DIABETIC KETOACIDOSIS DKA
WHAT IS DIABETIC KETOACIDOSIS?
DKA is an abnormal metabolic state caused by a deficiency in insulin leading to a triad of clinical features:
● Hyperglycaemia
● Ketonaemia
● Acidosis
In the absence of insulin, the body responds by the production of growth hormones, cortisol and glucagon. These hormones initiate the following metabolic processes:
● Glycogenolysis – the break down of body glycogen stores to glucose
● Gluconeogenesis – production of glucose from non-carbohydrate precursors
● Lipolysis – breakdown of triglycerides to free fatty acids and glycerol
The increase in glucose production leads to severe hyperglycaemia and the breakdown of fatty acids as an alternative form of energy produces ketone bodies causing a metabolic acidosis.
WHAT CAUSES DKA?
● Infection/sepsis – pneumonia, urinary tract infection, intra-abdominal sepsis
● Inappropriate insulin treatment
● Excessive alcohol consumption
● New diagnosis of diabetes mellitus
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WHAT ARE THE CLINICAL FEATURES?
DKA predominantly affects patients who suffer from type-1 diabetes. However, patients with type-2 diabetes who are prone to the development of ketosis can also develop the condition.
Symptoms and signs include
● Polyuria
● Polydipsia
● Tiredness/lethargy
● Nausea and vomiting
● Abdominal pain
● Kussmaul breathing
● Reduced consciousness
HOW CAN A DIAGNOSIS OF DKA?
Investigations should aim to confirm the diagnosis of DKA and then establish the underlying cause.
The following features must be present to confirm DKA:
1. Ketonaemia ≥ 3 mmol/L or significant ketonuria (> 2+ on urine sticks)
2. Blood glucose > 11 mmol/L or known diabetes mellitus
3. Bicarbonate < 15 mmol/L, venous pH < 7.3, or both
A detailed clinical history and performing a full systems examination is essential in finding the underlying cause of DKA. Baseline investigations should be performed and should include
● Full blood count/CRP
● Urea and electrolytes
● Liver function tests
● Amylase
● Blood cultures
● ECG
● Pregnancy test
MANAGEMENT OF DKA
FLUID RESUSCITATION
Administration of appropriate fluid to a patient suffering with DKA is the most important therapeutic intervention. Either 0.9% saline or balanced electrolyte solution can be used with appropriate potassium replacement as necessary. Concern has been raised regarding the use of 0.9% saline due to its chloride content and its potential to cause a hyperchloraemic acidosis. However, the National Patient Safety Agency has recognised that 0.9% saline is a fluid that is familiar to physicians and readily available on all wards. It is available in bags containing a predetermined concentration of potassium unlike a balanced electrolyte solution that would require potassium to be added to the bag separately, increasing the risk of drug errors. In view of this, it is recommended that 0.9% saline is the fluid of choice for use on medical wards when treating DKA. In a critical care environment, however, a balanced electrolyte solution is often the preferred fluid of choice and administration of potassium either peripherally or centrally is commonplace. It is therefore entirely appropriate to use a balanced electrolyte solution in this clinical setting.
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HYPERGLYCAEMIA
A fixed rate insulin infusion calculated according to patient weight (0.1 unit/kg/hr) should be administered to treat hyperglycaemia. Fifty units of Actrapid diluted in 50 mL of 0.9% saline to give a final concentration of 1 unit mL should be prepared. The therapeutic targets used in order to monitor response to treatment are as follows:
● Reduction in blood ketone concentration by >0.5 mmol/L/h
● Increase in venous bicarbonate by 3 mmol/L/h
● Reduction in capillary blood glucose by 3 mmol/L/h
Failure of these targets to be achieved raises suspicion that insufficient insulin is being administered. There are a number of factors that should be considered:
● An appropriate concentration of insulin is being delivered to the patient.
● Insulin is being transfused and the syringe driver is working correctly.
● The cannula being used to deliver the infusion is working.
If an insufficient concentration of insulin is being administered to the patient, the infusion rate can be increased by 1 unit per hour. A maximum rate of 15 units per hour of Actrapid should not be exceeded.
Capillary blood glucose levels can be checked hourly. If the glucose level falls below 14 mmol/L, supplementary 10% glucose is recommended at a rate of 125 mL/h. Care must be taken not to overload the patient with fluid.
ADMINISTRATION OF ELECTROLYTES
Serum potassium levels in the body will fall as the insulin infusion is commenced. During the initial resuscitation period, potassium should not be added to the fluid if the serum level is above 5.5 mmol/L. If the serum potassium levels are below 5.5 mmol/L and the patient is passing urine, then it should be replaced by giving 0.9% sodium chloride containing 40 mmol of potassium. In cases of severe hypokalaemia, critical care input is required to consider central venous potassium replacement.
FLUID REGIMEN MANAGEMENT FOR DKA
A typical fluid regimen can be seen in the table below for a 70-kg individual with DKA. However, every patient is different and underlying comorbidities must be taken into consideration and the fluid prescription adjusted accordingly to avoid fluid overload.
0.9% Sodium Chloride: 1000 mL over 1 hour
0.9% Sodium Chloride + Potassium Chloride: 1000 mL over 2 hours
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