Pharmacology
Endocrine
Question 20 of 180
Regarding the management of diabetic ketoacidosis (DKA), insulin infusion may be stopped after which of the following:
Answer:
The insulin infusion should be continued until blood ketone concentration is below 0.6 mmol/litre, blood pH is above 7.3 and the patient is able to eat and drink; ideally the insulin infusion should be stopped about an hour after giving subcutaneous fast-acting insulin and a meal.Management of Diabetic Ketoacidosis
Pharmacology / Endocrine
Last Updated: 11th August 2022
Diabetic ketoacidosis (DKA) consists of the biochemical triad of ketonaemia (ketosis), hyperglycaemia, and acidaemia.
Pathophysiology
DKA usually occurs as a consequence of absolute or relative insulin deficiency that is accompanied by an increase in counter-regulatory hormones (i.e. glucagon, cortisol, growth hormone, catecholamines). This type of hormonal imbalance enhances hepatic gluconeogenesis and glycogenolysis resulting in severe hyperglycaemia. Enhanced lipolysis increases serum free fatty acids that are then metabolised as an alternative energy source in the process of ketogenesis. This results in accumulation of large quantities of ketone bodies and subsequent metabolic acidosis. Fluid depletion occurs due to osmotic diuresis secondary to hyperglycaemia, vomiting, and inability to take in fluid due to a diminished level of consciousness.
Diagnosis
- Diagnostic criteria (all three must be present):
- Capillary blood glucose > 11 mmol/L
- Ketonaemia > 3 mmol/L or Ketonuria > ++
- Bicarbonate (HCO3-) < 15 mmol/L and/or venous pH < 7.3
Management (adults)
- Intravenous fluids
- Initial fluids:
- Systolic BP < 90 mmHg on admission
- 500 mL 0.9% sodium chloride should be given intravenously over 10 – 15 minutes and repeated if blood pressure remains < 90 mmHg whilst awaiting senior input. Most people require 500-1000 mL given rapidly.
- Consider involving the ITU/critical care team.
- Once systolic BP > 90 mmHg, 1 L 0.9% sodium chloride should be given over the next 60 minutes. The addition of potassium is likely to be required in this second litre of fluid.
- Systolic BP ≥ 90 mmHg on admission.
- 1 L 0.9% sodium chloride should be given over the first 60 minutes.
- Systolic BP < 90 mmHg on admission
- Continuing fluids:
- Regime:
- 0.9% sodium chloride 1L with potassium chloride over next 2 hours
- 0.9% sodium chloride 1L with potassium chloride over next 2 hours
- 0.9% sodium chloride 1L with potassium chloride over next 4 hours
- More cautious fluid replacement in young people aged 18-25 years, elderly, pregnant, heart or renal failure. (Consider HDU and/or central line).
- Accurate fluid balance chart, minimum urine output 0.5 ml/kg/hr.
- Regime:
- Potassium replacement:
- Potassium chloride should be included in the fluids unless anuria is suspected, and adjusted according to plasma-potassium concentration (measured at 60 minutes, 2 hours, and 2 hourly thereafter; and hourly if outside the normal range).
- Potassium levels:
- K+ Level >5.5 = nil replacement
- K+ level 3.5 - 5.5 = 40 mmol/L replacement
- K+ level <3.5 = senior review
- Other electrolytes:
- Venous blood gas for pH and bicarbonate should be checked at 60 minutes, 2 hours and 2 hourly thereafter.
- Plasma electrolytes should be checked 4 hourly.
- Initial fluids:
- Insulin
- An intravenous insulin infusion should be started at a concentration of 1 unit/mL, infused at a fixed rate of 0.1 units/kg/hour using 50 units human soluble insulin (Actrapid® or Humulin S®) made up to 50 ml with 0.9% sodium chloride solution.
- Established subcutaneous long-acting insulin therapy should be continued during the treatment of DKA at usual dose and time.
- Blood ketone and blood glucose concentrations should be checked hourly and the insulin infusion rate adjusted accordingly. Blood ketone concentration should fall by at least 0.5 mmol/litre/hour OR bicarbonate should rise by at least 3 mmol/L/hour and blood glucose concentration should fall by at least 3 mmol/litre/hour.
- The insulin infusion should be continued until blood ketone concentration is below 0.6 mmol/litre, blood pH is above 7.3 and/or venous bicarbonate is over 18 mmol/L and the patient is able to eat and drink; ideally the insulin infusion should be stopped about an hour after giving subcutaneous fast-acting insulin and a meal.
- Glucose
- Once blood-glucose concentration falls below 14 mmol/litre, glucose 10% should be given by intravenous infusion (into a large vein through a large-gauge needle) at a rate of 125 mL/hour, in addition to the sodium chloride 0.9% infusion.
- Consider reducing the rate of intravenous insulin infusion to 0.05 units/ kg/hour when glucose falls below 14 mmol/L.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
