Podcast – Hybrid Closed Loop Insulin Pumps in the ED

So the biggest challenge for me was always going to be with this morning’s talk, how to condense the topic, I can talk about all day into 15 minutes. So what I thought I’d do is talk instead about an increasingly frequent treatment option for people with type 1 diabetes, which causes a little bit of anxiety, namely hybrid closed loop insulin pumps.

So the outline of my talk, I’m going to just talk, very, do a really brief recap about insulin pumps and then talk about hybrid closed loops and how they’re slightly different. The majority of my presentation is going to be three different case presentations that might present to children’s ED and how best to manage them. So why do you guys need to know anything about hybrid insulin pumps?

Last year in December, NICE published a technology appraisal which stated that all people with type 1 diabetes adults and children should have access to this technology. And so over the next three to five years, NICE wanted to put all people with type 1 diabetes onto these systems. So you’re going to be coming across them whether you like it or not. Just a little recap about insulin pumps.

All they are is a syringe driver that the patient is wearing that gives a continuous infusion of fast-acting insulin. And the patient is connected to the pump 24 hours a day. They can disconnect it for short periods of time, half an hour if they’re having a shower or if they’re playing contact sports. But for all intents and purposes, they need to be connected to it 24 hours a day because it’s only giving them fast-acting insulin. The insulin is delivered by a soft cannula like a little gel code that sits in the subcutaneous tissue. It needs to be changed every three days. And the patient needs to bowl this insulin when they eat food. So they still need to carbohydrate count and then tell the pump to give a little shot of insulin to cover all food.

So because the half-life of fast-acting insulin is roughly 18 minutes, it means that if the cannula becomes kinked or dislodged or blocked for any reason they will quite quickly run out of insulin because they don’t have that safety net of basal insulin that people on multiple daily injections of insulin have. So once that insulin is stopped and they’re not getting it, they will very quickly start to get ketosis. So within four to six hours the blood keto levels will rising and within 10 to 12 hours they will be in DKA.

So hybrid closed loops are a really clever thing. They have three components. They have the patient wears an insulin pump that’s delivering fast-acting insulin. They also wear a continuous glucose monitor. So that’s measuring their blood sugar every two or three minutes. And it’s measuring not just the glucose but also giving a direction of travel so whether the glucose levels are going up or down. And that then links with insulin pump using closed-loop algorithm. You don’t need to know how the algorithm works. All of the different systems use slightly different algorithms. But to all intents and purposes what the algorithm is doing is using information from the continuous glucose monitor. And telling the pump whether the blood sugar is going up in which case the pump will deliver slightly more insulin or if the blood glucose is dropping it will deliver slightly less insulin or even suspend the pump completely for short periods of time.

So it’s a complete game changer for people living with type one diabetes because every five minutes the amount of insulin they’re receiving is changing. So it’s even better than being on an IV sliding scale in its reactivity. There are two main different types of closed-loop systems so there’s the patch system. And this is a pump where the pump is actually stuck to the patient and the cannula comes out of the back of the pump and is infusing the insulin. So that pump wants it stuck to the patient and it’s stuck there for three days. The other system is a tube system where the pump is separate and then is connected to the patient by a wire and a little subcutaneous cannula that they can clip and unclip. Other that the patient can get really really tight diabetes glucose control especially overnight. So if you’re asleep for eight to ten hours a night you can absolutely smash your diabetes. They’re very also very very good at avoiding high pose which is the main fear of a lot of people living with type one that they hate going high-po. The downside though is that these patients are increased risk of ketosis and therefore you need to be wary of that. Also the patients have to be slightly tech savvy.

So what could go wrong with these systems? So there are three basic things that can go wrong. Firstly connectivity issues. This is when the system isn’t bits of the system aren’t talking to each other or a bit of the system isn’t working. Now nobody is going to expect you to be able to sort that problem out but what you do need to do is recognize that there is a problem with the system and keep the patient’s diabetes safe. The second and by far in a way the commonest reason that patients present is because they’ve had problems with the cannula and they haven’t realised until too late that the cannula has blocked or kinked or become dislodged. And then the third issue is intercurrent illness. So these are kids, the kids get ill and if you’re ill and you have diabetes it can be slightly more complicated.

So there are three questions I want you to ask if you see a patient with type one diabetes is on one of these systems. Firstly is the patient in DKA. You need to make sure that they’re not in DKA. Have they got insulin on board and have they got some form of substrate glucose fluids through on board. So my three cases. Firstly, seven-year-old girl on hybrid closed loop presents to see children’s ED always in an evening shift isn’t it when nobody else is around. And she’s got a short history of vomiting and the parents have said that she’s got a gastro bug. So what further information do you need? Firstly you need to know what her glucose level is and the parents say well on her CGMS her continued glucose monitor it’s reading about 25. Her sugars have been high all day at school she hasn’t checked the blood ketones because they haven’t really thought to do that and also the glossweb and metarys. And they’ve been given correction doses via her pump but it doesn’t seem to be making any difference. So back to those three questions is she in DKA how she got insulin on board what fluids does she need? This is absolutely classic of a child who’s got their cannula blocked or kinked or dislodged. And the first thing you need to do is confirm that her blood sugar is high. So if her sugar levels are high then you need to check the ketones. And what you do next is completely given by what the blood ketone levels are doing. If the ketones are low so they’re less than 0.6 you’ve probably got time to give more boluses via the insulin pump and put in the blood sugar level and the pump will calculate how much insulin to give to correct the high sugar. If the levels aren’t coming down or in particular if the ketone levels are going up that tells you you need to do a set change. You also need to be pushing fluids if the child has been vomiting. If the ketones are moderately high so between 0.6 and 1.5 you need to give them a pen injection because the fact that the ketones are going up tells you that the closed loop is not delivering insulin as it should do. So you need to just bite the bullet and take them off that system. Give them you a little bit of time while they’re doing a set change. Give them some insulin so 10% of their total daily dose of insulin as fast-acting insulin and that needs to be given as a pen injection and then push fluids and make them change their set so they’re giving set their cannula, the insulin and the system and reach out their sugar in an hour and ketones in two hours. If the ketones are even higher if they’re above 1.5 the first thing you need to check is that they’re definitely not in decays. You want to do a blood gas to make sure that their pH is normal and then you’re going to give them 20% of their total daily dose of insulin as an over-appetus of pen injection. So how to calculate the total daily dose? So we’re increasingly telling patients, getting them to take note of what their total daily dose is and for most of the clinic letters from the diabetes clinic it will state what their total daily dose of insulin is at the top of that letter. However if you haven’t got that information and the patient doesn’t have that information you can roughly work out what their daily dose of insulin will be because primary school kids need about 0.7 to 0.8 units per kilo per day of insulin. That’s their total daily dose and people have to get a little bit more usually around 1 to 1.5 units per kilo per day.

If you take no other message home for other than this please take this home. Vomiting in somebody who has tight one diabetes is DKA until you have proven it’s not. Time again patients are missed and they present a primary care with vomiting and people always put it down to a gastrobook or in teenage kids down to a hangover maybe. But if you’ve got tight one diabetes you’re much more likely to be vomiting due to ketosis than anything else and check that they’re not in DKA check that pH is above 7.3 ketones or less than 0.6.

So, the second case is a three-year-old boy on a hybrid closed loop. He presents to the emergency department again in an evening shift again with a history of vomiting and they’ve diagnosed a gastrobook. So what information do you want? This child is slightly different. He’s been vomiting for three days and keeping very little down so his blood glucose has been in the normal range until today when he stopped really wanting to eat or drink anything. And his sugars are now running low and he’s not wanting to eat or drink anything and when the parents measure his ketones they’re high they’re 3.6. So what’s happening here is slightly different. So he has got a vomiting bug and because the hybrid closed loop is very clever it notices that he’s not eating very much and therefore his blood sugar levels and insulin requirement have gone down and it stops delivering as much insulin. So that holds him for the first 24 to 48 hours of having his gastro bug. But then starvation ketones start to kick in and as his starvation ketones go up he feels more and more sick and won’t eat or drink. And at that point he starts vomiting more and you’re in a vicious circle which you can’t get out of without intervening. The first thing to do is confirm that his sugar is low and that his ketones are high and if the glucose is lower in the normal range it suggests that the closed loop system is working as it should do. So the child is still getting some insulin because his blood sugar is low but not enough. He can’t give for himself more. He can’t have more insulin because he hasn’t got enough substrate on board so what you have to do is give him more substrate, give him more glucose. And the easiest way to do that is to just give him IV fluids 5% or 10% of the extra saline with a little bit of potassium in and I would have just run that in over a couple of hours. You don’t need to work out what his fluid rates needs to be 500 ml over 2 hours for a child this size will do him no harm whatsoever. The glucose level as it goes in will start to stimulate the system to the system will notice that his blood sugar is rising and start to give a little bit more insulin. So the combination of giving him more insulin, more glucose and fluids will effectively treat his ketosis. And then as he starts his ketone start to fall you’ll realise that he’ll start to eat and drink a little bit more.

So the last case is when something goes wrong with the system. There’s a 13 year old who smashes pump in a fit of rage. So at this point there is nothing that you can do to make the hybrid closed loop work. So what you need to do is just make sure that he is safe with his diabetes. So this will involve changing him back onto pen injections. So firstly does he need fast insulin? So check his glucose levels or check his ketones. If his glucose levels are okay so the less than 10 that suggests that he just needs to carry on having pen injections of insulin with food. And then there’s plenty of other fast insulin at that point. If his glucose levels are high you’ll need to give him a correction dose of fast acting insulin just as before. So if his ketones are moderately high give him 10% of his total daily dose as no rapid if his ketone levels are very high above 1.5 given 20% of his total daily dose. However because he can’t go back onto the closed loop system because he’s broken his pump you’ll need to give him some basal insulin as well. And that you can calculate just as 50% of his total daily dose. So this is why we’re increasingly getting patients to make a note of their total daily dose because in an emergency like this it can really help guide what insulin if you need to go back onto pen insulin to give them.

In summary hybrid closed loops are brilliant and they’re here to stay for the foreseeable future. You will see increasing numbers over the next three to five years. So most people with type 1 diabetes will be using these as their standard therapy. They deliver fast acting insulin so when they go wrong the risk of ketosis and then DKA is quite high. And if they’re vomiting if ever a child is vomiting and they have type 1 diabetes assume they’ve got DKA until you’ve proven that they haven’t. They do still need to bowl us though even though the system is giving a little bit more little bit less insulin with penure. They should have the thing they do still need to bowl us with food. The common is problem that they’ll present with is the cannula kinking blocking becoming dislodged. High sugar and high ketones give a pen injection and then get the patient to change their giving set change the cannula and calculate the correction dose using the patient’s total daily dose of insulin. If they’ve got low sugar and high ketones keep them on the hybrid closed loop system but give them more glucose. If the system is broken you just need to give them pen injections of insulin but don’t forget the new basal insulin as well as fast acting bolus of insulin.