Painful Disorders of the Respiratory System
Pain Management, Chapter 80, 649-659
Chapter outline
- Sensory Innervation of the Respiratory System 649
- Clinical Features of Chest Pain 650
- Specific Causes of Chest Pain 651
- Visceral Causes of Chest Pain 651
- Bronchial Inflammation: Bronchitis and Asthma 651
- Lymphangioleiomyomatosis 651
- Pulmonary Langerhans Cell Histiocytosis 652
- Sarcoidosis 652
- Pulmonary Hypertension 653
- Pleuritic and Chest Wall Pain 653
- Chest Wall Trauma Caused by Coughing 653
- Pulmonary Embolism 653
- Pleurisy from Adjacent Pulmonary Infection 654
- Pleurisy Associated with Systemic Inflammatory Conditions 655
- Pneumothorax 655
- Chest Pain After Thoracotomy 655
- Sickle Cell Disease 656
- Lung Cancer 656
- Primary Lung Cancer 656
- Superior Sulcus Tumors and Pancoast-Tobias Syndrome 656
- Mesothelioma 657
- Tumors of the Mediastinum 657
- Traumatic Chest Pain 658
- Cough 658
- Conclusion 658
This chapter reviews the causes of chest pain that occur with lung (and pleural) disease. Respiratory chest pain, with the exception of pleuritic pain (in association with pulmonary embolism or pneumonia), is generally not considered to be an important clinical feature. When faced with a patient with chest pain, a clinician often first excludes cardiac causation and then gastrointestinal disease before considering a respiratory cause. However, the lungs have a complex network of sensory fibers, and chest pain is a prominent symptom of most forms of respiratory disease. An accurate history and examination is usually used to determine the underlying etiology of respiratory system pain.
A description of the sensory innervation of the respiratory system is followed by a classification of different types of chest pain and a suggested clinical approach. Individual causes are then described in detail. A section on cough, which is a closely related symptom, is also included.
Sensory Innervation of the Respiratory System
The sensations that originate from the respiratory system include those of pain and related sensations, such as cough, dyspnea, and chest tightness. The complex and dense sensory innervation of the lungs is often not appreciated. Respiratory chest pain may arise from: (1) involvement of the parietal pleura/adjacent chest wall; or (2) the airways and the lung viscera. Pulmonary malignant disease may have features of both pleural and visceral pain.
Pleuritic/Chest Wall Chest Pain
The chest wall and parietal pleura have a rich innervation, supplied by the costal nerves. The stimulation of these areas causes pain referred to the adjacent chest wall. The central portion of the diaphragmatic pleura is innervated by the phrenic nerve, and the pain is referred to the ipsilateral shoulder. This form of pain is generally sharp and well localized.
Visceral Chest Pain
The visceral pleura and the lung parenchyma are generally considered to be pain insensitive. The passage of a needle into the lung for biopsy does not cause any sensation, and significant traumatic lung injury is painless. Lung cancer is not thought to cause pain unless it involves the parietal pleura or bronchi. However, the lung airways have a dense sensory network. Irritation of the larynx, upper airway, and tracheobronchial tree (e.g., by inhaled irritants or mucosal inflammation) induces a sensation of burning, rawness, and chest discomfort most often described by patients to involve the retrosternal and midthoracic areas.
The visceral sensations from the respiratory system go through afferent fibers that travel within the vagus nerve to its nuclei located in the medulla oblongata. The fibers reach the lung via the thoracic branches of the vagus and the trachea in its upper portion via the recurrent laryngeal nerve. The sensory pathway originates in close contact with the epithelium, submucosa, interstitium, smooth muscles, and pulmonary vessels, in three main groups of sensory receptors.
The slowly adapting stretch receptors (SARs) , mechanoreceptors connected to small myelinated afferent fibers, are thought to be located in the smooth muscle of the extrapulmonary and large intrapulmonary airways, respond to moderate lung inflation, and are responsible for the inflation and expiration Hering-Breuer reflexes. The inflation reflex consists of a reduction in the inspiratory time and prolongation of expiration with increased inflation; the expiration reflex is an increase in the respiratory rate associated with lung deflation.
The rapidly adapting stretch receptors (RARs) , also known as irritant receptors, are located in the lung parenchyma, bronchioles, and distal bronchi and are connected to small myelinated fibers. The main stimuli for these receptors are rapidly adapting lung deflation, bronchial deformation, and mucosal irritation. They are involved in the cough reflex, bronchoconstriction, and mucus production. The general agreement is that pain from irritation of the airways is the result of the activation of the rapidly adapting stretch receptors.
The C-fiber endings associated with the type J receptor, a term coined by Paintal, referring to the juxtapulmonary capillary location, reside close to the pulmonary capillaries and within the bronchi. They are chemosensitive but also are activated by mechanical stimuli and are connected to unmyelinated afferent fibers. As described by Coleridge and Coleridge, these receptors are involved in responses, such as bronchoconstriction, secretion of mucus, bradycardia, and hypotension, and can influence breathing rate. The organization of the nerves for visceral chest pain is shown in Fig. 80.1 .
Visceral pain sensation in the lung.
Pain receptors are diffusely present in the lung but are most concentrated in the upper airways and bifurcations of the bronchi. The three main sensory receptors are: (1) rapidly adapting receptors (RARs); (2) slowly adapting receptors (SARs); and (3) C fibers. These receptors respond to mechanical, irritant, and chemical stimuli. Impulses are then conducted via the vagus nerve to the brainstem.
In contrast to pleuritic chest pain, stimulation of the visceral pathway generally produces deep-seated, diffuse, and poorly localized pain. This particularly applies when the C fibers are stimulated.
Clinical Features of Chest Pain
The clinical features of pleuritic/chest wall pain and visceral pain differ, and other specific features are characteristic of different causes of chest pain.
Pleuritic/Chest Wall Pain
The pain associated with pleuropulmonary disorders is usually described as “pleuritic” in nature and usually increases with forced maneuvers, respiratory movements, coughing, or sneezing; however, it must be separated from respirophasic chest pain of musculoskeletal origin. Pleuritic chest pain may be acute in onset, sharp, often severe, and unilateral. It usually is made worse by deep breathing and coughing and is ameliorated by splinting of the affected side. Musculoskeletal pain also may vary with respiration but is not as intense; is made worse by extension, abduction, or adduction of the arms and shoulders; and usually is accompanied by tenderness of the muscle group involved. Most reviews state that potential musculoskeletal causes of chest pain represent 10% to 20% of the patients with chest pain of noncardiac origin. The sternum and its articulation with the ribs and clavicle are recognized as sites of involvement in some seronegative arthropathies, in particular those associated with pustular skin disease. In addition, rheumatoid arthritis (RA) has been reported to affect the chest wall and cause chest pain, and pleuritic chest pain is the most common symptom in lupus pleuritis and occurs in 86% to 100% of cases of lupus pleurisy. Tzietze syndrome is an uncommon but well-described chest wall syndrome. Initially reported in 1921, Tzietze syndrome is defined as a benign, painful, nonsuppurative localized swelling of the costocondral, sternoclavicular, or costosternal joints in the area of the second and third ribs (see chapter 78 ).
Visceral Pain
In contrast to the well-defined and localized pain that occurs with involvement of the parietal pleura and chest wall pain, visceral pain is less defined. Generally, this pain arises from stimulation of the bronchi and most commonly is associated with a burning discomfort that is localized to the retrosternal area. Pain localized to areas with atelectasis or collapse may also occur.
Clinical Features of Specific Conditions
A large number of causes of respiratory chest pain need to be considered. Some clinical features may suggest specific etiologies.
Pain that has a very acute onset is most commonly the result of pulmonary embolism. Another important cause is pneumothorax.
Severe and unrelenting pain that is present for a prolonged period (i.e., at least a month) is consistent with malignant disease. This is particularly the case with pain that prevents sleep. Progressive weight loss is also suggestive of cancer.
Fever, productive cough, and localized crackles suggest lower respiratory tract infection.
Patients who have pain on touching of the chest or who have focal tenderness on examination are likely to have chest wall involvement as the cause.
Specific Causes of Chest Pain
No generally accepted classification exists for causes of respiratory chest pain. Pain can be considered to be arising from involvement of the parietal pleura/chest wall, from the lung viscera, or in the context of cancer (which often has visceral and parietal/chest wall components). Specific causes are listed in Table 80.1 . Some conditions (e.g., cancer and pneumonia) are associated with both visceral and pleural pain.
Table 80.1
Causes of Respiratory Chest Pain
| VISCERAL |
| Asthma/bronchitis |
| Pneumonia/lung abscess |
| Atelectasis/lobar collapse |
| Lymphangioleiomyomatosis |
| Pulmonary Langerhans cell histiocytosis |
| Sarcoidosis |
| Pulmonary hypertension |
| PARIETAL PLEURA/CHEST WALL |
| Pulmonary embolism |
| Pleurisy in association with local infection |
| Pleurisy in association with systemic inflammatory conditions |
| Trauma to chest wall from coughing |
| Operative chest pain (e.g., thoracotomy) |
| Traumatic injury to chest wall |
| Pneumothorax |
| Sickle cell disease |
| CANCER |
| Primary bronchogenic lung tumor |
| Mesothelioma |
| Metastatic tumor |
Visceral Causes of Chest Pain
A large number of lung conditions have pain that is predominantly sensed through the vagal nerve afferents. Some of these conditions, such as asthma and infective bronchitis, are extremely common, and pain is generated through inflammation of the bronchi. Rarer systemic diseases that cause pain, including sickle cell anemia, lymphangioleiomyomatosis (LAM), and sarcoidosis, have less well-defined mechanisms. Many of these conditions are inflammatory and associated with the production of mediators, which stimulate the pain receptors.
Most commonly, the pain is not severe, and therapy is primarily directed at treatment of the underlying condition (e.g., with corticosteroids or with antibiotics).
Bronchial Inflammation: Bronchitis and Asthma
Asthma and chronic bronchitis are extremely common and cause bronchial inflammation. Asthma is an inflammatory disease of the airways that is characterized by increased responsiveness of the tracheobronchial tree to a variety of stimuli. Chronic bronchitis is defined by chronic cough and sputum production (for at least 6 months) and occurs particularly in smokers and those with chronic obstructive pulmonary disease (COPD). Asthma and chronic bronchitis produce bronchial inflammation, which causes the release of mediators (e.g., bradykinin, which stimulate the pain pathway).
An important feature is the occurrence of exacerbations in which increased airway inflammation (e.g., after exposure to an allergen or establishment of bacterial infection) leads to increased symptoms. Patients typically have a burning retrosternal chest pain that is of mild severity. Exacerbations are treated with standard medications that include corticosteroids, bronchodilators, and antibiotics. Fig. 80.2 shows an inflamed airway in a subject with bronchitis.
Picture of inflamed airway as visualized with bronchoscopy.
A, Shows a normal airway in contrast to B, an inflamed airway (as may occur with bronchitis). The inflammation causes the release of mediators, which cause pain. Typically a patient has poorly localized retrosternal pain of moderate severity.
Subjects with inflamed airways produce secretions or mucous, which may cause partial (atelectasis) or complete collapse of a lobe. This is not a well-recognized entity but, in the author's experience, is associated with distinctive chest pain. Subjects have a deep-seated continuous pain of acute onset and moderate severity of the area of the collapsed lung that resolves when the lung reinflates. The mechanism of pain involved is not clear but may involve the stretch and mechanoreceptors of the SAR and RAR nerve sensors. Fig. 80.3 shows an x-ray of a subject with lung collapse and localized chest pain.
Computed tomography scan of left lower lobe collapse.
This subject presented with recurrent left lower lobe collapse, which produced moderately severe continuous chest pain localized over this part of the lung.
Lymphangioleiomyomatosis
Lymphangioleiomyomatosis (LAM) is a rare disease that affects mainly premenopausal women and results from the proliferation of an atypical smooth muscle–like cell involving the small airway, pulmonary microvasculature, and intrathoracic and extrathoracic lymphatic systems. The proliferation of these LAM cells produces airway obstruction, cystic changes, and pulmonary hemorrhage. LAM is associated with the development of pneumothorax and chylothorax, both pleural complications that usually present as chest pain and breathlessness.
Patients with LAM most commonly present with dyspnea on exertion and nonproductive cough, but chest pain can be the initial symptom in 12% to 14% of the cases, according to different series. In patients with LAM, the frequency of spontaneous pneumothorax ranges from 60% to 81%, with a recurrence rate of 64% without pleurodesis or surgery. A chylous pleural effusion or chylothorax is the accumulation of chyle within the pleural space usually caused by a disruption in the thoracic duct or in the lymphatic flow within the chest. Treatment is primarily supportive.
Pulmonary Langerhans Cell Histiocytosis
Pulmonary Langerhans cell histiocytosis (PLCH) is a rare interstitial lung disease that forms part of a spectrum of diseases characterized by the proliferation and infiltration of different organs by cells known as Langerhans cells. Strongly associated with cigarette smoking, this disorder also has been previously referred to as primary pulmonary histiocytosis X, pulmonary eosinophilic granuloma, and pulmonary Langerhans cell granulomatosis. It usually affects young adults and has a variable and unpredictable course, ranging from asymptomatic to progressive disease with respiratory failure and death over months. Secondary spontaneous pneumothorax, a complication with a reported mortality rate in the literature of 16%, occurs in 4% to 17% of patients with PLCH during the course of the disease. Patients with PLCH are predisposed to the development of pneumothorax based on destructive changes in the lung parenchyma resulting from the disease. Thin-walled cysts, nodules (with or without cavitation), or a combination of these are present in the lungs of patients with PLCH. Although dyspnea and cough are common presenting features, spontaneous pneumothorax and chest pain can be the initial manifestation of PLCH, as occurred in 11% of a cohort of 102 patients with PLCH examined over a 23-year period at the Mayo Clinic.
Sarcoidosis
Sarcoidosis is a multisystem disorder of unknown etiology characterized by noncaseating, epithelioid granulomas in affected organs. It most commonly affects the lungs and associated lymph nodes, although any organ may be involved. Important extrapulmonary manifestations include skin, cardiac, eye, and neurologic involvement. The pathogenesis involves cytokine production by type 1 T-helper lymphocytes and macrophages, which form noncaseating granulomas. A diagnosis is established by a compatible clinical picture with the presence of granulomas on biopsy (and the exclusion of other causes). The clinical course of sarcoid is highly variable, ranging from asymptomatic disease to progressive respiratory failure. Most subjects have a good outcome but have acute flares of disease periodically.
The range of pulmonary manifestations includes pulmonary lymphadenopathy, bronchial sarcoidosis, and pulmonary fibrosis. Fig. 80.4 shows pulmonary changes of sarcoidosis. Chest pain is a frequent manifestation of sarcoidosis. This chest pain is not well described in the literature, but there seem to be several different forms. It may manifest as retrosternal chest pain that occurs with bronchial sarcoidosis with a mechanism that may be similar to that described in asthma or bronchitis. This form may occur with chest tightness and wheezing. Fleeting episodes of deep-seated pain may also occur, sometimes associated with general exacerbations. Pleuritic and chest wall pain may also occur in sarcoidosis.
Sarcoidosis.
A, Shows different mechanisms of lung pathology. B, Computed tomography scan of patient with sarcoid and changes of nodular infiltrate and mediastinal lymphadenopathy. This subject had both bronchial irritation and atypical fleeting sharp chest pain.
Acute manifestations of sarcoidosis generally respond well to treatment with corticosteroids. Whether treatment with immunosuppressive medications like cortisol changes long-term outcome (e.g., in pulmonary fibrosis) is not clear.
Pulmonary Hypertension
Patients with pulmonary hypertension may present with significant chest pain that radiates to the neck and arms. This pain has been described in patients with acute and chronic conditions associated with pulmonary hypertension. About half of patients who have primary pulmonary hypertension have chest pain. The mechanism involved in this pain is unclear, but acute dilation of the pulmonary artery and mechanoreceptors has been postulated to be involved in acute pulmonary hypertension resulting from a massive pulmonary embolism. Likewise for chronic primary pulmonary hypertension, the pain has been hypothesized to be induced over the right ventricle by the pressure overload, relative ischemia, or supply-demand imbalance and by compression of the coronary arteries by the dilated pulmonary artery. Pulmonary artery aneurysms are dilations of more than 4 to 5 cm that can be congenital or acquired and present with or without pulmonary hypertension and chest pain.
Pleuritic and Chest Wall Pain
As with visceral pain, a number of respiratory conditions may cause pleuritic or chest wall pain. This form of pain is often severe and nearly always well localized. Inflammation, trauma, and malignant invasion of tissue are the main mechanisms involved.
Chest Wall Trauma Caused by Coughing
Chest wall trauma caused by coughing is common but (similar to asthma and chronic bronchitis) is often not considered by clinicians. Severe, persistent, or paroxysmal coughing may cause damage to intercostal muscles and connecting ligaments and occasionally fractures. The pain may be quite severe and also prolonged, particularly if the patient is still coughing.
Treatment is aimed at the underlying cause (usually of cough) and simple analgesics. Unfortunately, cough suppressants are rarely better than placebo.
Pulmonary Embolism
Pulmonary embolism (PE) is a respiratory condition that is commonly considered to be associated with pleuritic chest pain. Approximately 250,000 patients are hospitalized annually in the United States because of venous thromboembolism.
Pleuritic chest pain with or without hemoptysis, dyspnea, and circulatory collapse has been classically associated with pulmonary thromboembolic disease. In the Prospective Investigation of Pulmonary Embolism Diagnosis study, more than half of the patients with chest pain or hemoptysis (56%) had pleural effusions. Reports are that 75% of patients with pleural effusion associated with pulmonary emboli have pleuritic chest pain. Dyspnea, when present, is usually out of proportion with the size of the pleural effusion. Patients with pulmonary emboli and associated pleural effusions may or may not have an associated parenchymal infiltrate; when present, these are more common in the lower lobes and are pleural based and convex toward the hilum (Hampton's hump). Pleural fluid analysis is nonspecific but can help rule out other causes, such as malignant disease, tuberculosis, or pneumonia with a parapneumonic effusion. The fluid may be transudative or exudative, sometimes bloody, and the white blood cell count usually ranges from 100 to more than 50,000 cells/mm 3 and may reveal large numbers of eosinophils and mesothelial cells.
The clinical diagnosis of pulmonary embolism is inaccurate, and some controversy exists in the literature over the diagnostic value and sensitivity of certain signs and symptoms, such as dyspnea and pleuritic chest pain. The diagnosis usually is based on the history and clinical suspicion plus finding of an unmatched ventilation-perfusion defect in a lung scan or with computed tomographic (CT) angiography (increasingly the test of choice). Fig. 80.5 shows a CT pulmonary angiogram of a saddle embolus.
Computed tomography angiogram showing pulmonary saddle embolus.
Anticoagulation therapy to prevent recurrent embolism is the cornerstone of treatment for pulmonary emboli. Therapy initially with heparin (standard or low–molecular weight) is instituted before the patient's condition is stabilized with oral anticoagulation. In life-threatening circumstances, the clot may be removed with fibrinolytic therapy or embolectomy.
Pleurisy from Adjacent Pulmonary Infection
The most common cause of pleurisy is pulmonary infection, particularly from bacterial pneumonia. The main common organisms that cause pneumonia in adults are Streptococcus pneumoniae, Moxarella catarrahalis, andHaemophilus influenzae . Staphylococcus aureus and Pseudomonas aeruginosa are important causes of nosocomial pneumonia.
Pneumonia may produce pleurisy with localized chest pain ( Fig. 80.6 ). A parapneumonic effusion occurred in 90 of 203 patients (44%) with pneumonia studied prospectively by Light and coworkers ; the investigators reported 10 patients who had a complicated pleural effusion based on positive cultures, a pleural fluid pH of less than 7.00, or glucose lower than 40 mg/100 mL.
Chest x-ray showing right upper lobe pneumonia.
This condition was associated with local pleuritic pain.
Some less common infections have a relatively high incidence of pleuritic chest pain. The fungus Histoplasma capsulatum , endemic in Ohio and the Mississippi River Valleys, may cause symptomatic disease in 5%, with most subjects having pleuritic chest pain. Other fungal conditions associated with pleurisy include histoplasmosis, blastomycosis, and coccidioidomycosis.
Lung abscess is a pus-containing necrotic lesion of the lung, often with an air-fluid level. A long list of pulmonary pathology, mainly infectious, but also noninfectious, may lead to the formation of an abscess. Bacterial pneumonia and mycobacterial, fungal, and parasitic infections have been reported as causes of lung abscesses. Pulmonary infarction after emboli, lung tumor, and necrotic lesions of silicosis may appear as a lung abscess. Fig. 80.7 shows a CT scan of a lung abscess. The treatment of pleurisy in this context is primarily directed at the underlying infection. Appropriate antibiotics to cover relevant organisms are necessary, usually given parenterally. Subjects with an infected effusion, empyema (pus on pleural tap), or abscess generally need drainage with a chest tube and may need thoracotomy and decortications. Simple analgesics are generally the only specific medication necessary.
Computed tomography scan of abscess.
This subject presented with malaise and left-sided pleuritic chest pain that necessitated operative drainage.
Pleurisy in Association with Systemic Inflammatory Conditions
Systemic inflammatory conditions may cause pleurisy with associated pain. This is most common in autoimmune diseases, such as RA, systemic lupus erythematosus (SLE), Sjögren's syndrome, scleroderma, polyarteritis nodosa, and Wegener's granulomatosis. The general mechanism appears to be deposition of autoantibodies, which cause a local inflammatory response and pleurisy.
Pleural involvement is the most common lung manifestation in RA (most commonly asymptomatic), and symptomatic pleurisy is a relatively common manifestation of RA that occurs in 3% to 5%. The effusion is characterized by very low glucose level and elevated rheumatoid factor. Pleurisy is an important finding in SLE.
Treatment primarily involves immunosuppression, particularly with high-dose corticosteroids. The pain with these conditions may be quite severe, and strong pain relief may be needed.
Pneumothorax
Pneumothorax refers to the presence of free air between the visceral and parietal pleura. Pneumothoraces are classified as spontaneous or iatrogenic. The vast majority are spontaneous.
Primary spontaneous pneumothorax most commonly occurs in young adults (especially male smokers) and appears to commonly arise from rupture of a pleural bleb on the surface of the lung, which causes an air leak. Secondary spontaneous pneumothorax occurs in subjects with an underlying lung disease, most commonly COPD. Iatrogenic pneumothorax occurs in the context of a penetrating chest wound that allows air to access the pleural space through the rib cage. Important causes of pneumothorax are listed in Table 80.2 . Pneumothorax is also shown in Fig. 80.8 .
Table 80.2
Causes of Pneumothorax
| Spontaneous |
| Primary (usually in thin young males) |
Secondary—many potential causes, including:
|
| Iatrogenic |
| Penetrating chest wound |
| Chest compression injury |
A pneumothorax is most commonly the result of spontaneous rupture of a pleural bleb (or pleural abnormality) that connects with a bronchus. Less commonly, pneumothorax may occur as a complication of an external penetrating injury. Open arrow , air from a bronchus.
The clinical manifestations are determined by the size of the pneumothorax. Complete lung collapse and mediastinal shift may occur in severe cases. Most commonly, subjects describe the very acute onset of chest pain and dyspnea. The chest pain may be pleuritic or continuous in nature and can be severe. The mechanism of the pain is not well understood but may relate to pressure on the parietal pleura. The acute lung collapse could itself contribute to pain (as suggested previously).
A pneumothorax of moderate size or causing significant clinical problems necessitates drainage by a variety of techniques, ranging from needle aspiration to thoracotomy.
Chest Pain After Thoracotomy
Thoracic surgery in which there is division of the intercostal muscles (e.g., thoracotomy) generally is associated with significant postoperative pain; inadequate treatment may result in complications that include atelectasis, pneumonia, and respiratory failure.
In addition, such subjects often have pain for prolonged periods (commonly for year) after such procedures. Chronic pain after thoracic surgery occurs in 25% to 60% of patients. Typically, this pain is moderately severe, continuous in nature, and localized. The pain may be the result of intercostal nerve damage or local muscle damage and may be resistant to treatment. Fig. 80.9 shows a thoracotomy scar.
Thoracotomy scar.
Incision of the chest wall is associated with a high incidence of chronic chest wall pain.
Sickle Cell Disease
Sickle cell disease is one of the most prevalent genetic disorders. This hemoglobinopathy derives from a substitution of glutamic acid by valine in the beta subunit of the hemoglobin molecule. The deoxygenated hemoglobin S forms large polymers that aggregate, leading to a change in the red blood cell shape, affecting its deformability and inducing vascular occlusion and hemolysis.
The pulmonary manifestations of this disorder include acute chest syndrome and chronic restrictive pulmonary disease characterized mainly by pulmonary hypertension. The Cooperative Study of Sickle Cell Disease followed the clinical course of sickle cell disease in 3751 patients at 23 centers from 1979 through 1988. The incidence rate of acute chest syndrome in the Cooperative Study of Sickle Cell Disease population was reported to be higher for patients with homozygous sickle cell disease (SS; 12.8/100 patient-years) and in patients with sickle cell β-thalassemia (9.4/100 patient-years). The incidence of acute chest syndrome was inversely related to age and was higher in children and lower in adults.
Lung Cancer
A number of different forms of lung cancer all may cause pain. Primary bronchogenic lung cancer is the leading cause of cancer death. Primary tumors from other organs frequently metastasize to the lung. Mesothelioma characteristically involves the lung pleura. Other less common thoracic tumors are sarcomas and thymomas. Lung cancer may cause pain by invasion of the bronchi, parietal pleura, chest wall, or adjacent structures, such as nerves.
Most patients with primary lung cancer (86%) and virtually all patients with mesothelioma die of the disease, so appropriate pain management is important. There is a lack of randomized trials that assess the use of pain relief in lung cancer. Approximately 75% of patients with advanced lung cancer have pain; however, effective management can be achieved in about 80% to 90% of subjects.
The World Health Organization (WHO) has developed a three-stage analgesic ladder for the management of cancer pain ( Fig. 80.10 ). If pain occurs, prompt oral administration of drugs should occur in the following order: nonopioids (aspirin and paracetamol); then, as necessary, mild opioids (codeine); and then, strong opioids, such as morphine, until the patient is free of pain. For calming of fears and anxiety, additional drugs, adjuvants, should be used. Adjuvant drugs include corticosteroids (to reduce edema and inflammation) and anticonvulsants and tricyclic antidepressants for neuropathic pain. For maintenance of freedom from pain, drugs should be given “by the clock,” that is, every 3 to 6 hours, rather than “on demand.” This three-step approach of administration of the right drug in the right dose at the right time is inexpensive and 80% to 90% effective. Surgical intervention on appropriate nerves may provide further pain relief if drugs are not wholly effective. Also, a number of other nonpharmacologic approaches may be useful. Reassurance to patient and family is important. Metastatic disease is usually treated with palliative radiotherapy.
Pain relief ladder for lung cancer as described by the World Health Organization.
Primary Lung Cancer
Primary lung cancer arises from the airways or pulmonary parenchyma. It is classified into two types: (1) small cell lung cancer (SCLC); and (2) non–small cell lung cancer (NSCLC). Approximately 75% of cancers are the NSCLC type; 20% are SCLC, and 5% are other types, including carcinoids, lymphoma, and sarcoma. The dominant risk factor is smoking; other factors include asbestos exposure and air pollution.
Most patients with lung cancer present with advanced disease. Chest pain is seen is 35% of patients at presentation. Persistent, deep-seated pain may arise from mediastinal, bronchial, pleural, or chest wall extension. Pleuritic pain may occur with pleural extension, obstructive pneumonitis, or pulmonary embolism.
Limited-stage small cell cancer is curable with chemotherapy, and limited-stage NSCLC is curable with resection. For most patients who do not have curable disease, a combination of chemotherapy and radiotherapy may be offered.
Superior Sulcus Tumors and Pancoast-Tobias Syndrome
Superior sulcus tumors represent a variety of benign and malignant tumors with apical extension into the superior thoracic inlet. The involvement of the first and second ribs and lower brachial plexus nerve roots T1, T2, and C8 and cervical stellate ganglion is associated with the Pancoast-Tobias syndrome, characterized by shoulder and arm pain radiating down to the inner aspect of the arm and forearm, weakness and atrophy of the hand muscles, and Horner's syndrome. Superior sulcus tumors include adenocarcinoma, large cell carcinoma, and squamous cell carcinoma of the lung. Sarcomas, metastatic disease, bacterial and fungal pneumonia, parasitic infections, tuberculosis, hematologic malignant diseases, and amyloidosis also can be associated with this syndrome.
The usual initial symptom is shoulder pain that radiates to the arm and neck. This pain is usually from the involvement of the brachial plexus, endothoracic fascia, ribs, and parietal pleura. The confusion of this syndrome with arthrosis or bursitis of the shoulder leads to common delays in diagnosis of 10 months, as reported in the literature. X-rays of a subject with Pancoast-Tobias syndrome are shown in Fig. 80.11 .
Tumor of the lung apex (Pancoast-Tobias syndrome).
A, Chest x-ray shows tumor in right lung apex. B, Computed tomography scan of same patient. This lesion may produce severe neuropathic pain from invasion of the brachial plexus.
Mesothelioma
Mesothelioma is a malignant tumor that arises from serosal surfaces, such as the pleura and peritoneum. The primary risk factor is exposure to asbestos. Often, a very long delay (>40 years) is seen between exposure and the development of cancer. It most commonly arises in the lung, although it may occur in the peritoneal cavity.
Patients with mesothelioma have a mean age of 60 years (range, 40 to 70 years) and a history of exposure to asbestos 20 or more years in the past. The most common presentation is a pleural effusion with dyspnea and in 60% chest pain. The chest pain tends to be severe and continuous and is not classically pleuritic. The pain may be referred to the shoulder or upper abdomen because of diaphragmatic involvement. Cough and weight loss are late manifestations. The chest radiograph shows a large pleural effusion in 75% to 90% of the cases. Pleural plaques are seen in the opposite hemithorax in about one third of patients. CT scan may show pleural involvement that is not visible in the plain radiograph because of effusion. The pleura is thickened with an irregular, nodular internal margin that is characteristic of this tumor. A CT scan of mesothelioma is shown in Fig. 80.12 .
Mesothelioma.
CT scan shows pleural thickening of the left pleura. The subject presented with the rapid onset of weight loss and intractable chest pain. Biopsy confirmed mesothelioma.
At presentation, 40% of patients have dyspnea, and more than 50% have a large pleural effusion. Patients without large effusions are more likely to have chest pain as the predominant symptom. Pleural fluid analysis reveals an exudate, serosanguineous in half of the patients; glucose and pH may be reduced, particularly in patients with large tumors. Cytologic examination of the pleural fluid is diagnostic in approximately 25% of cases. The diagnosis of malignant mesothelioma usually is made with thoracoscopy. Therapy for mesothelioma is rarely curative and is mainly palliative.
Tumors of the Mediastinum
Mediastinal tumors are symptomatic in 50% to 65% of the cases, according to different series. The most frequent symptoms are chest pain, cough, dyspnea, dysphagia, and recurrent respiratory infections. Additional conditions are syndromes from the compression of the specific structures, such as Horner's syndrome, superior vena cava syndrome, and spinal cord compression or bone erosion. Between them, the neurogenic tumors, arising from the sympathetic ganglia, intercostal nerves, and chemoreceptor cells, are common and can be benign or malignant. They usually appear on the chest radiograph as unilateral paravertebral masses. Benign tumors should be surgically resected; neuroblastomas are usually unresectable. A combined coordinated surgical effort including neurosurgeons, orthopedic surgeons, and thoracic surgeons is often necessary to approach some of these tumors, particularly when the spinal cord is involved.
Traumatic Chest Pain
Chest trauma is present in 60% of patients with multisystem injuries. A major clinical feature is the presence of pain usually severe in association with injury.
On arrival in the emergency department, and after a brief history and vital signs evaluation, a physical examination should be done to look for additional posterior wounds and injuries. If no breath sounds are heard on one side of the chest, and the patient's condition is hemodynamically unstable, a chest x-ray should be ordered and a thoracostomy tube should be considered. The output from the chest tube is noted, and the subsequent hours dictate whether or not a thoracotomy is needed. More than 100 mL of blood per hour of output usually indicates a lesion of a major pulmonary vessel or bronchial artery. Interventional radiology procedures are now available for embolization of arteries and vessels in the pulmonary circulation in cases of significant posttraumatic pulmonary hemorrhage. The most serious injuries that need immediate attention are airway obstruction, tension pneumothorax, open pneumothorax, massive hemothorax, flail chest, and cardiac tamponade, as detailed by Owens et al. When these have been ruled out, a second survey should consider the possibilities of simple pneumothorax, hemothorax, pulmonary contusion, traumatic aortic rupture, tracheobronchial disruption, esophageal disruption, traumatic diaphragmatic injury, and wounds penetrating to the mediastinum.
The treatment of rib fractures is directed toward pain control, effective clearance of secretions, and preservation of lung function to avoid complications. Complications and greater severity of injury are seen when more than three ribs are involved. Clearance of secretions and pain control are crucial. Although oral or intravenous narcotics, patient-controlled analgesia, and intrapleural catheters are common methods for pain management in these cases, epidural catheters have been suggested to be superior in controlling the pain and maintaining lung function. Special consideration should be given to fractures of the first and second ribs because of the common association with lesions of the great vessels seen with these fractures. Flail chest is the result of multiple rib fractures with chest wall instability that leads to abnormal or paradoxic movements with respiration (inward during inspiration and outward in expiration).
Patients with traumatic flail chest are usually in severe respiratory distress. For more than four decades, internal stabilization of flail chest has been advocated with mechanical ventilation, pain control, and muscle relaxants to prevent paradoxic motion of the chest wall. Positive end-expiratory pressure is used to treat the underlying contusion. Controversy has existed over whether improvement with use of positive-pressure ventilation, and expanding the lung, is the result of the pneumatic fixation of the chest wall or improved gas exchange and protective effect of positive end-expiratory pressure over the lung parenchyma. More recently, pain control and secretion management has been shown to decrease complications and need for mechanical ventilatory support in flail chest cases. Internal fixation is of value in patients with severe chest wall instability. Fig. 80.13 shows a CT scan of a traumatic hemothorax.
Computed tomography scan shows large right hemothorax.
This subject fell and fractured multiple ribs posteriorally and transverse sinus processes (of the vertebra). The subject had moderately severe pain and respiratory distress. Operative drainage was necessary.
Cough
Cough is a major clinical problem; postviral cough and chronic cough (lasting more than 8 weeks) may be the most common reasons to seek medical attention.
The cough reflex has three components: (1) an inspiratory phase; (2) a forced expiratory phase against a closed glottis; and (3) opening of the glottis with subsequent rapid expiration that clears the larynx, trachea, and large bronchi. This reflex is modified by input from the cerebral cortex. The afferent pathway is activated through receptors concentrated in the bronchial bifurcations, larynx, and esophagus, and impulses are conveyed through the vagus nerve (and also superior laryngeal nerve) to the brainstem. Relay neurons in the nucleus tractus solitaries transmit to the central cough generator.
A cough can be triggered by inflammatory/mechanical changes in the airways and by inhalation of chemical and mechanical irritants. The upper airways are particularly sensitive to stimuli. As in the pain pathway, there are three main types of sensory nerve receptors for cough: (1) RARs; (2) SARs; and (3) C fibers. These sensory nerve receptors receive input from ion channels and metaboreceptors for mechanical, irritant, and chemical stimuli. The afferent pathways of cough and pain overlap to a large degree, with the same receptors and nerves involved. In addition, mediation of pain and cough in the cerebral cortex also overlaps. Like pain, the cough reflex can be sensitized by chronic stimulation. The sensory pathways of cough are shown in Fig. 80.14 .
Cough sensory pathway.
The cough pathway is similar to the pain pathway. Mechanical, irritant, and chemical stimuli act on a variety of ion channels and metaboreceptors. The three main sensory receptors are: (1) RARs; (2) SARs; and (3) C fibers, which conduct impulses via the vagus nerve to the brainstem. AA, arachidonic acid; ASIC, acid sensing ion channel; B2, bradykinin2 receptor; EP, E prostanoid receptor; nAch, nicotine acetylcholine; RAR, rapidly adapting stretch receptors; SAR, slowly adapting stretch receptors; TRPA1, transient receptor potential channel A1.
Thus, cough and visceral respiratory pain can be considered to be closely related entities. Therapy for cough has recently emphasized the role of treatment of pain.
Conclusion
Chest pain is a major feature of respiratory disorders but has a relatively low profile for most practicing clinicians when compared with other causes, such as cardiac or gastrointestinal disease. Significant spectrum is found in the respiratory chest pain, but it can be considered to arise either from visceral pathways or involvement of the parietal pleura/chest wall. Visceral pain is generally less well defined. Successful management of this form of chest pain is dependent on an accurate diagnosis of the underlying cause.
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