1(E) Respiratory Failure Flashcards
When does respiratory failure occur
When gas exchange is inadequate resulting in hypoxia
What defines respiratory failure
PaO2 less-than 8kPa
What is type I respiratory failure
PaO2 less than 8kPa
Normal PCO2
What causes type I respiratory failure mainly
V-Q mismatch
What are 6 causes of V-Q mismatch
- PE
- Pneumonia
- Pulmonary oedema
- Asthma
- Emphysema
- Pulmonary Fibrosis
- ARDS
What else can cause type I resp failure
Alveolar Hyperventilation
Right-to-Left cardiac shunt
Define type II respiratory failure
Hypoxia (PaO2 < 8) with hypercapnia (PaCO2 >6)
What is the main mechanism if type 2 respiratory failure
Alveolar hypoventilation without V-Q mismatch
What are the 4 etiological categories of type 2 respiratory failure
- NM Disease
- Pulmonary Disease
- Chest wall disease
- Reduced resp drive
What are the 4 pulmonary diseases causing type 2 respiratory failure
- COPD
- Asthma
- End-stage pulmonary fibrosis
- OSA
What are 3 causes of reduced resp drive
CNS Tumour
Medication (Opioids)
Trauma
What NM disease may cause type 2 resp failure
Myasthenia Gravis MND Poliomyelitis Gullian Barre Cervical Cord Lesion
What does poliomyelitis affect
Anterior horn cells - causing a LMN lesion
What chest wall deformities can cause T2RF
Flail chest
Kyphoscoliosis
What is a mnemonic to remember symptoms of hypoxia
DRAC
What are symptoms of hypoxia
Dyspnoea
Restless
Agitated
Confused
What is a sign of hypoxia
Cyanosis
What are 3 consequences of long-term hypoxia
Polycythaemia
Pulmonary HTN
Cor Pulmonale
What is the main symptom of hypercapnia
Headache
What are 5 symptoms of hypercapnia
Headache Confusion Drowsiness Coma Peripheral Vasodilation
What are 4 signs of hypercapnia
Bounding pulse
Tachycardia
CO2 Flap
Papilloedema
If someone has a metabolic acidosis, what should be done
Calculate anion gap
How is the anion gap calculated
[Na+ + K+] - [Cl- + HCO3-]
What is a normal anion gap
10-18mmol/L
How is type I respiratory failure managed
15L Oxygen via non re-breathe mask
When is assisted ventilation indicated in type I respiratory failure
If hypoxic despite 60% oxygen
How is type II respiratory failure managed
Controlled oxygen therapy - start with 24% Venturi mask
What oxygen saturations are aimed for if a person is at risk of type 2 respiratory failure
88-92
If just given someone oxygen for type 2 respiratory failure, when should ABG next be checked
20-minutes later
If PCO2 is steady or lower in second ABG, what should be done regarding oxygen
increase to 28% venturi
When is NIPPV considered
PCO2 increased by 1.5kPa
If NIPPV is ineffective, what is performed
Intubation and mechanical ventilation
What are the two methods of oxygen delivery
Variable performance device
Fixed performance device
What are fixed performance devices
Able to control FiO2
Give an example of fixed performance device
Venturi mask
What are variable oxygen device
Cannot control exactly how much oxygen the individual recieves
What rate can nasal cannula deliver oxygen
1-4L/min
What % oxygen can nasal cannula deliver
25-40%
What is the advantage of nasal cannula
Patient is able to eat and drink
What are disadvantages of nasal cannula
- Nasal soreness
- High-flow oxygen can cause epistaxis
What is a Hudson mask also known as
Simple Face Mask
What concentration of oxygen can go through a Hudson mask
15L/min Oxygen
What is problem with simple face mask and what does this mean for its use
Imprecise concentration of oxygen. Means should not be used in type II resp failure
What is a non re-breathe mask
Hudson mask with reservoir bag
What is the action of the reservoir bag
Bag fills during expiration and empties during inspiration - increasing FiO2
What oxygen concentration can pass through non re-breathe mask
15L
When is non re-breathe mask used
Emergencies
What is a Venturi mask
Provides precise FiO2 - used for type II resp failure
What colour is the 24% Venturi mask
blue
What colour is the 28% Venturi mask
white
What colour is the 35% Venturi mask
yellow
What colour is the 40% Venturi mask
green
What colour is the 60% Venturi mask
red
According to BTS what are indications for non-invasive ventilation
- COPD with respiratory acidosis
- T2 RF due to chest wall deformity
- Cariogenic pulmonary oedema unresponsive to CPAP
- Weaning from tracheal intubation
