This sounds, umm, naughty...
Not sure how it's possible though. With my physical equipment, which I assume is standard, I can't inhale it through my nose unless I insert the ecig in one nostril, close the other one, tighten up around the inserted ecig, then sniff. I just tried this, and it works, but it's kinda weird and not entirely satisfactory. Also, I don't think I could do this in public. A hot flavor produces much eye-watering, as well.
Maybe you mean to mouth-inhale, then fully inhale, then breathe out through the nose - as against inhaling direct to the lungs? It's said that the mouth-lung-nose method will increase nicotine intake as vapor is more efficiently absorbed in the mouth and nose than in the lungs, due to the larger particulate size compared to smoke, and the way that nicotine is bound within the PG/VG mix. The particle size in vapor is said to be ten times larger than that in
tobacco smoke. And, if you spill
e-liquid on the skin, it is absorbed far less efficiently than pure nicotine.
There are numerous ways to inhale vapor. Holding it in the mouth first, then exhaling it through the nose, is said to be the most efficient for nic absorption. But it's all a matter of taste:-
1. Inhale direct to the lungs, exhale through the mouth.
2. Inhale direct to the lungs, exhale through the nose.
3. Inhale to the mouth, then to the lungs, exhale through the mouth.
4. Inhale to the mouth, then to the lungs, exhale through the nose.
5. Inhale to the mouth, then to the lungs, wait, exhale through the nose. (Thought to be the most nic-efficient.)
6. Inhale to the mouth, then exhale. (Cigar style.)
7. Puff repeatedly, inhale to the mouth occasionally, exhale. (Pipe style.)
8. Inhale shallow, direct to the lungs, exhale quickly through the mouth. (Nervous vaper.)
9. Pre-puff repeatedly, then as any of the above. (User of less-than-efficient mini ecig.)
...
ad nauseam.
Whatever floats your boat. You can't OD on nicotine unless you choose to, and it's not pleasant so people tend not to do so. Much like drinking cup after cup of high-strength coffee, or shots of whisky, most soon stop. Enough is enough - what is pleasant in small amounts ceases to be pleasant.