Cosmed Quark PFT, Manual

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74 - Quark PFT User Manual
Lung volumes tests (N
2
washout)
In the PFT lab the measurement of “Lung Volumes” usually refers to the measurement
of Total Lung Capacity (TLC), residual volume (RV), functional residual capacity
(FRC), and Vital Capacity (VC). These measurements are essential to assess lung
function, they are important for the diagnosis of restrictive disorders.
FRC is most commonly determined with one of three basic techniques:
1. Multiple-breath open circuit Nitrogen washout
2. Body
Plethysmography
3. Multiple-breath closed circuit Helium washout
COSMED Quark PFT uses the nitrogen wash-out technique to measure Lung volumes.
This method involves removing or “washing-out” the N2 gas present in a patient’s lung
by having the patient breathe 100% O2 for several minutes (usually 7 minutes or until
the final concentration of N2 is below 1.5-2.5%). Since the whole expired nitrogen
come from the initial lung volume, a simple equation allows to get FRC value.
The main parameters measured during this test are:
FRC Functional Residual Capacity
CEV Total ventilated volume during the test
Wash-out time Test duration
RV Residual Volume
TLC Total Lung Capacity
RV/TLC Motley index
Recommendations
•
The system must be calibrated before each test (See Calibration chapter)
•
The flowmeter must be connected properly to the breathing valve and the soft
mouthpiece must be properly fixed to the corresponding adapter.
•
Check that the O
2
cylinder is open and its output pressure is adjusted in the range 5-
6 bar.
Setting N2 wash-out options
1. Select Settings... from Options menu.
2. Select Multi-breath N
2
Wash-out
3. Set the desired value in all the fields described in the next table.