Hypopneas are scored based on a reduction in the rate of flow that lasts at least 10 seconds, they are not scored based on volume.
Inspiratory Flow Limitations are obstructive, limiting inpspiratory flow. So are *obstructive* hypopneas. They are actually kind of similar.
Central hypopneas are also scored based on the same reduction in flow rate as obstructive hypopneas but are different in that they lack respiratory effort.
None of your citations refute those facts. Nor do your repeated personal attacks on me. And, in fact, your own citation refutes your own claims. You wrote:
palerider wrote: ↑Sun Aug 05, 2018 2:58 pm
Because
flow limitations are a completely different thing from
hypopneas.
Flow Limitations are exactly what the name says... a limit to the rate of
flow, whereas
hyponeas are a reduction on
volume.
You can have hypopneas without flow limitations, and you can have flow limitations without even a hint of a hypopnea, or indeed any reduction in tidal volume (which is the amount of air inhaled and exhaled in a breath.
But your own citation says:
There are several potential consequences of inspiratory airflow limitation during sleep (see also Discussion). If the increased airway resistance achieved is sufficiently high, the tidal volume will fall (2, 3). In turn, if the high upper airway resistance and reduced tidal volume persist, then sleep-disordered breathing events will occur in the form of hypopneas (over a few breaths)
[emphasis added]
In other words, obstructive hypopneas are an extension of inspiratory flow limitations, not some "completely different thing".
Similarly, your claim that flow rate is a measure of volume relies on a misreading of a single sentence in the paper you cite ("This flow rate is defined as the mask minute ventilation."), a paper that actually measures and lists minute volume and flow rates
separately, because they are two different things:
Oxygen uptake, minute ventilation and air flow rates were measured with Metamax 1 (Cortex, Germany)...In the three tests with respirators, minute ventilation and flow rates were measured during the inhalation cycle...For each minute (4 and 5) the second part (30 s) was evaluated. For each breath during 30 s a highest inhalation flow rate was measured and the average, defined as mean peak inspiratory flow rate (PIFR), was calculated. The highest value for all the breaths during the period was defined as the maximal PIFR. This single value was on the average 10% higher than the mean PIFR during the minute. All minute volumes and flow rates are given in BTPS
[emphasis added]
They are calculating the minute volumes. The paper has *separate* figures for the minute vent rates (figure 3) and the flow rates (figures 4 and 5) - which they wouldn't and couldn't do if air flow rate == minute vent rate. Note they also list separate Minute Vent data ("VE (l/min) BTPS") and average flow rates ("Mean insp. flow raste (l/min) BTPS" ), which, again, they wouldn't and couldn't do if flow rate == Minute Vent
Flow rate isn't volume. It's flow
rate.
volumetric flow rate (also known as volume flow rate, rate of fluid flow or volume velocity) is the volume of fluid which passes per unit time;
https://en.wikipedia.org/wiki/Volumetric_flow_rate
Saying flow rate is a measure of volume is just like saying miles per hour is a measure of distance. Volumetric flow units don't tell you how much volume of gas there is, but rather the
rate of units of volume over time.
"Minute ventilation is defined as the volume of air inhaled (inhaled minute volume) or exhaled (expired minute volume) within any 60-s period."
Robert C. Basner • Sairam Parthasarathy, Eds, Nocturnal Non-Invasive Ventilation: Theory, Evidence, and Clinical Practice, Springer, 2015
To confirm that flow rate and minute vent are two different things, look no further than your Sleepyhead charts: