Management of DKA: Fluid Therapy (Nursing)

00:02 So, one of the things that we really need to be careful about is that you never want to give an insulin bolus at the start of therapy for a DKA patient. This seems a little counter intuitive.

00:15 It seems like well we should be giving the patient insulin because that's what they need to get this blood sugar down. But it turns out that giving a bolus of insulin when you're trying to start treating DKA actually increases the risk of cerebral edema. Your patient is likely to be fairly dehydrated. So, you're going to be giving them a bolus most likely of normal saline, it might be Lactated Ringer's, but usually normal saline. And that first bolus is going to go in even before you start your insulin via the infusion. When you do start the insulin, you're going to be running that continuously. So, generally for pediatric patients you're going to use 0.05 units/kilo/hour. Occasionally, if you have an older adolescent or pubertal or postpubertal patient or somebody that really shows that they are pretty resistant to insulin, you might be running them at 0.1 units/kilo/hour. And in smaller patients, patients that are less than 5 or if they just seem to be extremely touchy, really sensitive to that insulin, you might even be running them at 0.025 units/kilo/hour. And then once you get that rate of insulin that you're running it, you're going to run that continuously until they are out of the DKA.

01:42 It is really important to note that you're going to give that first fluid bolus and you're going to start an insulin via continuous infusion. When you start your insulin, you must have fluids running. You do not want to start your insulin therapy if you have not gotten your maintenance fluids yet, you need to start those at the same time, and that's going to look like something that we call the 2-bag system.

02:11 The 2-bag system is really so that you can manipulate the amount of dextrose that your patient is getting at any given time without having to get new bags of fluids from the pharmacy. Any of you guys who have tried to order new fluids from pharmacy knows that that takes a long time and we really want to be able to quickly react to that blood sugar going up and down in our patient. So, we're going to talk about what this 2-bag system looks like. You're going to be adjusting these 2 bags, the first bag that has just normal saline and the second bag that's going to have 10% dextrose plus the normal saline. This is going to allow you really to address those blood glucose levels. So, it is also important to note that the insulin is what's fixing the DKA. So, we don't want to have to stop the insulin. If our blood sugar starts going too low and we're running normal saline, the first reflexes to lower the amount of insulin that the patient's getting. But what we want to do instead is increase the sugar that they're getting because we want to allow that insulin to keep running. So, if our blood glucose is getting a little on the low side, we can just increase the amount of sugar that they're getting through their IV fluids and that allows us to continue running that insulin. So the provider is going to calculate the patient fluid rate depending on their deficit and they're going to take into account any fluid boluses that had been given either in the initial work-up or as you are doing ongoing therapy. It's important to note the initial fluid bags are most likely to be normal saline. Occasionally, you might see half normal saline running depending on the sodium levels of the patient. Half normal saline is not that common and really the standard should be to run normal saline. So the initial fluid bags might be ordered without potassium. Occasionally, DKA patients start out kind of with these higher levels of potassium and then if you remember from a previous slide when we start that insulin therapy, the insulin starts driving that potassium back into the cells. Once that happens even if your patient initially has pretty high potassium, it's going to start going lower and lower and lower. So, your bags might initially start out not having electrolytes in them and then eventually you're going to have to add those electrolytes. So once the potassium is a more normal level, then your bags are going to be normal saline with potassium added. Usually, the potassium is in the form of potassium acetate usually about 20 mEq/liter bag and then they're also going to be 20 mEq of potassium phosphate added to the bag. If you don't have potassium acetate or potassium phosphate available, sometimes you will also see potassium chloride. So the most important thing is getting that potassium added back to the bag once you see those levels start decreasing in the patient's laboratory values. So, once the rate has been determined, the nurse is going to adjust the rate of each bag based on an algorithm.

05:46 So, the percentage of dextrose is controlled by the rate on the bag. This is what allows you to really take into account what is happening with the patient's glucose.

05:56 So, what does that mean? So if you have a percentage of your rate from the normal saline bag at 100 and you have 0 percent rate from the dextrose bag, then your final dextrose concentration is 0% because you're running 100% of your fluids from just normal saline bag. Now, if you're running 75% of your fluids from the normal saline bag and 25% of your fluids from the bag that has dextrose in it, then your final dextrose concentration is now 2.5. If you have 50% from your normal saline, 50% from your dextrose, then you are at D5; 25% from your normal saline bag and 75% of your fluids coming from your dextrose bag will give you D7.5. And if you're running nothing from your normal saline bag and all of your fluids are coming from the bag with the dextrose, you're going to have D10%.

07:08 So, this is the way that you can think about how much dextrose you're giving your patient. So, let's go through it in example. If you have an 18-kg child that has DKA, there is going to be an algorithm that tells you if your blood sugar is more than 300 then we want all of those fluids to be coming from the bag with only the normal saline. We don't want the patient to be getting any sugar yet. Right? Their blood sugar is still pretty high. Now, if the blood glucose is between 299 and 250, then you're going to be getting 75% of the rate from your normal saline bag and 25% from your dextrose bag and on throughout this table. This is an example table. Your hospital will likely have an algorithm that looks very similar to this.

08:04 The numbers might be a little bit different, but it should be fairly close. So what is this going to look like for your patient? So, the provider calculates the hourly fluid rate to be 73 ml/hour. They figured out how dehydrated the patient was. They figured in all the fluid boluses that have been given and over the next 24-48 hours this patient's going to need 73 ml/hour. So, depending on what blood sugar you have is going to depend on how much of that 73 is going to come from bag 1 and how much of that 73 is going to come from bag 2. If your blood glucose is over 300, then all 73 ml/hour coming from bag 1. Right? If your blood glucose is 268, if you refer back to that table, we know that 75% of the fluids need to be from bag 1 which will be 55 ml and 25% of your fluids need to come from bag 2.

09:13 So 18 ml/hour. So you're setting your bag 1 pump for 55 ml an hour and you're setting your bag 2 pump for 18 ml an hour and in that way you're increasing just slightly the amount of dextrose that your patient is getting. What happens if your blood glucose goes down to 235? Well, you're algorithm is telling you that 50% of your fluid should be from bag 1 which is 37 ml an hour, 50% should be from bag 2 which is 37 ml an hour. So you're going to adjust those pumps again and make sure the bag 1 and bag 2 both of them are running at 37 ml an hour.

09:58 Now, our blood glucose is down to 189. So, 25% of fluids from bag 1, that's 18 ml an hour, 75% of fluids from bag 2, 55 ml an hour. So you're back to adjusting your pumps making sure bag 1 is running at 18, bag 2 is running at 55 ml per hour.

10:21 If your blood glucose is 135, then we don't want to stop that insulin. Remember our DKA hasn't resolved quite yet, we need to keep that insulin going but that blood sugar is pretty low so we need to increase that dextrose. So 100% of our fluids are now coming from bag 2.