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Flashcards in Respiratory Failure Deck (17):
1

inhalation occurs against what forces?

elastic and resistive

2

function of theupper airway

humidification
defence
stay open to allow inhalation

3

what does surfactant do?

improves compliance by reducing surface tension of fluid lining alveoli.
prevents alveoli collapse

4

why does gas exchange occur?

difference between partial pressures of O2 and CO2 between alveoli and pulmonary capillary across the A-C membrane. normally very efficitent

5

normal arterial blood gas values

O2=100
CO2=45
HCO3=22-30
O2 sat = >95%
pH=7.4

6

what is the A-a gradient adn what would cause an elevation in it?

it is the difference in partial pressures of oxygen between the arteriole (A) and the alveoli (a)
elevation of the gradient indicates impaired gas exchange

7

calculation for A-a gradient?

=(150-1.25xPaCo2) - PaO2

8

what is respiratory failure?

impairment of gas exchange between air and circulating blood leading to the inability to maintain arterial blood gas concentrations either by impairing exchange in the alveoli or inability to bring air in or out of the lungs

9

what is type 1 respiratory failure?

impaired gas exchange leading to hypoxaemia paO2<60mmHg

10

what is type 2 respiratory failure?

impaired ventilation leading to hypercapnia PaCO2>50mmHg

11

causes of hypoxaemia

1. reduced inspired O2
2. VQ mismatch (pneumonia, PE)
3. impaired diffusion (COPD, fibrosis)
4. shunt (total VQ mismatch, incluides where blood bypasses lungs altogether)
5. reduced ventilation

12

what could cause hypercapnoea

1. respiratory depression
2. blocked airways
3. respiratory pump failure
4. muscle fatigue

13

signs of respiratory failure

accessory muscle use
altered state of consicousness/drowsiness
confusion
increased resp rate (or decreased in severe)
low O2 saturation
cyanosis

14

investigations for suspected respiratory failure

arterial blood gases
investigations into cause eg CXR, bloods, CTPA, VQ scan, lung function/spirometry

15

management principles of respiratory failure

1. maintain O2 delivery (not too high in blue bloaters)
2. reduce work of breathing
3. maintain pH, electrolytes
4. target the cause
5. analgesia (dont cause depression tho)
6. calories

16

what is acute respiratory distress syndrome?

mass release of inflammatory mediators increases pulmonary capillary permeability leading to edema and diffusion impairment leading to impaired gas exchange and increased work of breathing

17

how can you go from type 1 to type 2 respiratory failure?

increased drive and work of breathing to compensate for hypoxemia leads to respiratory muscle fatigue, reducing ventilation and raising co2 levels