[Peter Brooks]

Pete, I’m puzzled by your calculations.  It seems to me that when resting, a pulsed machine setting of “5” is about equivalent to a continuous machine setting of “3”.

Assume that a pulsed machine on setting “5” outputs 1 liter/min (as seems to be indicated), and a continuous flow machine on setting “3” outputs 3 liters/min — 3 times as much.  However, output is not the same as input.  Using a pulsed machine, I inhale everything it produces because it only delivers when I inhale.  But that’s not the case on continuous flow.  For myself, even during exertion, I am inhaling only half the time, and exhaling the other half.  Therefore I am only using 1.5 liters of the 3 that’s being output, the rest is wasted.  When I’m at rest, I’m inhaling only 1/3 of the time, and therefore getting only 1 liter/min — the same as the pulsed machine on setting “5”.