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What would cause Hgb to plummet?

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Specializes in neuro/med surg, acute rehab. Has 5 years experience.

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psu_213, BSN, RN

Specializes in Emergency, Telemetry, Transplant. Has 6 years experience.

First of all, low sats are not related to low hgb. This is a big misconception in nursing. I had a doc explain it to me once (cuz I too used to get confused). Low hgb is having less trucks on the highway but they can still carry the same load. Sats (% of oxy on hgb) is the load.

It is true that low hgb does not cause low sats, however low hgb can mean tissue hypoxia even in the setting of "normal" sats. If hgb is low that means there is less oxygen carrying capacity in the blood. So even if 100% of the hemoglobin is carrying oxygen (hence sats of 100%), there is still less oxygen being delivered to the tissues if the hgb significantly decreased. To use the truck example, if you normally have 20 trucks delivering the load, but now you only have 5 trucks, less is going to be delivered. Saturation is only part of the picture for tissue oxygenation; yet, as nurses, we are taught be obsessed with that number.

Edited by psu_213

It is true that low hgb does not cause low sats, however low hgb can mean tissue hypoxia even in the setting of "normal" sats. If hgb is low that means there is less oxygen carrying capacity in the blood. So even if 100% of the hemoglobin is carrying oxygen (hence sats of 100%), there is still less oxygen being delivered to the tissues. To use the truck example, if you normally have 20 trucks delivering the load, but now you only have 5 trucks, less is going to be delivered. Saturation is only part of the picture for tissue oxygenation.

Not only that, but if gas exchange is impaired d/t a hemothorax, then the O2 sats would be affected.

psu_213, BSN, RN

Specializes in Emergency, Telemetry, Transplant. Has 6 years experience.

Just another theory: given the location of the surgery...is bleeding into the mediastinum possible? Did a slow bleed turn into a faster one? Was there some sort of sudden disruption to the hemostasis mechanism used during surgery?

marcos9999, MSN, RN

Has 5 years experience.

I'm pretty new at this but I was interested in your case so I did some research. Some causes of sudden loss of Hgb could be hemodilution, anticoagulants could loss through the digestive tract, stress can cause a lack of hgb production, kidney impairment could also cause hemodilution through water retention, Another reason for hemoglobin drop could be from destruction of red cells after receiving an allogeneic red cell transfusion, as seen in allergic transfusion reactions. Diet can also play a part.

lckrn2pa

Specializes in ER. Has 19 years experience.

I didn't read all the post but everything about this screams PE to me, within the 1st few sentences of your presentation.

Recent surgery, central cyanosis, SOB,fever (common in PE pts). This is a PE until proven otherwise.

psu_213, BSN, RN

Specializes in Emergency, Telemetry, Transplant. Has 6 years experience.

I didn't read all the post but everything about this screams PE to me, within the 1st few sentences of your presentation.

Recent surgery, central cyanosis, SOB,fever (common in PE pts). This is a PE until proven otherwise.

Could be a PE, but does that really explain the dramatic drop in hgb? Not that it can't be a PE and something else, but what is that something else?

brillohead, ADN, RN

Specializes in Cardio-Pulmonary; Med-Surg; Private Duty. Has 5 years experience.

Another way to look at the oxygen saturation issue -- pulse ox measures the amount of oxygen that is being carried on an individual "chunk of hemoglobin". You could have a patient with a 100% sat level who is severely hypoxic and quite cyanotic, if they have a low hemoglobin count to begin with, because even if each chunk is carrying a full load (100%) of oxygen, there still won't be enough oxygen to go around to all the tissues that need it. You can't relate O2 sat levels to the amount of oxygen that is circulating in the body unless you know that the hemoglobin levels are satisfactory.

Taking the truck analogy farther, let's say that a hypothetical body needs 90 cases of oxygen to maintain normal function, and a normal body has 100 pickup trucks driving around delivering oxygen and then refilling their load at the oxygen manufacturing plant, each truck carrying their full capacity of one full case of oxygen. Capacity carried by each truck = 100% load capacity = 100% O2 sat.

Then five pickup trucks get flat tires and are out of commission, so you now only have 95 pickups each carrying one full case. You now have 95 cases available in the body, but each truck is still carrying 100% of its load capacity, so O2 sat is still 100%, even though the actual number of cases has decreased by 5% (started with 100 cases, now only have 95 in circulation). But that's okay, because we had a bit of a cushion built in -- we had enough trucks to carry 100 cases, but we really only need 90 cases to get by.

Then there is a defective part on that model of truck, and twenty trucks all blow a head gasket at the same time. You're now down to only 75 trucks going around the body, but each truck still has a full case of oxygen, so O2 sat is still at 100%, even though there are only 75 cases available now instead of 100 cases like we started out. But with only 75 cases available, and with our previous statement that the body needs 90 cases in order to maintain normal function, we're going to start seeing some problems... we're running on an overall deficit because twenty-five percent of our trucks are out of commission. So even though all the remaining trucks are running at 100% capacity and we have a 100% O2 saturation level, we're turning blue because we are 15 cases short of the 90 cases we need for normal functioning.

So now imagine that there's a problem at the oxygen manufacturing plant as well, and production is slowed considerably -- they can't even keep up with the demands of the 75 trucks that are still on the road. When a truck comes in for a fresh load, they can only give them 85% of a case. Now each truck is only carrying 85% of a load, so the O2 saturation level drops to 85%. But since we had fewer trucks (75) to begin with, that means that there are only 64 cases of oxygen available in the body. So even with an 85% sat level reading, we're only running at 64% of actual capacity.

Hopefully this little story helps with mentally separating the O2 sat number from the actual volume of oxygen that is available to the body to use. Pulse ox readings are great, but always look at your patient first, the monitor second... remember, someone can be completely blue with a 100% O2 sat reading!

AlphaPig

Specializes in neuro/med surg, acute rehab. Has 5 years experience.

Ok, update on the patient. I was not able to look at her chart (because now with electronic charting you can trace everyone who looks at the chart and since I am not her nurse anymore, I could get into trouble) but I was able to glean some information from her doctor and the patient herself (who I visited on the step down room she is now in).

All of her scans were negative - she is not bleeding anywhere.

They gave her 2 units of blood and her Hgb went up to 9.0 where it stayed for two days before dropping to 8.2 the day I visited her.

The doctors have no idea why her Hgb refuses to stay up. Her admitting doctor told me they consulted Hematology but they haven't seen the patient yet. He said they are trying to put all the pieces together - her surgery, her auto-immune disorder, her lung spasms (which has pretty much resolved) - to figure out what is going on.

The patient appeared much better to me - no cyanosis, no SOB while resting, O2 sat 96% on 2L NC. Pt stated her right flank pain was now being controlled by her pain medicine and the spasms have pretty much stopped. Pt still feels weak.

So. . .basically they still don't know what is going on. I will continue to try to follow her case and will let you know. I wish I could see her chart.

FranEMTnurse, CNA, LPN, EMT-I

Specializes in LTC, CPR instructor, First aid instructor.. Has 24 years experience.

I had septicemia once. Would this cause a log hgb count? I was given 2 units of blood.

yeah, maybe she doesn't even have MG...

hematologic malignancy

Grumpy's Girl

Specializes in Critical Care. Has 34 years experience.

One more tidbit for the truck analogy: Less trucks, though with a full load, must work faster to deliver the goal amount, even faster if they are carrying less load on less trucks. Hence tachycardia. Hence increase RR to fill those less trucks that are running faster with O2.

As RRT members we encourage - esp new RNs- to call with questions if their senior nurses can't answer. One of the "triggers" to call RRT is the RN is "worried" about how their pt is doing. I guess "worried" is that developing nurse sixth sense that this patient has the potential to crash whether you can get the MD to feel it or not. The RRT will help you put together the pieces to see what has developed and what is probably coming and how to nip it in the bud or d/w MD. Those are good calls - nipping it in the bud. Each call is a learning experience. We teach and think out loud with the RN (and the family). It has been neat, now, to see that many times, by the time we get to the room, the nurses who called us have already started our routine. Talk about nipping it in the bud. We are a team. We have more pts getting over the crisis and staying in the room.

This is just a RRT aside. So keep in touch with your RRT resources.

Glad your pt is doing better, hope her mystery is solved soon.

alfa-sierra, BSN, RN

Specializes in Psych. Has 18 years experience.

Yes, only 5 trucks instead of 20. Yet, 5 trucks may be compensatorily overloaded and the total load still be close to what 20 normally loaded trucks would carry. That may explain why the blood drawn looked so thick and dark- more O2 clinging to fewer cells, fewer hemes, more O2 reacting with the same iron per cell.

still don't get the truck thing

psu_213, BSN, RN

Specializes in Emergency, Telemetry, Transplant. Has 6 years experience.

still don't get the truck thing

Uh, how so. It was an analogy...and I don't think it was that difficult to understand, although I could be wrong. What about it did you not understand?

It's hard on the floor (when I had 5 other patients) to truly stop and take a good look at the whole clinical picture. I feel like as floor nurses, we tend to focus on the task at hand/main problem and don't have the time to ever put all of the pieces together/get a feel for the whole person.

the above statement is true and scarey, because of this i no longer wish to work in a hospital.