Pulse Sensor Clip

Sorry, I attached two pictures only one made it, so here is the other one.

Is it possible to use a nellcor max-a disposable pulse oxi into a arduino.

I would imagine so yes.

I am having difficulties in detecting a pulse using the arduino.

What amplifier are you using, it is a very small signal and it needs amplifying.

When the two sensors across.

There is only one sensor, the two outputs from that sensor are shown in that diagram as SK and SA.

Must the monitoring led turned off?

No there is no reason to turn off the LED. Note that this is an IR LED, they work better getting through the skin.