Guide
5 Pages
Preview
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The Spiro Air LT is a volume displacement low resistance rolling seal Spirometer. It performs the standard testing of the Simple Spirometry and Flow Volume work as for any module within the Expair software family. The prime difference is the method of communication, the system uses a USB2 connection and this is also the total source of power for the unit. The configuration under the Expair’Tec Hyp’air Spiro Air tab is as follows; The driver loaded is the USBXpress driver, this communicates the volume and flow derived signals as well as in the major model integrating a full weather station with sensors for the ambient Temperature, Pressure and Humidity.
The testing possibilities for this model are as set in the Key numbers;
Static Spirometry (simple Spirometry) (Standard) MVV, maximal voluntary ventilation (optional) Vminute, minute resting ventilation profile (optional) Dynamic Spirometry (Flow volume analysis) (Optional)
The system can be set for the Spirometry set up in the normal way; Select the method for analysing the mid flow range MEF (FEF) this has two possibilites; The sum of the flow measured at 25% and 75% divided by 2 Or Forced vital capacity divided in half then divided by the integration of the time between 75% and 25% of the time. The other settings are to determine a method for the measurement of the FEV1, the tradition refers to the back extrapolation of the volume from a point equivalent to the Peak flow following the rise of the volume and
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where this line crosses the time axis to redefine this point as the zero time point and then to measure the exact volume one second forward from this point. This was a typical method with chart recorders and rulers. The more scientific method for computerised analysis is the area under a curve method, this innovation from Medisoft fits a one second block to the area under the curve defining the very best volume that may be obtained in one second through out the expiration effort. Scientifically this is a more accurate method to define a maximal volume in one second. The final selection is to read the ambient temperature prior to each start of the effort, in the normal mode the temperature is read on entering the test module and Validating the subject biographical data, with this selected the BTPS factor is updated with each measurement, this is often a requirement with research projects where the conditions must be monitored.
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Calibration: The calibration of the Spiro Air LT is a physical alignment of the digital reader to the signal seen by the system. This is set once and is then good for the life of the instrument. This relationship is verified by the Engineers at each service interval. In this example for 12 litre displacement the system has a linear output that reaches 3525 mv. The reading will also be taken at the zero (Spirometer Closed position) and this resulting voltage is the reading at 12 litres less the offset at zero. The routine checking by the USER is performed with the test screen. Set a subject file called: Last Name: Syringe First Name: Three ID No: ThreeLitre003 That way you can introduce different subjects for different syringe sizes. Then you can do the VC effort with the syringe and validate the volume is correct when corrected by the BTPS factor This is found on the subject biographical entry screen for the visit and expanded or collapsed with the grey icon on the lower right of the box.
Alternatively the Syringe icon in the test screen will set the correction factors to 1.00 for both inspiratory and expiratory allowing the syringe volume to be read directly. This choice of methods allows both the syringe and awareness of the impact of the BTPS factor on the measured values. Remember incorrectly applied the BTPS factor introduces an ERROR of 8% to 12% to any measured value! This should not be overlooked. For the general description of the Test Functions please refer to the general sections of the Expair manual, (excepting the Calibration which is specific to the Pneumotachograph).
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Special Notes: If the Spiro Air Lt starts to return strange values, this is likely to be a loss of communication on the USB, this can be Windows turning off the power to the port, if the ON/OFF switch on the rear of the instrument is turned OFF and then 30 seconds later turned ON the fault will clear as this operation draws enough current to correctly re-activate the USB port, unplugging and refitting will not necessarily produce the same effect. This is due to the USB port design looking for a minimum current draw to keep the port active correctly.
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