[f4uCL9dNSnQm]

No, the total surface of intestine is up to 40m^2, while the single lung has 100 m^2 for exchange. It might be a supplementary method at best.

[Qem]

That lung 2×100m^2 are enough for sustaining energy intensive human aerobic activities, like running a marathon. Perhaps 40m^2 is all is needed to sustain someone in low energy mode, bedridden.

[samus]

Even a compromised lung is capable of fully oxygenating blood for everyday situations. One just has to compensate by breathing faster, or cycling that liquid more frequently.