This may be of interest to students of the Alexander Technique, though not directly about that subject.

The following is from the book The Search for Bridey Murphy. (*)  I’ve inserted the footnote in the body of the text.

From a reprint of a New York Times article I had learned that a New York doctor had conceived the idea of an equalizing pressure chamber which enables the patient to stop breathing!
...
... Understand that it is not like an iron lung.  The chest doesn’t budge; the lungs make no movement; breathing actually stops.  The chamber is designed so that an equal pressure is maintained on both sides of the chest, and also on the upper and lower surfaces of the diaphragm.  Then, by manipulating the pressures within both the body and head compartments of the chamber, oxygen is brought into the lungs and carbon dioxide eliminated.  The volume within the lungs is kept constant, but the density changes.  All this without taking a single breath!

Footnote: The doctor who originated this therapy is quoted as saying,  “The effect of cessation on the central nervous system is of considerable interest.  The impulse for movement in the voluntary muscles in the extremities is strikingly diminished.  The patient may lie in the chamber for hours without moving his hands or changing his position.  The desire to smoke disappears when voluntary respiration stops, even in patients who have been accustomed to smoke two packages of cigarettes daily.  In many instances the relaxation is of such a nature that the patient does not require amusement. ...”

When company business next sent me to New York, I took advantage of my first free hour to rush to the office of the doctor who had created the pressure chamber. ...

Within a few days ... my wife and I were standing before a casket-like affair at a hospital in New York City. ...  With us were two doctors, researchers at the Columbia University division of the hospital and old hands with the pressure device.  “Are you sure you want to enter the chamber?” one of the doctors asked. ...

“Why do you ask?” was my question. ...  “Will this machine give me a rough time?”

“No, not at all,” he replied. “But some people have claustrophobia to varying degrees, and so they are terrified at the prospect of being closed up in narrow compartments.”

I wondered whether I had claustrophobia, decided I didn’t, and crawled into the chamber.  It is a sort of horizontal cylindrical structure with a dome which slides forward like that over the cockpit of a jet plane.  But in this cockpit you stretch out flat on a surface made comfortable by a mattress.  Then a partition, like a collar, slides down around the neck, separating the head and the body into two compartments.  The dome is pulled back, closing the chamber, and the air compressor is switched on.

At the start I had been told to inhale each time the doctor — I could see him easily through the Plexiglas dome — raised his hand and to exhale as he lowered it.  As his hand movements shortened, my respiration was to become shallower until he finally made a crosswise motion with his hands, like an umpire gesturing “safe.”  At this point I was to stop breathing entirely.

I did.  It was a pleasant, soothing sensation; I didn’t breathe for more than five minutes.  It was probably the only five minutes during my entire lifetime when I made no movement whatsoever.

Now how did that amazing machine work?

The book I just quoted from does not tell who the doctor was that the New York Times had interviewed, or the date.  I located the article, and it was Dr. Alvan L. Barach of the College of Physicians and Surgeons in New York, in Chicago on Jan. 31, 1947. (**)

Dr. Barach, however, neither invented nor built the breath stopping machine.  The machine was built by John Emerson (“Jack”), in Cambridge, Massachusetts, and the idea behind it was due to a man in Sweden.

The following is from the transcription of a talk John Emerson gave at Massachusetts General Hospital in 1985, reminiscing about his career inventing and manufacturing respirators:  “Some Reflections on Iron Lungs and Other Inventions.” (***)  My bracketed comments clarify the text.

[Evidently referring to a photo:] This machine, you’d think maybe was an iron lung, but this is for Al Barach.  This is one of the most sophisticated things we ever made.  That was for treating tuberculosis [to give the lungs a rest so they could have a chance to heal], and the patient was completely enclosed.

The Swedes developed this, a fellow named Thunberg, ... he just put the patients completely in the tank and changed pressures up and down quite rapidly and got ventilation by compression and rarefaction.  If you press here [making a gesture] on your chest, and bring equal pressure inside, the lungs won’t move.  But you can ventilate [that is, move enough air inside and back outside the lungs to sustain life] if you get enough difference in pressure.  [That is, oscillation of both pressures simultaneously, the pressures always being the same inside and outside the lung.]

This thing worked, ... for closing — what do you call them — the holes in the lungs [that is, it helped heal tubercular abscesses in the lungs], ...  we must have made 60 of those, and just at that time the sulfa drugs were coming, so that [machine] was out the window.

So, the machine gives air to both the inside and outside at the same time, then takes air from both the inside and outside at the same time.  The slight blowing and sucking alternate rapidly; air moves in at high pressure, out at low.  Since the pressure remains the same inside and out — though both vary — the chest and lungs never move.  You don’t breath (mechanically), yet you breath (respire).

I’m not sure how the two separate compartments, one for the head and one for body, work into this.

I wouldn’t mind trying one of those machines.  In the meantime I’ll just have to hold my breath.