Thoracic ultrasound Flashcards
What are the most common type of ultrasound used?
2d or B mode
What is the name of the transducer used to see inside of a person, what frequency does it use and why?
curved array transducer
low frequency 3.5 - 5MHz so travel far so can be used to see the diaphragm
What is the name of the transducer used to see superficial images, what frequency does it use and why?
linear probe - straight edge
Has higher frequency (7-12 MHz) and images are high resolution but don’t travel far.
How would you be able to determine whether a linear probe was used?
A line is seen in the ultrasound where the linear probe touches the skin e.g. to see the thyroid gland
What is the echogenic line?
The white line in an ultrasound is the visceral and parietal pleura rubbing together.
What is the gliding pleural (sliding lung) sign and what is its significance?
Pleura moving- if this is seen then the patient’s lung is normal and they haven’t got a pneumothorax
What are A lines and what causes them?
Horizontal lines - artefacts caused by sound going between air and lungs - normal
What colour do the ribs appear on an ultrasound?
Black
How can the lung be seen more easily in individuals with high BMI?
By looking for the ribs and the outline of the lung should be behind them
What are comet tails/b line artefacts, what causes them and what is their significance?
Vertical lines caused interlobular septa (indentations in the lung). This is normal.
Which 3 things show that the lung is normal?
- A lines
- B lines/comet tails
- gliding pleural (sliding lung) sign
What is interlobular septa
Tissue between secondary pulmonary lobules which have lymphatics and vessels
What is an M mode ultrasound and how would you determine a lung is healthy from one?
Ultrasound at one point and movement along that is measured over time - used for valve movements. Normal lung would show ‘sea shore’ - lung appears sandy like a beach
What are the uses of thorax ultrasounds?
- detects pleural effusion and guide drainage
- differentiate sub-pulmonary from sub-phrenic fluid
- assess tumour invasion of chest wall and pleura
- guide pleural and lung bipsy
- identify pneumothroax
- assess respiratory muscle function
How would a pleural effusion be identified on an ultrasound?
Black space between lung and chest wall
Which muscles are responsible respiration?
- diaphragm
- internal intercostals
- external intercostals
- accessory muscles (attach to sternum, clavicle and spaculae): sternocleidomastoid, scalenes, serratus and pectorals
What happens to the diaphragm, scalene, SCM and intercostals during inhalation?
- diaphragm contracts - moves down
- scalenes and SCM contract and elevate ribs and sternum goes anteriorly
- externals (and interchondral of internal intercostals) contract and elevate ribs
What happens to the diaphragm, scalene, SCM and intercostals during exhalation?
- diaphragm relaxes
- scalenes and scm relax
- internal intercostals contract (not interchondral part) and abdominal muscles so ribs move down
Which nerve innervates the diaphragm, what spinal level does it come from and what does damage to it cause?
Phrenic nerves from C3,4 and 5. Damage causes paralysis -diaphragm rise
Which angle is important to identify pleural effusion and what happens to it?
costophrenic angle - blunting of the angle occurs
What are the causes of an elevated diaphragm?
- enlarged liver
- subphrenic abscess: collection between liver and diaphragm
- trapped sub pulmonary fluid
What test should be done to identify whether the phrenic nerve is damaged, what would the results be in a normal and abnormal diaphragm?
forced inspiration - sniff test
normal - rapid caudal movement
abnormal - paradoxical movement so diaphragm moves up towards the head
What is also used during the sniff test to see the diaphragm movement?
Ultrasound
How should the transducer be angled to see the diaphragm?
Under the lung and upwards towards the diaphragm
What is a parasagittal plane?
Divides into left and right but not in midline
What is a paracoronal plane?
Coronal but angled between ribs
