basic CA-1 physiology question

[Jimmy LaRoux]

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If you start a case with a hct of 43 and end up with a hct of 28 can you estimate the blood loss with the following formula (normally used to calculate ABL)

EBV x [(start HCT - ending HCT)/start HCT] = ABL

 

[Jimmy LaRoux]

I guess my question is: is there a way (preferably easy way) to go from change in Hct to EBL.

 

[CremeSickle]

I find all those formulas useless, call me crazy.

In general (and based on pt clinical picture & Hx) i base ABL on 20% of EBV.

 

[AlternateSome1]

If you start a case with a hct of 43 and end up with a hct of 28 can you estimate the blood loss with the following formula (normally used to calculate ABL)

EBV x [(start HCT - ending HCT)/start HCT] = ABL

Wouldn't the fluids given skew this?

 

[Jimmy LaRoux]

yeah crystalloids/colloids are going to skew your Hct, (hemodilute)...still don't know how to take a change in Hct and predict a EBL

 

[leaverus]

Why bother with an equation? The "E" stands for estimated, not exact. I hate when the surgeon argues with me over what my estimate of blood loss is.

 

[deleted50478]

If you start a case with a hct of 43 and end up with a hct of 28 can you estimate the blood loss with the following formula (normally used to calculate ABL)

EBV x [(start HCT - ending HCT)/start HCT] = ABL

You could theoretically use the formula to estimate blood loss, but obviously you have to know the current Hct to calculate blood loss. If you already know the current Hct, what's the point in figuring out the blood loss? It's irrelevant. Is it just to prove the surgeon wrong when he says there was a small amount of blood loss and you think it's much more?

 

[InductionAgent]

yeah crystalloids/colloids are going to skew your Hct, (hemodilute)...still don't know how to take a change in Hct and predict a EBL

Some sources use the following formula, which would theoretically be more accurate in calculating allowable blood loss if intravascular volume is maintained with IV fluids. This is all assuming that you had adequately compensated for the NPO deficit prior to any significant blood loss.

ABL = EBV x (start HCT - minimum acceptable HCT) / [(start HCT + minimum acceptable HCT) / 2]

By using the average HCT in the denominator instead of starting HCT, it considers that as the pt bleeds and gets hemodiluted, he will progressively lose fewer RBCs / ml blood loss. (Every cloud has a silver lining.) This works to increase your ABL. Unfortunately it makes for a slightly more difficult formula. If you are being stingy with the fluids for some reason (e.g. renal failure), your original formula would be more appropriate.

As far as estimating blood loss based on a difference in HCT, your original formula would also be more appropriate since the above formula would tend to further overestimate blood loss in the event of hemodilution as a significant factor in the reduced HCT.