TMC PFT Practice 2023 with complete solution questions and answers

Tidal Volume measured with a respirometer at bedside or spirometry Normal= 300-700mL Expiratory Reserve Volume measured through spirometry from a slow VC Normal=1000mL and 20-25% of the VC Residual Volume FRC-ERV Normal=1500mL Helium Dilution Test Close circuit system used to determine FRC. Helium is diluted until equilibrium is reached. This normally takes 7 minutes but in severally obstructed patients it can take 30 minutes Nitrogen Washout Test open circuit method to determine FRC. Occurs in 7 minutes. Plethysmograph (Body Box) based on boyles law and may give higher FRC number than other test FRC normal=2500mL Inspiratory Capacity measured from simple spirometry from VC normal=3500mL (75-85% of the VC) Vital Capacity max amount of air that can be exhaled after max inspiration measured with respirometer (simple spirometry) Normal=4800mL Decreased Vital Capacity pneumonia, atelectasis, pulmonary edema, pulmonary fibrosis, kyphoscolosis, and lung cancer Forced Vital Capacity max amount of air that can be exhaled as quickly and forcefully as possible after max inspiration measured by simple spirometry Total Lung Capacity Normal=6000mL decreased TLC atelectasis, pulmonary edema, consildation increased TLC Emphysema RV/TLC Ratio TLC that remains in the lungs after maximal expiration Minute Ventilation Respiratory Rate x Tidal Volume Normal=5-10 L/min Increased Minute Ventilation hypoxia, hypercarbia, acidosis, or decreased lung compliance decreased minuted ventilation hypocarbia, alkalosis, and increased lung compliance FEV1/FVC less than 70% means an obstructive disease 70-85% of FVC exhaled in 1 second Peak Flow max flow rate during middle portion of FEV used in pre/post bronchodilator testing normal=6.5-10L/second How is Peak Flow measured? FVC or peak flow meter MVV Max volume of air moved in and out of lungs voluntarily in 10-15 seconds Normal=170 L/min What does MVV look at? overall lung function, ventilatory reserve capacity, and air trapping Diffusion capacity of the lungs represents gas exchange capabilities of the lungs, and how well the gas diffuses across the alveolar capillary membrane into the pulmonary capillaries Normal DCOL 25-30ml/min/mmHg Decreased DCOL O2 toxicity, emphysema, scarcodosis, and edema What is decreased in obstructive disease? FVC, IC, ERV, FEV1, FEV1/FVC, and MVV What is increased in obstructive disease? Tidal Volume, FRC, RV, RV/TLC severity of obstruction mild= 70-74% of predicted moderate= 60-69% severe disorder=50-59% severe=35-49% very severe= less than35% Restrictive disease everything is decreased or normal Increase in flow studies for pre/post bronchodilator study is? 12% Methacholine Challenge Test determines degree of airway reactivity to metacholine which stimulates bronchoconstriction In a methacholine challenge test, how much do you want to administer? enough to get a 20% decrease in FEV1 MIP (or NIF) max amount of negative pressure a patient can generate during inspiration normal= -80 cmH2O If cannot generate at least -20 cmH20 then patient does not have strong respiratory muscle strength MEP normal= 90-100 cmH2O if cannot generate at least 40 cmH20 that means the patient cannot maintain spontaneous respirations and cannot clear secretions