Respiratory Module 2

Question 1

What is shunting

Answer 1

• Occurs when blood enters the arterial systemic
  circulation without passing through ventilated
  areas of the lungs
• Can be physiological or anatomical
• VDS, PDA
• physiological shunts occur when blood passes
  through a zero v/q match area

Question 2

Caused of decreased FiO2

Answer 2

1. Equipment failure
2. High altitude (less O2 molecules per L of air)

Question 3

What are causes of reduced O2 carrying capacity

Answer 3

Anaemia
Carbon monoxide toxicity
Methaemoglobin
Cyanosis

Question 4

How does carbon monoxide cause toxicity

Answer 4

Binds to Hb with 250X the affinity but can only bind 2 of the 4 available sites - O2 carrying capacity decreased by 50%

Also when CM binds to O2 allosteric change to reduce capacity to let go of O2
Pulse ox will read 100% because Hb is bound

Question 5

What is methaemoglobinaemia

Answer 5

it is a variant of Hb that is that increases in toxic states

The iron is in the ferric state (Fe3+) instead of ferrous state (Fe2+) and therefore can not bind oxygen

Can cause heinz body anaemia

Question 6

Cyanosis is associated with what PaO2 and SaO2

Answer 6

PaO2 <60mmHG, SaO2 <90%

Question 7

what are methods of assess lung function in patients breathing room air

Answer 7

120 rule

A-a gradient

PaO2:FiO2

SpO2: FiO2

Question 8

How is lung function assessed in patient receiving supplemental air

Answer 8

PaO2: FiO2

Question 9

What is the 120 rule

Answer 9

A method of assessing lung function on room air
PaCO2 + PaO2
Should always be >120
<120 = parenchymal disease

Question 10

What is the A-a gradient

Answer 10

A method of assessing lung function on room air
PAO2 - PaO2
Normal gradient is <10mmHg
>15mmHg is consistent with pulmonary disease

Question 11

What is PaO2:FiO2 ratio

Answer 11

A method of assessing lung function on room air and supplemental air
Normal = 500

What is SpO2:FiO2 ratio

A method of assessing lung function on room air

Question 12

Causes of chylothorax?

Answer 12

• Idiopathic
• CHF
• LLT
• Thoracic duct trauma
• Pericardial disease
• Thoracic neoplasia
• Diaphragmatic hernia
• Cranial vena cava thrombosis

Question 13

Causes of haemothorax?

Answer 13

• Coagulopathy
• Trauma
• Neoplasia - in cats
• Angiostrongylus/aeluerostrongylus
• Iatrogenic - thoraco/pericardiocentesis, FNA,
  jugular cath placement
• Platelet disorder

Question 14

Secondary complications of chylothorax?

Answer 14

• Re-expansion PE
• Pseudoaddisons
• Left atrial rupture
• Pneumothorax
• Chronic atelectasis
• Fibrosing pleuritis

Question 15

Treatment of chylothorax?

Answer 15

Medical mx:
- Intermittent thoraco (can lead to complications
- Low fat diet
- Rutin (stimulates macrophagic activity to resorb
fluid

Surgical mx: more effective
- Pericardectomy + ligation of thoracic ducts
- Place a pleuroport: helps with future drain (s/c
port placed between ribs)

Question 16

What are the types of pneumothorax?

Answer 16

1. Open pneumothorax - can occur secondary to
   injuries or iatrogenic via chest drain (hole to the
   chest) - seal chest
2. Tension pneumothorax - One way valve is formed
   at site of leakage
   - Air accumulates and rapidly life threatening
   - Bulging chest and slow breathing

Question 17

How do you do a blood pleurodesis?

Answer 17

1. 5-10ml/kg autologous blood collected via jugular
   catheter aseptically in 20ml aliquats
   - no anticoagulants - injected directly into chest
2. Turn: Lateral, sternal, lateral every 15mins for
   2hrs

Traumatic ruptures tend to seal in 3-5 days
Spontaneous tends to need a thoracotomy for a lobectomy

Question 18

When does a pneumothorax need surgical management?

Answer 18

1. Necessary if open pneumothorax secondary to
   trauma
   - Needs flushing/exploration
2. Spontaneous continuous pneumothorax

Question 19

What is flail chest and how do you manage?

Answer 19

Flail chest: fractures occur in at least 2 adjacent ribs in at least 2 places per rib so that a free moving segment is created
- Free segment moves independently

Question 20

What are the diaphragmatic congenital hernias?

Answer 20

1. Pleurperitoneal diaphragmatic hernia
   
   • Can be subclinical for years -
   • Can be exacerbated by,
     vomiting/coughing/trauma
2. Hiatal hernia
   
   • Brachycephalic
   • Intermittent regurgitation
   • Slides or fixed hernia
3. Peritoneo-pericardial diaphragmatic hernia
   
   • Embyronic failure in the formation of the septum
     transverse resulting in direct communicaton
     between peritoneal and pericardial sac
   • Usually in the first year of life but can be
     subclinical for years
   • Tachypnoea, dyspnoea, v+, anorexia,
     borborygmi, muffled heart sounds
   • Often have other defects
   • Dx: pocus/rads/barium

Question 21

What are neuromuscular disorders that can affect respiratory system?

Answer 21

1. Toxoplasma/Neospora
2. Acute canine polyradiculoneuritis
3. Baclofen
4. Botulism
5. Tetanus
6. Myasthenia Gravis
7. Tick paralysis - not UK
8. Raised IP
9. Cerebral thrombosis

Question 22

How to calculate PAO2

Answer 22

PAO2 = 150 x 1.2 (PaCO2)
Used in A-a gradient to assess lung function on room air