Thank you for your message. The pulse oximeter will not work when the baby's heart rate is very low and perfusion is poor. When it appears that the pulse oximeter does not work, auscultation of the heart to establish the rate would be advised. As the newborn is resuscitated using the correct interventions according to the sequence of the flow diagram, the HR should increase, and pulse oximetry will start to work when the HR is about 60 bpm.
I hope this helps!
As Olivia stated, the pulse ox will not work if the pulse is too low, but the EKG should. Be sure you are dropping it onto the baby-- you should see the leads get attached. When I was first learning, I would drop the devices into the field, but must not have hit the "hot zone" because it was like I never did it.
Hope this helps.