5 ms·

It seems like it would be impossible to have a true double blind study with something like hyperbaric oxygen. Once the chamber reaches pressure, it is very obvi

It seems like it would be impossible to have a true double blind study with something like hyperbaric oxygen. Once the chamber reaches pressure, it is very obvious to the patient.

FredPret 5y ago
I wonder if one could compensate by having a control group with high-pressure but low-concentration oxygen
- jasonlaramburu 5y ago
  Would that be safe for the patients?
  - FredPret 5y ago
    I speak under correction but I think that's how diving works - high pressure air, with extra nitrogen. So the concentration of oxygen is less but the total amount is the same
    - BenjiWiebe 5y ago
      I too speak under correction, but usually the nitrogen gas is actually at a lower percentage or eliminated altogether. Pressurized nitrogen causes nitrogen narcosis, so the filler gas instead is commonly helium.
twic 5y ago
> Each treatment included 20‐minute pure oxygen inhalation (O2 = 99.9%, oxygen supply pressure 0.4 to 0.7 MPa, oxygen flow 10 to 15 L/h), 15 minutes interval, and then another 20‐minute pure oxygen inhalation (O2 = 99.9%, oxygen supply pressure 0.4 to 0.7 MPa, oxygen flow 10 to 15 L/h) under the pressure of 0.22 MPa (0.12 MPa on pressure gauge) in hyperbaric oxygen chamber (Medical Oxygen Chamber, SY3200‐8500, Yantai Hongyuan Oxygen Industrial Inc., Shandong, China). Controls that spring to mind would be to have the chamber pressurised to a lower pressure (if you're not already familiar with hyperbaric chambers, you won't know it's at a lower pressure), or to replace the pure oxygen with normal air. Showing a dose-response relationship to pressure or oxygen concentration would go a long way towards making up for the lack of a true negative control.
- CoastalCoder 5y ago
  IIRC from SCUBA diving, breathing pressurized normal air can result in nitrogen narcosis, at least while you're still under pressure. Not sure if there's a lingering effect afterwards, which IIUC is what we're talking about here.
  - twic 5y ago
    OTOH, if there is, using that as a control would give you a nice big signal!
  - LorenPechtel 5y ago
    Bring the chamber pressure down slowly enough to decompress.

It seems like it would be impossible to have a true double blind study with something like hyperbaric oxygen. Once the chamber reaches pressure, it is very obvious to the patient.

FredPret 5y ago

I wonder if one could compensate by having a control group with high-pressure but low-concentration oxygen

jasonlaramburu 5y ago
Would that be safe for the patients?
- FredPret 5y ago
  I speak under correction but I think that's how diving works - high pressure air, with extra nitrogen. So the concentration of oxygen is less but the total amount is the same
  - BenjiWiebe 5y ago
    I too speak under correction, but usually the nitrogen gas is actually at a lower percentage or eliminated altogether. Pressurized nitrogen causes nitrogen narcosis, so the filler gas instead is commonly helium.

twic 5y ago

> Each treatment included 20‐minute pure oxygen inhalation (O2 = 99.9%, oxygen supply pressure 0.4 to 0.7 MPa, oxygen flow 10 to 15 L/h), 15 minutes interval, and then another 20‐minute pure oxygen inhalation (O2 = 99.9%, oxygen supply pressure 0.4 to 0.7 MPa, oxygen flow 10 to 15 L/h) under the pressure of 0.22 MPa (0.12 MPa on pressure gauge) in hyperbaric oxygen chamber (Medical Oxygen Chamber, SY3200‐8500, Yantai Hongyuan Oxygen Industrial Inc., Shandong, China). Controls that spring to mind would be to have the chamber pressurised to a lower pressure (if you're not already familiar with hyperbaric chambers, you won't know it's at a lower pressure), or to replace the pure oxygen with normal air. Showing a dose-response relationship to pressure or oxygen concentration would go a long way towards making up for the lack of a true negative control.

CoastalCoder 5y ago
IIRC from SCUBA diving, breathing pressurized normal air can result in nitrogen narcosis, at least while you're still under pressure. Not sure if there's a lingering effect afterwards, which IIUC is what we're talking about here.
- twic 5y ago
  OTOH, if there is, using that as a control would give you a nice big signal!
- LorenPechtel 5y ago
  Bring the chamber pressure down slowly enough to decompress.