Why is the hypoglycemia very common complication during dialysis?

It is true that we often see the patient undergoing clinical and subclinical hypoglycemia during dialysis. But why the dialysis patients are more proven to get hypoglycemic attacks. Is it the dialysis which causing the hypoglycemia? Or some other cause.

Diabetes mellitus can make you hypoglycemic

We know that one of the most common cause for CKD is the diabetes. Patients with diabetes often has high blood sugar levels. This is due to the insulin insensitivity or lack of insulin. So can these patients undergo hypoglycemia during hemodialysis?

Some of these CKD patients on Metformin, some are on other oral hypoglycemic agents like Gliclacide. Even if the metformin do not cause significant hypoglycemia, some other medications can cause the hypoglycemia. In addition Insulin can cause on and off hypoglycaemic events.

Kidney disease can also cause hypoglycemia

Gluconeogenesis is the process of creating glucose inside the body. This mainly occurs when you are in a fasting state. The kidneys are the second most vital organ for this mechanism. It is second only to the liver. When you have CKD, structure of your kidney get damaged and ability of gluconeogenesis is also get reduced. As a result body fails to maintain the adequate amount of the blood sugar levels during dialysis or even at the day to day settings.

Mechanism of dialysis

Dialysis is a complicated process. There is a 15g to 20g of glucose loss during each dialysis session. This loss of plasma glucose can lead to subclnical hypoglycemia in most of the patients. However in some patients they are not fit enough to maintain this loss of glucose during dialysis. Therefore they can get a significant hypoglycemia during dialysis.

Therefore hypoglycemia during dialysis is a multifactorial complication. Although loss of glucose during dialysis do not cause significant symptoms, failure to maintain the gluconeogenesis causing the significant damage to the patient.

How to identify the hypoglycemia during dialysis?

In a usual setting an experienced healthcare professional can identify the hypoglycemic events easily. But during dialysis it is very difficult to identify the hypoglycemic events.
As an experienced clinician I have met patients with blood sugar levels of 20mg/dl but they were almost normal except few symptoms. But this is not a viable blood sugar level in a normal patient.
Therefore you need to have clear understanding about hypoglycemia during dialysis. If you are not specifically look it, you can’t identify most of the hypoglycemia during haemodialysis.

Symptoms of hypoglycemia during dialysis sessions

1. Hypotensive attacks
   Hypotension is the main symptom of low blood sugar levels during dialysis. If a patient develop a hypotension during dialysis, 1st thing to look is the hypoglycemia. Most of the times it is low blood sugar levels than the depletion of volume or some other cause.
   
   
2. Failure to maintain blood pressure with inotropes
   This is a common issue with patients undergoing the urgent hemodialysis due to Acute Kidney injuries. Most of they are critically ill and on inotrope support. But if a patient do not improve with proper inotrope support, we have to look for the hypoglycemia.
   
   
3. Altered level of consciousness
   Level of consciousness is a broad term. It include the orientation, the way of talking, level of intelligence and lot of other factors. In some instances I have met CKD patient with less than 20mg/dl blood sugar level with no significant alteration of consciousness.
   

Case 1. 27years old patient came to regular hemodialysis. He maintained his blood pressure levels and saturation well. No complaints too. But when I talk to him, I found some irrelevance of his sentence to each. I had some suspicion and checked the blood sugar level. It was 17mg/dl and immediate actions were taken.

Case 2. 54years old patient was in his regular haemodialysis. He was given a cup of tea while he was on dialysis. But the staff member noted that he failed to take his tea. He informed me. Then I asked for a blood sugar level. It was 27mg/dl and he was collapsed in few second. Immediate resuscitation was conducted and successfully recovered the patient.

4. Sweating during dialysis
   Sweating is a very common symptom of hypoglycemia. You can see it even in patients taking medication for diabetes. However surprisingly I rarely met hypoglycemic patients with sweating during dialysis. So I think you have a clear understanding on symptoms of hypoglycaemia during dialysis sessions. Then the next question is how to manage the hypoglycaemia during dialysis.
   
   
   

How to manage hypoglycemia during dialysis?

As I mentioned events of hypoglycemia is common and subclinical most of the times. However there are times you have to attend on events of hypoglycemia. Even if the pre dialysis and intradialysis blood sugar monitoring can be done, it is not a good and presence experience to patients. Even though the basic management of hypoglycemia is same in each complication, you have to attend the case depend on the symptoms too.

Hypoglycemia with hypotention.

Here the management of both hypoglycaemia and the hypotension should be done simultaneously.Soon as you note there is a hypotension the next action is to check the hypoglycemia.

• Start bolus of 100cc normal saline
• Give 1 vial of dextrose
• Reduce the blood flow rate and position the patient
• Repeat the blood pressure and blood sugar in 10 minutes
• If blood sugar is not enough repeat the dextrose infusion

Hypoglycemia with no response to inotropes

Inotropes are the medications to improve the blood pressure in critical patients. They have different actions. It is common that patient face significant reduction of blood pressure soon as they are connected to the dialysis machines. But it can be picked up with these medications. But if these patients do not improve the blood pressure with inotrope, it is worth to check the blood sugar level than next inotrope.

Hypoglycemia with altered level of consciousness

Hypoglycemia is not the only cause for altered level of consciousness during dialysis. There are lot of cause like electrolyte imbalance, stoke and etc. In addition there is a very important condition called Dialysis disequilibrium syndrome.

But before thinking of anything else, you should focus on hypoglycemia during dialysis. Because it is easily preventable cause for altered level of consciousness during dialysis.

Whenever a patient has a reduce level of consciousness;

• Check the blood pressure
• Check the blood sugar levels
• Look at the other neurological features
• Give bolus of dextrose irrespective of blood sugar levels unless it is too high
• Then only you can exclude other causes of altered level of consciousness.

Hypoglycemia with sweating during dialysis

Sweating is another presentation of hypoglycemia. But when someone has the sweating, it myocardial infarction should be ruled out.

• Check all vital parameters
• Give dextrose
• Check urgent ECG

How to prevent hypoglycemia during dialysis

Although hypoglycemia is commonly missed as subclinical incidents, we have to be prepared and look into it properly.

1. Ask patient to have proper meal prior to dialysis
2. Arrange a mid-dialysis snack or refreshment
3. Monitor CBS in high risk patients

Reference:

1. Vadakedath, S., & Kandi, V. (2017). Dialysis: A Review of the Mechanisms Underlying Complications in the Management of Chronic Renal Failure. Cureus, 9(8), e1603. https://doi.org/10.7759/cureus.1603
   
2. Abe, M., & Kalantar-Zadeh, K. (2015). Haemodialysis-induced hypoglycaemia and glycaemic disarrays. Nature reviews. Nephrology, 11(5), 302–313. https://doi.org/10.1038/nrneph.2015.38

Basic mechanism of dialysis

Before understating the dialysis disequilibrium syndrome, it is good to know the basics of dialysis and how it works on your body.

If your kidney get Acute Kidney Injury (AKI) or Chronic Kidney Disease (CKD), you may have to undergo a process called dialysis. What we do as dialysis is the providing of natural kidney functions by an artificial kidney attached to machine. The most important function of dialysis is the removal of waste products from the body like urea. In addition it help to maintain acid base balance and electrolyte balance of the body.

You can see more about dialysis here.

If you have understood this basic of dialysis, you might understand that urea is removed in each session of the dialysis.

Mechanism of dialysis disequilibrium syndrome (DDS)?

Osmotic pressure of our body is basically maintain by two particles. One is the Sodium (Na+). Other one is the Urea. Even though other electrolytes are affecting this process, only these two can give significant contribution to oncotic pressure.

As we mentioned we remove some amount of the urea with each dialysis. Therefore there is a reduction of osmotic pressure in the blood. When plasma osmotic pressure reduced, it can cause cells to take some fluid from plasma and keep the balance between them.

Same process occurs in the brain too. This will ultimately result in increased size (edema) in the brain cells. This cerebral edema can cause lot of neurological issues simply from headache to death at last. When the amount of removed urea is higher, the edema is higher and risk of dialysis disequilibrium syndrome is higher.

Who get the disequilibrium syndrome?

Dialysis induced disequilibrium syndrome (DDS) is commonly seen in patient who undergoes their 1st series of dialysis. However it can also be seen in other CKD patients too. Some studies show that it is common in patients who miss their dialysis sessions.In addition it can present in some patients who undergoes dialysis or CRRT following acute kidney injury.

Symptoms and signs of disequilibrium syndrome

1. Headache
2. Nausea
3. Dizziness
4. Confusion
5. Visual disturbance
6. Tremor
7. Seizures
8. Coma
   
   
   

How to prevent disequilibrium syndrome

Few decades ago, DDS is one of the common issues during dialysis. However with the development of the Nephrology and dialysis care, the disequilibrium syndrome has become a rare condition among the patients with Chronic Kidney Disease. Even though the dialysis disequilibrium syndrome is a rare complication, this should be considered as on of the serious complication of dialysis.

1. Initiate the dialysis with short cycles
   Usual hemodialysis session are continue upto 4 to 5 hours. However at the initiation of the dialysis, it is advice to limit the duration of dialysis for few hours. Usually 2.5hours – 3hours as maximum. As a result the risk of sudden reduction of urea is rare.
   
2. Use low blood flow rate
   When you dialysis, you can adjust the blood flow rate though the machine. Higher the rate of blood purification, higher the risk dialysis disequilibrium syndrome. Therefore you can try with a blood flow rate of 100 – 150 in initial dialysis sessions.
   
3. Monitor the Urea Reduction Ratio
   Usually you can monitor the urea reduction rate with pre and post dialysis blood urea samples. So if the URR is high, you can reduce the other parameters in future dialysis.
   
4. Initiate with low Ultrafiltrate (UF)
   In each dialysis session, we remove some amount of water from the body. When the volume of blood reduced, it cause sudden imbalance on osmolality. This also can lead to DDS. Therefore use low UF in early dialysis sessions.
   
   
   

Summery

As a summery dialysis disequilibrium syndrome (DDS) is not a common complication in novel Nephrology and dialysis care. However it was a common complication in history of hemodialysis. Why is this so important? Importance of dialysis disequilibrium syndrome is that its severe neurological complication. These can cause even sudden death. Therefore we have to take necessary precautions to prevent this condition during dialysis.

Reference articles

1. Zepeda-Orozco, D., & Quigley, R. (2012). Dialysis disequilibrium syndrome. Pediatric nephrology (Berlin, Germany), 27(12), 2205–2211.
   https://doi.org/10.1007/s00467-012-2199-4
   
2. S.M.Silver MD, R.H.Sterns MD, M.L.Halperin MD, Brain swelling after dialysis: Old urea or New Osmoles? American Journal of Kidney Diseases, Volume 28, Issue 1, July 1996, Pages 1-13
   https://doi.org/10.1016/S0272-6386(96)90124-9