Week 9 - CXR Interpretation Flashcards
Spirometry (Measures)
Measure the volume of air that the patient can forcible expel from their lungs after a max inspiration / How quickly the air can be expelled
- Measurements include FEV1 and FVC
What is spirometry used for?
Aid diagnosis, detect/quantify the degree of airway obstruction or restriction, monitor effects of treatment.
FEV1
- Forced expiratory volume in 1 second
- After a full inspiration, the volume of air expired in the 1st second of forced expiration.
- values between 80-120% of avg. are considered normal
FVC
- Forced vital capacity
- After a max inspiration, the max volume of air that can be forcibly expired in one breath.
- Critical in the diagnosis of obstructive + restrictive diseases.
Ratio of FEV1/FVC
Normal = ~ 80% Abnormal = <70%
Normal reading spirometry
FEV1/FVC > 70% (avg = 80)
FVC > 80% of predicted
FEV1 > 80% of predicted
Obstructive meaning spirometry
- Pt’s cannot EXHALE the air in their lungs quickly as something is obstructing their airways
- FVC often preserved or reduced but to a lesser degree.
- Pre/post bronchodilators used to assess degree of reversibility.
Obstructive reading spirometry
- Decreased FEV1/FVC ratio (<70%)
- Decreased FEV1 (<80% predicted)
- FVC normal or decreased but to a lesser degree
Obstructive gold classification (FEV1)
Mild - >/= 80%
Moderate = 50-79%
Severe = 30-49%
Very Severe = < 30% predicted
Obstructive airways could be due to:
- Bronchospasm (tightening of the muscles that line the airways (bronchi) in your lungs. When these muscles tighten, your airways narrow)
- Inflammation
- Secretion/mucus
- Loss of elasticity in bronchial walls (floppy airways)
Restrictive reading spirometry
- Something restricting the INSPIRATION of air into the lungs, so lung volumes are reduced.
- Look mainly for a decrease in FVC
- Increased or normal FEV1/FVC ratio
- Decreased FVC (<80% predicted)
- Decreased FEV1 (proportional to decreased FVC or normal)
Restriction in airways due to:
- Lung issues: Pulmonary fibrosis
- Chest wall issues: scoliosis, obesity
- Weak muscles/damaged nerves: MND, SCI (lacking ability to fully inspire)
Mixed reading spirometry
- Issue is with both intake of air into lung (restrictive) & exhaling of air out of lungs (obstruction)
- Decreased FEV1/FVC (<70% - obstruction)
- Decreased FVC (<80% predicted - restriction)
- Decreased FEV1 (<80% predicted - shows severity of obstruction)
Chest x-ray (CXR)
A 2 dimensional representation of a 3 dimensional object- height/width maintained, depth lost
Black on XR
(Translucent/translucency) Air/gas
Gray on XR
(Opaque/opacity) Fat, soft tissues, + water
White on XR
(Opaque/opacity) Bone and metal
The denser the tissue- the whiter it is
Patient & film details
- Labels: Name, MRN, date, time
- Orientation
- Projection
Projection (PA)
- Postero-anterior
- Rays passing from back to front, usually standing, scapula removed from view.
Projection (AP)
- Antero-posterior
- Rays passing from front to back, pt can be supine, scapula seen in XR
- less ideal
- Shows magnification of the heart/widening of the mediastinum (especially supine)
Film quality
Exposure, inspiratory effect, pt position.
- You should just see the intervertebral(IV) disc spaces behind the heart (but can see them easily behind the trachea)
Film quality (over-exposure)
- Film is darker (more translucent)
- Can see IV disc spaces behind the heart easily
- Easy to miss problems
Film quality (under-exposed)
- Film is whiter (more opaque)
- Can’t see IV disc spaces behind the heart/trachea
- May over-diagnose
Film quality (inspiratory effect)
- Taken at end of full inspiration
- Good inspiration: Count 6 ant. ribs or 9-10 post. ribs, cutting the diaphragm mid-clavicular line.
Film quality (position)
Medial ends of clavicles should be equidistant from spinous processes
Extrathoracic/thoracic (Soft tissues)
- Subcutaneous emphysema: Air/gas in the subcutaneous layer of the skin, often associated w/ a pneumothorax.
Extra-thoracic/thoracic (thoracic cage)
- Signs of osteoporosis (thinning)
- Rib fractures/abnormalities
- Chest shape abnormalities (i.e. scoliosis)
Intrathoracic
Mediastinum, Diaphragms, Lungs field
Intrathoracic (mediastinum)
Trachea - should be midline
Hila - made up of major bronchi, pulmonary veins/arteries, & lymph nodes (L hila higher than R)
Heart - < half of the internal diameter of the chest wall (positions 2/3 to the L + 1/3 to the R)
Intrathoracic (diaphragm- shape/angle)
Shape: coned
Angle: Costophrenic (betw. ribs/diaphragm) / cardiophrenic (betw. heart/diaphragm)
- blunting of costophrenic angle most commonly caused by PLEURAL EFFUSION
Intrathroacic (diaphragm- position)
- @ level of 6th ant. rib, 9-10 post. rib
- Lower on the L side than R
- Higher/raised: can’t take in DB, part of the lung on that side has collapsed, phrenic nerve damage.
- Lower/flatter: Hyper-inflated lungs (emphysema)
Intrathoracic (Lung Fields)
Looking for: lung boundaries, markings (fine white lines which are the pulmonary blood vessels), Horizontal fissure, lung zones
Lung zones
Upper- above 2nd ant. rib
Middle - Betw. 2nd/4th ant. ribs
Lower - Below 4th ant. rib
Apical Intercostal Catheter (ICC)
Drains air from pleural cavity; basal ICC drains fluid/blood
Abnormal CXR (CONSOLIDATION)
Define: Fluid filled alveoli (associated w/ pneumonia)
Signs: patchy opacity, air bronchogram’s, silhouette
Air bronchogram
A tubular outline of an airway (darker) made visible by filling of the surrounding alveoli by fluid (opaque)
Silhoette sign
Loss of the clear outline of a border of a thoracic structure
Lung appears opaque where air has been replaces
Can help localise which lobe is affected
Abnormal CXR (COLLAPSE)
- Also known as Atelectasis
-Define: Loss of air in the alveoli - Causes: inhaled foreign body, mucus plug, endobronchial tumour
- Signs: increased opacity in area, if large enough- there will be loss of lung volume w/ a shift of struc. towards the area of collapse (i.e. horiz. fissure, trachea, diaphragm, hila region)
Can also get silhouette sign
Abnormal CXR (PLEURAL EFFUSION)
- Define: Fluid in the pleural space
- Signs: Increased opacity, blunting of costophrenic angle, meniscus/fluid line
Abnormal CXR (PNEUMOTHORAX)
- Define: Air in the pleural cavity
- Signs: Visible pleural margin/edge, lack of lung markings betw. visceral + parietal pleural layers; increased translucency, collapsed (deflated) lung can appear more opaque
Tension pneumothorax
Air enters the pleural space during inspiration but cannot leave on expiration
- Signs: same as regular pneumothorax w/ the addition of a shift of structures away from side of pneumo.
Abnormal CXR (EMPHYSEMA)
- Define: Progressive disease of the lungs that primarily causes SOB, due to over-inflation of alveoli; lung tissue in exchange of gases (O2/CO2) is impaired/destroyed.
- Signs: Increased translucency, decreased lung markings, hyperinflation (low, flattened diaphragms, small long heart, horizontal ribs)
Hyperinflation
Low flat diaphragms, horizontal ribs, elongated heart
Abnormal CXR (PULMONARY OEDEMA)
- Define: Fluid in the extra-vascular spaces of the lungs.
- Signs: Bilateral patchy opacity +/- air bronchograms, enlarged hila regions w/ ‘bat wing’ pattern, “cotton wool” “fluffy”
Increased heart size
