Pulse Oximetry 'venous pulsations'

KatieMI, BSN, MSN, RN · Sep 16, 2016

Yes, you are right. The device needs good arterial circulation to work properly, and so putting it too tight makes reading unreliable. It should sit just right - not too loose, not too tight, - and it can take some time to adjust it properly andvavoid "sick sensor syndrome". Anything that obstruct microcirculation otherwise (forgotten tourniquet, increasing edema) will produce the same effect.

Feeling pulses has little to nothing in common with it. What we feel as pulse is macrocirculation (big arteries) where pretty much no oxygen exchsnge happens. Pulse oximeter works on the level of microcirculation/atreriolae. If one big artery gets occluded, pulse ox will go down but it will not be only one thing looking obviously wrong. There will be pallor, severe pain, etc. One circumstance where the difference can be employed, though, is patient after vascular surgery on extremity, patient with possible developing hematoma, or patient with high risk of thrombosis (venoys or arterial) in known area of the body. Two sensors are applied simultaneously, one on a "presumably healthy" part of body which serves as control, the second one on extremity which was operated on, over possible hematoma (flat sensors, the control usually goes on forehead) or where the thrombus might be most expected. The steady dropping of the second number signals problem. It is only important to use comparable parts of the body (two LEs, not hand vs leg).

greatgateway523 · Sep 16, 2016

Thank you! That term's actually new to me, but I assume Sick sensor syndrome means falsely diagnostic readings?

KatieMI, BSN, MSN, RN · Sep 16, 2016

Where I work (chronic critically sick population) the term was accidentally coined by nurses drawn to desperation by constant ringing caused by different unsignificant factors causing falsely low values. At that time, the rings were to be "addressed" within 30 sec per schmolicy, another schmolicy dictated that pulse oxymeter alarms could not be changed under any circumstances whatsoever, even with severe COPDers who never had it more than 85% to begin with. So when one of the Powers once appeared on the floor and asked what the madness was going on, someone replied like "sick sensor syndrome, sir/ma'am". The phrase stuck immediately. After that aforementioned schmolicies were quietly reworked to more realistic limits. We now use the phrase 7more as differential, aka "is the sensor sick, or the guy is going south?"

CCU BSN RN · Sep 16, 2016

Couple things

1. Yeah, you're right, too tight will affect

2. Make sure you're not taking a BP on the same arm as your pulse ox probe. You'll notice as the BP cuff tightens and occludes peripheral flow, your sat probe will get a crap pleth wave and then your numbers will go down.

It doesn't sound like you're using a reader hooked up to a monitor but IF YOU CAN/ARE, please make note of the pleth wave. If you're using rudimentary equipment on a general floor you don't always have the capability, but one of my peeves is when experienced nurses are convinced a patient is hypoxic when the pleth wave is a straight line, patient is moving around creating artifact, and patient is not displaying any signs of hypoxia.

HardStick69 · Sep 16, 2016

Ive had pt's with arythmias throw some crazy sp02 readings. When in doubt do an ekg and or get your history. Something about arythmia does this.