21 Respiratory Failure and Assisted Ventilation

Question 1

what is the clinical definition of respiratory failure?

Answer 1

PaO2 < 8.0 kPa while breathing on air, or PaCO2> 6.5kPa

Question 2

What ways can the body compensate for increased Oxygen demand?

Answer 2

lungs (increasing ventilation or V/Q mismatch)
blood (increasing Hb)
tissues (increasing cardiac output)
cells (change position of O2 dissociation curve)

Question 3

What are the 2 types of respiratory failure?

Answer 3

1 - hypoxaemic respiratory failure

2 -hypercapnic respiratory failure

Question 4

What is the physiological cause and effect of type 1 respiratory failure?

Answer 4

V/Q mismatch leads to a shunt as the body tries to compensate for a lack of oxygen

PaO2 < 8.0kPa with normal or a lil low PaCO2
(normal or high pH)

Question 5

What is the physiological profile of type 2 respiratory failure?

Answer 5

PaCO2 > 6.5kPa
hypoxaemia is always present
pH and HCO3 are dependent on level of hypercapnia

decreased minute ventilation relative to demand

increased dead space ventilation

Question 6

How might sepsis or a pulmonary embolus present?

Answer 6

hypotension with poor perfusion

also the case for cardiogenic airway obstruction

Question 7

What might stridor suggest?

Answer 7

upper aiways obstruction

Question 8

What might elevated jugular venous pressure suggest?

Answer 8

right ventricular pulmonary hypertension

Question 9

What disease should not be ruled out by a normal CXR?

Answer 9

pulmonary embolism

Question 10

what are the aims in treating respiratory failure?

Answer 10

primary - reverse and prevent hypoxaemia
secondary- control PaCO2 and respiratory acidosis

treatment of underlying disease

Question 11

What is the goal with oxygen thearpy?

Answer 11

to prevent tissue hypoxia
venous SaO2 < 40%
arterial SaO2 < 70%

Question 12

What is the FiO2 range usually used with nasal canula?

Answer 12

24 to 44% or 1 to 6 litres

Question 13

What are the advantages of Nasal Cannula therapy?

Answer 13

safe, comfortable, well tolerated

eating, talking, and ambulation

Question 14

What are the disadvantaged of Nasal Cannula therapy?

Answer 14

FiO2 varies with flow rate of breathing
extended use can break down skin and mucous membranes
tubing may be dislodged

Question 15

What are the ranges of FiO2 delivered with a face mask?

Answer 15

40-60%

minimum flwo rate is 5L to ensure flushing of CO2 from the mask

Question 16

What flow rates are given using a non re-breather mask?

Answer 16

80-90% (10 to 15L/min) to keep reservoir bag 2/3 full during inspiration and expiration

Question 17

What are the advantages of non re-breather mask?

Answer 17

delivers the highest O2 concentration

one way valve allows client to inhale maximum O2 from reservoir bag

2 exhalation ports have flaps preventing room air from entering

Question 18

What are the disadvantages of non re-breather masks

Answer 18

valve and flap must be functional

poorly tolerated by anxious or claustophobic patients

eating and drinking no no

Question 19

What flow rates are delivered using a Venturi mask?

Answer 19

24-55%

Question 20

What are the advantages of using a Venturi mask?

Answer 20

delivers precise oxygen conc.
no humidification required
good for those with chronic lung disease

Question 21

What are the forms of mechanical ventilation?

Answer 21

non invasive with mask

invasive with endobronchial tube

Question 22

What does mechanical ventilation do for hypercapnia?

Answer 22

increases alveolar ventilation and lowers PaCO2, correcting pH

rests fatigues muscles

Question 23

What does MV do for hypoxaemia?

Answer 23

O2 therapy alone won’t correct hypoxaemia caused by shunt

Question 24

What is the most common cause of shunt?

Answer 24

fluid filled or collapsed alveoli (pulmonary edema)

Question 25

What is BiPAP?

Answer 25

Non-invasive bilateral positive airway pressure ventilation

provided by a nasal mask or nasal prongs, or a full face mask

Question 26

What is the advantage of a BiPAP?

Answer 26

2 levels of positive pressure support
Ipap - inspiratory
Epap - expiratory (or CAP, PEEP)

Question 27

In what settings should non-invasive measures be considered?

Answer 27

COPD exacerbation
Cardiogenic pulmonary eddema
obesity hypoventilation syndrome
NMD
to facilitate weaning frrom invasive ventilation

Question 28

What does PEEP stand for?

Answer 28

Patient End Expiratory Pressure

Question 29

What does CPAP stand for?

Answer 29

Continuous Positive Airway Pressure

Question 30

What are the main uses of PEEP and CPAP?

Answer 30

treating/preventing atelactasis or alveoli collapse
improve gas exchange
treat hypoxemia
treat pulmonary oedema