24/04/2019
Respiratory Mechanics
and
Positioning
Respiratory Reasoning
Unravelled
Julia Bott
Consultant Physiotherapist
Respiratory programme Clinical Co-Lead KSS AHSN
Objectives
• The mechanics of breathing
o Normal
o Disrupted - Respiratory Conditions
• Obstructive
• Restrictive
• Breathing techniques and
Positioning to optimise mechanics
If time…..
• Respiratory compliance
• V/Q
How do we breathe?
………
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The Ventilatory Pump
It requires force to pump air
in/out of the lungs
3 main respiratory muscles
responsible
The Ventilatory Pump


The diaphragm
moves down and
flattens from it’s
normal ’dome’
shape – making
chest longer
‘piston’ action
↨
↨
The Ventilatory Pump
The intercostal
muscles pull the
ribs up and out,
making the chest
wider
‘bucket-handle’
action


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The Ventilatory Pump
↑↑
Small sternal muscles,
the scalenii, pull the
sternum upwards and
forward, making the
chest wider front to back

the ‘pump-handle’


The Ventilatory Pump
volume of chest
↑↑
cage increases


↨


↨
The Ventilatory Pump
volume of chest
↑↑
cage increases
pressure in chest
goes down …??
Boyle’s Law


↨
↨
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

The Ventilatory Pump
volume of chest
↑↑
cage increases
pressure in chest
goes down
– Boyle’s Law

pressure now less
than atmosphere


↨


↨
The Ventilatory Pump
volume of chest
↑↑
cage increases
pressure in chest
goes down
– Boyle’s Law

pressure now less
than atmosphere

bingo!...........air is
sucked in


↨
↨
The Ventilatory Pump
Exhalation is
by ….???
elastic ‘recoil’ of
lung tissue

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The Ventilatory Pump

Exhalation is
by natural
elastic ‘recoil’
of lung tissue
The Accessory Muscles of
Respiration


When more muscle power to breathe is
needed, such as in severe exertion, or
when very breathless, the accessory
muscles of respiration are recruited
These are shoulder and neck muscles



Upper fibres of traps
Sterno-cleido-mastoid
We need to fix the shoulder girdle to allow
them to work as respiratory muscles
The Accessory Muscles of
Respiration


When more muscle power to breathe is
needed, such as in severe exertion, or
when very breathless, the accessory
muscles of respiration are recruited
These are shoulder and neck muscles



Upper fibres of traps
Sterno-cleido-mastoid
We need to …..? To help them work as
accessory muscles
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The Accessory Muscles of
Respiration


When more muscle power to breathe is
needed, such as in severe exertion, or when
very breathless, the accessory muscles of
respiration are recruited
These are shoulder and neck muscles



Upper fibres of traps
Sterno-cleido-mastoid
We need to fix the shoulder girdle to allow
them to work as respiratory muscles
The Accessory Muscles of
Respiration


This is why patients with respiratory
disease find it very difficult to do things
with their arms raised, or when they are
moving their shoulders, or carrying
anything, as the accessory muscles need
the shoulders fixed to work properly
In extreme cases of disruption, death can
ensue…
Pathophysiology/mechanics
•Two main categories of
respiratory disease:
oObstructive
oRestrictive
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Pathophysiology/mechanics
Obstructive Conditions?
Pathophysiology/mechanics
Obstructive Conditions
•COPD
•Asthma
•Bronchiectasis
•Bronchiolitis
Pathophysiology/mechanics
Obstruction is caused
by… .??
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Small airways in COPD
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Pathophysiology/mechanics
Obstructive Conditions
Sequalae?.......
Obstructive Airways disease

Airway closure before end expiration
• gas trapping / hyperinflation - big lungs
• auto - (intrinsic) PEEP

Hyperinflation:
slow onset in COPD & rapid onset in
•
asthma
Obstructive Airways disease

Airway closure before end expiration
• gas trapping / hyperinflation - big lungs
• auto - (intrinsic) PEEP
• slow onset in COPD & rapid onset in asthma

worse on exertion – dynamic hyperinflation

…And the muscles of respiration?.......
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Obstructive Airways disease


Shortened respiratory muscles
•
in position of inspiration
•
low, flattened diaphragm
Contraction can’t produce excursion
abdomen may move paradoxically
•

Rapid, shallow respiration on effort

Accessory muscles recruited

Load falls to diaphragm when arms raised or moving
Pathophysiology/mechanics
Obstructive Conditions
Therapy Aims?......
Obstructive Airways disease
Therapy aims

(Reduce airways narrowing)
To empty the lungs of as much of the
extra air as possible
To return the muscles to a more optimal
length and the lung tissue to a more
optimum point on the V/P curve
This is especially important when
patients are exerting themselves to
reduce dynamic hyperinflation
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Pathophysiology/mechanics
Obstructive Conditions
Therapy Aims
Positioning
Based on recommendations from Bott J et al.
Guidelines for Physiotherapy management of
adult, medical, spontaneously breathing patient
www.brit-thoracic.org.uk/clinical-information/
physiotherapy/physiotherapy-guideline.aspx
Obstructive Airways disease
Positioning for mechanical advantage
 If accessory muscles are to work
effectively as respiratory muscles,
must …???. the shoulder girdle
Obstructive Airways disease
Positioning for mechanical advantage
 If accessory muscles are to work
effectively as respiratory muscles,
must fix the shoulder girdle
 And we can help get more efficient
muscle contraction by ???.... the
diaphragm
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24/04/2019
Obstructive Airways disease
Positioning for mechanical advantage
 If accessory muscles are to work
effectively as respiratory muscles,
must fix the shoulder girdle
 And we can help get more efficient
muscle contraction by ‘loading’ the
diaphragm
 How do we achieve both?
Obstructive Airways disease
Positioning for mechanical advantage

Forward lean sitting (FLS) / standing
Copyright ACPRC
Acprc.org.uk
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Copyright ACPRC
Acprc.org.uk
Obstructive Airways disease
Positioning for mechanical advantage

Forward lean sitting (FLS) / standing

Side lying with dependent (underneath) or
non-dependent (uppermost) hip flexed?
Loads diaphragm for better inspiratory aids return to
lengthened (domed) position
Copyright
Copyright
ACPRC
ACPRC
Acprc.org.uk
Acprc.org.uk
•Side lying with dependent hip flexed
•Loads diaphragm for better inspiratory effort
•Passively aids return to lengthened (domed) position
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Obstructive Airways disease
Breathing techniques for
mechanical advantage
Obstructive Airways disease
Therapy aims

(Reduce airways narrowing)
To empty the lungs of as much of the
extra air as possible
To return the muscles to a more optimal
length and the lung tissue to a more
optimum point on the V/P curve
This is especially important when
patients are exerting themselves to
reduce dynamic hyperinflation
Obstructive Airways disease
Breathing techniques for mechanical
advantage

Breathing control

Relaxed deep breathing

Pursed lips breathing-PLB
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Obstructive Airways disease
Breathing techniques for mechanical advantage

Blow-as-you-go!

Paced Breathing
Pathophysiology/mechanics
Restrictive Conditions
Restrictive lung problems

The problem is not in the airways,
but other parts of the thorax and/or
abdomen

What is restricted and why?

Which structures?

What conditions?
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Restrictive lung problems

lung tissue
• Inflammation / Interstitial lung disease eg
fibrosis / collapse: pneumothorax or
atelectasis - shrinking lung
chest wall – skeletal structure
musculo-skeletal deformity
Muscles – respiratory/abdominal
neuro-muscular weakness / paralysis
Restrictive lung problems

lung tissue
• Inflammation / Interstitial lung disease eg
fibrosis / collapse: pneumothorax or
atelectasis - shrinking lung

chest wall – skeletal structure
• musculo-skeletal deformity
Muscles – respiratory/abdominal
•
neuro-muscular weakness / paralysis
Restrictive lung problems

lung tissue
• Inflammation / Interstitial lung disease eg
fibrosis / collapse: pneumothorax or
atelectasis - shrinking lung

chest wall – skeletal structure
• musculo-skeletal deformity

Muscles – respiratory/abdominal
•
neuro-muscular weakness / paralysis
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Pathophysiology/mechanics
Restrictive Conditions
S equalae?.......
Restrictive lung problems

Difficulty expanding the lungs due to
poor ???....a combo
Restrictive lung problems

Difficulty expanding the lungs due to poor
compliance

May be lung compliance

Chest wall compliance

Or ventilatory compliance (a combination)
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Restrictive lung problems
Therapy aims

Reduce inflammation/oedema if the cause

Treat collapse (atelectasis or pneumothorax)

Support ventilation if due to weakness or
paralysis (non-invasive ventilation)

To try and allow/help the lungs to expand as
much as possible
Restrictive lung problems
Therapy aims

Reduce inflammation/oedema if the cause

Treat collapse (atelectasis or pneumothorax)

Support ventilation if due to weakness or
paralysis (non-invasive ventilation)

To try and allow/help the lungs to expand as
much as possible

To unload the diaphragm
Restrictive lung problems
Therapy aims

Reduce inflammation/oedema if the cause

Treat collapse (atelectasis or pneumothorax)

Support ventilation if due to weakness or
paralysis (non-invasive ventilation)

To try and allow/help the lungs to expand as
much as possible

To unload the diaphragm
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Pathophysiology/mechanics
Restrictive Conditions Therapy Aims
Positioning
Restrictive lung problems
Positioning for mechanical advantage
• ….???? worst
• .....???? bestException is tetraplegia - supine may be
better
Prop patient up with axillary pillows
Maintain trunk as upright as possible
Side lying with top hip flexed (recovery position)
Allows diaphragm to descend easily
Restrictive lung problems
Positioning for mechanical advantage
• Slumped sitting worst
• Upright or upright sitting bestException is tetraplegia supine may be better
Prop patient up with axillary pillows
Maintain trunk as upright as possible
Side lying with top hip flexed (recovery position)
Allows diaphragm to descend easily
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24/04/2019
Copyright ACPRC
Acprc.org.uk
Restrictive lung problems
Positioning for mechanical advantage
• Slumped sitting worst
• Upright or upright sitting best
• Maintain trunk as upright as possible
Prop patient up with axillary pillows
Side lying with top hip flexed (recovery position)
Allows diaphragm to descend easily
Exception is tetraplegia - supine may be better
Restrictive lung problems
Positioning for mechanical advantage
• Slumped sitting worst
• Upright or upright sitting best
• Maintain trunk as upright as possible
• Prop patient up with axillary pillows
Side lying with top hip flexed (recovery position)
Allows diaphragm to descend easily
Exception is tetraplegia - supine may be better
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24/04/2019
Restrictive lung problems
Positioning for mechanical advantage
• Slumped sitting worst
• Upright or upright sitting best
• Maintain trunk as upright as possible
• Prop patient up with axillary pillows
• Side lying with ..?? hip flexed (to unload the diaphragm)
Allows diaphragm to descend easily
Exception is tetraplegia - supine may be better
Copyright ACPRC
Acprc.org.uk
Side lying with upper/non-dependent hip flexed (recovery position)
Restrictive lung problems
Positioning for mechanical advantage
• Slumped sitting worst
• Upright or upright sitting best
• Maintain trunk as upright as possible
• Prop patient up with axillary pillows
• Side lying with upper hip flexed (recovery position)
• Allows diaphragm to descend easily (unloads it)
• Exception is??? tetraplegia - supine may be better
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Restrictive lung problems
Positioning for mechanical advantage
• Slumped sitting worst
• Upright or upright sitting best
• Maintain trunk as upright as possible
• Prop patient up with axillary pillows
• Side lying with top hip flexed (recovery position)
• Allows diaphragm to descend easily
• Exception is tetraplegia - supine may be better – why??
Restrictive Lung disease
Breathing techniques for mechanical
advantage

Tendency for extreme …….….?
Restrictive Lung disease
Breathing techniques for mechanical
advantage

Tendency for extreme tachypnoea
so what is the result….??
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Restrictive Lung disease
Breathing techniques for mechanical
advantage

Tendency for extreme tachypnoea so….

Poor /inadequate alveolar ventilation
Restrictive lung problems
Therapy aims?
Restrictive lung problems
Therapy aims

Reduce inflammation/oedema if the cause

Treat collapse (atelectasis or pneumothorax)

Support ventilation if due to weakness or
paralysis (non-invasive ventilation)

To try and allow/help the lungs to expand as
much as possible- how?
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Restrictive Lung disease
Breathing techniques for mechanical
advantage

Tendency for extreme tachypnoea so….

Poor /inadequate alveolar ventilation

Need to slow and deepen breathing

Which techniques then??.....
Restrictive Lung disease
Breathing techniques for mechanical
advantage

Tendency for extreme tachypnoea so….

Poor /inadequate alveolar ventilation

Need to slow and deepen breathing

Breathing control

Relaxed deep breathing

Blow-as-you-go

Paced breathing
Gas Composition of Air
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Gas Composition of Air
O2 %?
Gas Composition of Air
O2
20.93%
CO2 %?
Gas Composition of Air
O2
20.93%
CO2
0.03%
N2 %?
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Gas Composition of Air
O2
20.93%
CO2
0.03%
N2
79%
Gas Composition of Air
What is the role
of the N2?
Gas Composition of Air
N2 keeps the alveoli open
it is inert and can’t be absorbed
(at atmospheric pressure)
So…. what happens when we
replace some of this N2 with O2 by
increasing FiO2?
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Gas Composition of Air
N2 keeps the alveoli open
it is inert and can’t be absorbed
(at atmospheric pressure)
The more N2 is replaced with O2
The more O2 (gas) is absorbed over time
because of the A-a gradient
What will then hold the alveoli open?
Gas Composition of Air
Nuttin’ Honey!!!!
absorption atelectasis
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