Dx testing and Pulmonary imaging Flashcards
What are the dx tests used for dx pulmonary diseases?
- bronchoscopy
- CXR
- Chest CT
- Chest MRI
- V/Q scan
What is a bronchoscopy?
- direct visualization of trachea, bronchi, and segmental airways out to the 3rd generation of branching
- can be used to sample and tx lesions or abnormalities such as FBs, bleeding, tumors or inflammation in those airways
- can also be used as part of pre op evals
- may be rigid flexible or virtual
- may cause tachycardia, bronchospasm, or hypoxemia
- contraindicated in pts with cardiac problems or severe hypoxemia
What are the dx indications for bronchoscopy?
- cough
- hemoptysis
- wheeze
- atelectasis/ accumulated secretions
- unresolved pneumonia
- positive cytology
- bx of suspicious tissue
- abnormal CXR
- bronchial obstruction
- diffuse lung disease
- pre/post intubation
What are the therapeutic considerationf for use of bronchoscopy?
- Fbs
- accumulated secretions
- atelectasis
- aspiration
- lung abscess
- control of bleeding
What are the advantages of a rigid bronchoscopy? disadvantages?
- advantages: better control of the airway, easier to deal with large lesions, foreign bodies
- disadvantages: requires general anesthesia, higher rate of tissue damage/complications
What are CIs to rigid bronchoscopy?
- absolute CIs: inability to adequately oxygenate the pt during procedure
- coagulopathy or bleeding diathesis that can’t be corrected
- rigid bronchoscopy: aneurysm, marked kyphosis
- recent MI or unstable angina
- respiratory failure requiring mechanical ventilation
What are the components of the ventilating bronchoscope?
- light source and telescope
- prismatic light detector and attachment to light source
- telescope bridge
- aspiration and instrumentation channel
- connector to anesthesia
What are the complications of a ventilating bronchoscope?
- injury to teeth
- hemorrhage from the bx site
- hypoxia and cardiac arrest
- laryngeal edema
Use of the flexible bronchoscopy (pros and cons)?
- doesn’t require general anesthesia
- mainly for dx purposes
- limited intervention (sunctioning)
- can be used for intubation
- limited airway control
- can do bx, minor cautery
- very few complications in healthy pts
Use of flexible optic bronchoscopy?
- provides magnification and better illumination
- smaller size: permits examination of subsegmental bronchi
- easy to use in pts with neck or jaw abnormalities
- can be performed under topical anesthesia and useful for bedside exam of critically ill pts
- sunctioning of bx channel helps to remove secretions, inspissated mucus plug and small FBs
- can be easily passed through endotracheal tube or in tracheostomy opening
- limited use in children because of problem of adequate ventilations
Use of the virtual bronchoscopy?
- computer generated pictures of the endobronchial tree, which are constructed from computed tomography (CT) images of the thorax
- non-invasive, fine detail, and also provides info about structures outside of the airways
- cant be used for bx or tx
Limitations of the CXR?
- 2 dimensional image of 3 dimensional structure
- x-ray findings may lag behind other clinical features
- normal x-ray doesn’t rule out pathology
- dependent on good quality image
- ** not really helpful in PE dx
Hierarchy of relative densities from least dense (dark) to most dense (light)?
- gas (air)
- fat (fat layer in soft tissue)
- water (same density as heart and blood vessels)
- bone (the most dense of tissue)
- metal (fbs)
What 3 main factors determine the technical quality of the radiograph?
- inspiration: CXR should be obtained with the pt in full inspiration to help assess intrapulmonary abnormalities, at full inspiration the diaphragm should be observed at about the level of the 8th to 10th rib posteriorly, or 5th to 6th rib anteriorly
- penetration: the lower thoracic vertebrae should be visible through the heart, bronchovascular structures behind the heart (trachea, aortic arch, pulmonary arteries) should be seen
- rotation: can be assessed by observing the clavicular heads and determining whether they are equal distance from spinous processes of the thoracic vertebral bodies
Problems with underexposure and overexposure (penetration) of CXR?
- in underexposed CXR: cardiac shasow is opaque, with little or no visibility of the thoracic vertebrae
- the lungs may appear much denser and whiter, much as they might appear with infiltrates present
- overexposure: heart becomes radiolucent and lungs become proportionately darker, in an overexposed CXR: air filled lung periphery becomes extremely radiolucent and often gives the appearance of lackng lung tissue, as would be seen in condition such as emohysema
What are the 4 major positions that are utilized for producing a CXR?
- PA
- lateral
- AP
- lateral decubitus
PA position?
- std position for obtaining routine adult CXR
- pt stands upright with anterior chest placed against front of film
- shoulders are rotated forward enough to touch the film, ensuring that the scapulae don’t obscure a portion of the lung fields
- usually taken with pt in full inspiration
- PA film is viewed as if pt is standing in front of you with his/her right side on your left
Lateral position?
- pt stands upright with left side of chest against the film and arms raised over the head
- allows the viewer to see behind the heart and diaphragmatic dome
- is typically used in conjunction with a PA view of the same chest to help determine the 3D position of organs or abnormal densities
- ordered as PA and lateral views
AP position?
- used when pt is debilitated, immobilized or unable to cooperate with PA procedure
- film is placed behind the pts back with pt in supine position
- because the heart is a greater distance from the film, it will appear more magnified than in a PA
- the scapulae are usually visible in the lung fields because they are not rotated out of the view as they are in a PA
The lateral decubitus position?
- pt lies on either right or left side rather than in a standing position as with a regular lateral xr
- XR is labeled according to side it is placed on
- often used in revealing a pleural effusion that can’t be easily observed in an upright view, since effusion will collect in dependent position
What are the anatomical structures in the chest?
- mediastinum
- hilum
- lung fields
- diaphragmatic domes
- pleural surfaces
- bones
- soft tissues
Location of mediastinum?
- trachea should be centrally located or slightly to the right
- the aortic arch is the first convexity on the L side of the mediastinum
- pulmonary artery: next convexity on the left, the branches should be traceable as it fans out through the lungs
- the lateral margin of superior vena cava lies above the R heart border
Location of the heart on a CXR?
- 2/3 of heart should lie on L side of chest, 1/3 on R
- heart should take up less than half of thoracic cavity
- left atrium and left ventricle create the left heart border
- R heart border is created entirely by the R atrium (R ventricle lies anteriorly and therefore doesn’t have border on PA)
Location of the hilum on CXR?
- Hila consist of primarily major bronchi and pulmonary veins and arteries
- the hila are not symmetrical but contain the same basic structures on each side
- the hila may be at same level but the left hilum is usually higher than the R
- both hila should be of similar size and density
Location of lungs on CXR?
- visible markings throughout lungs due to pulmonary arteries and veins, continuing all way to chest wall
- both lungs should be scanned starting at apices and working downward comparing the L and R lung fields at the same level (as done with ausculatation)
- on a PA: minor fissure can often be seen as faint horizontal line dividing RML from RUL
- major fissures arent usually seen on PA view
Location of the diaphragm on a CXR?
- left dome is normally slightly lower than R due to elevation of the liver, located under the R hemidiaphragm
- cosophrenic recesses are formed by diaphragms and chest wall
- on the PA: costophrenic recess is seen only on each side where an angle is formed by the lateral chest wall and the dome of each diaphragm (costophrenic angle)
Pleura visibility?
- pleura and pleural spaces will only be visible when there is abnromality present
- common abnormalities seen with pleura include pleural thickening or fluid or air in pleural space
Soft tissue on CXR?
- thick soft tissue may obscure underlying structures:
thick soft tissue due to obesity may obscure some underlying structures such as lung markings - breast tissue may obscure the costophrenic angles
- lucencies within soft tissue may represent gas
What bones will be visible in the CXR?
- ribs
- clavicles
- scapulae
- vertebrae
- proximal humeri
- the bones are useful as markers to assess pt rotation, adequacy of inspiration, and x ray penetration
Should you make a dx from an abnormal finding on a CXR?
- no only should describe what you see rather than a dx (a CXR alone isn’t dx but is only one piece of descriptive info used to formulate a dx)
- descriptive words such as shadows, density, or patchiness, should be used