Osmotic Diuresis: Hyperglycemia (Nursing)

00:01 Now we're talking about osmotic diuresis.

00:04 Now what I love to do is help you connect the dots to other things that you've learned.

00:09 So hang with me.

00:10 I'm going to help you understand how mannitol is connected to osmotic diuresis.

00:15 What? In a DKA lecture? Yes because hang with me a promise.

00:21 I'll get you there.

00:23 Hyperglycemia is elevated blood sugar.

00:26 So blood that has elevated levels of glucose is filtered through through the kidneys.

00:31 So that's why we end up with a really high blood sugar they end up even with glucose in your urine because the kidneys can't deal with this higher level of glucose that's in the blood.

00:42 And so it ends up dumping it into the urine.

00:46 See the glomerular filtration of more glucose in the renal tubules can reabsorb creates super high levels of glucose in the urine.

00:55 The higher the patient's blood glucose is the more glucose you're going to find their urine.

01:01 So he talked about why they have high blood sugar.

01:05 We talked about how that blood sugar ends up getting dumped into their urine or glucosuria.

01:10 Now we're talking about osmotic diuresis.

01:14 This is what we meant when we said remember in serum osmolarity goes up, well, you have increased urination because the substances that are being filtered through those kidneys have such a high concentration, body's trying to get back to homeostasis.

01:28 Remember the reference to mannitol.

01:30 Well, you may have heard that called an osmotic diuretic.

01:34 You know, that furosemide is a loop diuretic.

01:37 Mannitol is an osmotic diuretic.

01:40 It has the same effect on the body as far as causing water to dump out as it would if the patient had high blood sugar.

01:47 So when you're thinking about osmotic diuresis in the context of somebody who has high blood sugar, you're thinking, whoa, that blood is really concentrated or high osmolarity because of all the excess glucose.

02:01 The body tries to go back to homeostasis dumping water into the intravascular space.

02:06 It's running it through the kidneys.

02:08 So they pee out a lot of fluid and they're very dehydrated.

02:12 Same thing when we use an osmotic diuretic like mannitol, we change the osmolarity of the intravascular space and you pull off lots of fluid.

02:22 We specifically use those in patients with elevated intracranial pressure.

02:26 Okay, so you're learning even just more about DKA and HHS.

02:32 Here's a great picture of the kidneys.

02:34 Now you see we've got a renal artery.

02:36 That's the big red one on top.

02:38 And we've got the renal vein then coming out of the kidney, you have the ureter.

02:43 Hey, doesn't it feel good to recognize these structures.

02:46 I'm telling you. I always encourage students, celebrate every step of the way when you know something recognize it, right, now we've got some really cool animations for you here that are coming up.

02:58 I just want you to have the landmarks: kidney, renal artery, renal vein and ureter because remember blood comes in the kidney gets filtered, exits back out the vein, and then the other tube what isn't reabsorbed by the kidneys is dumped into the ureter to leave the body in the form of urine, you know the concept but high serum glucose damages those nephrons and here it comes.

03:25 Those little cubes stacked up on each other, those are what we did to represent glucose.

03:30 High serum glucose damages the nephrons.

03:34 So when that artery is delivering blood that's super high in sugar.

03:38 It's heading into that kidney going to be filtered through the nephrons and you can see how things are kind of getting stuck.

03:45 Look at the next step.

03:47 When the serum glucose is high, it's more than the kidneys can reabsorb into the bloodstream.

03:53 So it's got to go somewhere.

03:55 You just saw the blood come into the artery, kind of rotate through the kidneys right to be filter, then some of it exited out through the vein goes back out to the body because the kidney can't reabsorb all of it.

04:07 What does it do with the rest of it? There's only one place for it to go.

04:13 Excess glucose is dumped or excreted into the urine and that's why it's called glycosuria.