[2] Diabetic Ketoacidosis Flashcards
What is diabetic ketoacidosis?
A medical emergency with significant morbidity and mortality, characterised by hyperglycaemia, acidosis, and ketonaemia
What are the diagnostic criteria for diabetic ketoacidosis?
- Ketonaemia of 3mmol/L and over, or significant ketonuria of more than 2+ on standard urine sticks
- Blood glucose of over 11mmol/L, or known diabetes mellitus
- Bicarbonate below 15mmol/L, and/or venous pH less than 7.3
What are the limiitations of the diagnostic criteria of diabetic ketoacidosis?
- Hyperglycaemia may not always be present
- Low blood ketone levels do not always exclude DKA
What patients is DKA normally seen in?
Patients with type 1 diabetes
What % of T1DM patients have an episode of DKA in 1 year?
3.6%
What % of DKA episodes in hospital patients did not primarily present with DKA?
8%
Can DKA present in people with type 2 diabetes?
It can but people with T2 are much more likely to have a hyperosmolar hyperglycaemic state
Who does ketosis-prone T2DM more commonly occur in?
Patients who are older, overweight, and non-white
What does DKA occur due to?
Lack of insulin in the body
What is the result of the lack of insulin in the body in DKA?
- Glucose cannot be taken into the tissues, causing glucose levels to spill over into urine
- Release of free fatty acids from adipose tissue
What is the result of glucose spilling over into urine in diabetic ketoacidosis?
Water and solutes follow, causing osmotic diuresis leading to polyuria, polydipsia, and dehydration
By what process are fatty acids released from adipose tissue in DKA?
Lipolysis
Why does lipolysis occur in DKA?
Because the body has entered starvation mode due to its inability to metabolise glucose in the cells for energy
What happens to the fatty acids released in DKA?
They are converted into ketone bodies in the liver in a process called beta-oxidation
What happens to the ketone bodies in DKA?
They are metabolised to produce energy
What is the problem with the production of ketone bodies in DKA?
They have a low pKa, and therefore turn the blood acidic, producing metabolic acidosis
What are the precipitating factors for DKA?
There may be no obvious precipitant, but possible factors include;
- Infection
- Discontinuation of insulin (deliberate or accidental)
- Inadequate insulin
- Cardiovascular disease, e.g. stroke or MI
- Drug treatmentm e.g. steroids, thiaides, or SGL2 inhibitors
What kind of stress has the potential to initiate DKA?
Any physiological stress, e.g. pregnancy, trauma, or surgery
How long do the symptoms of DKA take to develop>
Usually develop within 24 hours
What should not delay the time to treatment in DKA?
Taking a history
What are the symptoms of DKA?
- Polyuria and polydipsia
- Vomiting
- Dehydration
- Altered mental state, even coma
- Weight loss
- Weakness
- Lethargy
What investigations are done in DKA?
- Examination
- Capillary blood glucose
- Urine dipstick testing
- Assay of blood ketones if available
- Blood testing
- ECG
- CXR
What are the examination signs of DKA?
- Signs of gross dehydration
- Acetone smell (like pear drops) on breath
- Tachypnoea or Kussmaul respiration
What signs of gross dehydration may be present in DKA?
- Dry mucous membranes
- Decreased skin turgor/skin wrinkling
- Sunken eyes
- Slow capillary refill
- Tachycardia
- Hypotension
What is Kussmaul respiration?
Very deep, slow rhythmic breathing
What blood tests may be done in DKA?
- Plasma glucose
- FBC
- Electrolytes
- Urea and electrolytes
- ABG
- Plasma osmolality
- Tests to determine cause if indicated, e.g. CK, amylase, blood cultures etc
What happens to plasma glucose in DKA?
Elevated
What happens to the FBC in DKA?
Raised WCC often seen
What happens to electrolytes in DKA?
Na and K may be raised
What happens to urea and creatinine in DKA?
Elevated
What does the ABG show in DKA?
Metabolic acidosis with low pH and high HCO3-
What happens to plasma osmolality in DKA?
It is raised, but not by as much as in hyperosmolar hyperglycaemic state
How do you calculate plasma osmolality?
Plasma osmolality = 2( [Na]mmol/L + [K]mmol/L + [urea]mmol/L + [glucose]mmol/L )
How high should plasma osmolality be in DKA?
290mOsm/kg
When might the plasma osmolality suggest an alternative diagnosis of hyperosmolar hyperglycaemic state?
If it is higher tahn 320mOsm/kg and there is not significant ketonaemia
How is the anion gap calculated?
The anion gap = [Na]mmol/L – ( [Cl]mmol/L + [HCO3]mmol/L )
What happens to the anion gap in DKA?
It is elevated at >13mmol/L
What are the differential diagnoses in diabetic ketoacidosis?
- Alcoholic ketoacidosis
- Hyperosmolar hyperglycaemic state
- Lactic acidosis
- Other causes of metabolic acidosis, e.g. aspirin overdose
- Acute pancreatitis
- Sepsis without ketoacidosis
- Acute abdomen
- Ketoacidosis due to starvation
What features on admission indicate the need for HDU/ICU monitoring and central venous access?
- Blood ketones >6mmol/L
- Venous bicarbonate <5mmol/L
- Venous/arterial pH <7.0
- K <3.5mmol/L on admission
- GCS <12
- Sats <92% on air (assuming no respiratory disease)
- Systolic BP <90mmH
- Pulse >100 or <60 bpm
- Anion gap above 16
How is diabetic ketoacidosis managed acutely?
- Start fluid
- Test VBG for pH, bicarbonate, bedside and lab glucose and ketones, U&Es, FBC, CRP, CXR, ECG
- Add 50 units of human soluble insuiln to 50mL 0.9% saline, and infuse continuously at 0.1unit/kg/hour. Continue initiating long-acting insulin in newly diagnosed T1DM.
- Assess the need for potassium
- Continue fixed rate insulin
- Find and treat infection/cause for DKA
What fluid should be given in the acute management of diabetic ketoacidosis?
1L 0.9% saline over 1 hour.
If systolic BP <90mmHg, then give 500mL bolus over 15 minutes, and reassess. If still <90mmHg, give another 500mL bolus over 15 minutes and seek senior review. If remains under 90mmHg, involve ICU
What treatment outcome should be aimed for in the acute management of diabetic ketoacidosis?
- Fall in blood ketones of 0.5mmol/L/hour
- Rise in venous bicarbonate of 3mmol/L/hour, with a fall in blood glucose of 3mmol/L/hour
What should be done if not achieving treatment outcome goals in the acute management of DKA?
Increase insulin infusion by 1 unit/hour until target rates are achieved
How often should capillary blood glucose and ketones be measured in the acute management of DKA?
Hourly
How often should VBG be checked in the acute management of DKA?
2, 4, 8, and 12 hours, or more frequently if indicated
When should fixed rate insulin be continued until in DKA?
Until ketones <0.6mmol/L, venous pH >7.3, and venous bicarbonate >15mmol/L
When should you consider a catheter in DKA?
If not passed urine by 1 hour
What urine output should be aimed for in DKA?
0.5mL/kg/hour
When should an NG tube be considered in DKA?
If vomiting or drowsy
Who should be started on LMWH in DKA?
All patients
How is DKA managed once glucose reaches 14mmol/L
Start 10% glucose at 125mL/hour to run alongside saline, to prevent hypoglycaemia
What is the typical fluid deficit in DKA?
100mL/kg
So for an average 70kg man, you need to replace 7L
Give an example of a suitable fluid regime in DKA for a 70kg man
An example regime is 1L over 1 hour, then 1L over 2 hours, 1L over 2 hours, 1L over 4 hours, 1L over 4 hours, 1L over 8 hours, 1L over 8 hours.
The regimen may not be appropriate for all, so reassess frequently, especially in young, elderly, pregnant, or comorbidities
What is the typical potassium deficit in DKA?
3-5mmol/kg
What causes the potassium deficit in DKA?
Plasma potassium falls with treatment, as potassium enters cells
Should you add potassium to the first bag of fluids in DKA?
No
How much potassium should be added to fluids in DKA?
It should be based on the most recent VBG.
- If serum potassium is >5.5mmol/L, don’t add potassium
- If serum potassium is 3.5-5.5mmol/L, add 40mmol/L KCl to IV fluid
- If serum potassium <3.5mmol/L, seek help from HDU/ICU
What are the complications of diabetic ketoacidosis?
- Cerebral oedema
- Pulmonary oedema
- Arrhythmias
- Myocardial suppression
- Venous thromboembolism
- Myocardial infarction
- Adult respiratory distress syndrome
