hyper osmolar hypergylcaemic state

Question 1

What is HSS

Answer 1

medical emergency where Hyperglycaemia results in osmotic diuresis, severe dehydration, and electrolyte deficiencies.

Question 2

Who is at risk

Answer 2

HHS typically presents in the elderly with type 2 diabetes mellitus (T2DM)

Question 3

What is dangerous to give to HHS patients

Answer 3

It is extremely important to differentiate HHS from diabetic ketoacidosis (DKA) as the management is different, and treatment of HHS with insulin (e.g. as part of a DKA protocol) can result in adverse outcomes.

Question 4

What are the possible complications of HHS

Answer 4

HHS has a higher mortality than DKA and may be complicated by vascular complications such as myocardial infarction, stroke or peripheral arterial thrombosis. Seizures, cerebral oedema and central pontine myelinolysis (CPM) are uncommon but documented complications of HHS.

Question 5

What is the onset of HHS

Answer 5

HHS comes on over many days, and consequently the dehydration and metabolic disturbances are more extreme.

Question 6

What is the pathophysiology §

Answer 6

Hyperglycaemia results in osmotic diuresis with associated loss of sodium and potassium
Severe volume depletion results in a significant raised serum osmolarity (typically > than 320 mosmol/kg), resulting in hyperviscosity of blood.
Despite these severe electrolyte losses and total body volume depletion, the typical patient with HHS, may not look as dehydrated as they are, because hypertonicity leads to preservation of intravascular volume.

Question 7

What general features may you see

Answer 7

fatigue, lethargy, nausea and vomiting

Question 8

What neurological features may you see

Answer 8

altered level of consciousness, headaches, papilloedema, weakness

Question 9

What haematological features may you see

Answer 9

hyperviscosity (may result in myocardial infarctions, stroke and peripheral arterial thrombosis)

Question 10

What cardiovascular features may you see

Answer 10

dehydration, hypotension, tachycardia

Question 11

What are the diagnostic features

Answer 11

1. Hypovolaemia
2. Marked Hyperglycaemia (>30 mmol/L) without significant ketonaemia or acidosis
3. Significantly raised serum osmolarity (> 320 mosmol/kg)
   Note: A precise definition of HHS does not exist, however the above 3 criteria are helpful in distinguishing between HHS and DKA. It is also important to remember that a mixed HHS / DKA picture can occur.

Question 12

What are the goals of management

Answer 12

1. Normalise the osmolality (gradually)
   the serum osmolality is the key parameter to monitor
   if not available it can be estimated by 2 * Na+ + glucose + urea
2. Replace fluid and electrolyte losses
3. Normalise blood glucose (gradually)

Question 13

What are the estimated fluid losses

Answer 13

Fluid losses in HHS are estimated to be between 100 - 220 ml/kg (e.g. 10-22 litres in an individual weighing 100 kg).

Question 14

How to determine rate of rehydration

Answer 14

assessing the combination of initial severity and any pre-existing co-morbidities (e.g. heart failure and chronic kidney disease). Caution is needed, particularly in the elderly, where too rapid rehydration may precipitate heart failure but insufficient may fail to reverse an acute kidney injury.

Question 15

What is the first line IV replacement

Answer 15

Intravenous (IV) 0.9% sodium chloride solution is the first line fluid for restoring total body fluid.

Question 16

What to do next if serum osmolarity is not declining despite positive balance with 0.9% sodium chloride

Answer 16

fluid should be switched to 0.45% sodium chloride solution which is more hypotonic relative to the HHS patients serum osmolarity

Question 17

What is the aim for iv fluid replacement

Answer 17

aim to achieve a positive balance of 3-6 litres by 12 hours and the remaining replacement of estimated fluid losses within the next 12 hours.

Question 18

Why is a rapid reduction unfavourable

Answer 18

A steep decline in serum osmolarity may also precipitate CPM. (Central pontine myelinolysis)

Question 19

What should be plotted on a graph during monitoring

Answer 19

Guidelines suggest that serum osmolarity, sodium and glucose levels should be plotted on a graph to permit appreciation of the rate of change. They should be plotted hourly initially.

Question 20

How can osmolarity be calculated if lab not available

Answer 20

2Na + glucose + urea

Question 21

What does a reduction in serum osmolarity lead to

Answer 21

A reduction of serum osmolarity will cause a shift of water into the intracellular space. This inevitably results in a rise in serum sodium (a fall in blood glucose of 5.5 mmol/L will result in a 2.4 mmol/L rise in sodium).

Question 22

What indicates insufficient fluid replacement

Answer 22

If the inevitable rise in serum Na+ is much greater than 2.4 mmol/L for each 5.5 mmol/L fall in blood glucose this would suggest insufficient fluid replacement. Rising sodium is only a concern if the osmolality is NOT declining concurrently.

Question 23

What is a safe rate of plasma glucose decline

Answer 23

A safe rate of fall of plasma glucose of between 4 and 6 mmol/hr is recommended. The rate of fall of plasma sodium should not exceed 10 mmol/L in 24 hours.

Question 24

What is the target blood glucose

Answer 24

A target blood glucose of between 10 and 15 mmol/L is a reasonable goal.

Question 25

How long does complete normalisation of electrolytes and osmolality take

Answer 25

may take up to 72 hours

Question 26

Why does insulin cause a dramatic fall in glucose

Answer 26

Because most patients with HHS are insulin sensitive (e.g. it usually occurs in T2DM), administration of insulin can result in a rapid decline of serum glucose and thus osmolarity.

Question 27

Apart from CPM what else can insulin treatment lead to

Answer 27

Insulin treatment prior to adequate fluid replacement may result in cardiovascular collapse as the water moves out of the intravascular space, with a resulting decline in intravascular volume.

Question 28

What is measured to determine if insulin is required

Answer 28

Ketones

Question 29

When is insulin administered

Answer 29

If significant ketonaemia is present (3β-hydroxy butyrate is more than 1 mmol/L) this indicates relative hypoinsulinaemia and insulin should be started at time zero (e.g. mixed DKA / HHS picture).

Question 30

What is the recommended insulin dose

Answer 30

The recommended insulin dose is a fixed rate intravenous insulin infusion given at 0.05 units per kg per hour.

Question 31

How pronounced are the potassium changes

Answer 31

Patients with HHS are potassium deplete but less acidotic than those with DKA so potassium shifts are less pronounced