When i went to the ER for my fast heartbeat i'm like 60% sure that i heard the nurse say she was going to take my "oxygen level" but i'm not positive. Could anybody tell me what your oxygen level is and how it is related to cardiac function? Also, How do they check for oxygen? i think she clipped a little thing on my finger for a minute.

Hi, the little thing on your finger measures your oxygen satuaration levels in your blood. If your heart is not functioning properly then your O2 levels may be low. This is what they were looking for. They can also do a blood test that would also be accurate. Anything below about 94% they may be concerned about. People with respiratory or pulmonary problems may also have low oxygen levels.

Good to know, i think she said mine was like either 96% or 98% cant remember which.

96% or 98% is fine. They take pretty much everybody's oxygen level in the ER, because it's so easy to do by simply clipping the thing (pulse oximeter) onto your finger. There's absolutely no reason to be concerned about their having taken your blood oxygen levels because it's a completely standard procedure.

The finger clip works by shining light through your finger and measuring how much of the light is able to pass through. The amount of oxygen in your blood affects how much light can shine through.