VIVA: Clinical Building Blocks

Question 1

Describe and interpret this VBG

Answer 1

• Primary metabolic acidosis* / HAGMA (AG 34)
• Respiratory compensation*, predicted CO2 20
• Severe hyperglycaemia*
• AG >20
• Mild hypochloraemia
• Corrected Na+ 142 and K+ 4.1 and uncorrected values within normal reference range
• Delta-ratio 1.25 consistent with pure HAGMA

Most likely diagnosis is DKA*

• Primary metabolic acidosis with respiratory compensation and glucose abnormalities to pass

Question 2

What are the priorities of treatment for DKA?

Answer 2

2/4 to pass:
- Careful rehydration/fluid replacement/IV fluids
- Insulin: infusion or subcutaneous depending on severity
- Electrolyte monitoring/management (managing K+ and Na+)
- Seek and treat precipitant of DKA

Question 3

Describe and interpret this ECG

Answer 3

Complete AV dissociation*
Atrial rate 60-80bpm
Slow ventricular escape rhythm 30bpm
RBBB
Left axis deviation
Nil ST changes
T wave inversion V1-3

Complete/3rd degree AV block*

• AV dissociation or CHB to be at standard

Question 4

What are the causes of complete heart block?

Answer 4

3 needed to pass:
- Ischaemic especially inferior or anterior myocardial infarction
- Cardiomyopathy
- AV nodal blocking drugs (e.g. calcium channel blockers, beta blockers, digoxin)
- Electrolyte abnormalities (e.g. hyperkalaemia)
- Idiopathic degeneration of conducting pathway (Lenegre or Lev’s disease)
- Fibrotic disorders/sarcoidosis/amyloidosis/autoimmune disease
- Post cardiac surgery, ablation or PCI

Question 5

Describe these images. What is the diagnosis?

Answer 5

• Erect AXR showing multiple * centrally distributed distended * bowel loops
• Multiple air/fluid levels *
• Hernia not seen
• Diagnosis is bowel obstruction *

*needed to pass

Question 6

Describe the abnormality. What structure may be injured?

Answer 6

• Spiral/oblique fracture mid-shaft R humerus * with displacement
• Radial nerve may be damaged *

*needed to pass

Question 7

Describe the abnormalities in this ABG:
- pH 7.2
- pCO2 52
- pO2 110
- HCO3 18
- BE -2
- Lactate 3.0

Answer 7

• Acidaemia/acidosis pH 7.2
• Hypercapnia thus respiratory acidosis *
• Low bicarbonate and negative base excess with high lactate therefore metabolic acidosis *
• Hyperoxia
• Interpretation: mixed respiratory and metabolic acidosis *

*needed to pass

Question 8

What are the possible causes of a mixed respiratory and metabolic acidosis?

Answer 8

2 to pass:
- Sepsis
- Pneumonia
- CCF/APO
- Infective exacerbation of COPD or any other acute respiratory illness
- Salicylate toxicity

Question 9

Describe and interpret this ABG:
- pH 7.2
- pCO2 57
- pO2 71
- HCO3 24

Answer 9

• Acidaemia
• High pCO2
• Normal HCO3
• Hypoxia
• Acute respiratory acidosis * consistent with respiratory failure
• Consistent with tiring patient requiring escalation of management (pharmacotherapy / assisted ventilation)

Question 10

Describe the common causes of respiratory acidosis

Answer 10

3 to pass:
- Central respiratory depression (e.g. drugs including opiates/sedatives/anaesthetics, CVA, raised ICP, seizure)
- Neuromuscular disorders
- Lung or chest wall injury/abnormality (e.g. infection, trauma)
- Airway obstruction (e.g. COPD, asthma)
- Hypoventilation due to pulmonary disease (e.g. cancer, effusion, pneumonia, atelectasis)

Question 11

Describe the abnormalities seen on this ABG:
- pH 7.52
- pCO2 29
- pO2 66
- SaO2 91%

What conditions could cause this result?

Answer 11

• Alkalaemia
• CO2 low, thus primary respiratory alkalosis *
• Low pO2 and SaO2: profound hypoxaemia *
• Raised A-a gradient 47
• Interpretation: hypoxia leading to hyperventilation and respiratory alkalosis
• Causes (2 needed to pass): any NON-central causes (infection, asthma, PE, pulmonary oedema, etc)

*needed to pass

Question 12

Describe the XR. What other important adjacent structures are at risk from this injury?

Answer 12

• Posterior dislocation of R elbow *
• Radial head *, coronoid process of ulna, articular surfaces of humerus * (trochlea or capitulum), empty olecranon fossa *
• Bony fragment in olecranon fossa (not on this image)
• Nil other obvious injury
• Other structures at risk include median nerve and brachial artery (anterior), and ulnar nerve (posteromedial)

*needed to pass

Question 13

Describe this XR

Answer 13

• Tibial plateau fracture *
• Depressed lateral condyle *
• Lipohaemarthrosis * (on lateral view)

*needed to pass