e., not acute symptom management), the regular use of long-acting formulations has been reported to be more effective than short-acting bronchodilators, and once- or twice-daily dosing promotes improved compliance. These drugs are, however, more expensive ( Table 33-2 ). Inhaled forms (via metered-dose inhaler or nebulizer) are typically better tolerated and have fewer side effects, but they require additional patient and caregiver education for correct administration. The results of this education have demonstrated important benefit, however.
| Drug Class | Drug Name | Mechanism and Dosing Interval | Cost |
|---|---|---|---|
| β-agonists | Albuterol (generic) | Short acting (q4–6h) | $30 (inhaler) |
| Metaproterenol (Alupent) | Short acting (q4–6h) | $56 (inhaler) | |
| Pirbuterol (Maxair) | Short acting (q4–6h) | $95 (autoinhaler) | |
| Albuterol (Ventolín) | Short acting (q4–6h) | $36 (inhaler) | |
| Terbutaline (generic, Brethine) | Intermediate (q6–8h) | $31 (oral, subcutaneous, intravenous) | |
| Albuterol (Proventil) | Intermediate (q6–8h) | $38 (inhaler) | |
| Levalbuterol (Xopenex) | Intermediate (q6–8h) | $65 (inhaler) | |
| Formoterol (Foradil) | Long acting (q12h) | $97 (inhaler) | |
| Salmeterol (Serevent) | Long acting (q12h) | $98 (inhaler) | |
| Anticholinergics | Ipratropium (generic) | Short acting (q4–6h) | $34 (inhaler) |
| Ipratropium (Atrovent) | Intermediate (q6–8h) | $77 (nebulized) | |
| Tiotropium (Spiriva) | Long acting (q24h) | $120 (inhaler) | |
| Inhaled steroids | Triamcinolone (Azmacort) | Intermediate (q6–8h) | $90 (inhaler) |
| Flunisolide (AeroBid) | Long acting (q12h) | $75 (inhaler) | |
| Fluticasone (Flovent) | Long acting (q12h) | $92 (inhaler) | |
| Beclomethasone (QVAR) | Long acting (q12h) | $74 (inhaler) | |
| Budesonide (Pulmicort) | Long acting (q12–24h) | $148 (inhaler) | |
| Combination | Combivent, DuoNeb (Albuterol/Ipratropium) | Short acting (q4–6h) | $74 (inhaler) |
| Advair (Fluticasone/Salmeterol) | Long acting (q12h) | $148 (inhaler) |
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