Respiratory Module 2 Flashcards
What is shunting
- 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
Caused of decreased FiO2
- Equipment failure
- High altitude (less O2 molecules per L of air)
What are causes of reduced O2 carrying capacity
Anaemia
Carbon monoxide toxicity
Methaemoglobin
Cyanosis
How does carbon monoxide cause toxicity
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
What is methaemoglobinaemia
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
Cyanosis is associated with what PaO2 and SaO2
PaO2 <60mmHG, SaO2 <90%
what are methods of assess lung function in patients breathing room air
120 rule
A-a gradient
PaO2:FiO2
SpO2: FiO2
How is lung function assessed in patient receiving supplemental air
PaO2: FiO2
What is the 120 rule
A method of assessing lung function on room air
PaCO2 + PaO2
Should always be >120
<120 = parenchymal disease
What is the A-a gradient
A method of assessing lung function on room air
PAO2 - PaO2
Normal gradient is <10mmHg
>15mmHg is consistent with pulmonary disease
What is PaO2:FiO2 ratio
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
Causes of chylothorax?
- Idiopathic
- CHF
- LLT
- Thoracic duct trauma
- Pericardial disease
- Thoracic neoplasia
- Diaphragmatic hernia
- Cranial vena cava thrombosis
Causes of haemothorax?
- Coagulopathy
- Trauma
- Neoplasia - in cats
- Angiostrongylus/aeluerostrongylus
- Iatrogenic - thoraco/pericardiocentesis, FNA,
jugular cath placement - Platelet disorder
Secondary complications of chylothorax?
- Re-expansion PE
- Pseudoaddisons
- Left atrial rupture
- Pneumothorax
- Chronic atelectasis
- Fibrosing pleuritis
Treatment of chylothorax?
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)
What are the types of pneumothorax?
- Open pneumothorax - can occur secondary to
injuries or iatrogenic via chest drain (hole to the
chest) - seal chest - Tension pneumothorax - One way valve is formed
at site of leakage
- Air accumulates and rapidly life threatening
- Bulging chest and slow breathing
How do you do a blood pleurodesis?
- 5-10ml/kg autologous blood collected via jugular
catheter aseptically in 20ml aliquats
- no anticoagulants - injected directly into chest - 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
When does a pneumothorax need surgical management?
- Necessary if open pneumothorax secondary to
trauma
- Needs flushing/exploration - Spontaneous continuous pneumothorax
What is flail chest and how do you manage?
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
What are the diaphragmatic congenital hernias?
- Pleurperitoneal diaphragmatic hernia
- Can be subclinical for years -
- Can be exacerbated by,
vomiting/coughing/trauma
- Hiatal hernia
- Brachycephalic
- Intermittent regurgitation
- Slides or fixed hernia
- 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
- Embyronic failure in the formation of the septum
What are neuromuscular disorders that can affect respiratory system?
- Toxoplasma/Neospora
- Acute canine polyradiculoneuritis
- Baclofen
- Botulism
- Tetanus
- Myasthenia Gravis
- Tick paralysis - not UK
- Raised IP
- Cerebral thrombosis
How to calculate PAO2
PAO2 = 150 x 1.2 (PaCO2)
Used in A-a gradient to assess lung function on room air