Only One Acceptable Curve in an Older Participant
Mr. Okafor is a 74-year-old retired machinist with COPD who is being tested for the first time in a community clinic. He has mild hand arthritis and hearing loss, but no cognitive impairment. After instruction, he completes four forced maneuvers. The technician records: Trial 1-FEV1 1.42 L, FVC 2.40 L, back-extrapolated volume (BEV) 0.18 L, cough during the first second, no plateau. Trial 2-FEV1 1.55 L, FVC 2.85 L, BEV 0.12 L, exhalation lasted 7.5 s with a clear plateau, no cough. Trial 3-FEV1 1.48 L, FVC 2.50 L, BEV 0.10 L, exhalation stopped at 4.0 s without plateau, no cough. Trial 4-FEV1 1.53 L, FVC 2.60 L, BEV 0.20 L, no cough, exhalation 6.5 s with plateau. The technician plans to report trial 2 as the best result and stop because four trials were done.
1. Evaluate acceptability of each trial using standard criteria. Which trials are acceptable?
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Use BEV ≤0.15 L or 5% of FVC, whichever is greater. Trial 1: FVC 2.40 L, 5% = 0.12 L, so the limit is 0.15 L; BEV 0.18 L exceeds it, and the cough in the first second is also unacceptable. Trial 2: FVC 2.85 L, 5% = 0.1425 L, limit 0.15 L; BEV 0.12 L passes, exhalation 7.5 s with plateau, no cough-acceptable. Trial 3: stopped at 4.0 s without plateau-unacceptable early termination, so FVC is likely underestimated. Trial 4: FVC 2.60 L, 5% = 0.13 L, limit 0.15 L; BEV 0.20 L exceeds it-unacceptable. Only trial 2 is acceptable. A session needs at least three acceptable trials and two reproducible FEV1 and FVC values, so the technician should not stop.
2. What coaching and technical adjustments would you use, and when would you stop?
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Re-coach rather than simply repeating: check upright posture, chin slightly elevated, nose clip, and a tight mouth seal. Demonstrate a rapid start with no hesitation, then 'blast out and keep going until I say stop.' Use a count or hand signal for hearing loss, and allow him to rest his arms because of arthritis. Watch for a slow start, which raises BEV, and for early termination by watching his chest and the volume-time display. Obtain at least two more acceptable trials; then compare the largest two FEV1 and FVC values-they should be within 0.150 L. Stop when he has three acceptable, two reproducible trials, or after about eight trials, or sooner if he is fatigued or symptomatic. Document which trials were unacceptable and why.