clinical assessment of respiratory disease

Question 1

what is ultrasonography and what does it produce

Answer 1

use of a probe to produce high frequency sound waves that are reflected from the boundaries of internal organs and tissues, before detection by a transducer array, producing a 2D image

Question 2

what 4 planes can ultrasonography use and relevant image interpretations

Answer 2

axial/transverse (right of patient corresponds to left of image), longitdudinal/coronal (cranial left, caudal right), paracronal/parasagittal plane, longitudinal/sagittal (cranial left, caudal right)

Question 3

why is paracronal/parasagittal plane most useful for thoracic ultrasounds

Answer 3

less rib artefact

Question 4

interpretation of ultrasound image colours (white, grey, black)

Answer 4

reflected at densest tissue (bone) so appears black, absorbed in less dense tissue so grey or white

Question 5

properties and use of a 3.5MHz probe

Answer 5

lower resolution but increased depth of view, so used for deep organs and diaphragm; curved array produces a fan of ultrasound beams to get round the ribs

Question 6

properties and use of a 7-12 MHz probe

Answer 6

smaller with flat surface (linear array), producing a higher resolution image with a limited depth of view, so used for superficial imaging

Question 7

ultrasonic appearance of normal lung anatomy

Answer 7

visceral and parietal pleura visible, with the echogenic line representing both pleura; will naturally have some bumps and move slowly/smoothly back and forwards underneath chest wall; artefacts will be present below echogenic lung

Question 8

ultrasound appearance of ribs

Answer 8

placing probe across ribs will lead to indentations, forming black shadows as all sound reflected

Question 9

what do comet tails/’B line artefacts’ represent

Answer 9

interlobular septa, which runs perpendicular to the lung surface

Question 10

what is the interlobular septa

Answer 10

boundaries between secondary pulmonary lobules

Question 11

what is M-mode ultrasound

Answer 11

1D display of motion of echo-producing interfaces displayed against time

Question 12

on normal M-mode, what should the image look like

Answer 12

sea shore

Question 13

describe the normal sea shore image produced on M-mode ultrasound

Answer 13

lung pleura look striated and lung ‘sandy’, while chest wall should be comprised of straight horizontal lines

Question 14

give 6 uses of ultrasound for imaging thorax

Answer 14

detect pleural effusion and guide drainage, differentiate sub-pulmonary from sub-phrenic fluid, assess tumour invasion of chest wall/pleura, guide pleural/lung biopsy, pneumothorax identification (white line of pleura will disappear), assessment of respiratory muscle function

Question 15

what is pleural effusion

Answer 15

build-up of excess fluid between the layers of the pleura outside the lungs

Question 16

what should be a normal image of a normal lung in relation to no pleural effusion

Answer 16

a trace of black should exist between lung edge and chest wall

Question 17

what does an image show of a larger pleural effusion

Answer 17

several cm of fluid can accumulate

Question 18

how do you calculate the volume (ml) of pleural effusion

Answer 18

200 x distance on ultrasound

Question 19

what can compression make the lung look like on an ultrasound if there is a large pleural effusion

Answer 19

makes lung look solid (becomes smaller as larger external pressure), and not like lung tissue

Question 20

describe the use of sniff testing

Answer 20

sniffing stimulates phrenic nerve to cause rapid caudal movement of the diaphragm (if damaged then will cause paradoxical, absurd cranial movement)