Vaman Khadilkar *
MD, MRCP (UK) DCH (London)
Pediatric & Adolescent, Endocrinologist. *
|Basics of pathophysiology|
- There is a relative or absolute insulin deficiency
- Elevated levels of stress hormones
- Increased serum osmolarity
- Oxygen dissociation curve is shifted to the left
- Tissue hypoxia and shock
- Osmotic diuresis
- Na, K is lost in the urine with ketones
- Total fluids: Replaced is a combination of maintenance + deficit + ongoing losses
- Maintenance: 1500 ml/m2/day at all ages
- Deficit: 5-10% generally 10% is assumed as the clinical signs of dehydration are less pronounced
- Ongoing losses: Urine output + loss in the vomitus and gastric aspirate
Initial fluid should be normal saline or ringer lactate. In the first 1-2 hrs the fluid is given at a rate of 10-20 mL per kg to stabilize the circulation. When the blood sugar drops to 250 mg% add 5% dextrose to the fluid so that the risk of hypoglycemia is reduced. Total fluid replacement should be divided as 1/3 in the first 6 hours, next third in the next 12 hours and next third in the next 18 hours (Total 36 hours).
Total body potassium is always depleted. Potassium replacement should be started after the initial hour (after the rapid fluid correction is over). It can be started even earlier if the initial potassium is lower than 3 mmoL/L. In places where urgent electrolytes are not available ECG should be used. Rate of K administration should be 20-30 mmoL/l of fluids. Ideally potassium should be replaced as half phosphate and half chloride.
Routine provision of bicarbonate is unnecessary. With insulin therapy lactic acid is metabolized to bicarbonate. Bicarbonate therapy can overcorrect acidosis. It can lead to hypernatremia and hyperosmolarity, hypokalemia. It may also lead to paradoxical CNS acidosis. It may however be used only when: pH <7.0, symptomatic hyperkalemia and poor myocardial contractility. WHEN GIVEN, IT SHOULD BE GIVEN AS A SLOW IV INFUSION OVER A PERIOD OF 2-4 HOURS AND NEVER AS BOLUS.
Initial bolus of 0.1 units per kg iv. Infusion is made as 50 units in 500 ml of normal saline. Initial 50-60 ml is run off through the tubing to saturate binding sites. Infusion is then given through an infusion pump. INSULIN INFUSION MUST BE CONTINUED UNTIL ACIDOSIS RESOLVES and NOT when sugars are controlled. Half an hour before the infusion is discontinued subcutaneous regular insulin is given in a dose of 0.25 iu/kg Monitoring Schedule.
Initial Investigations: Glucose, electrolytes, blood gas, creatinine, osmolarity, blood count and culture is collected at the beginning Subsequent schedule:
- Glucose: 1-2 hourly
- Electrolytes: 1-2 hourly
- ABG: At 2, 4, 6, 10 and 24 hours.
- Consciousness: Using a scale like Glasgow coma or APUD should be monitored 2 hourly
Complications of Fluid and Electrolyte Therapy:
- Brain edema
How to suspect brain edema:
- Change in the level of consciousness in a child who was improving
- Bradycardia and other signs of raised ICT
Prevention of brain edema:
- Slow rehydration over 36-48 hours
- Use of isotonic solutions for rehydration
- Avoid hypotonic or hypertonic solutions (such as bicarbonate bolus)
- Early detection by vigilance
Treatment of Developing Brain Edema:
- Mannitol 20% i.v. in a dose of 0.5 to 1 gm/kg may be repeated every 15 minutes if necessary
- Reduce rate of fluid input
- Nurse the child in head-up position
- Assisted ventilation
|How to Cite URL :|
|Khadilkar V.. Available From : http://www.pediatriconcall.com/fordoctor/ Conference_abstracts/report.aspx?reportid=298|