Pulmonary Function Tests in Clinical Practice
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This review of pulmonary function tests in clinical practice provides a simplified approach to interpreting most diagnostic tests in the field of respiratory medicine. It contains more than 125 illustrated diagrams, 50 tables, and 30 illustrative examples.
beginning of the time axis (with permission from American Thoracic Society2). 14 PULMONARY FUNCTION TESTS IN CLINICAL PRACTICE (c) The patient cannot or should not continue to exhale.1,2 Note: A good end of the study can be shown in the FV curve as an upward concavity at the end of the curve. A downward concavity, however, indicates that the patient either stopped exhaling (prematurely) or started inhaling before reaching the RV; Figure 1.10. This poor technique may result in underestimation
COPD,63–68 pulmonary hypertension,69–72 ILD,73,74 and CF75,76) Evaluation for impairment/disability77–82 Other indications Diagnosis of exercise-induced asthma83–87 Identification of gas-exchange abnormalities42,44 Titration of supplemental O2 rate during exercise64,88–93 Absolute contraindications91,94,95 Active cardiac disease (acute MI, unstable angina, active arrhythmias, uncontrolled CHF, severe aortic stenosis, aortic dissection, endocarditis, myocarditis, pericarditis) Active pulmonary
main cause of breathlessness in patients with COPD (emphysema); Figure 9.10. FIGURE 9.8. Behavior of VT and RR during exercise is similar to SV and HR. Note that VE and VO2 maintain a linear relationship. EXERCISE TESTING 175 FIGURE 9.9. Patients with lung disease reach their predicted VEmax early, notice that the calculated MVV (i.e. the predicted VE max) is less than the predicted MVV in patients with lung disease. Elite athletes may approach their predicted MVV with a supranormal VO2. •
compensate for the decreased stroke volume may indicate that the patient was on a β-blocking agent. Case 3 A 25-year-old female, Caucasian, who is known to have an idiopathic cardiomyopathy, underwent a CPET to assess the need for a cardiac transplant. Weight 68 kg; height 171 cm. 198 PULMONARY FUNCTION TESTS IN CLINICAL PRACTICE • Test details – Instrument: Cycle ergometer – Technique: Incremental – Reason for exercise termination: fatigue. – Modified Borg scale: for dyspnea (6); for leg
ratio may not be seen. The morphology of the FV curve can give a clue, as the distal upward concavity may show to be more pronounced and prolonged; Figure 1.17.48–50 Another clue is the prolonged FET evident in the VT curve; Figure 1.17. However, the clinical significance of these mild changes is unknown. – In emphysema and because of loss of supportive tissues, the airways tend to collapse significantly at low lung volumes, giving a characteristic “dog-leg” appearance in FV curve; Figure 1.18.9