Thirty per cent of children with diabetes present with vomiting and secondary dehydration from the development of acidosis and ketosis. Diabetic ketoacidocis is a medical emergency. The clinical presentation may vary from polydipsia and polyuria or abdominal pain and vomiting to dehydration and weight loss with rapid acidotic breathing. It is important to check the blood glucose in any child who presents with any of these signs or symptoms.
Assessment
Assessment includes the clinical assessment, particularly of the level of dehydration and the laboratory investigations. The level of dehydration is often overestimated.
Degree of dehydration
• Mild-nil (<4%): no clinical signs
• Moderate (4–7%): easily detectable dehydration, e.g. reduced skin turgor, poor capillary return
• Severe (>7%): poor perfusion, rapid pulse, reduced blood pressure, i.e. shock.
Investigations
• Blood glucose, urea, electrolytes.
• Arterial or capillary acid/base
• Urine: ketones, culture
• Check for precipitating cause, e.g. infection (urine, FBC, blood cultures; consider CXR)
• Islet cell antibodies and insulin antibodies in newly diagnosed patients.
Management
Fluid requirements
If hypoperfusion is present, give normal saline at 20 ml/kg weight stat. This should be repeated until the patient is hemodynamically stable with warm, pink extremities and rapid capillary refill time. If more than 30 ml/kg weight is needed, call for senior advice. Rehydration should continue with normal saline.
The child should be kept nil by mouth (except ice to suck) until alert and stable. A nasogastric tube should be inserted if he or she is comatose or has recurrent vomiting. It should be left on free drainage. Rehydration can be completed orally after the first 24–36 hours if the patient is metabolically stable.
Maintenance fluids
If the blood sugar falls very quickly, i.e. within the first few hours, you should change to normal saline with 5% dextrose. When the blood sugar reaches 12–15 mmol/liter, use 0.45% NaCl with 5% dextrose. You should aim to keep the blood sugar at 10–12 mmol/liter.
If the blood glucose falls below 10–12 mmol/liter and the patient is still sick and acidotic, increase the dextrose in the infusate to 7.5–10%. Do not turn down insulin infusion.
Bicarbonate
Bicarbonate is usually not necessary if shock has been adequately corrected and should not be required in most cases. You must remember that treatment of the dehydration will correct the acid-base disturbance. In extremely sick children (with pH <7.0±HCO3<5 mmol/liter), small amounts of sodium bicarbonate can be given after discussion with the consultant endocrinologist. It should be given over 30 minutes with cardiac monitoring.
The acid base status must then be reassessed.
Note:
• Remember the risk of hypokalemia.
• Continuing acidosis usually means insufficient resuscitation.
Insulin
The insulin should be prepared by adding 50 units of clear/rapid-acting insulin (Actrapid HM or Humulin R) to 49.5 ml 0.9% NaCl (1 unit per ml solution). The insulin infusion may be run as a sideline with the rehydrating fluid via a 3-way tap, provided a syringe
pump is used. Ensure that the insulin is clearly labelled.
You should start at 0.1 units/Kg weight per hour in newly diagnosed children, and in those already on insulin who have glucose levels >15 mmol/liter. Children who have had their usual insulin and whose blood sugars are <15 mmol/liter should receive 0.05 units/kg weight per hour. Adjust the concentration of dextrose to keep the blood glucose at 10–12 mmol/liter.
Adequate insulin must be continued to clear acidosis (ketonemia).
The insulin infusion can be discontinued when the child is alert and metabolically stable (blood glucose <10–12 mmol/liter, pH>7.30 and HCO3>15). The best time to change to subcutaneous insulin is just before meal time. The insulin infusion should only be stopped 30 minutes after the first subcutaneous injection of insulin.
Potassium
Potassium chloride should be added to each bag of i.v. fluid once the patient has urinated. Add this at a rate of 40 mmol/liter if the body weight <30 kg, or 60 mmol/liter if >30 kg. You should measure the levels 2 hours after starting therapy and 2–4 hourly thereafter.
Specimens should in general be arterial or venous. Give no potassium if the serum level is >5.5 mmol/liter or if the patient is anuric.
Admission to ICU
Consider admission to the ICU if the patient is under 2 years of age at onset or if in coma, cardiovascular compromise or is having seizures. Strict monitoring must continue while the child is transferred to ward or to the ICU .
Monitoring during transport to ICU
• Strict fluid balance; check all urine for ketones
• Hourly observations: pulse, BP, respiratory rate, level of consciousness and pupils
• Hourly glucose (Glucometer) during insulin infusion; other biochemistry as clinically indicated
• 4 hourly temperature measurements
Added hazards during the management of ketoacidosis include:
1. Hypernatremia.
Measured serum sodium is depressed by the dilutional effect of the hyperglycemia. To ‘adjust’ sodium concentration, use the following formula:
i.e. 3 mmol/liter of sodium to be added to the measured result for every 10 mmol/liter of glucose above 5.5 mmol/liter. If Na is >160 mmol/liter, the case should be discussed with the consultant. The sodium should rise as the glucose falls during treatment. If this does not happen or if hyponatremia develops, it usually indicates overzealous volume correction and insufficient electrolyte replacement. This may place the patient at risk of cerebral edema.
2. Hypoglycemia.
Hypoglycemia can occur during correction of the hyperglycemia. If the blood glucose is <2.2 mol/liter give i.v. 10% dextrose 5 ml/kg weight. Do not discontinue the insulin infusion. Continue with a 10% dextrose infusion until stable. Cerebral edema. Some degree of subclinical brain swelling is present during most episodes of diabetic ketoacidosis. Clinical cerebral edema occurs suddenly, usually between 6 and 12 hours after starting therapy (range 2–24 hours). Mortality or severe morbidity is very high without early treatment.
3. Cerebral edema
Occurrence of cerebral edema is reduced by slow correction of the fluid and biochemical abnormalities. Optimally, the rate of fall of blood glucose and serum osmolality should not exceed 5 mmol/liter per hour, but in children there is often a quicker initial fall in glucose. Patients should be nursed head up. The warning signs are :
Warning signs of cerebral edema
• First presentation, long history of poor control, young age (<5 years)
• No sodium rise as glucose falls, hyponatremia during therapy, initial adjusted hypernatremia
• Headache, irritability, lethargy, depressed consciousness, incontinence, thermal instability
• Very late—bradycardia, increased BP and respiratory impairment
Treatment consists of:
• Mannitol 20% 0.5 g/kg weight i.v. stat if hemodynamically stable. Give immediately when the clinical diagnosis is made—do not delay for confirmatory brain scan.
• Reduce fluid input to 2/3 and replace deficit over 72 hours rather than 24 hours.
• Nurse head up.
• Transfer immediately to ICU.
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