Simple cannulas are cheap. Oxysavers/Oxymizers are expensive.
Ok, yes. But I used to do the same with those when I used them. They just can’t be washed,due to the stuff inside.
Any recommendations for a fingertip pulse oximeter? I’m interested (at present) more out of curiosity value than with a view to letting my life depend on its accuracy. I’m planning a few flights to 10000 feet + possibly quickly to 13000 and back down again if my aircraft can get that high in the limited time.
Ebay has them on offer from gbp 7 to gbp 240. Presumably they differ to some extent in terms of accuracy, robustness, battery life, readability and ability to work in sunlight?
I have bought them down to about £30 and found them as accurate as my original £300 (2002) Nonin one, which BTW stopped working a long time ago, despite being repaired.
£7… no idea but I always buy the best I can afford 
They should not be affected by sunlight unless, I guess, the sunlight is shining alongside your finger into the cavity.
I once saw someone who compared several devices and did not come up with significant differences in readings between them. Mine is “German”: Pulsoximeter PULOX PO-200 (just Google it). From memory I paid about 40 €. Now I see them advertised at 30 €.
The readings are consistent with what I would expect at a given altitude without oxygen, and with oxygen I read ca. 90% The HR readings are consistent with what I see from other sources too.
I suppose there could be individual differences in the readings depending on the skin on your finger, the depth of the blood vessels etc.
The way a pulse oximeter measures SpO2 corrects for background light and the tissues between the blood and the sensors. It works by measuring relative absorption of two specific wavelengths, and it figures out which part of the absorption is caused by blood (the bit that changes with the pulse) and which by the surrounding tissue (the bit that is constant). The precision of that measurement simply depends on two factors – constant emission of the light source (LEDs) and constant response by the light sensor, both of which does not require particularly expensive components. After that, it is just an algorithm / lookup table on a chip.
That’s why these things can be cheap and still work with precision – the cost is not driven by the actual measurement mechanism, but by the longevity of the components used and all the stuff around it (case, display, battery etc.)
I suppose there could be individual differences in the readings depending on the skin on your finger, the depth of the blood vessels etc.
We have expensive plug-in ones at work, and their results generally correlate very well with the results of blood gas samples sent to the labs. The exception would be with children – they often seem to get low readings for some reason – perhaps wriggliness – and if you retest a well-looking child with a different probe and/or machine their sats will magically improve from the somewhat alarming 85% to 100%. We also have a carboxyhaemoglobin (blood CO levels) monitor which is fickle and requires you to put your finger in a black plastic cover and turn the lights out.
My general impression is that they have become not necessarily more accurate over the past few years, but more usable. They take less time to give you a reading, and seem to do so in a more reasonable way. e.g. we have an old one which, when it’s not picking up very well will start with a reading of about 80% which gradually rises to a more realistic level. If the sensor comes loose briefly it goes back to the start. I’ve no reason to think that the end reading is less accurate than the other devices, but I always find it makes me a little anxious.
An interesting paragraph caught my eye in one of the recent AOPA newsletters:
The oxygen requirements are now more operational so the previously defined hard limits at 10,000 feet and 13,000 feet are no longer binding, provided the crew can operate safely and the passengers are not harmfully affected. (NCO.OP.190 amended July 2016)
Following their link (“EU law”: http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32016R1199&from=EN):
NCO.OP.190 is replaced by the following:
‘NCO.OP.190
Use of supplemental oxygen
(a) The pilot-in-command shall ensure that all flight crew members engaged in performing duties essential to the safe operation of an aircraft in flight use supplemental oxygen continuously whenever he/she determines that at the altitude of the intended flight the lack of oxygen might result in impairment of the faculties of crew members, and shall ensure that supplemental oxygen is available to passengers when lack of oxygen might harmfully affect passengers.
(b) In any other case when the pilot-in-command cannot determine how the lack of oxygen might affect all occupants on board, he/she shall ensure that: (1) all crew members engaged in performing duties essential to the safe operation of an aircraft in flight use supplemental oxygen for any period in excess of 30 minutes when the pressure altitude in the the passenger compartment will be between 10 000 ft and 13 000 ft; and (2) all occupants use supplemental oxygen for any period that the pressure altitude in the the passenger compartment will be above 13 000 ft.’;
My reading is that if you have no objective measure of whether you need oxygen, then the previous limits still apply. However, if you had a pulse oximeter and could shows that you had reasonable sats e.g. at 14,000 feet – then you might reasonably fly to this altitude?
Agreed but it’s more than that. The pilot has to make an determination beforehand. The Key bits "__*Shall ensure*…. supplemental oxygen continuously……__ " and “when he/she she determines the lack of oxygen might….”.
In the company I fly with, we use supplemental oxygen at all times above 10 000ft and, using the “shall determine… might….” bit we also mandate availability at night and/or single pilot operation above 8000ft.
Oxygen in Switzerland
I am checking the possibilities for a Mountain High O2D2-2G based oxygen system. Based on a tip from @Peter I selected the CFFC-048 carbon fiber cylinder. As there is no configuration with this cylinder and an European valve, I asked the Swiss representative of MH if they can supply it. Their answer surprised me (a bit, I’ve already got used to the ways Switzerland blocks a lot of things from the rest of the world):
It is difficult to fill up American cylinders in Switzerland. The oxygen shops/plants are not allowed to do so. From our experience we suggest that you rent a Swiss oxygen cylinder from an oxysgen shop/plant, e.g. PanGas. PanGas has a lot of shops in Switzerland. The process is problem free.
The original text in German:
In der Schweiz ist es schwierig, die amerikanischen Sauerstoffflaschen wieder aufzufüllen. Den Sauerstoffwerken in der Schweiz ist dies untersagt. Aus Erfahrung empfehlen wir eine Schweizer Sauerstoffflasche in einem Sauerstoffwerk z.B. PanGas zu mieten. PanGas verfügt über viele Depotstellen in der Schweiz
Diese Abwicklung ist dann stet problemlos.
Does anyone have experience in Switzerland? Is it really difficult/impossible to use foreign cylinders? What about the non-aviation possibilities mentioned in other threads here on EuroGA, has anyone found/used any in Switzerland?
