Hey,

I am currently investigating acute respiratory distress syndrome (ARDS) in mice via intra-tracheal infection of mouse lungs with E.coli. Thus far I have validated our model using histological approaches. However, I would also like to have some real time monitoring to assess the progression of the infection/ARDS symptoms. I have been doing peripheral blood oxygen measurements. However the SpO2 % measurements can have high variability across my experiment. the pulse oximeter we use takes quite a long time to read a stable measurement, sometimes I can be stuck measuring a single mouse for 20 minutes. Often, I get two stable readings from my mice. For example, control uninfected mice ideally would have 99% SpO2 saturation. however I can also get a clean stable reading at ~85%. For my infected mice, the values vary. Since there is no standard, its quite tricky to determine which measurement is true. For example, an infected mouse, 6 hours post infection, can have a reading of 77% SpO2 and can then immediately read stably, at 50%.

I am aware of ensuring the mouse is accustomed to being restrained and recovers from that stress before measure blood oxygen. In addition, extremely low stable readings (60%