Back Pressure: Important or not?

I've seen musicians perform with broken and sprained limbs, severe cuts, stomach viruses, colds and a plethora of other injuries and maladies which might put other people out of commission. We hide injuries from professors, family and even collegueges to prevent ourselves from being taken out of the event.  I am no different.

What will absolutely prevent me from performing?  Not breathing.  If you can't breath, you can't play any instrument.  The oboe requires not just 'normal air' but also immense amounts of back pressure.  I've played with stuffy head colds, and thankingfully only passed out once.  Once was all it took to teach me how hard and far I could push myself when I'm sick.  The pain caused by the building back pressure when you've got a cold is unlike any migraine or headache I've ever experienced.

So you can understand why I was estactic when my end of January cold seemed to have no effect on my back pressure.  There was no pain, no fluid in the lungs, no reason for me to postpone my recital.  Sure, playing made me a little more tired than usual but nothing I couldn't handle.  Green lights all the way.

The first hint of trouble came the week before my recital in rehearsals, but nothing bad enough to postpone my recital.  It was not until the night of my recital, when the trouble hit full force.  In the first solo piece, the Dittersdorf oboe concerto, I began experiencing a strange phenomenon.  I've found no other way to describe this, so feel free to laugh and offer suggestions.  I still had air in my lungs to play and my lips were still covering the reed properly.  Yet there was air escaping through my sinuses and out my nose, preventing any semblance of back pressure.  No back pressure, no sound.  Well, that's not really correct.  There was a sound.  Ever laugh through your nose, like a snorting type of laugh?  That was the sound, except I had no control over it.  I tried dropping my air support to lower the pressure on my sinuses.  That helped, but only to a point.  Not to mention dropping air support is never a good idea.  I had nothing left, but to keep going.  

I did.  I couldn't just quit at that point, so I pulled out my inner performer and kept my head high.  Due to an amazing accompanist, I was able the stretch different phrases to keep things as musical as possible.  I made the decision to do the best I could with what I had.

I'm not sure what I could have done to prevent, or even predict, this problem.  It is not one that I've experienced before or even heard others talk about encountering.  Hopefully it will not be something I will have to deal with again, although I know it will be one of those things that would make me seriously consider postponing a recital.