Volume of blood in thals body

Hi,

1- Normally the volume of blood in adults is 5 to 6 liters ( average ) . Is it the same  in non transfused  thal patients as they have their counts low and all their blood works are in the low side??

2- Another questions is that i can see from your posts that each kg in the body needs 15 ml of blood to be transfused. So a maxium an adult gets is 1000ml if he is 70 kg. So how can this small quantity increase the Hb knowing that the body has an average of 5 to 6 liters of blood. How does it work and the majority of blood in the body is the muted one??


3- Last question, can a thal change his/her all blood  instead of transfusion. Like in dialysis when patients sit on machines to clean all their blood. is there anything like this were you can change your blood so it can last longer than transfusion.  hope it is not a stupid question

Manal

Helloooooooooo any opinions,

Manal

Hi Manal,

1) The blood volume may actually rise in chronic anemia. Although the red cell volume is lower, it is made up by higher plasma volume.

 From http://web2.airmail.net/uthman/anemia/anemia.html

Although (by definition) total body red cell mass is decreased in anemia, in the chronically anemic patient the total blood volume paradoxically is increased, due to increased plasma volume. It is as if the body were trying to make up in blood quantity what it lacks in quality.

Blood volume is inversely related to hemoglobin level.

http://www.ncbi.nlm.nih.gov/pubmed/6776764?ordinalpos=10&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

Correlation between transfusion requirement, blood volume and haemoglobin level in homozygous beta-thalassaemia.
Gabutti V, Piga A, Fortina P, Miniero R, Nicola P.

We examined the relationship between blood volume, mean haemoglobin maintained and transfusion requirement in an extensive series (166 cases) of uniformly treated patients with homozygous beta-thalassaemia. The blood volume is increased in all the subjects and this increase appears inversely proportional to the mean haemoglobin level maintained. When this is above 12 g/dl, the blood volume is nearly normal. The transfusion requirement of patients kept between 10 and 14 g/dl is constant. Maintenance of a high haemoglobin level in thalassaemic patients inhibits erythropoiesis to a considerable degree with a reduction of the haemopoietic tissue and hence of the total blood volume.

PMID: 6776764 [PubMed - indexed for MEDLINE]

2) Keep in mind that the goal is to raise the hematocrit (the percentage of volume that is red blood cells) by only 5-10% of the total blood volume. The volume transfused will be less if packed red cells are given instead of whole blood, as the hematocrit of the packed RBC's will be 60-75%. There is a mathematical formula for determining how much blood needs to be taken to raise the hematocrit a specific amount.

From http://www.scinfo.org/transfus.htm

Formulas of use in Blood Transfusion (Useful Approximations):

Total Blood Volume = 70 cc X Weight in kg.or 75 cc X Weight in Kg (With chronic anemia).

Red Cell Volume of Patient = Total Blood Volume X Hematocrit

Giving 3 cc/kg of packed red cells will raise the hemoglobin by 1 gm/dl

Giving 10 cc/kg of packed red cells will raise the hematocrit by 10 points (vol%) or hemoglobin by about 3 gm/dl

Quick Formula to Approximate Volume of Red Cells for Transfusion

Transfusion volume = [Total Blood Volume X (Hcrit goal - Hcrit pre Tx)]/ Hcrit of Donor Unit

Example: For 50 kg person with pre-transfusion Hcrit 23%, goal Hcrit 30%, average PRBC unit Hcrit 70%,

[(75 cc/kg) (50 kg) (0.30 – 0.23)]/0.70 = 375 cc (or 7.5 cc/kg)

Hematocrit of donor unit average values in transfused units

Whole blood donor unit average Hematocrit = 35%

Packed red cell unit average Hematocrit = 70%

PRBC unit with AdSol averages Hematocrit = 60%

Those being treated for acute anemia, aplastic crisis, heart failure, splenic sequestration, and bleeding should be given packed cells to raise the hematocrit to 28 - 33 vol.%. Patients should receive further transfusions based on symptoms.

In the example in bold, to raise the hematocrit 7 points, 375 cc packed RBC's are needed. A simple example using whole blood taken of 1000 ml and a 35% hematocrit  in a person with a 6000 ml total volume, would raise the total blood volume about 17% and the red cell volume about 6%, so a pre-transfusion hematocrit of 25 would be 31 post-transfusion.

3) There is no way to treat blood to increase its Hb content other than by adding blood. Dialysis does what the kidneys aren't doing to clean and filter the blood, but this doesn't change the blood. Putting the same blood back into a thal would result in the same Hb level.

The only way to change blood for a thalassemic would be to replace some or all of it. This is called an exchange transfusion and is used more in emergency situations where blood needs to be replaced or diluted, such as in a sickle cell crisis or in utero transfusions in alpha thalassemia major. In sickle crisis, blood is removed and replaced with normal blood to reduce the percentage of sickle cells in the blood. This can relieve the sickling crisis. Because the total of red cells isn't higher after the exchange transfusion, iron does not become an issue. With thals, removing red cells and replacing them with red cells would be somewhat self-defeating as you would be lowering the Hb at the same time you are raising it. With sickle cell the ultimate goal is maintaining the same Hb, so this balancing out of Hb isn't a drawback as it would be with thalassemia.  I also don't think this would have enough effect on how long the blood lasted to justify it, as transfused blood begins to break down from the moment it is donated and does not last nearly as long as blood one's own body produces. There is also the time involved transfusing, the effects of transfusion on the body, and the amount of matched blood that would regularly be needed, that have to be considered. In alpha thal major where no useful hemoglobin is produced, exchange transfusion to replace the completely useless blood, is the only possibility for survival.

Thank you Andy so much , this is really very informative.

With thals, removing red cells and replacing them with red cells would be somewhat self-defeating as you would be lowering the Hb at the same time you are raising it.

But i don't understand why i will be lowering the Hb, it should be the same as of the donor ??

Another question please, why sometimes the increase in hematocrit is not reflected on the HB. Sometimes i can see in Ahmad's tests that the hematocrit has increased by 1.5  or 2 but i don't see this increase in the Hb.
Once, his Hb was 6.6 and the hematocrit was 19. The following month, his Hb was 6.3 and the hematocrit was 21.4

Thanks Andy

Manal

1) You must remember that the blood recipient does not have an Hb of zero before a transfusion. If you remove blood, the Hb will drop, so when you add blood back you have to make up for this drop in Hb. Replacing an equal amount of blood might lead to a slight increase in Hb if the donor blood is higher in Hb but it will not add to the Hb like a transfusion does when no blood is removed. For example, if you remove a unit of blood with Hb of 6 and replace it with a unit with an Hb of 12, you will have some increase but that is somewhat offset by the blood it replaced, so you would have an increase but not as high if you just add blood, without removing any.

2) The relationship between hematocrit and hemoglobin levels is linear and hematocrit is roughly 3 times the hemoglobin level. The slight variations you have seen may be related to the accuracy of the tests themselves. Hydration level and the Hb of the transfused blood may also have some small effect. Hb can change with temperature and time of day, so small differences are not necessarily real differences. The expertise of the tech doing the tests and the method used to test also can be factors.