Some doctors are sad enough to wear their white coats in public, but most comfort themselves with a thwack on the back

Why do doctors always come at you from the right?

I'm sorry?

Well, I've been in hospital a lot lately ...

I'm sorry.

And every time the doctors came to see me, they approached my bed from the right-hand side, never the left. Why is that?

It may be the right-hand side to you, but to the doctor approaching you it's the left, and we do it that way for the very simple reason that we're told to do it that way at medical school. And if you don't do what you're told at medical school, you don't pass your exams and you get kicked out, destroying your future livelihood, heaping anguish on your previously proud parents and sending you all towards an early grave.

I take your point, but why are you taught it in the first place?

Well, I'd like to think it was for some good reason, such as to aid the examination of the heart. But in fact, British hospitals were all built with the bedside locker on the patient's right, so the religious trinkets would always be at the right-hand side.

So doctors approached from that side to be closer to God?

No, doctors approached from that side because the grapes and chocolates were next to the trinkets, and they could pocket a few under the pretence of listening to the back of the chest.

Talking of chest examination, why do doctors do that tapping thing with the fingers?

Percussion?

If you say so.

Percussion isn't just tapping, young lassie, it's a finely honed skill whereby the left middle finger is placed firmly over the chest wall ...

Why the left middle finger?

Because that's the way it is, OK?

Yeah, all right. Only asking.

And what are you trying to achieve?

I've no idea. I'm not sure if anyone knows. It's just something else we're taught to do at medical school to fill in the five years.

There must be a reason for it.

Well, yes. It's to make a satisfying, resonant, thwacking sound.

And if you don't?

It either means you're not very good at it, or that the lung you're percussing hasn't got enough air in it to resonate. It could be collapsed, or full of fluid or infection.

Fascinating. I was in a pub recently and these people in the corner were percussing each other. Were they medics?

Almost certainly. Percussion is far more than a diagnostic tool, it's a symbol of doctorhood. Some doctors are sad enough to wear their white coats in public, but most just comfort themselves with a quick thwack on the back. Nobody else does it, except bogus doctors, who seldom resonate enough.

Can you get too much resonance?

Yes. Suppose you're a consultant sitting in an aeroplane and the person next to you starts to get very short of breath. You pull up his Polo shirt, pull out your percussing finger and discover one side of the chest wall is hyper-resonant. That means pneumothorax.

Why?

Because air has escaped into the pleural cavity, between the chest wall and the lung, forcing the lung to compress down and threatening respiratory viability.

I love it when you use those long words.

There are plenty more in chest examination. How about "tactile vocal fremitus"?

Sounds yummy.

That's when you place the flat of the hand on the patient's chest and get him to say "99".

Because the ice-cream man's arrived?

No, to assess the transmission of sound vibration through the chest.

Anything else?

Yes. "Whispering pectoriloquy" is perhaps the silliest medical term ever and has something to do with the chest, but I can't remember what.

Great. So what do you do to the respiratorially unviable passenger?

You ask the hostess to pour a double brandy whilst fetching you a coat- hanger and gentlemen's catheter from the overhead locker. Then you pounce on the hapless junior doctor three rows behind and force him to puncture the chest wall and release the trapped air, while you drink the brandy and prepare your celebratory address to the waiting press conference.

Dream on ...