DIABETIC KETOACIDOSIS Flashcards
In what proportion of children is diabetic ketoacidosis the presenting feature of previously undiagnosed type 1 diabetics?
6%
What is the pathophysiology of diabetic ketoacidosis?
Deficiency of insulin blocks use of glucose leading to hyperglycaemia which leads to ketone build up as fat is metabolised.
As glucose levels exceed the renal threshold, an osmotic diuresis ensues with severe dehydration and loss of sodium and potassium.
What are some of the precipitating factors of diabetic ketoacidosis?
Infection
Missed insulin dose
Myocardial infarction
What are the symptoms of diabetic ketoacidosis?
Abdominal pain
Polyuria
Polydipsia
Weight loss
Vomiting
Lethargy
On examination, what are the signs of diabetic ketoacidosis?
Acidosis causes:
Ketone on breath
Kussmaul breathing: rapid, deep, sighing respiration
Dehydration:
Dry mucous membranes
Loss of skin turgor
Tachycardia, hypotension if severe
Cerebral oedema causes:
Headache
Slowing of pulse and hypertension
Decreased consciousness
Seizures and focal neurological signs
What are the diagnostic criteria for ketoacidosis as described by the Joint British Diabetes Society?
Glucose above 11 mmol/L or known diabetes mellitus
pH lower than 7.3
Bicarbonate less than 15 mmol/L
Ketones above 3mmol/L
OR
Urine dipstick shows ++ ketones
What might the FBC of a child in diabetic ketoacidosis show?
Raised WCC
What is the pH cut off for severe ketoacidosis?
Below 7.1
If a child has mild or moderate DKA (pH of 7.1 or above), what percentage fluid deficit should be assumed?
5%
If a child has severe DKA (pH below 7.1), what percentage fluid deficit should be assumed?
10%
How do we manage a mild or moderate child with diabetic ketoacidosis (pH of 7.1 or above)?
Fluids (0.9% saline) - not as a bolus. Add 5% to their maintenance fluid requirement. Can be oral.
Add 20 mmol of potassium to every 500 mls of fluid as they are likely to be potassium deplete
Start ACTRAPID insulin infusion (0.05-0.1 units/kg in 0.9% saline) 1 or 2 hours after fluids are started
Change fluids to 0.9% saline + 5% glucose once glucose hits 14 mmol/L
How do we manage a severe child with diabetic ketoacidosis (pH less than 7.1)?
Fluids (0.9% saline) - not as a bolus. Add 10% to their maintenance fluid requirement. Must be IV
Add 20 mmol of potassium to every 500 mls of fluid as they are likely to be potassium deplete
Start ACTRAPID insulin infusion (0.05-0.1 units/kg in 0.9% saline) 1 or 2 hours after fluids are started
Change fluids to 0.9% saline + 5% glucose once glucose hits 14 mmol/L
How do we calculate the maintenance fluid requirement for a child in DKA in ml/hour?
If they weigh less than 10 kg, give 2 ml/kg/hour
If they weigh between 10 and 40 kg, give 1 ml/kg/hour
If they weigh more than 40 kg, give a fixed volume of 40 ml/hour.
How do we calculate the deficit fluid requirement for a child in DKA in ml/hour?
(Deficit % x weight) / 48 hours
Remember that fluid replacement in children is always done over 48 hours.
A 6 year old boy is brought into A+E with abdominal pain and vomiting. His mother gives a history of weight loss and polyuria. A BM reads 24 and DKA is diagnosed. You are asked to prescribe fluids for this boy. He is 20kg and a blood gas shows a pH of 7.15. What amount of fluids will he need in ml/hour?
Deficit 5 % x 20 kg = 1000 mls
Divide over 48 hours = 21 ml/hr
Plus maintenance 1ml/kg/hr = 20 ml/hr
Total = 41 ml/hour
How will the fluid requirement in a child in DKA change if on presentation a bolus of fluid was needed for resuscitation purposes?
If more than 20 ml/kg 0.9% sodium chloride has been given by intravenous bolus, subtract any additional bolus volumes from the total fluid calculation for the 48-hour period ie if 30 ml/kg has been given subtract 10 ml/kg from the calculations.
A 60 kg 16 year old girl is brought into A+E with abdominal pain and vomiting and a dropping GCS. Her mother gives a history of weight loss and polyuria. A BM reads 35 and DKA is diagnosed. Her BP on admission is 60/30 but she is eventually resuscitated with 1.8 litres of 0.9% NaCl. A blood gas shows her pH is down at 6.9. You are asked to prescribe fluids to treat her DKA. What amount of fluids will she need in ml/hour?
Deficit 10 % x 60 kg = 6000 mls
Minus 10ml/kg resuscitation fluid = - 600 ml (remember that if more than 20 ml/kg 0.9% sodium chloride has been given by intravenous bolus, you must subtract any additional bolus volumes from the total fluid calculation for the 48-hour period ie if 30 ml/kg has been given subtract 10 ml/kg from the calculations)
Divide over 48 hours = 5400/ 48 = 113 ml/hr
Plus maintenance fixed rate = 40 ml/hr
Total = 113 + 40 = 153 ml/hour
What amount a potassium should be added to the fluids of a child in DKA?
20 mmol per 500 mls of fluid
What is the dose of insulin that should be given to a child in DKA?
0.05 or 0.1 units/kg/hour by infusion
Remember that this must be 1-2 hours after starting IV fluids, not before
Having started a child in DKA on insulin, at what point should you change the fluids from sodium chloride 0.9% to sodium chloride 0.9% + dextrose 5%?
Once the blood glucose level reaches 14 mmol/L
Having started fluids and insulin for a child in DKA, how should observe this child over the following hours?
Hourly blood glucose
Neurological status at least hourly
Hourly fluid input:output
Electrolytes 2 hours after start of IV-therapy,
then 4-hourly
1-2 hourly blood ketone levels
What are the major complications of diabetic ketoacidosis?
Cerebral oedema
Gastric stasis
VTE
Cardiac arrhythmia - hypokalaemia
Acute respiratory distress syndrome
Acute kidney injury
What do children that die in a diabetic ketoacidotic crisis die of?
Cerebral oedema from loss of sodium and rapid fall in glucose due to insulin therapy being too high
