Interpretation

Question 1

What causes a raised anion gap metabolic acidosis?

Answer 1

Increased acid production/ingestion
Not endogenous measured ions
Lactic acidosis
DKA (ketosis)
Aspirin OD
Methanol/ethylene glycol poisoning

Question 2

What causes a reduced anion gap metabolic acidosis?

Answer 2

Increased loss of bicarb (diarrhoea, ileostomy)
Retention of H+ ions:
Renal tubular acidosis
Addison’s

Question 3

Name 4 causes of metabolic alkalosis

Answer 3

Vomiting (loss of HCl)
Loop + thiazide diuretics
Conn’s
Milk alkali syndrome (calcium + alkali intake)

Question 4

For a lack of haemosiderin in CSF to rule out SAH, what time frame is necessary?

Answer 4

For test to be 99% sensitive, 12hrs after onset of symptoms is necessary

Question 5

Why is haemosiderin over blood preferred in the diagnosis of SAH?

Answer 5

Blood can be due to a traumatic tap

Haemosiderin is from previous blood in CSF

Question 6

How do you confirm NG tube placement?

Answer 6

pH measurement of aspirate is 1st line (below 5.5)

Chest xray is 2nd line if pH is altered due to PPIs or recent NG feeding

Question 7

Features of CXR to confirm NG tube placement?

Answer 7

NG tube descends in the midline
Bisects carina
Is below diaphragm
10cm past the gastro-oesophageal junction

Question 8

How do you always start an x-ray interpretation?

Answer 8

This is a (frontal) (chest) radiograph of M(rs) X Y, DOB X/Y/Z, taken on the X/Y/Z
There are (no) previous films to compare findings
The film is (not) technically adequate
(rotation, inspiration, penetration, exposure)

Question 9

What shows non-rotation on a CXR?

Answer 9

Equidistance of each clavicle from spinous process

Question 10

What shows adequate inspiration in a CXR?

Answer 10

Anteriorly the 5-7th rib should intersect the diaphragm at the mid-clavicular line

Question 11

What shows adequate penetration on a CXR?

Answer 11

Vertebrae should be visible behind heart

Question 12

What shows adequate exposure on a CXR?

Answer 12

Entire thoracic cage (apex lungs-> below diaphragm)

Question 13

What features show large bowel as opposed to small bowel?

Answer 13

Large bowel: haustra, normal diameter 6cm colon, 9cm caecum. Located peripherally in abdomen due to adhesion to peritoneum
May contain mottled faces and air
Small bowel: valvulae coniventes the whole width of bowel, normal diameter 3cm, located centrally in abdomen

Question 14

Give an example of a basic spiel for an AXR

Answer 14

This is a supine AP abdominal radiograph of Jayne Lister, date of birth 11/4/1970. The film is technically adequate with appropriate exposure. No prior imaging is available for comparison.
Both the small and large bowel appear within normal limits. Other abdominal viscera appear normal within the limits of this projection. No obvious bony pathology is identified. No abnormal calcification is seen. In summary this is a normal plain radiograph of the abdomen

Question 15

Most common causes of small and large bowel obstruction

Answer 15

Small: adhesions from previous surgery, hernias, cancer
Large: Cancer, diverticular strictures, volvulus, hernias

Question 16

What affects the trachea’s position?

Answer 16

Pushing of trachea – large pleural effusion / tension pneumothorax

Pulling of trachea – consolidation with lobar collapse