Transcript Respiration - LearningSpace

Respiration
My notes
Learning Objectives
• Relate structure to function of the respiratory
system
• Give an account of the mechanisms of
ventilation: at rest, during exercise, swallowing &
during vocalisation
• Be aware of how a selection of common
conditions may affect lung function and the
relevance for SLTs
• Demonstrate knowledge of assessment and
treatment options for clients with lung conditions
Anatomy
• Refer to self directed study
The Thoracic Cavity
The Sternum
• Manubrium
• Body of sternum
•
Xiphoid process
The
Respiratory
Tree
(Airway)
The Diaphragm
The Plura
• 2 cavities-each containing a lung
• Outer parietal membrane, inner visceral membrane,
with fluid filled pleural cavity between them
Functions of fluid:
Acts as a lubricant
Surface tension forces ‘hold membrane together’
Blood supply
Separate blood supplies:
Parietal supply is systemic
Visceral supply is pulmonary
This has implications for fluid exchange
Ventilation
• Breathing or ventilation is a collective
term for two processes: inspiration and
expiration.
• Inspiration is an active process requiring
energy to drive muscular contraction.
• Expiration is largely a passive process,
achieved through relaxation and elastic
recoil of chest and lung structures.
Inspiration
• Inspiration is an active process driven by nerve
impulses from respiratory centres in brain.
• Activity in the phrenic and thoracic spinal nerves
results in contraction of the diaphragm and
external intercostal muscles.
• Expansion of chest cavity creates a lower air
pressure relative to outside of the body.
Expiration
•
When the body is at rest, the process of expiration
is passive, and is the result of elastic recoil of airway
tissues.
• Expiration can be made active during body
exertions, by using additional muscles in the ribcage (internal intercostal muscles) and abdomen
(abdominus rectus).
• This use of energy during forced expiration is an
important clinical consideration for persons with
airway disease.
The muscles of respiration
Muscle
Action
Diaphragm
Draws central tendon inferiorly facilitating inspiration
External intercostals
Draws the ribs upwards increasing volume of thoracic cavity
for inspiration
Internal intercostals
Draws the ventral part of the ribs downwards decreasing
volume of thoracic cavity for expiration
Abdominal muscles
External oblique
Internal oblique
Expiratory:
Pulls abdominal wall inwards increasing intra-abdominal
pressure and causing diaphragm to move into thoracic cavity
Displace rib cage downwards and inwards
Inspiratory:
Direct fascilitation of diaphragmatic action
Contract in phase with expiration
Transversus
abdominis
Rectus abdominis
Scalenius Anterior
Raises first rib for inspiration
Scalenius Posterior
Raises the first rib of inspiration
Scalenius Posterior
Raises second rib for inspiration
Sternocleidomastoid
Raises the first rib and sternum ‘pump handle’ action
The respiratory tree
•
•
•
•
•
•
•
•
Upper respiratory tract: nasal cavity and pharynx
Trachea
Primary (or main) bronchi
Secondary bronchi
12-13 generations of tertiary bronchi
Terminal bronchioles at generation 16
Then 3 generations of respiratory bronchioles
3 generations of alveolar ducts open into 300
million alveoli
Alveoli
• Alveoli are the
structures of gaseous
exchange in the lung
Alveolar capillary membrane: where
gas exchange takes place
• The alveolar membrane is composed primarily
of Simple Squamous epithelium which is very
thin so as to provide the minimum distance
possible for gaseous exchange.
Gas exchange
• Exchange of gasses (O2 & C02) across the alveolar
membrane occurs as a result of the pressure
differences across the alveolar capillary membrane
• Diffusion requires a concentration gradient.
• The concentration (pressure) of O2 in the alveoli must
be kept higher than the level in the blood to allow O2
to move into the blood.
• Conversely the concentration (or pressure) of CO2 in
the alveoli must be kept at a lower level than in the
blood. This allows CO2 to move into the alveoli and
ultimately be expired
Pulmonary Clearance
• The lining of the
respiratory system is
ciliated
• Mucus is produced in
goblet cells
Removal of inhaled particles
Particles trapped in mucous and moved by cilia
Particles >4.5 micrometres trapped in nasal passage
Smaller particles trapped in bronchial tree by mucociliary
escalator
Process can be effected by
• Stress
• Heavy dust exposure
• Cigarette exposure
• Infectious agents
• Temperature (cold)
• Poor ventilation
Lung volumes
Volume
Volume and description
Total lung capacity
The total volume the lung can
accommodate (4-8L)
Tidal volume
Volume of air moved during a normal
breath (0.4-1L)
Residual Volume
Volume of air remaining in the lungs
despite maximal exertion (1-1.5L)
Forced vital capacity FVC
The maximal volume of air which can be
moved in and out during a single breath
following a maximal inspiration (4-5L)
FVC1
Lung Volumes
Control of Respiration
• Respiration is largely controlled by nervous
activity.
• Mediated by the respiratory centres found in
the brainstem.
• Breathing is largely an involuntary process,
controlled by rhythmic nerve impulses
originating in the respiratory centres.
• Three major areas of the brainstem involved
in breathing have been identified..
Respiratory centres
• Dorsal respiratory group (DRG) in the medulla:
– Appears to be the respiratory pacemaker
(inspiratory centre).Has cyclic on/off activity
producing12-15 breaths per minute.
• Pontine respiratory group (PRG):
– also called pneumotaxic centre. Inhibitory
impulses from here fine tune breathing.
• Ventral respiratory group (VRG) in the medulla:
– Role not exactly clear, but has mixture of neurons
involved in inspiration & expiration. Mainly
involved in forced breathing.
Influences on the respiratory centres
• Higher brain centres in the cerebral cortex can exert voluntary
control over breathing as well as hypothalamic centres involved
in emotion & pain.
• Peripheral chemoreceptors in vascular system and central
chemoreceptors in brain detect changes to oxygen, carbon
dioxide and acidity levels.
• Stretch receptors and irritant receptors in lungs and activity
receptors in muscles and joints also send messages to
respiratory centres.
Ventilation during exercise/excursion
Ventilation during speech.
To achieve phonation and articulation, the normal pressurized
air stream of expiration is transformed into a series of pulses by
constricting the air stream at the vocal folds in the larynx or at
other locations in the respiratory tract and oral cavity (the vocal
tract)
For each phoneme* or physical segment of a sound a specific
frequency of vibration is generated which passes through the
vocal tract.
This is a highly complex process in which certain frequencies
are enhanced and others are damped down by manipulating
the shape of the vocal tract and the pressure and rate of
airflow.
.
The demands of speech production are so different from the
other functional demands that the normal control and pattern of
ventilation have to be overridden.
Speech is created during the expiratory phase and respiratory
muscle activity and elastic recoil has to be used to maintain and
vary the pressure gradient across the vocal cords.
The respiratory cycle must also be coordinated so that
appropriate divisions of speech into phonemes, syllables,
words, phrases and sentences can occur.
The inspiratory cycle increases in volume and becomes more
rapid, taking about 0.6 sec compared to about 2 seconds in
normal quiet breathing.
The expiratory cycle is prolonged to conserve the speech
divisions. In some instances it may occur over a period of
about 30 seconds.
For speech to be maintained in an effective manner, an
adequate pressure must be maintained across the vocal cords.
This would become difficult if the expiration was to proceed to
residual volume (as in a maximal forced expiration) and
normally the next inspiratory cycle occurs at a lung volume well
above residual volume.
In normal conversation this will occur at a volume of about 1.5
litres above residual capacity. In loud speech this volume will
have to be increased to a point were it approaches inspiratory
capacity.
Clearly any increased inspiratory capacity requires greater
involvement of the external intercostal muscles and possibly
the accessory muscles of inspiration
The control of air pressure across the vocal cords during the
expiratory phase requires a complex interaction of the muscles
of inspiration (to counteract the tendency for elastic recoil) as
well as the muscles of expiration (particularly as the expiratory
movement proceeds and lung volume declines).
The complexity and particularly the rapidity of the controls is
such that normal mechanisms of efferent (motor) activity and
associated afferent (sensory) feedback would take too long and
as a result vocalisation involves a complex series of learned
neural patterns.
1.
2.
Respiration during swallowing
INVESTIGATION
Observations
• Respiratory rate
• Breathing pattern
– Diaphragmatic
– Thoracic
– Clavicular
Think yourselves lucky, when I trained we had to
wear just bra and were very, very embarrassed
Pulse Oximetry
Vitaolgraph ‘alpha’
Mini Wright Peak Flow meter
http://www.youtube.com/watch?v=6kbgZWS5wH0
The Forced
Expired
Volume
(FEV1)
An indication of lung compliance (ability to breathe efficiently).
LUNG CONDITIONS
Pneumonia
• Inflammatory condition of the lung
Pneumonia and SLT
• Aspiration pneumonia
Chronic Obstructive Pulmonary Disease
Chronic Bronchitis
Excess mucus production form the large airways
Daily cough. 3 months/year. 2 consecutive years
No obstruction
Obstructive Bronchitis
• Small airway
obstruction with
inflammation and
fibrosis
Emphysema
• Destruction of alveolar walls
• Abnormal enlargement of air spaces
• Loss of elasticity
• Impaired gas transfer
• Obstruction of airways
• Smoking is biggest cause
• A1antitripsin deficiency
COPD and SLT
• Dysphagia
• Communication
Management
Voice/ Communication
Swallowing
• Team working
• Medication
• Nutrition and hydration
• Anxiety
• Breathing techniques and pacing
• Specific techniques