The one where he rants about Pulse Oximetry


Maybe not a complete, out of my mind, drooling, almost incomprehensible rant, but a rant none the less.

Pulse Oximetry was hailed as the “Fourth Vital Sign” back in the early 1990s when it started to filter it’s way out of units into Emergency Departments and EMS systems. It really wasn’t but it was a great slogan to sell it to the skeptical.

Pulse Oximeters are indirect measuring devices. That is they don’t directly sample the blood, they do it with LEDs. Which are the first cousins to LASERs. Really, would Britney Spears lie to you? So, a Pulse Oximeter shines a LED light into your finger and measures the amount of light absorbed by the blood and calculates hemoglobin saturation. Just in case you wanted to know.

I’m not sure I’ve ever seen a more misused technology in EMS, one with questionable benefit to the patient. Pulse Oximetry is supposed to be used as a trending tool, not a spot check. Yet invariably I see practitioners place the probe on a finger, get a reading, and then toss the device back into their bag. What, pray tell, does a reading of 100% tell you about a patient? Now, a reading of 84% does tell you something about the patient, but I’m not sure I’d like to work with a medic or EMT that can’t tell a hypoxic patient without using a Pulse Oximeter. I AM sure that I wouldn’t want one treating a loved one.

So, what does a Pulse Oximetry reading of 100% tell you? It tells you that the patient’s blood is well saturated with Oxygen. Great news, but again not all that important, especially as a spot check. My resting Pulse Oximetry reading is 96%, sometimes 97%. I don’t feel hypoxic, I don’t get Dyspnea on Exertion. No, I don’t need home O2 or intubation, I just have a low Pulse Oximetry reading.

Don’t even start me on medics and EMTs that use the thing just to get a pulse. Touching a patient? How radical.

What that number doesn’t tell you is how well the patient is ventilating. The old “in with the good, out with the bad” from the Looney Tunes cartoons. Here are some patient types that might have good readings despite being really, really, sick. CHFers, COPDers, Pulmonary Emboli, Carbon Monoxide Poisoning, Smoke Inhalation and of course Asthmatics.

Any of those patients can, and have, had readings of 100%. I’ve seen it and I’ll bet you have too.

So, how do we really assess a patient’s ventilatory status? It’s really simple, in fact you probably learned it your first week in EMT school.

Look at the patient. How hard are they working to breath? Retractions? Tripoding? Prolonged expirations? Are they working to inhale, exhale, or both? What does their skin color look like? If they have dark skin, look at the oral mucosa, it should be pink. Most importantly, do they have that “I’m gonna die right here in front of you” look?

Listen to the patient. Can they speak? How many words can they speak between breaths. Five or more is good. Listen to lung sounds. That $5000.00 stethoscope is good for more than just looking cool for the cute young nurses and EMTs. Ronchi, rales (crackles is what a particular brand of breakfast cereal does), wheezes, stridor? Good breathing isn’t noisy, you should hear a gentle rush of air moving in and out. If you don’t hear anything, you either spent way to much for that stethoscope, have the bell turned the wrong way, or an about to die patient on your hands.

Feel the patient’s skin. Is it wet and cold? Hot and dry? Wet and hot?

Do that for every patient no matter what the call is dispatched as. Do it on transfers, do it on ankle fractures, do it on idiots that call for a toothache. Do it until it becomes automatic. Do it until you can do everything I wrote in the preceding three paragraphs automatically. Know what is normal and what isn’t. Soon, you’ll be able to walk into a room and in about thirty seconds have a pretty good idea of what the patient’s ventilatory and respiratory status is.

Before you know it, you’ll hardly glance at the little beeping box and will never need it to tell you if a patient is sick.

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After a long career as a field EMS provider, I'm now doing all that back office stuff I used to laugh at. Life is full of ironies, isn't it? I still live in the Northeast corner of the United States, although I hope to change that to another part of the country more in tune with my values and beliefs. I still write about EMS, but I'm adding more and more non EMS subject matter. Thanks for visiting.


  1. And why do patient’s with disease still sat either high or low? Because O2 can be displaced by other gases on hemoglobin….and COPD are obvious..I think you should be writing this basic airway assessment chapter for me! Awesome rant…with good information!Thanks!

  2. yes! YES!Earlier today we responded to a call for a 90 year old female w/ difficulty breathing. History of COPD.Standing next to her it was SO easy to hear wheezing; she could speak only a few words @ a time; she sat in classic tripod position.An EMT on the engine company that responded with us slapped the pulse ox on her, “O2 sat 97%, she’s fine! oh, and pulse of 86.”I proceeded to put her on a non-rebreather while we set up for a breathing treatment.

  3. Well said. Seems a lot of the technology we have access to tends to supplant good old fashioned assessment skills, and way too many people get complacent. Seen it happen too often, if the patient isn’t hooked up to the monitor, folks forget those things they learned in the first week of nursing school too, or the first week of ER orientation. Things like the assessment value of ‘pink, warm, and dry’ – and little lessons like ‘look at the patient’ instead of the monitor.I enjoy your blog – thank you!

  4. Thank you so much for this post! I always hear providers railing on the pulse oximeter, but they can never tell me why they don’t like it.I agree with everything you’ve said, and it bothers me to no end when I see someone get pulses from that machine; it doesn’t tell you anything about the pulse, if it’s weak, strong, bounding, equal on both sides, etc.I’m going to link this post to a few, if you don’t mind! Great blog, too, by the way!–Sam

  5. Aside from tracking trends, the best prehospital use of a pulse oximeter is to provide the receiving ED with the patient’s room air sat. Nothing as frustrating as watching the respiratory failure patient that you have been treating slowly improve, then crash as soon as the ED staffers take them off of your interventions (O2, neb, CPAP, etc) “so [they] can get a room air sat.”

  6. What is the value of a room air sat? In 1980s, they had to get a “room air blood gas”. I always thought this strange as if the patient is in acute distress on oxygen, they aren’t going to get better off oxygen. It’s a number that makes the ED staff feel better, but has no value for the patient.

  7. I can still remember the days before we had pulse oximetry on the units and had to actually assess the patient. (wow..what a concept). Now if we could just get new medics to treat the patient and not the machine. I agree about using it for trending as I find this is more important than the actual number displayed on the screen ( a number that can be easily influenced by many, many factors)I think part of the problem is a lack of actual education on the proper use of the device and its limitations in the field.

  8. I have to say that I love you. I rarely use it and get bitched at all the time by the ED staff because of it. I mean if my patients presentation improves with my treatment that is what I want to see not the numbers on the screen. Treat the patient not the equipment! 4th vital sign? I thought that was lung sounds.

  9. I thought the fourth vital sign was insurance. :-)Pulse oximetry is useful, other than when used as a behavior modifying projectile, in the context of a thorough assessment, when used by someone who knows how to put the information into the proper perspective. Even then it is overrated.SJ,People who insist on a room air pulse ox or a room air gas are sometimes known as killers. Of course, there are plenty of apologists who will claim that the lack of oxygen had nothing to do with the rapid onset of death. The patient’s death may be inevitable, but we should not assist the doctors and nurses who suffocate these patients.

  10. I didn’t mean to imply that a room air sat was important; my point was that by obtaining it as I start my interventions, I can often head off inappropriate “care” at the receiving facility. Its importance is in the minds of some ED nurses as “proof” of the efficacy of their interventions.My typical use of spO2 is attaching the extra wire to my LP12 along with BP cuff and ECG leads. Then I mostly ignore the monitor unless I need the data. It’s like having a reasonably competent partner in the back track vitals for me; I can get them when I want them, including a trend.The toys are handy, but the Mark I human senses are quite good at picking up most of the same things that the gadgets do. It should always come back to inspection, palpation, auscultation, and conversation (with the patient). A point that I occasionally think that needs “blunt object emphasis” to get through the skulls of some of my coworkers.

  11. medic 3,If you see an apparent need for oxygen, why withhold oxygen?What information does a room air sat provide?How does withholding oxygen to measure a room air sat help the patient?The use of room air sat is to treat the chart. Charts do not die without oxygen. A room air sat does not to treat the patient. A room air sat is withholding treatment from the patient.”I didn’t mean to imply that a room air sat was important;”Then why delay care for it?Why is it more important than prompt treatment with oxygen?”my point was that by obtaining it as I start my interventions, I can often head off inappropriate ‘care’ at the receiving facility.”You mean obtaining it as you delay intervention with oxygen?By doing this, aren’t you extending the “inappropriate ‘care'” to the ambulance or to the scene?”Its importance is in the minds of some ED nurses as ‘proof’ of the efficacy of their interventions.”So, some ED nurses are dangerous to patients. Your response to this is to change your behavior, rather than try to change their behavior?

  12. Rogue Medic,I never said that I withheld oxygen, in fact I specifically said that I obtain their sats “as I start my interventions.” I can’t tell if you are establishing a deliberate straw man, trolling, or have poor reading comprehension; but whatever the reason, I do not appreciate the mischaracterization of what I had written.That being said, it takes less than 10 additional seconds to clip on the pulse oximeter probe and plug it into the monitor. Less time than my EMT takes to open the O2 tank, prep the oxygen delivery device of choice, and place it on my patient. A delay of up to 10 seconds while I continue my assessment (real assessment: inspection, palpation, auscultation, and conversation) is in fact entirely appropriate as it can determine the necessity of oxygen or other drug interventions (hyperventilation v air trapping asthmatic for example). This is in no way comparable to removing an established intervention for the purposes of getting a baseline.FYI, I also delay some other interventions to complete essential elements of my assessment. For example: -I check the patient’s breathing before ventilating them, even if they look bluish. -I take a 12-lead ECG before administering nitro because I have seen patients’ ECG changes vanish after a course of nitro, so the local hospital won’t send them for an emergent cath without “proof” of a STEMI. A significant number of those patients then re-developed their chest pains and ST elevations and were “emergently” cathed hours later. By delaying my chest pains treatment protocol to take the ECG (and also blood samples) I affect the level of definitive care provided at the facility. As the science emerges, some of this may later be shown to be unnecessary (so I’ll stop), some may be termed essential (and I’ll say “I told you so”). But I can’t read the future; I can work my current system to the advantage of my patient.-I inspect the oral mucosa, upper chest/neck skin, auscultate lung sounds, and get a brief history for my trouble breathing patients as a part of determining the appropriate care (neb, O2 alone, CPAP, verbal calming, epi/benadryl, intubation, etc). Providing oxygen to the hyperventilating patient actually worsens the hyperventilation syndrome. Although to the newer provider, they may look like they are in need of oxygen.As some other blogging paramedic wrote, assessment is the single most important EMS skill. I agree with this statement. The direct consequence of this is that interventions are delayed for an assessment. Depending on the patient, any the elements of the assessment may be shown unnecessary after the fact. (“12-lead shows no acute changes? Guess it wasn’t necessary then!”) That is why the experienced paramedic will chose the “most important” elements of the assessment to go before interventions and allow the others to follow. Is a room air sat an important element of assessment? Not really in most cases. But is a delay of somewhere between 0 and 10 seconds worth the impact that walking in with the facility-required sat number has on the ongoing care and management of that patient? Sometimes. Especially for the very severe cases where being removed from those interventions may lead to the crash of the patient. This applies to drawing blood and taking a diagnostic quality 12-lead ECG before starting chest pain interventions as well as pulse oximetry in the trouble breathing patient. As I said, I have seen the acute ECG changes vanish running through the local chest pains protocol (we’re urban and don’t do tPa). Having the blood drawn at the time of the cardiac ischemia and the 12-lead displaying ST changes has made the difference in hospital treatment for those patients.Well, this has become quite verbose. I don’t disagree with you in principle regarding timely interventions, but not all delays are unacceptable. Some are actually beneficial in the long term for the patient.

  13. medic 3,I have seen few people obtain sats that quickly. Often the patient is moving or has nail polish on (that leads to some getting nail polish remover to play with this), or something else that interferes with obtaining an accurate number.I still see little benefit in the room air sat. I think you are encouraging the hospital in their lust for room air sats.The rest of your comment is excellent and I agree with it. Signs of a right ventricular infarction should also delay NTG administration. There is a very good article about RVI, by Gene Gandy, here (the page loads in an odd way, but if you scroll down the article is there) – Recognition and Treatment of Right Ventricular Myocardial Infarction

  14. Excellent post. It should be printed and handed out to EMT’s and Medics both in school and out.

  15. Thank you! This needs to be drilled home to everybody. Pulse Oximetry is disgustingly overused and way too heavily relied on. I can’t tell you how many times I get calls from nurses because “the sat is low” when they obviously have not assessed the patient beyond doing a halfass job of slapping a probe onto someones fingers.

  16. The pulse ox should be banished from the truck. Assess your patients; you can tell within 30 seconds if they need oxygen.

  17. From the patient/family view – I found the use of the pulse ox in ICU and long term acute care to be maddening. My dad was in ICU for 4 mos, on vent 6 wks of that, then trached, then finally off the vent. All along, if his pulse ox was 94+, there was no attention paid to his resp status, regardless other indicators. If the thing went low and started to beep, nurse after tech after nurse after tech would come in, jiggle it, and say, “These things are so fussy” or “he needs to keep his hand still” (he was not conscious) or “I’ll have the RT change that lead.” In other words, fix the machine, ignore the pt UNTIL the machine is fixed. We were “hysterical family members” when we asked for the RT in response to signs WE could see of changes in his resp status (sounds, heaving chest movements, change from normal rate/depth to fast/shallow, etc.). “Don’t worry, his saturation is fine!” It was so hard to watch him slide into distress & have to turn blue before getting help because the stupid pulse ox said “everything is fine.” As I said, maddening.

  18. kathy,We are but poor servants of the flashing beeping machines. Thinking is to be discouraged. If we can’t get the beeping to stop we call someone else. We want the beeping to be a problem with the equipment or with the patient misbehaving, because we don’t know how to assess patients any more. Copying good numbers off of the machine makes for happy workers. Thinking is bad. The goal of medicine is to prevent situations where thinking is required.If you can’t put a number on it, it isn’t a problem.

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