Week 2 Flashcards
In what 8 scenarios should a check x-ray be requested?
- Shortness of breath
- Acute chest pain
- Investigation for malignancy
- Following severe trauma
- Pneumonia
- Chronic lung diseases
- Pleural diseases
- Peritonitis
What is the lingula?
A combined term for the two lingular bronchopulmonary segments of the left UPPER lobe.
Made up of: Inferior lingular segment, superior lingular segment
What is the process for interpreting a chest XR?
- Admin and Technical (PD PO RIP)
- Patient id
- Date
- Projection: PA/AP
- Orientation: L or R
- Rotation
- Inspiration: Full inspiration detected by rib count (10 from back, 6 from front)
- Penetration: Exposure so that vertebral bodies just visible behind back - Structures (ABCDEFGH):
- Airway: Trachea, Bifurcation of bronchi visible
- Breathing: Check expansion of lungs, check lung fields, opacities
- Cardiac: Heart size, borders of heart
- Diaphragm: Right hemidiaphragm 1 rib higher than left, identify stomach bubble, look for free air below right diaphragm
- External structures: Surrounding bones
- Fat and soft tissues: Breast shadows, examine subcutaneous fat
- Great vessels: Aortic arch, pulmonary arteries, veins in the mediastinum, calcium deposits
- Hidden areas: Apices, mediastinum widening, aortic dissection, mediastinal emphysema, behind the heart for lingular pneumonia
What is the carina?
The ridge of cartilage of the trachea at the bifurcation
What is possible reason for a missing rib from a CXR?
Tumour grown around the rib. If the CXR is PA thent he tumour is posterior to rib
What are the review areas of the CXR?
Apices
Behind the heart
Below the diaphragm (Space between liver = gas)
What are the 4 areas of error that can occur when taking a CXR?
PA vs AP Film: PA preferred as the magnification of heart is reduced = film more reliable
Rotation: For optimum rotation, there must be an equal distance between the medial ends of the clavicle and the spinous processes of the vertebrae
Penetration: Over-penetration appears dark, Poorly penetrated appears light/fuzzy
Inspiration vs Expiration: Inspiration preferred as structures more densely packing into thorax
What are the two major types of solid structures in the interstitial fluid?
Collagen
Proteoglycans filaments
What substances generates the Colloid Osmotic/Oncotic Pressure?
Plasma proteins (mainly albumin)
This creates a difference in the abundance (and consequently pressures) between capillaries and extracellular fluid
Which is lower, the plasma or interstitial osmotic pressure?
Interstitial
What is the capillary hydrostatic pressure and what does it cause fluid to do?
Pressure difference between either end of the capillary
Forces fluid out of capillary into the interstitium
Drops from arterial to venous end
What is interstitial hydrostatic pressure and what effect does it have on fluid?
Pressure within the interstitial fluid.
When positive= forces fluid into the capillary
When negative= Draws fluid into the interstitium
What 4 features is the lympathetic system in control of?
- Concentration of proteins in interstitial fluids
- Volume of interstitial fluid
- Interstitial pressure
- Immune response
Venous return is a major determinant of…
Cardiac output due to myogenic response of the ventricles
Factors affecting venous return?
- Sympathetic innervation: Increases tone, hence decrease capacity of vein, more blood flow to heart. Hence increase in CO
- Muscle Pumps: Muscle relaxed= Valve closed, blood in vein. Muscle contracted= Valve open, blood flow to heart
- Postural effects: Equal pressure when recumbent, when standing drop in head and increase in legs.
- Inspiratory movements Leads to pressure difference between peripheral veins and heart as thorax pressure decreases
- Blood volume
What is orthostatic (postural) hypotension?
Decrease in bp when going from supine to upright.
Reflex vasoconstriction in legs and lower abdomen
What are the boundaries of the anterior mediastinum?
Anterior: Sternum
Posterior: Pericardium
Lateral: Lungs + pleura
What are the boundaries of the superior mediastinum?
Superior: Thoracic inlet Inferior: Sternal angle at T4/5 Anterior: Manubrium Posterior: T1-4 Lateral: Lungs + pleura
Thymus: Structure? Location? Function? Arterial supply? Venous drainage?
Structure: Bi-lobed
Location: In anterior mediastinum between manubrium, sternum and pericardium. Extends from jugular notch to 4th CC
Function: Programming t-lymphocytes, recognizing self antigens
Arterial supply: Internal thoracic and inferior thyroid arteries
Venous drainage: Left brachiocephalic vein
Name the 5 bony landmarks of the venous plane of the superior mediastinum?
- Post. to sternoclavicular joint: Internal jugular and subclavian veins join to form right and left BCVs
- Post to manubrium: Left BCV passes anterior to arch of aorta
- Post to 1st R costal cartilage: RBCV and LBCV join to form SVC
- Post to 2nd R costal cartilage: Arch of azygos vein joins SVC
- Post. to 3rd costal cartilage: SVC enters right atrium
What areas do the following veins drain:
- Azygos
- Subclavian
- Internal jugular
- Azygos: Posterior chest wall
- Subclavian: Upper limb
- Internal jugular: Head and neck
All drain to their corresponding BCV
What two veins drain into the LBCV and not the right?
- Internal thoracic: Drains ant. chest wall
2. Thyroid veins: If protruding above manubrium, could be at risk in tracheostomy
What are the three branches of the aortic arch?
- Brachiocephalic trunk (gives RCC, RSV arteries)
- Left common carotid
- Left subclavian
What two arteries “clasp” the trachea?
Left common carotid
Brachiocephalic trunk