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KNOWLEDGE COMPETENCIES
Identify various radiologic and pulmonary anatomic features relevant to interpretation of chest x-rays.
Describe different systems and principles of management for chest tubes.
Describe the etiology, pathophysiology, clinical presentation, patient needs, and principles of management of acute respiratory failure (ARF).
Compare and contrast the pathophysiology, clinical presentation, patient needs, and management approaches for common diseases leading to ARF:
Acute respiratory distress syndrome (ARDS)
Acute respiratory failure
Chronic obstructive pulmonary disease (COPD) exacerbation
Acute severe asthma
Interstitial lung disease
Pulmonary hypertension
Pneumonia
Pulmonary embolism (PE)
Venous thromboembolism (VTE)
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SPECIAL ASSESSMENT TECHNIQUES, DIAGNOSTIC TESTS, AND MONITORING SYSTEMS
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Chest radiography is an important tool in respiratory assessment, providing visualization of the heart and lungs. Chest x-rays are a complement to bedside assessment. Critical care nurses need to know basic radiographic concepts and how to optimize portable chest x-ray technique, as well as how to systematically view a chest x-ray image.
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Chest x-rays are obtained as part of routine screening procedures, when respiratory disease is suspected, to evaluate the status of respiratory abnormalities (eg, pneumothorax, pleural effusion, tumors), to confirm proper invasive tube placement (ie, endotracheal, tracheostomy, chest tubes, and pulmonary artery catheters), or following traumatic chest injury.
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An x-ray is a form of electromagnetic radiation used by imaging machines to create radiographic image. Only a few rays are absorbed by air as beams pass through the atmosphere, whereas all rays are absorbed by metal as the beams attempt to pass through a sheet of metal. When nothing but air lies between the film cassette and the x-ray source, the radiographic image is blackness or radiolucency. If density increases, more beams are absorbed between the film cassette or detectors and the x-ray source, and the radiographic image is whiteness or radiopacity. As the x-ray beam passes through the patient, the denser tissues absorb more of the beam, and the less dense tissues absorb less of the beam. There are four distinct radiographic densities: white, light gray, darker gray, and black. Many institutions are replacing traditional x-ray film with detectors that convert the x-ray-energy to a digital radiograph. These images can then be stored and distributed in a digital format.
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The lungs are primarily sacs of air or gas, so normal lung parenchyma looks black on chest films. Conversely, the skeletal thorax appears white, because bone is very dense and absorbs the most x-rays (Table 10-1). The heart and mediastinum appear gray because those structures are made up of mostly water and muscle or tissue. Breast tissue is made up of mostly fat and it appears whitish-gray. Structures of the thorax are made radiographically visible if they are surrounded by air. Conversely, they are obscured if adjacent to consolidation or fluid.
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