Altitude effects on stomach upsets

[Genghis the Engineer]

I was reading an Australian report the other day on an F/O in a Sabb 340 who suffered debilitating stomach cramps (or something along those lines) as the aircraft climbed to altitude - went onto 100% oxygen, the captain diverted, and as they descended onto the approach, he became sufficiently fit to participate in the landing actions.

This got me thinking - 100% oxygen is a standard panacea for all ills on an aeroplane, and often does make a big difference. However, the implication here is that the thing that really made a difference to him was reduced cabin altitude (whilst still on 100% O2) rather than the partial pressure of oxygen.

Can anybody offer a mechanism whereby increased pressure / reduced cabin altitude will improve somebody's condition, where increasing partial pressure of oxygen alone would not?

G

[mnehpets]

Can anybody offer a mechanism whereby increased pressure / reduced cabin altitude will improve somebody's condition, where increasing partial pressure of oxygen alone would not?


Maybe he had the bends?

- S

[Genghis the Engineer]

Maybe he had the bends?

- S

The ATSB report said it was diagnosed by a physician on return as food poisoning.

(VH-KDQ, 22 June 2010, reported in ATSB Bulletin Jul-Sep 2010) if you want to look it up).

G

[Bad medicine]

Simply Boyle's Law. Gas expands and stretches the gut as the ambient pressure reduces - especially in the small bowel where it can't easily escape. Then on descent, the pressure increases, and the volume decreases. Ye canna change the laws of physics.

[homonculus]

The oxygen is a red herring.

Most likely he had gut rot - food poisoning - which may cause colicy pain ie pain that comes and goes. It got better. Again coincidence

The main issue with depressurisation is if there is gas in a body cavity. If the guts are not working they absorb gas. Depressurisation causes the gas to expand, causing pain and possibly rupture of the guts. If the guts are handled, they stop working for a few deays (ileus) so flying after an abdominal operation is a no no and we normally stop passengers flying for two weeks

Tumours and other pathology may also cause obstruction so that the guts upstream from the obstruction become distended - same problem

A laparoscopy - keyhole surgery - passes gas into the peritoneum - the abdominal cavity. This too will expand on depresurisation so flying is normally banned for 3 days

Gas in other cavities - the chest, joints and teeth - can also cause pain on depressurisation

Flying freight doesnt have this problem - unless it is livestock

[gingernut]

Assuming he's young, fit and otherwise well, I'm with the simple GI disturbance opinion. It's known locally here as "a bad pint." Further towards Wigan, as a "bad pie."

Symptoms of which are probably exacerbated by Boyle's Law. Luckily, the effects are generally not long lasting nor chronic.

Ever seen the wrappers on a bread roll expand on ascent. And in the days when one could take a 1 liter plastic bottle of Roller Cola on an aircraft, how it imploded after that last swig before the seat belt sign went on. Good old Bobby has a lot to answer for, although he does make exceptionally good altimeters.

100% oxygen is helpful for making cabin staff look useful, or, for disgusing the fact that the patient is dead.

Also fatal when the passenger has chronic COPD and the impetus for breathing is hypoxia:)