Intro to Pulmonary Diagnostics Flashcards
Pulmonary mechanics of inspiration
Intercostal muscles and diaphragm contract Lungs expand Air drawn in
What is the only artery in the body that carries deoxygenated blood?
Pulmonary artery
Pulmonary mechanics of expiration
Passive process Depends on elastic recoil of lungs
Airway obstruction.
Asthma Chronic bronchitis COPD Results in air trapping due to decreased expiratory flow
Fingernail clubbing
Many causes including -lung cancer -TB -Cystic Fibrosis -Endocarditis
CXR
Common indications -pneumonia -pneumothorax -CHF Noninvasive Low radiation exposure Cost: $200-350
Pulmonary function testing
Spirometry -measures volume and speed of airflow on inspiration and expiration. Used to diagnose and assess asthma, COPD, pulmonary fibrosis Noninvasive, safe
CT scan of the chest
Used to diagnose -PE -pneumonia -aortic dissection -lung cancer Much higher sensitivity than a CXR Higher radiation (100-400X) Higher cost ($1800)
Spiral CT
Continuous, rotating beam Quicker, higher resolution than conventional CT
Multirow CT
Latest generation of CT Thinner slices, improved resolution
CT for PE
CT is the preferred study to assess for PE because it is highly sensitive and non-invasive
With IV contrast
Look for filling filling defects in pulmonary arteries or branches
Will also show alternate causes of sxs
Ventilation/perfusion scan
(V/Q Scan)
Also used to asses for PE when important to reduce radiation exposure or when contrast can’t be administered (renal dz/allergy)
Ventilation: radionuclide inhaled to assess ability of air to reach all parts of lungs
Perfusion: IV radionuclide to assess blood circulation
V/Q Mismatch: where normal airflow, but impaired perfusion
Results can be normal, low probability, intermediate probability, or high probability
Low or intermediate probability cannot r/o PE
Pulmonary Angiography
Diagnose PE
Insert catheter under fluoro into pulmonary arteries and inject dye
Invasive, higher risk.
Same sensntivity as CT so has largely been replaced
D-Dimer
Fibrin degredation product released by a clot
Elevated with PE, DVT
If pt has low to moderate risk of PE and has normal D-Dimer, can r/o PE
Very sensitive (95%), but not very specific (50%)
False positives with: inflammation, cancer, pregnancy, advanced age, trauma
Sputum Culture
Used to identify specific organism causing pneumonia
May be contaminated by oral flora
WBC
Often, but not always, elevated with pneumonia
Neither sensitive nor specific
Bronchoscopy
Fiberoptic scope to view airways
Search for tumors, foreign bodies, source of hemoptysis
Obtain biopsies
Low risk
During a PA CXR, which way does the patient stand?
The rays flow from posterior to anterior, with the anterior chest closest to the film.
During a lateral CXR, which way does the patient stand?
With their left side up against the film.
AP CXR
Usual portable technique
Heart shadow is magnefied
Often times, the patient is also supine:
DIaphragms are higher, lung volume is decreased
Lateral decubitus CXR
Patient lying on side
Useful for detecting pleural effusion
Densities
Lead > Mineral > Soft Tissues > Fluid > Fat > Air
Mineral–very dense, appears white
- calcifications, bone
Soft tissues
- muscle, mediastinal structures
Fluid
- Heart, vessels
Fat
- Breasts
Air
- Lungs, gastric bubble, trachea, bronchi
CXR Reading Method
Label: pt’s name, age, sex
Orientation: R vs L side
Technique: Penetration, rotation, inspiration
Interpretation
Proper penetration
Should barely be able to see outline of vertebral bodies within heart shadow down to diaphragm
Bronchovascular structures should be visible
On lateral films: Vertebral bodies should darken as you move caudally because more air in lower lobes
Rotation
Make sure clavicular heads are equal distance from spinous processes
Rotated film can distort appearance of heart and mediastinum
Inspiration
CXR should be shot at full inspiration
Should be able to count 8-10 posterior ribs
General things to interpret on CXR
Heart and great vessels
Lungs
Soft tissues
Bones
Heart and Great Vessels
Cardiac silhouette normally 1/2 or less of thoracic width on PA
Check aortic knob, mediastinal width, SVC
Lungs
(CXR Interpretation)
Lung fields:
- Infiltrate, atelectasis
- Nodules, mass
- Pneumothorax
Vasculature
- Hilar and pulmonary vessels
- Peripheral vasculature–seen in lateral 1” of lung, clearer in lower fields on upright films
Costophrenic Angle
- Pleural effusion blunts angle
- Right diaphragm higher than left
Soft Tissues
- Breasts
- Chest wall
- Neck
- Mediastinum
- trachea should be midline
- identify tracheal bifurcation
- look for mediastinal widening
- hilar mass or lymphadenopathy
Bones
Look for lesions or fractures of:
clavicles
scapulae
humeri and shoulder joints
ribs
spine
Silhouette Sign
If a pulmonary opacity is in contact with the heart border, then the heart border will be obscured
Commonly seen with RML and left lingular infiltrates
CXR Findings in CHF
Cardiomegaly
Cephalization of pulmonary flow
Interstitial Edema-lungs whited out
Kerley B Lines
Fluid in fissures
Pulmonary Edema
Pleural Effusions-blunted costophrenic angles
Cephalization of Pulmonary Flow
Normally pulmonary blood flow is more prominent in dependent areas of lung (near bases)
When congested it is also prominent toward head
Kerley B Lines
Short, horizontal lines found in lower lung periphery
Seen MC’ly in CHF
Pneumothorax
Lung space is black, with area where lung is pronounced and shriveled
Subtly, a pleural line can be noted where the lung has separated from cavity
Tension Pneumothorax
Life-threatening
L mediastinal shift, decreased venous return (can kink aorta and vena cava)
May rapidly lead to cardiac arrest
Needs emergent needle thoracotomy
COPD Changes
Diffuse hyperinflation with flattening of diaphragms
Atelectasis
Collapse or incomplete expansion of part of the lung
Linear or curvilinear increased density on CXR, often associated with volume loss
May see elevated diaphragm because lung collapses on itself
Solitary Pulmonary Nodule
Can be innocuous or malignant
More likely to be benign if calcified
Try to compare to previous CXR
Consider CT/biopsy to evaluate
Pulmonary Mass
Well-defined opacity
Suspicious for malignancy
