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CDHB

Diabetic Ketoacidosis (DKA)

General Principles and Precautions

• DKA is defined by hyperglycaemia with positive plasma ketones and an arterial pH ≤7.30 and/or a plasma bicarbonate ≤15 mmol/L. Plasma or capillary beta-hydroxybutyrate is typically >1.2 mmol/L.
• DKA is associated with significant mortality, particularly in the older patient with an underlying acute medical condition precipitating ketoacidosis. Death from DKA in young, otherwise healthy patients, is often associated with inadequate electrolyte (particularly potassium) and fluid replacement.
• Cerebral oedema may complicate childhood and adolescent DKA. A deterioration in the level of consciousness, despite improving biochemistry, suggests this complication. Monitor level of consciousness and undertake fluid replacement slowly.
• Some patients with Type 1 diabetes present with hyperglycaemia, ketonuria but no acidosis (normal pH or bicarbonate) and can be safely managed as a Day Case. Make sure the patient does not have hyperglycaemic hyperosmolar non ketotic state. Seek advice.

Discuss the management of these patients with the Diabetes Physician on call.

Common Causes of DKA

• Insulin withdrawal or reduction.
• Myocardial infarction, stroke, trauma or other medical stress.
• Infection such as pneumonia, gastroenteritis, influenza, urinary tract infection, meningitis.

Baseline Investigations

• Glucose.
• K, Na, Cl, urea and creatinine. (Creatinine may be falsely elevated if ketones are high due to interference with the assay). Measurement of ketone bodies e.g., plasma or capillary beta-hydroxybutyrate.
• Venous pH and bicarbonate, rather than arterial pH, may be sufficient if patient has mild DKA only.
• CBC + diff.
• Cultures of blood and urine and any other material as indicated.
• CXR.
• ECG.

Treatment

If the patient is severely ill (arterial pH <7.1 or obtunded or has DKA complicated by other medical conditions) consider admission to the Intensive Care Unit. Patients on long acting insulins such as glargine or detemir, who are suffering from mild/moderate metabolic disturbance only, can continue their long acting subcutaneous insulin at a reduced dose, e.g., 70% usual dose, whilst receiving IV Actrapid™ therapy.

Monitoring

• All patients requiring intravenous insulin need a flow chart documenting potassium, fluid balance, insulin dose, blood glucose, pH and/or capillary ketones (beta-hydroxybutyrate).
• Effective osmolarity (2xNa + glucose, in mmol/L) should be monitored in severely unwell patients or in those with hypernatraemia. Effective osmolarity measures only osmolytes that draw fluid from one compartment. Urea, which diffuses freely across membranes, is excluded from the calculation. Serum effective osmolarity is closely related to mental status. Coma is usually present when effective osmolarity is >340 mosm/L.
• Patients who have access to a Medisense Optium™ or Optium Xceed™ meter can test for capillary beta-hydroxybutyrate. Some wards (for example, AMAU) have access to this meter. Inpatient capillary beta-hydroxybutyrate test strips can be prescribed on the drug chart through the hospital pharmacy. This test provides a better measure of changes in DKA status than does monitoring of urine ketones.
• Patients with DKA have a beta-hydroxybutyrate measurement >1.2 mmol/L and often much higher. If beta-hydroxybutyrate is <1.2 mmol/L and the patient is unwell, consider other diagnoses.
• If the patient is severely ill, sodium, potassium, and glucose should be checked hourly for the first 4 hours then at 4 hourly intervals, over the next 12 hours.
• Venous blood gases can be used to monitor progress once the patient is improving.
• Vital signs should also be closely monitored in severely ill patients (e.g., pulse, temperature, respiration, blood pressure, weight and mental status).

IV fluids

• The usual first choice of rehydrating fluid is sodium chloride 0.9%.
• The amount and speed of fluid replacement will be dictated by the clinical findings (e.g., degree of weight loss at presentation, hypotension, JVP or CVP, concomitant heart failure).
• A common replacement regimen in patients without heart failure is 1 L sodium chloride 0.9% over the first hour, then 500 mL over the second hour, then 500 mL 2-4 hourly thereafter, adjusted according to urine output and other clinical findings.
• Aim to correct major metabolic disturbance slowly.
• Sodium chloride 0.45% is rarely needed. Many patients will experience a rise in sodium following correction of hyperglycaemia. In occasional patients, initial IV therapy may result in sodium continuing to rise above the normal range, however effective osmolarity (2x sodium + glucose; see Monitoring for further information) may be falling appropriately with treatment.
• When the blood glucose approaches 15 mmol/L, change to 4% glucose and sodium chloride 0.18%.
• See below for potassium replacement. Many patients can receive potassium replacement using ready mixed 30 mmol potassium chloride in 1 L sodium chloride 0.9% or 1 L 4% glucose and sodium chloride 0.18%. Some patients will however require further potassium added to sodium chloride 0.9%. For safety reasons, potassium replacement must be given via an infusion pump.

Insulin

• Add 50 units Actrapid™ to 50 mL sodium chloride 0.9% in a 50 mL syringe.
• Administer IV using a pump such as an IVAC.
• The nursing staff will purge 10 mL through the plastic tubing, to saturate the insulin binding sites on the tubing.
• Start with an insulin infusion of around 5 mL (5 units) per hour, 'piggy backed' together with IV fluids such as sodium chloride 0.9% if glucose >15 mmol/L or 4% glucose and sodium chloride 0.18% if glucose is ≤15 mmol/L.
• Increase or decrease the insulin infusion rate according to the rate of fall of glucose.
• Aim to normalize glucose over >24 hours, no faster.
• When the glucose has fallen to around 20 mmol/L, slow down the rate of infusion of insulin (refer to the sliding scale).
• When glucose has fallen to around 15 mmol/L, change IV fluid replacement to 4% glucose and sodium chloride 0.18% or 5% glucose.
• If satisfactory progress is not occurring (particularly if the acidosis is not resolving) reassess volume status to ensure adequate repletion, check for hyperchloraemia and check the insulin mixture is correctly prepared and consider increasing the insulin infusion rate.

Suggested Starting Sliding Scale for IV Insulin Administration

Note: Patients with increased insulin sensitivity (e.g., thin, elderly patients) or insulin resistance (e.g., patients with marked centralized adiposity) will probably require modification of this sliding scale.

Potassium replacement

• Patients with DKA are depleted in total body potassium despite the fact that most have a normal, or even elevated, serum potassium at presentation. Unless the patient is anuric, potassium replacement will be required within two hours of commencing insulin, or sooner if baseline potassium is low.
• The key to adequate potassium replacement is regular monitoring.
• Most patients can have pre-mixed 30 mmol/L potassium chloride in sodium chloride 0.9%. Occasionally, patients with severe total body potassium depletion will require greater concentrations.
• Discontinue potassium replacement once the patient is eating or potassium above 5 mmol/L.

Changing from IV to subcutaneous insulin

• When acidosis has been corrected and the patient is eating well, consider discontinuing IV fluids and IV insulin.
• The half-life of IV insulin is short and there should be at least a 2 hour overlap from IV to subcut insulin especially if intermediate or long acting insulin has just been given.
• In patients already on a long acting insulin (e.g., glargine, detemir) prior to admission, consider continuing this insulin throughout hospitalization but at a reduced dose (70% usual dose).
• If the patient has newly diagnosed Type I diabetes, estimate the likely subcut insulin requirements from the previous 24 hours IV insulin requirement.
• All patients changing over to subcut insulin should be commenced on an insulin regimen which includes a long-acting component, for example either Humalog Mix25™ before breakfast and the evening meal, or isophane NPH (Humulin NPH™ or Protaphane™) at bedtime with aspart (NovoRapid™) or lispro (Humalog™) with main meals.
• If the patient is converting to subcut aspart (NovoRapid™) or lispro (Humalog™) insulin, a small dose of long acting insulin such as isophane NPH (Humulin NPH™ or Protaphane™) may also be required at the time the IV infusion is discontinued.

Note: Use of sliding scale subcut Actrapid™ on its own is inappropriate and is likely to delay stabilization of diabetes.

Additional Notes

• Do not strive for rapid correction of hyperglycaemia - the underlying principle is to avoid hypoglycaemia and correct salt and water loss.
• If gastric stasis is present and you are concerned about aspiration of gastric contents, consider inserting a nasogastric tube.
• Abdominal pain and hyper-amylasaemia often occur in DKA. The raised amylase may be the result of extra-pancreatic secretion and does not necessarily mean the patient has pancreatitis.
• IV bicarbonate is rarely, if ever, necessary. Consider IV bicarbonate only if pH is very low (<7) and then give enough to raise the pH to 7.1. Give 1 mmol sodium bicarbonate per kg over 30-60 minutes with 10-20 mmol of potassium and review pH in one hour.
• Always refer the patient to the Diabetes Service to assess overall diabetes management.

Topic Code: 1367