Week 2 Flashcards
What is the aim of lung function tests
assess the effectiveness of lung function to meet metabolic demands of the body’s tissues
- ventilation
- pulmonary blood flow
- diffusion
- control of ventilation
What is spirometry
a physiological test of lung function, assessing the mechanical properties of the pulmonary system
- timed measurement of how the lungs work and is used to
- measure how effectively air moves into and out of the lungs : how fast it flows and how much volume
–provides measure of airway size, lung size and muscle strength
Uncomplicated, non invasive investigation
affordable, portable equipment
minimal training required to perform
most broadly used test
**important test to detect, quantify and monitor diseases that limit ventilator capacity
What is COPD
Chronic Obstructive Pulmonary Disease
Indications for spirometry (8)
screening, detecting and assessing for respiratory disease
Assessing respiratory function
differentiating respiratory and cardiac diseases as the cause of breathlessness
diagnosing respiratory diseases - obstructive vs restrictive
Assessing the severity of disease
Assessing the response to treatment
Assessing pre-operative risk
Occupational health related assessments
Complications of spirometry
Requires maximal effort and subject cooperation -Transient breathlessness oxygen desaturation syncope chest pain cough light-headedness bronchospasm
Contra-indications of spirometry
High positive intr-thoracic pressure and its transmission to vascular, abdominal and other body parts may be detrimental = best to delay spirometry
Recent eye surgery (1-4wks) or recent brain surgery(3-6wks)
Recent thoracic and abdominal surgery (in last 7 days)
Aneurysms (cerebral or abdominal)
Recent CVAs
Unstable cardiac function / angina or recent myocardial infarction in past 7 days
uncontrolled hypertension
haemoptysis of unknown cause
Pneumonthorax in last 3 weeks
Nausea, vomiting or diarrhoea
Untreated pulmonary embolism
What can cause an inaccurate result
Chest or abdominal pain pain in mouth or face stress incontinence dementia recent alcohol consumption
Patient related problems with spirometry
variable or submaximal effort insufficient inspiration or expiration leaks between the lips and mouthpiece slow or hesitation at the start of the test cough particularly within the 1 sec glottis closure tongue blocking mouth piece
Repeatability criteria for spirometry
to ensure that the tests are producing reliable and consistent results
these criteria determine when more than 3 manoeuvres are required to achieve an accurate result
- the difference between the best FEV1 and the second best FEV1 must be within 0.15L
- -if FEV is
Acceptability Criteria for spirometry
•Used to determine that the patient has performed the test manoeuvre correctly
•Criteria required to be met:
–Test begins from full inspiration (start of test)
-Rapid start of test (start of test)
–Continuous maximal expiratory flow (end of test)
–Expiration time >6 secs (adult) and >3 secs (child) or no change in volume for at least 1 sec (end of test)
–No obstruction, hesitation or artefact impeding the blow (end of test)
On x-ray signs of a pneumothorax
- visible lung edge - sharply outlined diaphragm
- loss of lung parenchyma markings within the lung fields
Pneumothorax is
A pneumothorax involves damage to the lung tissue and pleura so that air accumulates within the pleural space.
Presenting complaints of a pneumothorax
- pleuritic chest pain
- dyspnea – decreased breath sounds on affected side
- tachypnoea
- tachycardia
- low O2 sats (not necessary in all cases)
- history of recent chest wall injury (not necessary in all cases)
- previous history of spontaneous pneumothorax (not necessary all cases)
- tracheal deviation (late sign).
Haemothorax is
A haemothorax involves damage to the lung tissue and pleura so that fluid (i.e. blood) accumulates within the pleural space.
On x-ray signs of haemothorax
On an upright x-ray, a haemothorax may present with a visible fluid level. aka. Air-fluid level
–No mensicus sign
Although the cause of a pleural effusion is quite different to a haemothorax, radiologically they are similar in appearance.
On x-ray signs of Pleural Effusion
–Fluid collects in pleural cavity
–Collects in the costophrenic angles
–“Mensicus sign”
Acid-Base balance Equation
H2O + CO2 = H2CO3 = H+ + HCO3-
Hyperventilation signs and symptoms
•Low PaCO2
•Rise in pH
•Symptoms
–Tingling around the mouth and extremities
–Light‐headedness
–Syncope
•Secondary hyperventilation occurs in Metabolic Acidosis
Clinical signs of hypercapnia
- Confusion
- Flapping tremor
- Warm extremities
- Drowsiness
- Bounding pulse
- Headache
- Flushed skin
- Coma
Clinical Signs of Hypoxaemia
- Restlessness
- Confusion
- Aggression
- Sweating
- Fittng or convulsions
- Plucking
- Increased RR, HR and BP
- ECG changes
- Blurred vision, tunnel vision
- Pallor
Type 2 Respiratory Impairment
•High PaCO2 (>50mmHg)
•Usually low PaO2
•Due to inadequate alveolar ventilation
•Type 1 Respiratory Impairment – can lead to Type 2
•Treatment
•Improve ventilation
•SaO2
– no help to monitor as doesn’t monitor CO2
Type 1 Respiratory Impairment
•Low PaO2 (
3 Disorders of Gas Exchange
- Hypoxia
- Hypoxeamia
- Impaired oxygenation
Hypoxia is
any state in which tissues receive an
inadequate oxygenation to support normal
aerobic metabolism
Hypoxeamia is
any state in which the O2 content in arterial blood is reduced
Impaired oxygenation
hypoxaemia resulting from reduced transfer of O2 from lungs to the bloodstream. PaO2
Oxyhaemoglobin Dissociation
Curve shifts to the left when
increase PH
decrease PCO2
decrease temp
decrease 2,3 DPG
Oxyhaemoglobin Dissociation
Curve shifts to the right when
decrease PH
increase PCO2
increase temp
increase 2,3 DPG
Haemoglobin Oxygen Saturation SaO2
•PO2 doesn’t tell us how much O2 is in blood
–Measures free, unbound O2 molecules (tiny
proportion of the total)
•Almost all O2 molecules in blood are bound to Haemoglobin (Hb).
•The amount of O2 in blood depends on 2 factors:
–Hb concentration
–Saturation of Hb with O2
Normal pH
7.35-7.45
Normal PCO2
35-45mmHg
Normal HCO3
22-26
Normal PO2
80-100mmHg
Normal BE
-2.0-2.0
conditions that may result in the appearance of air bronchograms
- pneumonia / lung consolidation
- atelectasis
- pulmonary oedema.
Oxygen therapy is
the administration of oxygen to a patient at concentrations greater than that in ambient air with the intent of treating or preventing the symptoms and manifestations of hypoxia.
Interpretation of spirometry results
Once the acceptability and repeatability criteria have been met and at least 3 test manoeuvres completed, the best results need to be selected for interpretation
The American Thoracic Society and European Respiratory Society 2005 Spirometry guidelines state
Stipulate that the best test values are selected by
-identifying that the best test values are selected by:
-identifying the highest FVC and FEV1 measurements from acceptable and repeatable tests.
- these do not need to be from the same manoeuvre
-Identify the manoeuvre with the highest sum of FEV1 + FVC = best curve
-Identify other indices that need to be reported from the best curve (e.g. PEF, FEVt etc)
Only data from acceptable and repeatable efforts are to be included
Predicted Reference values
interpretation begins with comparison between patients actual spirometry values and predicted values for health individuals of the same age, height, gender and ethnic origin
Patients values
Lower limit of normal (LLN)
Predicted value = average value which has been calculated form typical normal healthy subjects
The data allows for a normal range (bell curve) to allow for variation in lung size
LLN = the point in the normal range below which only 5% of normal subjects values fall
- any values below the LLN are considered abnormal
- not all spirometry curves give you LLN’s
Interpreting Diagnostic Patterns
Interpretation of spirometry involves recognising abnormalities or patterns in the measurements while evaluating results against the patients clinical state
What are four diagnostic patterns
normal
obstruction - cannot blow out quickly
restriction - small lungs
mixed - small lungs and cannot blow out quickly
What is normal
normal FEV1, FVC and FEV1/FVC
What is obstruction
Reduced FEV1 and FEV1/FVC
normal FVC
What is mixed
Reduced FEV1, FVC and FEV1/FVC
Percentage of FEV1 predicted value mild degree of severity
> 70%
Percentage of FEV1 predicted value moderate degree of severity
60-69%
Percentage of FEV1 predicted value moderately severe degree of severity
50-59%
Percentage of FEV1 predicted value severe degree of severity
35-49%
Percentage of FEV1 predicted value very severe degree of severity
> 35%
Reversibility testing
spirometry used to assess airway reversibility
patient is tested pre and post bronchodilator
used to diagnose and treat patients reversible airways disease i.e. COPD and asthma, by assessing the effects that bronchodilators have on lung function
Define a significant change post bronchodilator
Increase in FEV1 or FVC of 12% or > and
Change must be at least 0.2L
Absolute change in FEV1 = (post bronchodilator FEV1- baseline FEV1
% improvement FEV1 = Post bronchodilator FEV1 - baseline FEV1 / baseline FEV1) x 100
How to assess reversibility
Conduct 3 acceptable and repeatable test manoeuvres prior to bronchodilator and a long time since last bronchodilator
patient takes bronchodilator
after 10 mins, no later than 25 mins conduct 3 more acceptable and repeatable manoeuvres
Why do physio’s care about ventilation?
Breathing is essential to life
ventilation strategies are essential to your physio toolkit
Aim :
-identify ventilation problems or those at risk of these problems
select and implement most appropriate technique for that individual
Respiration
Respiratory controller to respiratory muscles to rib cage & pleura and abdomen to movement of air to alveolar ventilation
Characteristics of Respiratory controller
respiratory centre - involuntary
cortical control - voluntary
conditions that may affect this
- pharmacological
- head injury
- tumour
- CVA
Pathway to muscles
nerve conduction and synapses
conditions that may affect these
- guillian barre syndrome
- spinal cord injury
- MS
Respiratory Muscles
Diaphragm
intercostals
SCM
Scalenes
conditions that may affect these -myopathies muscular dystrophy fatigue surgery
Rib cage and pleura
Bones -Rib #'s -Post surgery -Scoliosis Abnormal chest wall compliance Pleura -pneumothorax -Haemothorax -Pleural effusion
Abdominal
pressure changes
- distended
- obesity
- pregnancy
- constipation
- abdominal surgery
- pancreatitis
Abnormal mechanics (muscle flaccifity)
-spinal cord injury
guillian barre
Movement of air
inhibition - pain
-surgery
chest trauma
compression
-tumour
pneumo or haemothorax
cardiomegaly
Alveolar Ventilation
Bronchi to alveoli
- secretions within bronchi
- tumour within bronchi
- asthma
- Bronchitis
Within alveoli
- decreased surfactant
- pulmonary oedema
- inflammation of tissue -pneumonia
What does FRC stand for
Functional Residual Capacity
What is Functional Residual Capacity
Volume of gas in the lung after a normal expiration
Balance between the inward recoil of the lungs and the outward recoil of the chest wall
Volume of gas that participates in gas exchange during inspiration and expiration
-Gas exchange still occurring even when not breathing
Closing Capacity (CC)
Volume of air in lung when small airways in dependant lung start to collapse during expiration
Healthy individuals
- CC approx. =RV
- CC > FRC
Critical Opening Pressure
The pressure needed to overcome surface tension and achieve initial re-inflation of collapsed regions
Inflating alveoli is similar to blowing up a balloon
Physiotherapy techniques to improve ventilation
Pain relief positioning breathing exercises demand ventilation / mobilisation facilitation techniques incentive spirometry positive expiratory pressure devices non-invasive ventilation oxygen therapy
Pain relief
physiotherapists don’t prescribe or administer
required to optimise inspiratory volume
PT
-monitor patient’s pain levels before, during and after treatment
time tr
What do chest X-rays do
provide an insight into the lungs and chest wall
used as the main radiological investigation of the chest
indicated in almost any condition in which pulmonary abnormality is suspected
do have limitations
-x-rays findings tend to lag behind other measurements
CXR views
frontal -PA vs AP
Lateral
Lateral decubitus
PA
posterioanterior view
beam passed from posterior to anterior of patient
optimum view for the lungs
usually done erect (standing) allows for full inspiration with shoulders abducted
gas passes upwards - pneumothorax
fluid passes downwards - pleural effusion or haemothorax
AP
anteriorposterior view beam passed from anterior to posterior of patient sitting or supine position disadvantages -mediastinum is magnified poor inspiration due to sitting rotation
Lateral
labelled side is closest to the cassette
beam passes through laterally
confirms if PA/AP equivocal opacity is real
Lateral decubitus
patient lying on their side beam passes anteroposteriorly used to problem solve -pneumothorax -pleural effusion
Abnormalities
can be identified as
- too black
- too white
- too big
- in the wrong place
X ray reading
patient details
position
technical adequacy
systemic interpretation
Assessment of technical adequacy
inspiratory effort
rotation
angulation
exposure
Inspiratory effort
anterior aspects of at least 6 ribs sit above right hemidiaphragm
complications
- cardiac size may appear enlarged
- crowding of vessels at the lung bases
Rotation
vertical line drawn through the centre T1-T4
Each clavicle should be equidistant from the median end
complications
-heart size and shape
-relative density of lung fiends, one side looks blacker
Angulation
clavicle should be projected over the posterior 3rd rib
Exposure
should be able to see T4, not T5 Over exposed -appears black - low density lesions are missed Under exposed -falsely white
Opacity vs Lucency
Tissues absorb x-rays differently to produce film black = air slightly lighter than black= fat grey = soft tissue light grey = bone
Systemic approach to interpretation
Tubes and lines lung fields hilum Heart and mediastinal contours diaphragm including underneath costophrenic angles trachea bones soft tissue comparison with previous imaging
Tubes and Lines
endotracheal tube (ETT) Tracheostomy Tube Intercostal catheter (ICC) Central venous lines (CVL) Swan ganz catheters Nasogastric tubes (NGT) Pacemaker leads Pittfalls
Lung fields
should be equal transradiancy
horizontal fissure - hilum to the 6th rib in the axilla - displaced a sign of collapse
compare size
Hilum
Pulmonary vein and artery, bronchi and lymph
left hilum higher than right
compare shape and density should be concave
Distance apex to hilum = distance base to hilum
Heart
check that the heart is normal shape
maximum diameter is >50% of the transthoracic diameter
- 1/3 to right of midline
- 2/3 to left of midline
Check no abnormally dense areas of heart shadow
cardiophrenic angles
Mediastinum
borders
- fuzziness normal at angle between heart and diaphragm
- fuzzy edges in other areas suggest problem with neighbouring lung
- -collapse or consolidation
trachea should be visible
Diaphragm
2 hemidiaphragms - right and left
right is higher than left
costophrenic angles
angles between the diaphragm and ribs laterally
should be well defined acute angles
trachea
should be central but deviates slightly to the right
if shifted suggest a problem with mediastinum or pathology within the lungs e.g. collapse
Bones
look at the ribs, scapulae and vertebrae
follow the edges of each individual bone for any fractures
compare density of bones between each side
Soft tissue
look for any enlargements of soft tissue areas
Pleural effusion
fluid collects in pleural cavity
collects in the costophrenic angles
-“meniscus sign”
Pneumothorax
lack of lung markings
inferiorly - deep sulcus sign and sharply outlined diaphragm
Tension pneumothorax
Ipsilateral disaphragm depressed and flattened
mediastinum and heart pushed to other side
Haemothorax
Air fluid level
no meniscus sign
Collapse
displacement of mediastinum, hilum, fissure - volume loss
elevation of hemidiaphragm
decrease in rib spacing
opacity
Consolidation
air filled spaces replaced with fluid, blood, sputum
Don’t forget
rib # and subcutaneous emphysema
The measurement of pH and the partial pressures of oxygen and carbon dioxide in arterial blood
Pa02 and PaCO2 used to assess the state of acid base balance in blood and how well lungs are performing their job of gas exchange
Gases move down partial pressures
air in alveolar - higher partial pressure of 02 and lower partial pressure of CO2 than capillary blood
PaCO2
PaCO2 is controlled by ventilation and the level of ventilation is adjusted to maintain PaCO2 within the right limits
Normal values
pH - 7.35-7.45 PCO2 35-45mmHg PO2 - 80-100mmHg HCO3 - 22-28 BE (-)2.0 - 2.0
Hypoxic drive
chronically high PaCO 2 levels (chronic hypercapnia)
Receptors become desensitized to CO2 levels
Body then relies on receptors that detect the PaO2 to gauge the adequacy of ventilation stimulus = hypoxic drive
Need to limit administering supplemental O2 when hypoxemic as an increase in O2 will depress ventilation leading to a rise in PaCO2
Haemoglobin oxygen saturation SaO2
PO2 doesn’t tell us how much O2 is in the blood
-measures free, unbound O2 molecules (tiny portion of the total)
Almost all O2 molecules in blood are bound to haemoglobin (Hb)
The amount of O2 in blood depends on 2 factors
-Hb concentration
-saturation of Hb with O2
Review pages
15- 2& 3
16 -1
Alveolar ventilation and PaO2
factors that dictate Pa02
- alveolar ventilation
- matching of ventilation with perfusion (V/Q)
- concentration of O2 in inspired air (FiO2)
`V/Q mismatch and shunting
Allows poorly oxygenated blood to re-enter the arterial circulation - lowering PaO2 and SaO2
Overall alveolar ventilation is maintained, V/Q mismatch does not lead to an increase in PaCO2
FiO2 and Oxygenation
FiO2 - the % of O2 in the air we breathe in
Exact FiO2 requirement varies depending on severity of oxygenation impairment and mode of delivery
Increasing FiO2 will not reverse a rise in PaCO2 in inadequate ventilation cases
Disorder of Gas exchange
Hypoxia - any state in which tissues receive an inadequate oxygenation to support normal aerobic metabolism
Hypoxaemia - any state in which the O2 content in arterial blood is reduced
Impaired oxygenation - hypoxaemia resulting from reduced transfer of O2 from lungs to the bloodstream, PaO2
Type 1 respiratory impairment
Low PaO2 (>80mmHg) Normal or low PaCo2 Implies defective oxygenation despite adequate ventilation
Severity
-mild PaO2 60-79mmHg
Moderate PaO2 40-59mmHg
Severe PaO2
Clinical signs of Hypoxaemia
Restlessness confusion aggression sweating fitting or convulsions plucking increased RR, HR and BP ECG changes Blurred vision, tunnel vision Pallor
Type 2 respiratory impairement
High PaCO2 (
Clinical signs of hypercapnia
Confusion flapping tremor warm extremities drowsiness bounding pulse headache flushed skin coma Review Page 19 -2
Hyperventilation
Low PaCO2 Rise in pH Symptoms -tingling around the mouth and extremities -light headedness -syncope
Secondary hyperventilation occurs in metabolic acidosis
Acid base balance Pg. 20-2
H2O + CO2 = H2CO3 = H+ + HCO3
Maintaining acid base balance
Maintain blood pH H+ ions removed -respiratory mechanisms --removal of CO2 --Minutes to hours -Renal mechanisms --kidney adjust H+ in urine and HCO3 excretion in response to changes in metabolic acid production --days to develop
Disturbances of Acid-‐Base Balance
PaCO2 raised - respiratory acidosis
PaCO2 raised - respiratory alkalosis
HCO3 raised - Metabolic Alkalosis
HCO3 Low - Metabolic Acidosis
Steps to analysing ABG’s
pH - is there an acidosis or alkalosis
look at PaCO2
-decreased pH/increased PaCO2 or increased pH/ low PaCO2 = respiratory problem
Is it an acute or chronic respiratory problem
Look at HCO3
-decreased pH/ decreased HCO3 or increased pH/increased HCO3 = metabolic problem
pH is compensated / uncompensated/partially uncompensated
Oxygen therapy
is the administration of oxygen at concentrations greater than that in ambient air correct hypoxaemia (PaO2
Goal of oxygen therapy
return to normal or near normal tissue oxygenation without causing
-a reduction in ventilation
increase in PaCO2
Oxygen toxicity
Oxygen and physio
is a drug - prescribed by a Dr
physio
-assess oxygen delivery to ensure correct mode of delivery
-assess the need for oxygen with exercise
-advise whether oxygen therapy is sufficient
-can alter prescription in certain situations
Dangers of OxT
Chronic respiratory failure
oxygen toxicity
depression of ciliary function
absorption atelectasis
Mode of delivery
low flow (variable performance devices ) -nasal prongs -Hudson mask -rebreather masks (partial and non-rebreather) High flow (fixed performance devices ) -venturi mask -high flow
Nasal prongs
inexpensive comfortable, less noticeable can eat and drink may cause pressure areas and mucosal damage flow rate - 1-4L/min FiO2 - 0.24-0.36 (low concentration)
Hudson mask
Inexpensive
patient may find mask hot, confining and uncomfortable
vent holes on sides for release of exhaled gases and to mix with room air
need flow rate >5L/min to prevent rebreathing of exhaled gases
FiO2 - 0.35-0.50 (mod concentration)
Rebreather masks
partial rebreather mask
-exhaled oxygen from the anatomical dead space is conserved
-insufficient flow causes rebreathing of CO2
FiO2 - 0.4-0.6 (high concentration)
Nonbreather mask
-one way valve between reservoir bag and mask and over exhalation parts of mask
-prevents exhaled gases and room air from entering
-FiO2 - 0.6-0.8 (very high concentration)
Short term use only
Venturi mask
more expensive
high flow rate
able to accurately determine FiO2
FiO2 - 0.24-0.6
High flow circuits
accurately determine FiO2
Can deliver via nasal prongs, mask, tracheostomy
usually used with humidification
FiO2 - 0.3- 100%
Ciliary function
adversely affected by -age -artificial airways dehydration inhaled anaesthetics lack of sleep medications - e.g. narcotics, sedatives oxygen therapy smoking
Prevent adverse effects of ciliary function by
hydration - oral or IV fluids
Humidification
nebulisation
Swedish nose (tracheostomy)
Humidification
mechanism
-gas is blown over a reservoir of heated sterile water and absorbs water vapour, which is then inhaled by the patient
Humidification indications
thickened secretions consolidation major infection artificial airway High FiO2
Nebulisation
Mechanism
-converts solution into fine droplets (aerosol particles) suspended in a stream of gas, carried into the airways via mouthpiece or mask
used to deliver
-medications- bronchodilators, corticosteroids, antibiotics, antifungals, mucolytics, hypertonic saline
Moisten the upper airways - normal saline
Nebulisation cont
particle size and deposition
- 1-10 microns
- pattern of deposition in bronchial tree depends on
- particle size
- methods of inhalation
- degree of airflow obstruction
Nebulisation application
need flow rate of 6-8L/min
can be by medical air or oxygen
mouth breathing
Long term oxygen therapy
shown to improve the length and quality of life in selected patient with severe chronic airflow limitation
- continuous
- intermittent
- exercise
