Acute Blood Loss

by Carlo Raj, MD

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    00:01 At this point, we’re looking at the largest category of anemias and this would be normocytic.

    00:07 We’ll begin our discussion by looking at non-hemolytic anemias with an MCV between 80-100.

    00:14 Of all the non-hemolytic anemias, the ones that students tend to be a little confused with would be acute blood loss.

    00:21 And the only reason for that is because the students feel as though that, well, the RBCs are being destroyed because you’re losing it and then obviously externally they get destroyed.

    00:31 But understand, when you’re actually losing it, they are not being destroyed on their way out.

    00:37 So therefore, you still must consider this to be a non-hemolytic.

    00:42 And then the reason you call this normocytic or refer to it as being normocytic is because you’re losing equal quantity of RBCs and then plasma.

    00:50 So this is whole blood that you’re actually losing.

    00:53 And so therefore, when you actually conduct a measurement, you end up finding an MCV between 80-100.

    01:02 So that will be the trickiest, but once you understand the definition, then we can move forward.

    01:06 And also think as to what you want to do with this patient.

    01:10 Oftentimes, it would be a patient that is feeling hypotensive.

    01:15 And so therefore, IV fluid is something that you want to give.

    01:18 And with that, meaning to say that IV fluids do not contain RBCs.

    01:23 That is not packed RBCs, is it? Major cause is trauma.

    01:27 Obviously, if there is enough blood loss and this discussion would also be in your best interest to bring some of those concepts that we looked at earlier in nephrology and as to what actually controls volume and also controls your osmolarity.

    01:43 And when there is enough blood loss and volume loss, then the priority of the body is to then address the volume at some times at the expense of your osmolarity.

    01:53 And that discussion we have had prior.

    01:55 Now with anemia, what else might then cause acute blood loss? Well, GI bleeding.

    02:00 If there is a bleeding ulcer severe enough or secondary to portal hypertension and if there is esophageal varices that at some point extremely dangerous because you’re worried about rupture and bleeding.

    02:13 And diverticuli.

    02:14 By that, at some point, remember one of the common causes of painless rectal bleeding is diverticulosis.

    02:23 And if there is enough blood loss, then your patient is going to be in the state of normocytic non-hemolytic anemia because the blood is being evacuated from the body.

    02:34 Now with all that said, here it is in text.

    02:37 There is no anemia initially even though the patient feels as though that he or she is tired.

    02:43 Because there is loss of RBCs.

    02:46 But the fact that you’re losing an equal proportion of RBC and plasma, the sign of anemia -- or laboratory-wise, there is no anemia initially.

    02:56 However, you know the patient is going to feel quite hypertensive and fatigued.

    03:02 At first, let’s say that we leave the replacement to itself.

    03:07 Meaning to say, physiologically, how long does it take for the body to then replenish, well, this loss? If we leave it to the body itself, well, the plasma is the first thing to be replaced and that is usually with the help of the kidney in which it’s trying to retain the plasma obviously.

    03:25 Well, the kidney is not the bone marrow, so it’s not going to be responsible for producing RBCs, is it? However, the kidney is responsible for releasing EPO.

    03:36 It does take time for the EPO to then work on the bone marrow where it then starts producing your RBCs.

    03:44 Now, once that plasma -- Now, there are 2 ways that we can do this.

    03:48 We can leave it for physiology naturally for the plasma to then be replenished or more likely the scenario is going to be with this type of acute blood loss, especially secondary to trauma, the patient is now given saline.

    04:04 And so therefore, it just replaces the plasma compartment only, correct? So if it’s the only compartment that you’re replacing is the plasma fluid, then obviously here, you’re going to then reveal the anemia because you’re diluting the RBCs.

    04:19 So at first, the whole blood has been lost, but then once you replenished the plasma, then it’s the RBCs that are not there that, oh, look at this, the anemia has now been unveiled.

    04:30 I hope that makes sense.

    04:32 Then as far as the bone marrow is concerned, it takes about, well, approximately a week, keep it simple for it to then respond with reticulocytosis.

    04:42 What does that mean to you? It means that now, the body recognizes, oh my goodness, the RBCs are not present, and so therefore the bone marrow has to now churn out more RBCs.

    04:52 As it does so, well, reticulocytosis.

    04:54 What’s reticulocyte? It’s an immature RBC, about 24 hours, okay? Completely different from a previous version of the progenitors known as your erythroblast or normoblast.

    About the Lecture

    The lecture Acute Blood Loss by Carlo Raj, MD is from the course Normocytic Anemia – Red Blood Cell Pathology (RBC).

    Included Quiz Questions

    1. Kidney
    2. Liver
    3. Thymus
    4. Spleen
    5. Bone marrow
    1. 1 week
    2. None of these
    3. 1 year
    4. 6 months
    5. 4 weeks
    1. RBCs are lost with plasma.
    2. Only plasma is lost.
    3. More RBCs are lost than plasma.
    4. More plasma is lost than RBCs.
    5. Only RBCs are lost.

    Author of lecture Acute Blood Loss

     Carlo Raj, MD

    Carlo Raj, MD

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