8976 Lecture Notes - Lecture 8: Pneumothorax, Exhalation, Asthma
2 Jul 2018
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Department
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Lung Function Testing for Physiotherapy
- Spirometry + flow volume loops (dynamic lung volumes)
- SpO2 = O2 saturation (pulse oximeter)
- End tidal CO2 (ventilated patients)
- Maximum inspiratory/expiratory pressures (strength of muscles using MIP’s + MEP’s)
- Sleep studies – gas exchange, breathing
Spirometry
http://www.youtube.com/watch?v=AzXpNAEb8gU
Why: Impaired ventilator function most common physiological abnormality affecting the
lung.
Indications:
- Detecting/assessing respiratory disease + symptoms (eg. Breathlessness, wheeze)
- Differenting respiratory form cardia disease
- Differentiating obstructive from restrictive disease
- Assessing response to treatment (eg. Bronchodilators)
- Preoperative risk stratification prior to surgery.
Measures: forced vital capactity (FVC), and how much in the first second (FEV1).
Spirometry quantifies the volume expelled from the lungs per unit time (seconds).
Method: Breathe tidally, using maximal effort breathe right in as much as you can right to
the top of your lungs (reach TLC), then put your mouth on the spirometer and blow out as
fast and as much as you can (for at least 6 seconds), and then keep blowing some more
(close to empty as possible = RV).
VC = relaxed manoever (not forced)
FEV1 = forced expired volume in 1 sec in (ml or L’s)
FVC = forced vital capacity (mL or L’s)
find more resources at oneclass.com
find more resources at oneclass.com
Results: for volume are reports at body temperature and pressure saturated (BTPS).
Evaluation: Compare what normal values are vs the ones presented. Eg. Age (^^ up to 20F +
25M) and d. following that. Gender (M>F). Height (taller = bigger lungs). Ethnic
(Caucasians>Africans>Chinese>Polynesians).
Normal Values = 80 – 120% of predicted values.
Abnormal = anything less than 80% of predicted.
Choose highest value from Trials and compare to predicted.
FEV1/FVC Ratio
What percentage of total air expelled is expelled within the first second.
Use results from same trial to calculate (not maximums).
If you get less than 70% of the air out in the 1st second = significant airway obstruction.
^ Results = not obstructive.
find more resources at oneclass.com
find more resources at oneclass.com
Flow Volume Loops:
Flow = change in volume / change in time
Measured in litres/second at BTPS (standard body temp, pressure saturated).
Normal = straight-sided triangle
Height = peak expiratory flow rate (L/sec, or L/min).
Peak Expiratory Flow:
- Index of large airway obstruction
- Influenced by patient effort (>85% VC)
- Used to monitor asthmatics (especially with poor perception of airway narrowing):
oTrends in lung function
oTrigger factors
oEffects of treatment
Tidal breathing (loop), inspiration + manoeuvre.
FRC = Functional residual capacity
Maximal Expiratory manoeuvres generate large positive intra-pleural pressure (between
pleura) as all inspiratory muscles are used to pull in air.
There is no change in pressure through the whole manoeuver, it is flow that decreases.
Each point shows the maximum flow at a given volume.
Lower lung volume = less tethering forces at alveolar level.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Spirometry + flow volume loops (dynamic lung volumes) Maximum inspiratory/expiratory pressures (strength of muscles using mip"s + mep"s) Why: impaired ventilator function most common physiological abnormality affecting the lung. Detecting/assessing respiratory disease + symptoms (eg. breathlessness, wheeze) Measures: forced vital capactity (fvc), and how much in the first second (fev1). Spirometry quantifies the volume expelled from the lungs per unit time (seconds). Fev1 = forced expired volume in 1 sec in (ml or l"s) Fvc = forced vital capacity (ml or l"s) Results: for volume are reports at body temperature and pressure saturated (btps). Evaluation: compare what normal values are vs the ones presented. Normal values = 80 120% of predicted values. Abnormal = anything less than 80% of predicted. Choose highest value from trials and compare to predicted. What percentage of total air expelled is expelled within the first second. Use results from same trial to calculate (not maximums).
