Hello how are you greetings to everyone today we are going to review what is the calculation of the body surface area I remind you that this topic and some others can be found on our official website Diario Médico Puntos and also on our YouTube channel so I invite you to subscribe let's begin [Music] The first thing we need to know to calculate the body surface area is precisely the formula that is used to carry out this calculation in this case we are going to have two formulas that are going to be used to calculate the body surface area the first is used in children under 10 we achieved in this case we are going to have to multiply the weight by 4 and to the result we are going to add 9 to our figure that we obtain we are going to divide it by 7 this is a formula that is only used for children under 10 kilograms weight by 49 between 100 for those patients who are greater than 10 kilograms we are going to have that it looks a bit like the formula weight by 47 and in this case the result obtained we are going to divide it by weight plus 90 so in those over 10 kilos will be weight times 47 between weight plus 90 it is important that you write down have on hand or remember these formulas so that when you want to calculate the body surface area during a visit during a guard duty which is useful to calculate liquid medications or just to calculate the body surface area keep these two formulas in mind let's see some examples so that the formulas are clearer to us and it can be easier for us to calculate the body surface area let 's start with the example in the case that our patient weighs less than 10 kilos in this case we are going to select a patient of 8 kilograms if we take into account the formula that I showed you a few moments ago for those under 10 kilograms we are going to substitute the values in this formula the first thing we have to do is substitute the weight by 4 + 9 you can do the operation from home so you don't get lost and so you can see where the results come from 8 x 49 gives us a result of 41 if we follow our formula we would have to divide this by 100 it gives us a result of point 41 therefore in our patient less than 10 kilograms the body surface area would be 0.41 square meters I remind you or I suggest that in this case we can save a step if when multiplying our weight by 49 as in our example 8 by 4 plus 9 gives us 41 we only go over the point and although it is 0.41 what it gives us as surface now we are going to move on to our example in the case that our patient is greater than 10 kilos here it is important to emphasize that let's say the weight of our patient does not matter anymore as long as it is greater than 10 kilos we are going to use this formula in this case for the example we are going to select a patient with 23 kilos again we go to our formula that I had already shown you at the beginning and remember it is weight by 47 / weight plus 90 at this moment we are going to substitute in the formula the weight which is 23 kilos by 4 and the result we are going to add 7 so here we will have that it is a total of 99 secondly or the second step will be to add the weight plus 90 which in this case gives us 113 and in the end to complete our entire operation we only have to divide the result of the first equation by the result of the second equation in this case if we divide 99 by 113 we have a result of point 87 therefore we will have that the body surface area of our patient greater than 10 kilos in this case 23 is 0.87 square meters of body surface area [Music] well I hope these formulas have been useful to you, you can use them, it is important that you write them down, learn them, and I remind you that in the comments you can tell us about other topics after that area that we review quickly, useful for the visit passes for the guards and I invite you to follow us on twitter diario de médico on facebook diario de un médico and also visit our official page see you soon [Music]