MALIGNANT AIRWAY OBSTRUCTION
Malignancy-related airway compromise is usually an insidious process that results from a mass originating in the oropharynx, neck, or superior mediastinum progressively obstructing air flow.6,8 Acute compromise may occur with supervening infection, hemorrhage, or loss of protective mechanisms, such as muscle tone. Iatrogenic factors, such as radiation therapy, may create additional difficulties by producing local inflammation with tissue breakdown. It is helpful to classify airway impairment due to malignant tumor obstruction in two manners, as to location—from the lips and nares to the vocal cords (upper airway) versus those from the vocal cords to the carina (central airway)—and, as to nature of the obstruction—endoluminal, extraluminal, or mixed. Almost regardless of the cause, airway obstruction usually presents with symptoms of shortness of breath and signs of tachypnea and stridor. The physical examination may show evidence of a mass in the pharynx, neck, or supraclavicular area.
Patients with airway obstruction due to a malignant tumor are evaluated with a combination of plain radiographs, CT, and endoscopic visualization.6,8 Direct laryngoscopy is discouraged because injudicious manipulation of the upper airway may convert a partial obstruction into a complete one by provoking bleeding or edema.9
Emergency management includes the administration of supplemental humidified oxygen and maintenance of the best airway possible through patient positioning. Heliox—typically a 50:50 mixture of helium and oxygen—may provide symptomatic improvement in upper airway obstruction due to cancer when combined with other therapy.10
Mechanical intervention for critical airway obstruction from a tumor is rarely required in the ED. For patients with critical upper airway obstruction, emergency transtracheal jet ventilation or cricothyroidotomy could be lifesaving if the obstruction is above the vocal cords (see chapter 30, "Surgical Airways"). However, the presence of an overlying tumor or swelling may render such procedures technically difficult. Alternatively, passage of the endotracheal tube beyond the area of obstruction is a consideration when the patient is progressing to complete airway occlusion.6,9 This is best done using awake fiberoptic intubation with a 5-0 or 6-0 endotracheal tube, wire reinforced, if possible. Placement of such a tube can provide symptomatic relief and time until procedures with more sustained benefit can be performed.
The two procedures that provide sustained relief of airway obstruction are neodymium-yttrium-aluminum-garnet laser photoradiation for vaporization of obstructing tissue and placement of a self-expanding stent at the stenotic site; these two modalities are often combined.11,12 Alternatively, variations of radiotherapy—endobronchial brachytherapy, photodynamic therapy, and external-beam radiation therapy—can be directed to the obstructing tumor, but the time for symptomatic response is longer than the mechanical approaches of laser photoradiation and stenting.
BONE METASTASES AND PATHOLOGIC FRACTURES
Anatomic disruption of bone weakened by preexisting conditions is termed a pathologic fracture. Pathologic fractures due to malignancy most commonly affect the axial skeleton (calvarium included) and the proximal aspect of the limbs. Most pathologic fractures are due to metastases from solid tumors (e.g., breast, lung, prostate) that localize in areas of bones with high blood flow, identified as containing red marrow.13 Most patients with pathologic fractures have a known malignancy. Patients with bone metastases usually present with localized pain and a benign outward appearance of the involved area.
Malignancy alters the normal radiographic appearance of bone, including loss of trabeculae with indistinct margins (osteolytic, or "moth eaten"), poorly demarcated areas of increased density (osteoblastic), and/or a periosteal reaction. Plain radiographs may identify only about half of metastatic bone lesions.14 Advanced imaging is often required; CT with IV contrast, particularly when using reconstruction software, can visualize three-dimensional bone integrity and soft tissue extension, whereas MRI best delineates soft tissue and bone marrow involvement. A total-body radionuclide bone scan can be used as a screening tool to identify areas of increased bone activity that could represent additional metastatic spread.14 However, areas of radionuclide localization on the bone scan are not specific for cancer, and additional imaging studies of these areas are necessary for confirmation.
Treatment priorities are pain relief and restoration or salvage of function. For acute pain or fracture, parenteral analgesics are recommended for rapid treatment. Patients with bone metastases often require long-acting oral opioids and other adjunctive medications for pain relief (see chapter 38, "Chronic Pain"). Approximately 80% of painful bone metastases can be helped with palliative radiotherapy, although it may take several weeks after completion of a typical 5-day course of treatment to experience maximal benefit. The majority of pathologic fractures require open surgical repair.
MALIGNANT SPINAL CORD COMPRESSION
Up to 20% of cancer patients will develop neoplastic involvement of the vertebral column, and 3% to 6% will develop spinal cord compression.4,5,6,15 Most cases of malignant spinal cord compression are due to metastases to vertebral bodies from solid organ tumors. with the thoracic vertebrae being the most common location for such metastases. Spinal cord compression occurs when these metastases enlarge, erode through the vertebral cortex into the spinal canal, and compress on the spinal cord. Less common causes of malignant spinal cord compression include local spread from paraspinal tumors through the intervertebral foramen or tumors (primary or metastatic) directly involving the spinal cord or meninges.
Approximately 90% of patients with malignant spinal cord compression will have back pain (Table 240-2). Such pain is often described as unrelenting, progressive, worse when supine, and located in the thoracic vertebral area. Approximately 80% of patients with malignant spinal cord compression have a prior diagnosis of cancer, so individuals with known cancer and back pain should undergo radiographic imaging. Other symptoms of malignant spinal cord compression may include muscular weakness, radicular pain, and bladder or bowel dysfunction. Weakness is most apparent in the proximal extremity musculature and may progress to complete paralysis. Sensory changes initially may be confined to a band of hyperesthesia around the trunk at the involved spinal level and that eventually becomes anesthetic distal to the level. Urinary retention (with overflow incontinence), fecal incontinence, and impotence are late manifestations.
TABLE 240-2Malignant Spinal Cord Compression ||Download (.pdf) TABLE 240-2 Malignant Spinal Cord Compression
|Suspect || |
Patient with known cancer: especially lung, breast, prostate
Thoracic location: 70%
Progressive pain and worse when supine
Motor weakness: proximal legs
Sensory changes: initially radicular, later distal anesthesia
Bladder or bowel dysfunction: late findings
|Imaging || |
Plain radiographs: may detect vertebral body metastases but less sensitive and specific for malignant spinal cord compression
MRI: modality of choice, image entire vertebral column
CT myelography: used when MRI not available or accessible
|Corticosteroids || |
Dexamethasone, 10 milligrams IV followed by 4 milligrams PO or IV every 6 h
Consider starting in ED if imaging is delayed
|Radiotherapy || |
Standard approach, beneficial in approximately 70%
No specific radiotherapy regimen proven superior
Prognosis highly dependent on pretreatment neurologic function
|Surgery || |
Consider in highly selected cases, such as
Patient in good general condition and able to undergo extensive surgery
Appropriate prognostic life expectancy
Rapidly progressive symptoms
Clinical worsening during radiotherapy
Unstable vertebral column
MRI is the imaging modality of choice to define the site and degree of cord compression and to identify the presence of additional vertebral lesions. The entire spinal column is usually imaged due to the potential for multiple level involvement, although because cervical metastases are unusual, it may be reasonable to not image the cervical spine if there are no symptoms referable to that region. CT with or without myelography is used when MRI is contraindicated or inaccessible. Plain radiography may identify an abnormality in approximately 80% of patients with painful vertebral metastases. However, plain radiographs are less useful in patients with suspected malignant spinal cord compression, because radiographic findings do not always correlate with the level of spinal cord compression, and causes of malignant spinal cord compression other than vertebral body metastases will not produce visible changes in vertebral body radiographic appearance.
Use opioid analgesics for initial pain control. Consider administration of corticosteroids in the ED, especially if there will be a delay in MRI or CT myelography.4,5,6,15 Typically dexamethasone, 10 milligrams IV bolus, followed by 4 milligrams PO or IV every 6 hours, is used. Further treatment, with continued corticosteroids, radiation therapy, surgery, or a combination of modalities, will depend on the life expectancy of the patient, extent of disease, and degree of motor impairment. Radiation therapy has been the typical treatment for patients with malignant spinal cord compression, and a beneficial response is seen in approximately 70% of those treated.16 The overall prognosis for those treated with radiotherapy is highly dependent on pretreatment functional ability; approximately 90% of those who can walk at the time of diagnosis remain ambulatory after radiation treatment, about half of those who have motor function but cannot walk will recover ambulatory ability with radiotherapy, but few patients with complete paraplegia at the time of diagnosis will recover lower extremity motor function. Therefore, malignant spinal cord compression is considered a radiotherapy emergency. Select patients with malignant spinal cord compression may benefit from surgical tumor resection, including those with neurologic impairment (Table 240-2).15 Because of the complex decision making from among the therapeutic options, specialists in oncology, radiotherapy, and spinal surgery should be consulted early.
MALIGNANT PERICARDIAL EFFUSION WITH TAMPONADE
Pericardial involvement, often with effusion, occurs in up to 35% of patients with all types of cancer, although the effusions are often small and remain undiagnosed.4,5,6 Symptomatic pericardial effusions occur less frequently and usually result from lung or breast cancer. Other etiologies for pericardial effusions in patients with malignant disease include other tumor types (such as melanoma, leukemia, or lymphoma) and a complication of treatment (radiotherapy or chemotherapy).
Symptoms and physical examination findings are a function of pericardial fluid accumulation rate and volume (see chapter 55, "Cardiomyopathies and Pericardial Disease"). Large effusions can develop gradually and are surprisingly well tolerated. Symptoms of a pericardial effusion include dyspnea, orthopnea, chest pain, dysphagia, hoarseness, and hiccups. Physical findings include distant cardiac sounds, jugular venous distention, and a pulsus paradoxus.
A sudden increase in fluid between the nondistensible pericardium and compressible heart creates a cardiac tamponade: the low-pressure right heart is unable to accept vena caval return or pump forward to the pulmonary arteries, and the left ventricle cannot fill or produce a sustainable ejection fraction. Signs and symptoms include accentuation of those noted with pericardial effusion with additional manifestations of circulatory shock. There is usually tachycardia, hypotension, and a narrowed pulse pressure.
The ECG may demonstrate reduced voltage in the QRS complex throughout all leads, a reflection of the insulating characteristics of the effusion. Electrical alternans is a classic, although infrequent, finding with a large pericardial effusion. The cardiac silhouette on chest radiography may appear large, reflecting the gradually accumulated effusion in the stretched pericardial sac. Echocardiography is the diagnostic tool of choice, being noninvasive, portable, and highly accurate in trained hands. Echocardiography can not only detect the presence of a significant pericardial effusion but also assess cardiac function and identify physiologic changes associated with cardiac tamponade.
Asymptomatic pericardial effusions do not require specific treatment. Patients with symptomatic effusions should undergo pericardiocentesis, ideally with echocardiographic guidance. See chapter 34, "Pericardiocentesis." Most often, this procedure can await the arrival of the specialist and transport of the patient to the appropriate procedural area. If patients with cardiac tamponade require emergent pericardiocentesis in the ED, use a portable US device to guide needle direction during the procedure.
Malignant pericardial effusions are treated depending on the tumor type and overall patient condition. Reduction in fluid production can be done by treating the tumor with appropriate systemic chemotherapy or radiotherapy. Intrapericardial chemotherapy may be useful in tumors sensitive to these agents. A pericardial window or partial pericardial resection can be done to prevent accumulation of fluid within the pericardial space. A percutaneous indwelling intrapericardial catheter can also prevent accumulation of fluid, but with the risks associated with percutaneous devices. Malignant pericardial effusion typically indicates the presence of advanced disease, and most patients die within 1 year after diagnosis.
SUPERIOR VENA CAVA SYNDROME
The term superior vena cava (SVC) syndrome describes the clinical effects of elevated venous pressure in the upper body that result from obstruction of venous blood flow through the SVC.4,5,6,17,18 This syndrome is most commonly caused by external compression of the SVC by an extrinsic malignant mass. The most common tumors associated with malignant SVC syndrome are lung cancer in 70% and lymphoma in approximately 20%. Benign conditions and intravascular thrombosis (precipitated by indwelling vascular catheters or pacemaker leads) currently account for about one third of all SVC syndrome cases. SVC syndrome rarely constitutes an emergency; the vast majority of patients do not materially deteriorate during the initial 1 to 2 weeks after diagnosis. The exception is when neurologic abnormalities are present due to increased intracranial pressure.
Symptom development correlates roughly with the severity of obstruction and the rate of narrowing. If compression occurs over weeks, collateral vessels dilate to compensate for impaired flow through the SVC. Most patients will describe symptoms developing a few weeks before seeking medical attention. Clinical manifestations correlate with a jugular venous pressure of 20 to 40 mm Hg (2.7 to 5.4 kPa), as compared with a normal range of 2 to 8 mm Hg (0.3 to 1.0 kPa). The most common symptoms are facial swelling, dyspnea, cough, and arm swelling.18 Less common symptoms include hoarse voice, syncope, headache, and dizziness. In rare but extreme cases, venous obstruction can lead to increased intracranial pressure that produces visual changes, dizziness, confusion, seizures, and obtundation. Physical examination findings may show swelling of the face and arm, sometimes with a violaceous hue or plethora, and distended neck and chest wall veins.
The plain chest radiograph will usually show a mediastinal mass in cases of malignant SVC syndrome. CT of the chest with intravascular contract is the recommended imaging modality to assess the patency of the SVC.17,18 MRI is useful for patients who cannot receive IV contrast. Contrast venography is rarely needed, except in uncertain cases or as part of an intravascular interventional procedure. In patients with a known diagnosis of lung cancer, biopsy for pathologic confirmation of a malignancy is usually not required. For patients without a known intrathoracic cancer, tissue confirmation of a malignant cause is highly desirable before initiation of radiotherapy and required before initiation of chemotherapy.17,18
Initial management is with head elevation to decrease venous pressure in the upper body and supplemental oxygen to reduce the work of breathing. Corticosteroids and loop diuretics are commonly used, but there is no evidence that they contribute to clinical improvement, with the exception that corticosteroids would be expected to be helpful when the cause of the obstruction is lymphoma.
Radiation therapy is effective in reducing symptoms in approximately 75% of patients with SVC syndrome, reflecting the approximate incidence of radiosensitive tumors producing this disorder.18 Many patients will experience a reduction in symptoms within 3 days after the start of radiation treatment. The mechanism by which radiotherapy reduces symptoms in SVC syndrome is unclear, because the majority of patients receiving such treatment do not achieve complete relief of the obstruction. It is likely that continued development of collaterals contributes to the reported benefit seen during radiotherapy.
Intravascular stents, with or without angioplasty, can be used to reduce obstruction to SVC flow.17,18 These stents appear to produce a more rapid improvement in symptoms and signs compared with radiotherapy or chemotherapy, suggesting a preferential benefit in patients with severe manifestations who require urgent treatment.18 Stent placement should also be considered for malignant causes that do not respond well to radiotherapy or chemotherapy (like mesothelioma), for benign causes (like fibrosing mediastinitis), or for intravascular thrombosis associated with an indwelling catheter.17,18
Chemotherapy is effective in producing symptomatic relief from SVC syndrome in approximately 80% of patients with lymphoma, 80% of patients with small-cell lung cancer, and 40% of patients with non–small-cell lung cancer. For these chemotherapy-sensitive cancers, there is no evidence of benefit from additive radiotherapy, again indicating that dilation of venous collaterals may play a role in clinical improvement.
Patients with SVC syndrome due to intravascular thrombosis can be treated with catheter-directed fibrinolytics.18 Removal of an inciting intravascular object, such as a central venous catheter, should be considered. Postfibrinolytic anticoagulation is generally recommended to prevent recurrence, although there is no firm supporting evidence.18 For cancer patients with an indwelling central venous catheter, there is no proven role for prophylactic anticoagulation to reduce the risk of venous thromboembolism.19
Recurrence of SVC syndrome is seen in approximately 20% of lung cancer patients treated with radiotherapy and/or chemotherapy and 10% treated with intravascular stents.18 For patients with malignant SVC syndrome, survival is dependent in the causative cancer; with lung cancer, median survival is approximately 6 to 12 months.