this Quora post about giraffes:

Is there anything special about the respiratory system of a giraffe given that its nose and its lungs are so far apart?

That’s a very interesting question. Just yesterday, a question about breathing through a hose deep underwater made me think of some Renaissance drawings (Leonardo?) of men standing on the bottom under water and breathing through long hoses to the surface. One reason that wouldn’t work is that human lungs aren’t large enough or our respiratory muscles strong enough to blow “dead air” out of such a long hose and draw fresh air all the way in from the atmosphere to the human. (An even greater reason, but not pertinent to giraffes, is that the water pressure at such depths would make it impossible to expand the chest to inhale.)

That raises an interesting question about giraffes. If a human can’t ventilate a snorkel any more than 16 inches (0.4 m) long, how can a giraffe ventilate a trachea that’s 2.3 m long?

The answer may lie in huge lungs and very slow breathing.

Without giraffe’s lungs being as large as they are( which is eight times larger than human’s) giraffe’s would be having to breathe the same air over and over. Because of the giraffe’s trachea being so long and narrow, there is a big volume of “dead’ air inside. However, by the giraffe’s breathing rate being one-third slower than man’s breathing, this is to help with this dead air problem. When a giraffe takes a new breath, the “old” breath is not totally done for yet.

That interpretation is not undisputed. This study says the giraffe trachea does not have an abnormal volume of dead space, but is unusually narrow for the animal’s size. Unfortunately, this is only available in abstract.

The issue of tracheal ventilation may also explain why giraffes are largely nonvocal animals. It may be too difficult to blow air through a larynx fast enough to make useful, energy-efficient sound. Questions also come to my mind about respiration during running, as giraffes are well known for their endurance.