I currently have three pulse oximeters set up at the same time:
- Ohmeda 3900P with ear-clip sensor OR finger sensor
- Masimo Radical with finger sensor
- Quartz Q400 with finger sensor
All three have data logged to PC's.
When I finish the breath-hold, I can measure the 'response' time (delay), by checking to see how long it takes for the SaO2 to reach a minimum.
For example:
4'00" static
Minimum SaO2 occurs at 4'25" on the oximeter
This implies a delay of 25 seconds.
The delay also strongly depends upon your 'perfusion', i.e. how much blood is flowing to your fingers/ears etc.
If you have cold hands, the delay is much longer.
With WARM hands, I have found that my finger sensors have a delay/response time of 23-30 seconds, and the ear-clip sensor has an astonishing response time of 10 seconds.
Also, the ear-clip sensor catches brief transient desaturations much better than the finger sensor. This means that on inhale statics, all three oximeters drop to about the same SaO2, but on exhale statics, where the drop is much faster and shorter, the ear clip sensor consistently drops to 4-6% lower SaO2 than the finger sensors.
Masimo now makes a forehead transflectance sensor, but it costs $430. I was hoping to get one but I have other expenses.
I also have a transcutaneous O2/CO2 monitor. This is very interesting because it measures your PO2 and PCO2, not your SaO2. Your PO2 decreases linearly with apnea, unlike the SaO2 which changes at strange rates (seems to accelerate at the end because of the shape of the Hb-O2 curve).
Eric Fattah
BC, Canada
- Ohmeda 3900P with ear-clip sensor OR finger sensor
- Masimo Radical with finger sensor
- Quartz Q400 with finger sensor
All three have data logged to PC's.
When I finish the breath-hold, I can measure the 'response' time (delay), by checking to see how long it takes for the SaO2 to reach a minimum.
For example:
4'00" static
Minimum SaO2 occurs at 4'25" on the oximeter
This implies a delay of 25 seconds.
The delay also strongly depends upon your 'perfusion', i.e. how much blood is flowing to your fingers/ears etc.
If you have cold hands, the delay is much longer.
With WARM hands, I have found that my finger sensors have a delay/response time of 23-30 seconds, and the ear-clip sensor has an astonishing response time of 10 seconds.
Also, the ear-clip sensor catches brief transient desaturations much better than the finger sensor. This means that on inhale statics, all three oximeters drop to about the same SaO2, but on exhale statics, where the drop is much faster and shorter, the ear clip sensor consistently drops to 4-6% lower SaO2 than the finger sensors.
Masimo now makes a forehead transflectance sensor, but it costs $430. I was hoping to get one but I have other expenses.
I also have a transcutaneous O2/CO2 monitor. This is very interesting because it measures your PO2 and PCO2, not your SaO2. Your PO2 decreases linearly with apnea, unlike the SaO2 which changes at strange rates (seems to accelerate at the end because of the shape of the Hb-O2 curve).
Eric Fattah
BC, Canada