Fluids, Electrolytes, and Nutrition: PICU Handbook

Definition

• Hyperglycemia (> 200mg/dl)
• pH < 7.3 or HCO3 < 15 mmol/L
• Ketonuria and ketonemia

Severity

• Mild: pH < 7.3 / HCO3 < 15
• Moderate: pH < 7.2 / HCO3 < 10
• Severe: pH < 7.1/ HCO3 < 5

Labs

• Blood gas q2 till pH > 7.3
• Accucheck q1 while on insulin gtt
• BMP admission and q24
• Serum Na and K q2 until stable
• HBA1C on admission
• CBCD
• Cultures as appropriate
• Endocrine labs

Clinical features

• Dehydration
• Kussmaul Respirations
• Nausea, Vomiting and Abdominal pain
• Lethargy/Obtundation
• Leucocytosis with left shift
• ↑ serum amylase

General goals of therapy

• Rehydration
• Correct acidosis
• Correct ketosis
• Restore BG to normal
• Avoid complications
• Treat precipitating event

Pathophysiology

• Insulin deficiency
• ↑ counter regulatory hormones (Glucagon, GH and Cortisol)
• ↑ Gluconeogenesis
• ↑ Glycogenolysis
• ↑ Lipolysis
• ↑ ketogenesis

Average fluid/electrolyte deficits (range)

• Water: 70ml/kg (30-100)
• Na: 6mEq/kg (5-13)
• K: 5mEq/kg (3-6)
• Cl: 4mEq/kg (3-9)
• P: 0.5-2.5mEq/kg

Risk factors for cerebral edema

• Age < 5 yrs
• Initial Fluid bolus > 20ml/kg
• Severe acidosis (pH < 7.1)
• Elevated BUN
• ↓Na despite improving BG
• HCO3 therapy

Monitoring

• Q1 neurochecks
• Q1 accucheck
• Q2 VBG with Na and K
• Strict I/O
• Urine ketones

Fluid therapy

• 1.5 x maintenance fluids
• Add Dextrose to IVF once BG < 250-300 mg/dl
• Order 2 bags of IVF
  1. NS or 1/2 NS with 20meq/l of K Phosphate and 20meq/l of K acetate
  2. D10 NS or D101/2 NS with 20meq/l of K Phosphate and 20meq/l of K acetate 
• Titrate fluid rate from these bags to maintain BG 100-200
• Avoid hypotonic fluids if concerns of cerebral edema
• Add K to IVF once UO documented and no renal failure

Insulin therapy

Infusion at 0.05-0.1u/kg/hr till pH > 7.3 and HCO3 > 15

Transition to SQ insulin

Allow PO diabetic diet, administer SQ insulin, wait 30 minutes and D/C IV insulin and IVF

Hyperkalemia

• Spurious hyper K+ (lab error)
• Excess ingestion
• Fasting
• Drugs (Succinylcholine, B-Blockers, K+ sparing diuretics)
• Tumor lysis
• Hyper K+ Periodic Paralysis
• Acute/Chronic renal failure
• Adrenal insufficiency
• Low renin states

EKG changes with high K+

1. Peaked T waves
2. Prolonged PR interval
3. Absent P waves and widened QRS (Sinusoidal wave pattern)
4. Ventricular arrhythmias

Treatment for hyperkalemia

• Calcium Gluconate 100 mg/kg
• Glucose 1g/kg
• Insulin 0.1 unit/kg
• Kayexalate
• Na HCO3 1-2 mEq/kg
• Albuterol
• Dialysis

Hypokalemia

Without K+ deficit: alkalosis, B-agonist, familial periodic paralysis, thyrotoxic periodic paralysis, excessive insulin

With K+ deficit: decreased intake, renal losses (hyperaldosteronism, osmotic agents, diuretics), extrarenal losses (GI losses - V/D, NG suction, laxative abuse)

EKG changes with low K+

1. T wave flattening or inversion
2. ST depression
3. Appearance of U wave

Other important changes with low K+:

• Skeletal Muscle weakness
• Adynamic ileus

Hypochloremia

With Metabolic alkalosis: vomiting, diuretics, NG suction, steroids

With Hyponatremia: adrenal insuff, edematous states, SIADH, renal failure

Hyperchloremia

With Metabolic acidosis (normal AG): drains, carbonic anhydrase inhibitors, RTA, NH4Cl, diarrhea

Iatrogenic: 3%, 7% NaCl therapy

Hypomagnesemia

Decreased intake: TPN, malnutrition, anorexia

Increased losses

• GI: malabsorption (small bowel dz, UC, bowel resection, pancreatitis, CF)
• Renal: tubular d/o (RTA), postrenal transplant, DKA, hypercalciuria, hyperaldosteronism, meds
• Miscellaneous: epi, B-agnostic, thyrotoxicosis, blood transfusion w/ citrate, burns

Hypermagnesemia

• Renal failure
• Iatrogenic administration (antacids, enemas, TPN)
• Megadose vitamin-mineral supplements
• Mg infusions (status asthmaticus, eclampsia)

Hypophosphatemia

• Respiratory alkalosis
• TPN use (especially premies)
• Refeeding syndrome
• Thermal burns
• DKA
• Alcohol withdrawal

Hyperphosphatemia

• Increased intake: phosphate supplements, enemas
• Decreased renal excretion: acute/chronic renal failure, hypoparathyroidism, heparin, vit D intox
• Redistribution (extracellular to intracellular): tumor lysis syndrome, rhabdomyolysis, hemolysis, crush injuries, hyperthermia, respiratory acidosis, metabolic acidosis

*From Handbook of Pediatric Intensive Care by Gale Pearson

Enteral nutrition

Enteral Nutrition is the preferred route if safe Gut atrophy occurs w/in 3 days of stopping feeds Enteral feeds maintain gut physiology, cell mass, and integrity of intracellular junctions

Trophic feeds (~5-10cc/kg) may result in less bacterial translocation

If pt is at high risk of aspiration, trans-pyloric (TP) tube feedings should be used

Infants (3 -10 kg)

• Breast milk or standard formula
• Use comparable formula (ie soy, cow, low fat)
• Standard concentration 20 kcal/oz
• May be prepared to 24, 27, or 30 kcal/oz for pts w/ high nutrient needs or volume restriction

Children 1-10 yr (10-40 kg)

• Use pediatric formulas (Pediasure, Nutren Jr)
• Standard concentration is 30 kcal/oz or 1kcal/cc

Adolescents

• For > 40 kg, consider adult formulas
• Standard concentration is 1.2 kcal/cc

Electrolyte requirement

Growth goals

Parental nutrition

• Use NVN (neonatal) in neonates <3 kg or < 2 mos
• Use PVN (pediatric) for pts > 2mos to 35-40 kg
• Use AVN (adult) for pts > 40 kg

Amino acids – Begin at intended goal concentration, adjustfor metabolic condition or organ function

Dextrose – Begin w/ D12.5W and advance based on glucose levels by 5% increments

Lipids – Initiate on first day of parenteral nutrition, typicall yinfuse over 20 hr. Keep < 30-40% of total calories.

Calories / ml of parenteral nutrition

Kcal/ml from non standard solutions =
{(3.4 X % Dextrose) + 4 X %AA)} / 100 = kcal /ml

Lipid goals for age

Children are in a steady state of growth, development, and organ maturation which make their responses to injury / illness unpredictable.

Energy requirements

• Infants require ~4 times more energy than adults
• Cannot be in anabolic and catabolic states at same time
• Needs are based on estimates of basal requirements adjusted for stress & activity

Protein requirements

• Markedly elevated during illness
• Pts progress through period of negative nitrogen balance when ill
• Exogenous protein may maximize protein synthesis and decrease net protein loss
• Important to provide adequate protein early in illness to prevent wasting

Carbohydrate requirements

• Exogenous carbs will reduce need for gluconeogenesis and spares breakdown of proteins
• Glucose oxidation rates may be elevated by stress, resulting in hyperglycemia
• In volume restricted pts, may need higher glucose infusions to provide basal metabolic requirements

Fat requirements

• Require minimum of 0.5 gm/kg/d to meet essential fatty acid needs

From Roger's Handbook of Pediatric Intensive Care, 4th Ed.