A 63-year-old man with progressive exertional dyspnea has bibasilar crackles and clubbing. Pulmonary function tests show reduced total lung capacity and reduced DLCO. During treadmill testing his oxygen saturation drops substantially despite an appropriate increase in cardiac output. Which of the following gases is most likely becoming diffusion limited across his alveolar membrane during exercise?
- A)Helium
- B)Carbon dioxide
- C)OxygenGABARITO
- D)Nitrous oxide
- E)Nitrogen
Explicação
Oxygen is usually perfusion limited in healthy lungs, but in interstitial fibrosis it can become diffusion limited, especially during exercise when capillary transit time falls. Thickened alveolar membranes reduce equilibration, leading to exertional desaturat... Ver explicação completa e trilha adaptativa →