Positioning

Question 1

What’s the point of positioning

Answer 1

To maximise respiratory function, the lungs require adequate ventilation of alveoli, adequate blood supply to exchange and transport co2 and o2

Question 2

What’s ventilation perfusion matching

Answer 2

For gas exchange to occur ventilation and Perfusion need to be in place at the same time this is ventilation perfusion matching, the v/q ratio quantified this match

Question 3

What’s a v/q ratio

Answer 3

VQ increases independently from the to the bottom of the change occurs in the vertical plane regardless of body position, Q is increased to a greater extent because gravity exerts a greater effect on blood than inspired out

Question 4

Why are the lower regions (dependent) of the lung better ventilated

Answer 4

Because alveoli in the upper areas (non dependent) are already inflated because of the weight of the hanging lung, in side lying the lower hemi diaphragm is pre stretched by abdominal pressure and therefore has an advantage over the upper diaphragm causing twice the excursion

Question 5

What’s ventilation

Answer 5

The movement of Air in and out of the lungs, not evenly distributed, primarily gravity dependent in a breathing adult, follows a ventilation gradient in the lung

Question 6

What’s perfusion

Answer 6

Blood flow in the capillary beds, gravity dependent in the spontaneously breathing adult allows a perfusion gradient down the lung tissue, changes with exercise and posture

Question 7

What are the regional differences in ventilation

Answer 7

Lower regions ventilate better than upper, intra pleural pressure less negative at the bottom than the tops of the lungs, lower lung has greater potential for increased ventilation

Question 8

What’s VQ like in an upright position.

Answer 8

Alveoli in lower regions have greater potential to expand than alveoli in upper regions

Question 9

What factors influence VQ

Answer 9

Ventilation: pleural pressure altered lung compliance
Lung expandability
Altered airways resistance
Lung volume
Physiological dead space
Shunt
Perfusion wastes ventilation, circulatory disorders

Question 10

How to utilise body position

Answer 10

To maximise ventilation maximise diaphragmatic function, optimise VQ matching, but also decrease WOB, drain sputum

Question 11

What’s mechanical ventilation

Answer 11

Positive pressure ventilation reverses ventilation away from dependent lung because: diaphragm pushed down passively, airflow takes path of least resistance, increased perfusion in dependent region compresses lung and accentuates perfusion gradient, dependent region prone to collapse, absorption atelectasis at higher concentrations

Question 12

What happens in mechanical ventilation

Answer 12

Perfusion not affected, occurs in lung, lower most in side lying position! Ventilation occurs in upper lung, upper lung hanging in chest wall- held open, air pushed in by mechanical ventilation will take path of least resistance, no ventilation and perfusion match, if someone has no ventilation perfusion stays the same, ventilation may occur in lower lung as well= ventilation perfusion match

Question 13

What’s total lung capacity

Answer 13

The total volume of gas in lungs after max inspiration depends on size and sex. Sum of other lung volumes- residual volume pm expiratory reserve volume, tidal volume

Question 14

What’s vital capacity

Answer 14

Volume of gas exhaled after full inspiration

Question 15

What’s functional residual capacity

Answer 15

Position dependent 
Seated position= good FRC 
stand up= FRC even better
Lying down= FRC good
Supine position= lower FRC

Question 16

What’s closing volume

Answer 16

Volume at which alveoli start to collapse

Question 17

What’s the relationship between functional residual capacity and closing volume, patient with reduced FRC, more likely to have areas with collapsed alveoli

Answer 17

Close relationship, FRC can be reduced by disease or disorder, if FRC decreases more likely to get closer to closing volume

Question 18

What’s dead space

Answer 18

Anatomical dead space- gas left in mouth and nose when we breathe
Alveolar dead space isn’t involved in gas exchange due to a lack of blood supply
Physiological dead space- anatomical and alveolar dead space

Question 19

Why are the alveoli in the non dependent (upper) regions already inflated

Answer 19

Because of the weight of the hanging lung, pleural pressure gets less negative

Question 20

What problem is positioning best for

Answer 20

Unilateral problem

Question 21

How do you position a patient with consolidation in right lung

Answer 21

Right lung won’t ventilate, not path of least resistance so the good lung is down

Question 22

What position would you put someone In with consolidation in their right lung

Answer 22

Left lung down or sitting up, lung has collapsed

Question 23

What’s postural drainage

Answer 23

Drainage of secretions by effect of gravity, each position places the tard get lung segments superior to carina

Question 24

What’s the clinical application of PD

Answer 24

limited by: more active clearance techniques being used, precautions,

Question 25

Why are positions of ease useful

Answer 25

High wob results in breathlessness, increases energy use and oxygen demand, position to optimise respiratory muscle function without excess energy demand, optimise diaphragm, decrease active fixation which uses muscular contraction