Pectus excavatum distorts FEV1 reading

[UyauAmet]

Are there other COPD sufferers out there with pectus excavatum, and how does this effect the accuracy of your FEV1 reading? According to recent chest x-ray and CT-scan I have Stage 3 COPD with chronic and widespread emphysema and bronchitis. I have been experiencing periods of extreme breathlessness and a recent sleep apnea test showed my oxygen levels drop as low as 82% when sleeping. When sitting quietly it is usually around 92% and resting heart rate around 60 (now around 50 since being put on metoprolol beta blockers for arrhythmia). Due to the pectus excavatum and associated flared lower ribs I have always had about a 25% larger lung capacity than normal, around 5.2 litres. My last FEV1 reading was 101%, and because of this my doctor had thought I only had Stage 1 COPD until the recent scans and oxygenation testing. I have not been able to do the 6 minute walk test due to chronic osteoarthritis in both knees so my doctor was going mainly on my symptoms of fatigue and breathlessness. Is there anyone else with pectus excavatum and COPD, and what has been your experience?