Thoracic ultrasound

Question 1

What are the most common type of ultrasound used?

Answer 1

2d or B mode

Question 2

What is the name of the transducer used to see inside of a person, what frequency does it use and why?

Answer 2

curved array transducer

low frequency 3.5 - 5MHz so travel far so can be used to see the diaphragm

Question 3

What is the name of the transducer used to see superficial images, what frequency does it use and why?

Answer 3

linear probe - straight edge

Has higher frequency (7-12 MHz) and images are high resolution but don’t travel far.

Question 4

How would you be able to determine whether a linear probe was used?

Answer 4

A line is seen in the ultrasound where the linear probe touches the skin e.g. to see the thyroid gland

Question 5

What is the echogenic line?

Answer 5

The white line in an ultrasound is the visceral and parietal pleura rubbing together.

Question 6

What is the gliding pleural (sliding lung) sign and what is its significance?

Answer 6

Pleura moving- if this is seen then the patient’s lung is normal and they haven’t got a pneumothorax

Question 7

What are A lines and what causes them?

Answer 7

Horizontal lines - artefacts caused by sound going between air and lungs - normal

Question 8

What colour do the ribs appear on an ultrasound?

Answer 8

Black

Question 9

How can the lung be seen more easily in individuals with high BMI?

Answer 9

By looking for the ribs and the outline of the lung should be behind them

Question 10

What are comet tails/b line artefacts, what causes them and what is their significance?

Answer 10

Vertical lines caused interlobular septa (indentations in the lung). This is normal.

Question 11

Which 3 things show that the lung is normal?

Answer 11

• A lines
• B lines/comet tails
• gliding pleural (sliding lung) sign

Question 12

What is interlobular septa

Answer 12

Tissue between secondary pulmonary lobules which have lymphatics and vessels

Question 13

What is an M mode ultrasound and how would you determine a lung is healthy from one?

Answer 13

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

Question 14

What are the uses of thorax ultrasounds?

Answer 14

• 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

Question 15

How would a pleural effusion be identified on an ultrasound?

Answer 15

Black space between lung and chest wall

Question 16

Which muscles are responsible respiration?

Answer 16

• diaphragm
• internal intercostals
• external intercostals
• accessory muscles (attach to sternum, clavicle and spaculae): sternocleidomastoid, scalenes, serratus and pectorals

Question 17

What happens to the diaphragm, scalene, SCM and intercostals during inhalation?

Answer 17

• 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

Question 18

What happens to the diaphragm, scalene, SCM and intercostals during exhalation?

Answer 18

• diaphragm relaxes
• scalenes and scm relax
• internal intercostals contract (not interchondral part) and abdominal muscles so ribs move down

Question 19

Which nerve innervates the diaphragm, what spinal level does it come from and what does damage to it cause?

Answer 19

Phrenic nerves from C3,4 and 5. Damage causes paralysis -diaphragm rise

Question 20

Which angle is important to identify pleural effusion and what happens to it?

Answer 20

costophrenic angle - blunting of the angle occurs

Question 21

What are the causes of an elevated diaphragm?

Answer 21

• enlarged liver
• subphrenic abscess: collection between liver and diaphragm
• trapped sub pulmonary fluid

Question 22

What test should be done to identify whether the phrenic nerve is damaged, what would the results be in a normal and abnormal diaphragm?

Answer 22

forced inspiration - sniff test

normal - rapid caudal movement

abnormal - paradoxical movement so diaphragm moves up towards the head

Question 23

What is also used during the sniff test to see the diaphragm movement?

Answer 23

Ultrasound

Question 24

How should the transducer be angled to see the diaphragm?

Answer 24

Under the lung and upwards towards the diaphragm

Question 25

What is a parasagittal plane?

Answer 25

Divides into left and right but not in midline

Question 26

What is a paracoronal plane?

Answer 26

Coronal but angled between ribs