4 Acid-base Imbalances and Rehydration Management Part: 2

Transcript

Welcome! back to Fluid therapy in cattle.

In the last class, we have seen about the various electrolyte acid-base imbalances and how to tackle that. In this class, we are going to see how to calculate the bicarbonate requirement in specific conditions.

(showing the slide)So, in this slide, we are seeing the Rumen Lactacidosis, which is mainly because of rapid ingestion of fermentable carbohydrates in animals, where we get roman lactic acidosis.

How to calculate the bicarbonate requirement? It is based upon the formula : millimole of bicarbonate required is equal to 0.3 multiplied with bodyweight multiplied with the base deficit.

mmol of HCO3 required= 0.3 * bodyweight * base deficit

This formula shows how to calculate the base deficit, but in field conditions, it is very difficult to calculate the base deficit, as the base deficit can be assessed by a blood gas analyzer, which is not available in the field. If it is available to fine, if it is not available, we can use the thumb rule.

We can classify this type of acidosis into Mild, Moderate, and Severe.

If it is a Mild acidosis, you can use the best deficit as( -5), if it is Moderate use the base deficit as (-10), if it is Severe use the base deficit as(-15). If you substitute this in the base deficit formula: 0.3 multiplied with bodyweight multiplied with the base deficit, we will get the millimole of bicarbonate requirement. Now we will always understand when we are going to deal or substitute in a case of an example.

Now let us take an example:

Calculate the bicarbonate required for 100 kg cattle.

So we know the formula, the availability of the formula is, bicarbonate requirement is equal to body weight multiplied with 0.3 multiplied with base deficit

HCO3 requirement = bodyweight * 0.3 *base deficit

considering this cattle as a Moderate acidotic or Moderate Rumen Lactacidosis, we substitute 100 kg multiplied with 0.3 multiplied with (-10), which will give you (-300) millimole of bicarbonate,

= bodyweight * 0.3 *base deficit

= 100 kg * 0.3 * (-10 mmol) = -300 mmol

This is the required bicarbonate that has to be given to this animal.

On the contrary to the calculated millimole, the availability is only in ml. What is that? We have got 5% ampoule as a -10 ml ampoule or 7.5% 10 ml ampoule or 25 ml ampoule. So the calculated is millimole or bicarbonate, but it is available as a percentage. Infield condition, how to calculate millimole from the percentage solution? There is a thumb rule:

Each ml of 7.5% = 0.89 mmol of bicarbonate

So for 0.89 mmol, we need 1 ml of 7.5% solution

For 300 mmol we need = (300 * 1)/0.89 = 337 ml

Thus 337 ml of 7.5% NaHCO3 will provide 300 mmol of bicarbonate

Each ml of 7.5% will give you 0.89 millimole of bicarbonate, so substituting this in the example which we are dealing with, for 0.89 millimoles, we need 1 ml of 7.5% solution, to rewrite this so 300 millimoles we need 337 millimoles or ml of sodium bicarbonate. Thus in a correct 337 ml of 7.5% sodium bicarbonate, it will require 337 ml re-emphasize this thus 337 ml of 7.5% sodium bicarbonate will provide 300 millimoles of bicarbonate. Here we are going to see an example with a small ruminant namely the goat weighing 10 kg, having a Moderate acidosis:

So the formula we already know, bicarbonate requirement is equal to body weight multiplied with 0.3 multiplied with the base deficit.

HCO3 requirement = body wt * 0.6 * base deficit

= 10Kg * 0.6 * (-10 mmol)

= -60 mmol

Kindly note in the case of a small ruminant, you have to substitute 0.6, so the bicarbonate requirement is equal to body weight multiplied with 0.6 multiplied with the base deficit. That is the only difference, instead of 0.3 you are going to put as 0.6. So, substitute that 10 kg multiplied with 0.6 multiplied with ( -10), we will get ( -60) millimole because it is a deficit, it is in the negative sign. So 60 millimole is required for this 10 kg goat. The difficulty faced in the cattle is also known in the case of goats, so substituting bicarbonate requirement is equal to (-60) millimole. So for 0.89 millimoles we require 1 ml of 7.5% solution, for 60 millimoles will require 67.4 ml, this is based upon your 7.5% solution. Suppose, if your own availability is a 5% solution, what you will do? the 5% will supply 0.6 millimoles of bicarbonate. so substituting that 0.6 millimoles, we require 1ml of 5% solution, for 60 millimoles we require 100 ml of 5% sodium bicarbonate. Bicarbonate requirement is (- 60) millimole, if you are using 7.5% sodium bicarbonate we need 67.4 ml, if you are using a 5% solution we require 100 ml of 5% solution. But some people substitute this acidosis or compensate this acidosis with Lactated Ringer’s Solution(LRS), if it is to be given by Lactated Ringer’s Solution(LRS), kindly note there is a thumb rule 500 ml will supply only 25 millimoles of bicarbonate. To rewrite 1 ml will supply 0.05 millimole of bicarbonate, so we need 1.2 liters of Lactated Ringer’s Solution to compensate for this 60 millimole. So for 10 kg goat, we need 1.2 liters. You can understand our Indian cattle weighs about 350 to 450 kg bodyweight, you can calculate how many sachets of 500 ml of Ringer’s Lactate is needed to effectively treat this condition. So, if at all if it is the acidosis and if you want to compensate or neutralize that, kindly give sodium bicarbonate at the rate of body weight multiplied with 0.3 multiplied with the base deficit, if it is a cattle but if it is a goat kindly use 0.6 instead of 0.3.

Now we have seen 2 examples, wherein each

Case A is 100 kg cattle which required 300 millimoles so we gave 337 ml of 7.5% solution.

Case B: we had 10 kg of goat, we required 60 millimoles and we were given 67.4 ml of 7.5% solution.

Both required treatment with sodium bicarbonate. Case A did not die, but Case B died, as soon as we gave IV bolus of sodium bicarbonate. Why? The answer to this puzzle of the question is take-home points: never exceed 2 millimoles per kg per minute(2 mmol/kg/min).

If you are administering sodium bicarbonate never exceed 2 millimoles per kg per minute. So if you are substituting with Case A and Case B:

Case A is 100 kg, 2 millimoles are 200 millimoles per minute( 200/minute).

Case B, it is 2 millimole multiplied with 20 kg, it is 40 mmol, approximately 40 ml.

So this 40 ml, we are usually taking in a syringe and then doing is an IV bolus, which exceeded the 2 millimoles per kg per minute, so it has caused the death. So take-home lesson is never to administer sodium bicarbonate IV bolus if the body weight is less than 50 kg. So what to do? if it is 50 kg and less mix the sodium bicarbonate in saline or dextrose normal saline and then give IV so that the rate of administration of sodium bicarbonate will not exceed 2 millimoles per kg per minute. so thereby saving the animal. Now we also have 8.4% of sodium bicarbonate in the field, in such cases never administering faster than 1 ml per kg body weight per minute, so the same like 7.5%, so your caution should be exercised it should not be more than one number per kg per minute.

Now in this lesson, we have seen about How to calculate the bicarbonate requirement in the case of cattle and calf.

Remember for cattle we have used 0.3 as the standard factor, for small ruminants you use 0.6. Another important thumb rule is never to administer more than 2 millimoles per kg per minute as far as sodium bicarbonate is concerned, which is very crucial to save a life.

In the next lesson, we are going to see about the Importance of Heat stress and how to overcome it.

Thank you!