Lung Function Booklet Flashcards
Explain how to measure peak expiratory flow (PEF)
- Patient takes a full breath in (i.e. TLC) and then exhales as rapidly as possible into a suitable measuring instrument
What are the most common measuring instruments of PEF?
- Wright’s peak flow meter: not very precise, portable
- Spirometer: a flow-measuring device with a continuous output, more precise
What is the unit of measurement of PEF?
L/min.
What is the pattern of normality of PEF?
- 36 y.o. male, height 183cm: 620 (+/- 60) L/min
- Diurnal variation: lower in morning than in evening, should be less than 10%
What are the most common measuring instruments of PEF?
- Wright’s peak flow meter: not very precise, portable
- Spirometer: a flow-measuring device with a continuous output, more precise
What is the unit of measurement of PEF?
L/min.
What is the significance of a abnormal values for PEF?
This suggests airflow obstruction.
Describe dynamic lung volumes
- FEV1 and FVC are measured during a forced expiration from TLC to RV (like PEF)
- FEV1:FVC indicates lung volume and airway calibre that allows that air volume to be exhaled
What is the most common measuring instrument of DLVs?
Spirometer.
Explain how to measure peak expiratory flow (PEF)
- Patient takes a full breath in (i.e. TLC) and then exhales as rapidly as possible into a suitable measuring instrument
What is the pattern of normality of PEF?
- 36 y.o. male, height 183cm: 620 (+/- 60) L/min
- Diurnal variation: lower in morning than in evening, should be less than 10%
What is the unit of measurement for PEF?
L/min.
What is the pattern of normality of DLVs?
36 y.o. male, height 183cm:
- FEV1 = 4.5 (+/- 0.5) L
- FVC = 5.6 (+/- 0.6) L
- FEV1:FVC = 81 (+/- 5%)
What is the significance of a reduced value for DLVs?
- Fall in FEV1 and fall in FEV1:FVC suggests airway obstruction
- Fall in FEV1 but FEV1:FVC remain same suggests restrictive ventilatory problem
What is the most common measuring instrument of DLVs?
Spirometer.
What is the unit of measurement for DLVs?
- FEV1 and FVC are expressed as absolute volume in L
- Sometime expressed as % in reference to predicted values
- Compared to atm T and P (ATPS) or to body T and P (BTPS)
- FEV1:FVC ratio expressed as %
What is the pattern of normality of DLVs?
36 y.o. male, height 183cm:
- FEV1 = 4.5 (+/- 0.5) L
- FVC = 5.6 (+/- 0.6) L
- FEV1:FVC = 81 (+/- 5%)
What is the significance of a reduced value for DLVs?
- Fall in FEV1 and fall in FEV1:FVC suggests airway obstruction
- Fall in FEV1 but FEV1:FVC remain same suggests restrictive ventilatory problem
What is the most common measuring instrument of SLVs?
Apparatus comprises of;
- Two bags: one for initial gas mix, one to collect sample
- A valve to switch between both bags
- A system to remove CO2 from first bag
- An O2 source to add O2 into first bag
- Series of analysers to measure O2, CO2 and inert gas concs
What is the unit of measurement for SLVs?
- All in L
- TLC, VC RV, TV, FRC
- RV/TLC
What is the unit of measurement for SLVs?
- TLC, VC RV, TV, FRC: litres
- RV/TLC: %
What is the pattern of normality of SLVs?
36 y.o. male, height 183cm;
- FRC = 3.7 (+/- 0.7) L
- RV = 1.9 (+/- 0.4) L
- VC = 5.6 (+/- 0.6) L
- TLV = 7.3 (+/- 0.8) L
- RV/TLC = 25 (+/- 0.4) % (increase in obstructive, decrease in restrictive)
What is the significance of a reduced value for SLVs?
Obstructive;
- Increased TLC, RV, FRC
- Increased RV/TLC ratio
Restrictive;
- Decrease all
- Normal/low RV/TLC ratio
