SPIROMETRY…In a spirometry test, you breathe into amouthpiece that is connected to aninstrument called a spirometer. Thespirometer records the amount and therate of air that you breathe in and outover a period of time.
Lung volume measurement can be done in two ways: •The most accurate way is to sit in a sealed, clear box that looks like a telephone booth (body plethysmograph) while breathing in and out into a mouthpiece. Changes in pressure inside the box help determine the lung volume.
•Lung volume can also be measured when youbreathe nitrogen or helium gas through a tube for acertain period of time. The concentration of thegas in a chamber attached to the tube is measuredto estimate the lung volume.•To measure diffusion capacity, you breathe aharmless gas for a very short time, often onebreath. The concentration of the gas in the airyou breathe out then is measured. The differencein the amount of gas inhaled and exhaled canhelp estimate how quickly gas can travel from thelungs into the blood.
Pulmonary function tests are done to:•Diagnose certain types of lung disease (especiallyasthma, bronchitis, and emphysema)•Find the cause of shortness of breath•Measure whether exposure to contaminants at workaffects lung functionIt also can be done to:•Assess the effect of medication•Measure progress in disease treatment
Spirometry measures airflow. By measuring how much air you exhale,and how quickly, spirometry can evaluate a broad range of lung diseases.Lung volume measures the amount of air in the lungs withoutforcibly blowing out. Some lung diseases (such as emphysema andchronic bronchitis) can make the lungs contain too much air. Other lungdiseases (such as fibrosis of the lungs and asbestosis) make the lungsscarred and smaller so that they contain too little air.Testing the diffusion capacity (also called the DLCO) allows the doctorto estimate how well the lungs move oxygen from the air into thebloodstream.
Normal value of PFTs is depend upon subject height ,ageand sex normal resultsAre expressed as a percentage .A value is usuallyconsidered abnormal if it less than 80% of predicted value.Abnormal value usually mean that subject may have somechest or lung disease
PULMONARY FUNCTION ANALYZERS(PFA)Three basic type of measurement made in pulmonaryclinicVentilation: simple inhalation and exhalation.Distribution: This is measurement quantify the degree oflung obstruction and also determine the residualvolume(second method by inhaling Nitrogen)Diffusion: This measurement is performed to determine therate at at which gas is exchanged with the blood stream.
PFA provide a completeevaluation of lung functionor the respiratory process
It allows rapid analysis ofnitrogen concentration(volume%) in respiratory air.
NITROGEN LINEARIZER: In case ofnitrogen washout during human physiologicalinvestigation require stable linear input device. forthis purpose it was necessary to obtain a precisionof 0.02% nitrogen (0.02% of the avg nitrogenusually encountered during a breath near the endof the wash out)
By using low drift op-amp in nitrogen analyzer
B : BODYT : TEMPERATUREP : PRESSURES : SATURATION
BTPS : ABBREVATION is used for bodytemperature ambient pressure saturatedwater vapors condition of a volume of gasfor humans normal respiratory tracttemperature is measured at 37 degreeCelsius ,ambient pressure and the partialpressure of water vapors at 37 degree Celsiusat 47 mm Hg