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PFT Final Exam Study Guide With
Complete Solutions 2024
List obstructive and restrictive pulmonary disorders - correct answers Obstructive: CF, bronchitis, asthma, bronchieactasis, emphysema, vocal cord dysfunction, tumors, obstructive sleep apnea Restrictive: ILDs, kyphoscoliosis, obesity, pleurisy, pleural effusions, pneumothorax Identify the disease processes with air trapping - correct answers COPD (emphysema, bronchieactisis), asthma, CF Identify the disease processes with diffusion defects - correct answers Pulmonary Fibrosis, emphysema Relate pulmonary history to indications for performing PFTs - correct answers History of cough, shortness of breath, wheezing, obesity, pulmonary disease, smoking Describe and list preliminary patient testing requirements
- correct answers Hold bronchodilators 6 hours pre PFT, hold smoking for 24 hours before PFT, don't eat 6 hours before PFT
Explain why various preliminary requirements are necessary - correct answers To get the best and most accurate results for the PFT, and so the patient doesn't throw up during the test Relate the proper testing sequence, protocols, and patient instructing techniques - correct answers Protocols: Tests have to be performed in a certain order, can't do a N2 washout right before a DLCO Instruction: tests are effort dependent, instruction and coaching is vital, proper feedback to patient is important, some patients can't do it (document this) Calculate percent of predicted and discuss the basis of predicted values - correct answers (Measured value / predicted normal) x 100 = % predicted Determine whether spirometry is acceptable and reproducible - correct answers VC acceptability: volumes should be 150 ml of each other, VC should be within 200 ml of FVC value FVC acceptability: two largest FVC values within 150 ml, two largest FEV1 values within 150ml, report the highest FEV1, even if from separate maneuvers
pleural effusion/scarring reduced chest wall expansion (neuromuscular, kyphosis) Distinguish between large and small airway obstruction by evaluating flow-volume curves - correct answers Larger airways are the top of curve, smaller airways are represented at the end of the expiratory curve Determine whether there is a significant response to bronchodilators - correct answers 12% change, and 200 ml increase in post (Post-Pre)/Post Be able to describe the single-breath DLCO technique - correct answers The patient exhales to residual volume, then inspires to total lung capacity. Then the patient holds their breath for 10 seconds, then exhales again to residual volume. A sample of the gas is collected and analyzed for carbon monoxide. Be able to determine DLCO acceptability - correct answers Volume-time tracing, smooth rapid inspiration from residual volume to total lung capacity, inspiration should be rapid but not forced, volume inspired should be at least 90% of the previous recorded VC
Be able to identify normal and abnormal values of the DLCO and what disease processes may influence these values - correct answers The DLCO represents the amount of CO that travels across the AC membrane. Normal = around 25 CO/min/mmHg A decreased DLCO is often a restrictive disease like pulmonary fibrosis and pulmonary edema. Emphysema is the only obstructive disorder with reduced DLCO. Be able to describe testing methods to measure static lung volumes including gas dilution methods and body plethysmography - correct answers Nitrogen washout: N concentration in your lungs is about 75-85% and if you breathe in 100% O2 you will wash out all of the nitrogen in your lungs. Helium dilution: A known volume of helium is added to room air in a spirometer. The patient breathes through the system until the helium concentration falls to a steady level. Body Box: patient pants against a closed shutter in a closed body box. Change in mouth pressure and body box are measured, volume is estimated by measuring changes in the pressure of the body box. The breathing pattern results in loops and the computer then measures their slopes to calculate the VTG (thoracic gas volume).
Measure and assess tidal volume and minute ventilation - correct answers Vt = the amount of gas inspired or expired during each respiratory cycle. -average: 400-700 mL -Reduced in severe restrictive processes Ve = The volume of gas expired per minute -Vt x RR = Ve -Normal is 5 to 10 L/min -VD + VA Identify at least 2 causes of decreased minute ventilation
- correct answers Hypocapnia, metabolic alkalosis, respiratory center depression, neuromuscular disorders Calculate the VD/VT ratio - correct answers {(PaCO2 - PECO2) / PaCO2} x Vt List at least 2 causes of increased VD/VT ratio - correct answers A large VE could be a large increase in in VD. Pulmonary hypertension can cause a decrease in deadspace.
Some diseases that trap gas preventing new gas from being perfused to the blood stream are sometimes considered dead space diseases like emphysema. Describe the HAST - correct answers The hypoxia inhalation test. Subject breathes in 15% FiO2 (the rest is N2) for 20 minutes. Monitor the heart with an electrocardiogram, SpO2 with oximetry, and dyspnea with the borg scale. Early termination: SpO2 less than 80%, change in ECG rhythm, ST-T wave depression/elevation, symptoms suggesting intolerance Who is it for? Pts. with COPD, asthma, severe restrictive disease, CF, CAD, CHF, when traveling by air or high altitude destinations. The British Thoracic Society recommends HAST in subjects with a resting sea level SpO2 between 92 subjects with a resting sea level SpO2 between 92 and 95% and additional risk factors such as and 95% and additional risk factors such as hypercapnia, FEV1 < 50% predicted, restrictive hypercapnia, FEV1 < 50% predicted, restrictive disease, or lung cancer.
Field walk tests: ISWT- incremental shuttle: speed increased until the patient stops or 20 minutes has passed. ESWT- endurance shuttle: ISWT done first to determine max speed, pt. walks a predetermined percentage of this speed for as long as possible, time and distance are recorded. 6 MWT- 6 minute walk test, self paced test, distance is the goal. Work: kpm= work of moving a 1 kg of pass a vertical distance of 1 meter against the force of gravity. Energy= VO2, metabolic equivalents or METs; 1 Met = 3.5 mL O2/min/kg Be able to interpret a basic CET - correct answers What is monitored? HR & rhythm, BP, CO2, SpO2, spirometry Max HR: 220-age, 85% of max HR = max effort Max ventilation: 35 x FEV1, MVV = maximal voluntary ventilation in L/min Ventilatory limited = exceeds a 10-15 L/min different in minute volume and max ventilation, Mve max is more than 70% of MVV Cardiac limited = HR increases past max, changes in EKG, CO goes down, SV goes down, BP goes down or extremely high (past 250 SBP), oxygen pulse does not increase to expected levels
Be able to describe two methods of performing bronchial challenge tests - correct answers Methacholine challenge: causes smooth muscle contraction, can also be used with manitol (causes reaction in the histamine cycle), manitol test is positive with a 15% change in FEV1. 5-breath dosimeter: patient inhales slowly and deeply with a breath hold for 5 breaths, perform an FVC maneuver to obtain the FEV1 at 30 seconds and 90 seconds after breath 5, the cycle of administering the drug followed by testing continues until you have a 20% drop in FEV1. 2-minute tidal breathing: uses an SVN for particle size to reach the medium and small airways, patient uses a normal breathing pattern for 2 minutes, and then spirometry is repeated at 30 and 90 seconds at the ned of the test. Exhaled nitric oxide: asses airway inflammation, FENO reported in parts per billion; the patient exhales to RV, inspires to TLC, patient exhales slowly and evenly: more than 35 ppb (25 in children) in adults indicates eosinophilic inflammation of the airways Forced oscillation technique: measures respiratory impedance, apply oscillating gas to the respiratory system and measures the pressures generated, impedance is the force needed to overcome resistance and compliance Be able to list two indications for preoperative pulmonary function tests - correct answers Smoking history, symptoms of pulmonary disease, abnormal physical examination findings, abnormal chest x-ray, obesity,
List the values that determine qualification for disability - correct answers FVC and FEV - tests the patient's ability to mechanically ventilate DLco and ABG analysis - evaluate how well a patient oxygenates and ventilates from a gas exchange perspective Exercise testing- evaluates the patients ability to breathe during exertion Be familiar with the calorimetry testing protocol and how to read the exam results - correct answers Effort: Maximum heart rate reached. RER close to 1. Ventilatory Limited: VE max less than 70% of MVV and the absolute difference is greater than 10 to 15 L/min. Yes answer = no ventilatory limitation No answer= ventilatory limited Cardiac Limited: HR increases and may exceed maximum targeted HR. Changes in EKG rhythm. Cardiac output goes down or does not increase appropriately. Stroke volume goes down or does not increase appropriately.
Blood pressure decreases or does not increase appropriately. Be able to describe at least one type of volume displacement spirometer - correct answers Bellows-type spirometers -bellows or wedge bellows -fold and unfold in response to breathing -most are hooked to a potentiometer -Problems: sticking of the bellows causes inaccurate numbers, leaks in the bellows Water-seal spirometers -Consists of a large bell suspended in a container of water with the open end of the bell below the surface of water. -Kymograph - a rotating drum that moves at a certain speed. A pen is attached and makes a tracing of the breathing test. -Spirometer can also be activated by a potentiometer. -A device that produces an analog DC voltage signal depending on its position, like a dimmer switch connected to a light. The signal is proportional to the position of the bell. -Now days it is digitized. -If a single large bore tubing is used, you will need a CO absorber (soda lime).
He dilution = free breathing valve Be able to state how different types of gas analyzers are used in the pulmonary function laboratory. - correct answers Oxygen Polarographic electrodes A platinum cathode is used without a membrane Zirconium fuel cells When zirconium coated in platinum is heated to 700 to 800 degrees C acts as an electrode Infrared absorption (CO2 and CO) analyzers Based on absorption of infrared radiation Can measure small changes Emissions spectroscopy analyzers Giesler tube ionizer (N2 analyzer) Requires a vacuum pump A patient performs three FVC maneuvers using an analog spirometer. The technologist reports that all maneuvers had a back-extrapolated volume of less than 5% and 150 mL. The maneuvers met all other criteria for acceptability and repeatability. The technologist should: - correct answers a. Repeat all maneuvers
b. Correct the FEV1 and all other flows by the amount of the back-extrapolated volume c. Perform at least one more maneuver d. Report the average of the three FVC values How long should the pulmonary function technologist wait after giving inhaled β-agonist before conducting post- bronchodilator testing? - correct answers a. 5 minutes b. 15 minutes c. 30 minutes d. 45 minutes A decrease in lung compliance is consistent with all of the following EXCEPT: - correct answers a. Fibrosis b. Pulmonary edema c. Pulmonary emboli d. Emphysema Which of the following assessments can be made when the FEF50% is decreased and the FIF50% is normal? - correct answers a. Variable extrathoracic obstruction is present b. Variable intrathoracic obstruction is present c. Fixed airway obstruction d. No obstruction, this is normal
b. Wait 4 hours to repeat the entire spirometry testing c. Have the patient take 2 more puffs of albuterol and repeat the post spirometry testing d. Wait 15-20 minutes before performing the post bronchodilator testing. If a physician were looking at PFT results to determine small airway involvement, which parameter would you suggest he look at. - correct answers a. FVC b. FEV c. FEF25%-75% d. MVV If a patients prebronchodilator FEV1 is 2.2 L and the postbronchodilator FEV1 is 2.4 L is there a significant response to the bronchodilator? - correct answers a. Yes b. No c. Not enough information to determine A 25 y/o male has an uncorrected DLCO of 24. L/min/mmHg (69% of predicted) but no history of pulmonary disease. Which of the following might explain these findings? I.. Left to right shunt II.. Carboxyhemoglobinemia
III.. Congestive heart failure IV. Anemia - correct answers a. I and II only b. III and IV only c. I, II, and III d. II, III, and IV In an emphysema patient the DLCO will be decreased due to all of the following, EXCEPT: - correct answers a. Decreased surface area b. Increased surface area c. Reduction in pulmonary capillary bed d. V/Q abnormalities All of the following factors will account for a decreased DLCO in the absence of pulmonary disease, EXCEPT: - correct answers a. Decreased hemoglobin b. Measurements made at sea level c. Increased carboxyhemoglobin d. Decreased capillary blood volume Why is carbon monoxide used to measure the diffusion capacity? - correct answers a. Physiologically normal b. Less expensive c. Compatible with helium
