Highest possible oxygen concentrations
Highest possible oxygen concentrations
Hello
I am a Consultant Anaesthetist and also have Cluster Headaches. Oxygen is a recognised treatment. This post helps explain how we can achieve the high inspiratory concentrations that are most desirable. It is not to explain how oxygen works.
It is very difficult to get 100% oxygen ("pure") into the lungs but we can get close. The speed at which we breathe in can be above 60 litres per minute and up to 120 litres a minute when stressed (in pain). No plain cylinder flows come anywhere near this - even in hospitals where maximum from wall outlests is 15 litres a minuite. So when we start our breath air is "pulled in" from elsewhere and this dilutes the oxygen concentration. Our pattern of breathing also makes a difference. Rapid shallow breaths will not be as effective as slower deeper breathing. (In medical-speak it is alveolar ventilation we are attempting to achieve). What can we do to offset this?
A tight fitting mask will discourage air being sucked in and a resevoir bag that fills (with oxygen) has its contents "pulled in" in preference to outside air. It is important the resevoir bag does not completely collpase while inspiring. In reality some air will always get in to dilute the oxygen coming from the cylinder. Slow deep breathing to minimise this can help increase concentrations.
A demand valve greatly increases flows and shuts off the oxygen when not inspiring, so the cylinder should last longer (than without).
Everything I read states that 100% oxygen is delivered. This is true but getting it into the lungs for gas exchange will decrease the % that actually arrives there. The only way to achieve 100% oxygen concentration is to have a tube passed into the lungs and deliver 100% oxygen down that! (Intubation). Not recommended unles having an operation anyway!
And finally; it is thought that high oxygen decreases cerebral blood flow. It so happens that breathing rapidly also decreases the carbon dioxide in the blood which also causes a decrease in cerebral blood flow (in the short term) due to vasoconstriction (narrowing of blood vessels). Breathing fast can cause other unpleasant feelings and even fainting so be careful. Good luck all.
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Thank you - very informative!
Thank you. How long can you use the oxygen tank for in one go? My husband is having an episode and used it for 30 mins, wants to go back on but doesn't know how long he can use it for during one session. I know there can be lung damage if you're on it for too long but I have no idea what "too long" is!
Using oxygen as a rule of thumb:
get on the oxygen as soon as the pain starts
stay on until the pain has gone then....
stay on for a further five minutes to mop up the attack
using oxygen in this way not only aborts an attack it can prevent rebound attacks. This way of doing it has been gathered from information from sufferers over a long period of time, so this is purely anecdotal and not medical advice per se.