Positioning

Question 1

Respiratory function requires

Answer 1

> adequate ventilation of alveoli

> adequate blood supply to alveoli (perfusion)

Question 2

Ventilation

Answer 2

> Movement of air in and out of lungs (which is not evenly distributed)
Upper regions are stretched open by gravity + weight of suspended lung (have less potential to expand)
Lower regions have greatest potential for ventilation (intrapleural pressure is also less negative lower down)
- slinky reference
*Side lying will reduce abdominal pressure and put pre-stretch on lower hemi-diaphragm (stronger contraction)

*However in mechanical ventilation - no contraction from diaphragm means lower areas are more difficult to expand - air will take path of least resistance so will go into upper airways (also reduced N2 in air provided will mean less air keeps alveoli open and may start to collapse)

Question 3

Perfusion

Answer 3

> Blood flow in capillary beds
gravity dependent - affected more so than air in lungs (ie gradient down lung if upright)
Changed by exercise and pressure
* Referred to as Q - quotient = how we measure perfusion

Question 4

V/Q Ratio

Answer 4

> 0.8 = normal but 1 = perfect
Factors that affect:
V
- pleural pressure (more negative means more difficult to expand)
- altered lung compliance (expandability)
- Altered airway or airflow resistance
- Lung Volume
- physiological dead space (less air in gas exchange areas)
- ‘Shunt’ = plenty of blood flow but can’t get air to it
Q
- Wasted ventilation (adequate gas but can’t get blood to it)
- Circulatory disorders

Question 5

What is positioning

Answer 5

> Deliberate placement of patient to maximise physical and psychological well-being
In cardiorespiratory it is normally about maximising ventilation and diaphragm function to then optimise the V/Q ratio
+ if possible decrease WoB + sputum
I.E - Optimise respiratory function

Question 6

Positions

Answer 6

> Side-lying:

• No abdomen compressing diaphragm
• pre-stretch on lower hemi-diaphragm
• V/Q potential is maximised on lower lung (more compromised area upwards - not a cure-all)

> Standing:
- No abdomen compression
- V/Q potential is in lower areas
(Sitting

Question 7

Decreasing WoB

Answer 7

> High WoB
- breathlessness
- distressed breathing pattern
- Increased energy use - requiring more O2
By positioning we can:
- Maximise Diaphragm
- Decrease active fixation of shoulder girdle - freeing up accessory muscles to aid breathing + conserve energy