Pediatric fluids and electrolytes

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Pediatric fluids and electrolytes

  1. 1. Pediatric Fluids and Electrolytes Rachel Sykes, PharmD, BCPS Clinical Assistant Professor Ernest Mario School of Pharmacy Rutgers University Saint Barnabas Medical Center September 27, 2007 Objectives• Describe how pediatric body composition changes over time• Identify the three main components of fluid therapy• Calculate the maintenance fluid rate for a child using the Holliday -Segar Method• Determine appropriate fluid components for a hospitalized child Objectives• Calculate fluid rates for a child with dehydration• Determine a 3% saline volume and rate for a child with severe hyponatremia• Recommend an oral rehydration regimen for a child with mild dehydration 1
  2. 2. Body Fluids • Total Body Water = Extracellular Fluid (ECF) + Intracellular Fluid (ICF) • ECF = Plasma + Interstitial Fluid • Total Body Water expressed in terms of % body weight (adolescent or adult): ICF (30-40%) Interstitial Plasma (15%) (5%) Changes in Body WaterBehrman RE, Kliegman RM, Jenson HB. Nelson Textbook ofPediatrics. 17 th Ed. Philadelphia, PA: Elsevier Science; 2004. Change in Body CompositionMiller RD. Miller’s Anesthesia . 6 th Ed. Philadelphia, PA: Elsevier Science; 2005. 2
  3. 3. “Babies are like bags of water” Full-term: 75% waterhttp://chfs.ky.gov/dph/ach/ecd/newbornscreening.htmhttp://www.inmagine.com/rubberball-single-image-set-photos/Rubberball-rbv005 Premature babies: 83% waterhttp://www.sciencemuseum.org.uk/antenna/babybrainscans/http://www.jupiterimages.com/popup2.aspx?navigationSubType=itemdetails&itemID =22684522 Regulating Water and Electrolytes • What makes someone thirsty? – Increase in serum osmolarity – Volume depletion • Dehydration causes increased serum osmolarity – Antidiuretic hormone (ADH) released – SIADH – ADH is released even when the serum osmolarity is low 3
  4. 4. Fluid Therapy• Three types of fluid therapy – Maintenance fluid Fluid to compensate for – Deficit ongoing normal losses – ReplacementFluid to compensate Fluid to for ongoing losses compensate for during medical fluid loss prior to treatment medical treatment Case #1 • A 5 year-old boy is admitted to the hospital after a bike accident where he lost a significant amount of blood. During his hospital stay he has a chest tube placed for a few days. The patient is treated in the hospital for one week and is then discharged home. • What types of fluid therapy does he need? Maintenance Fluid • Where does the body lose fluid? – Urine – Insensible losses • Respiratory, skin, feces – Intrinsic losses • By -product of metabolism • What makes kids different? – Higher metabolic rate and evaporative losses 4
  5. 5. Insensible Losses • Factors affecting insensible losses – Respiratory rate • Age • Pain • Ventilator – Environmental temperature • Phototherapy – Congenital skin defects Gastroschisishttp://www.nlm.nih.gov/medlineplus/ency/imagepages/9028.htm Omphalocelehttp://www.nlm.nih.gov/medlineplus/ency/imagepages/9030.htm 5
  6. 6. Respiratory Rates Respiratory Rate Age Group (per minute) Infant 30-60 Toddler 24-40 Preschool Age 22-34 School Age 18-30 Adolescent 12-16HazinskiMF. Anatomic and physiologic differences between children andadults. Deficit Fluids • Causes of dehydration – Inadequate intake – Blood loss – Fever – Catabolic state • Extra solutes, need extra fluid in order to excrete Replacement Fluids • Type of fluids replaced depends on what ’s being lost – Cerebrospinal fluid drains • Generally replaced with normal saline – Chest tube drains • Generally replaced with albumin, particularly after heart surgery 6
  7. 7. Calculating Maintenance Fluids • Holliday-Segar Method Fluid per day Rate per hour1st 10 kg 100 mL/kg/day 4 mL/kg/hrNext 10 kg 50 mL/kg/day 2 mL/kg/hrWeight > 20 kg 20 mL/kg/day 1 mL/kg/hr This method assumes that 100 kcal expended requires 100mL water Maintenance Fluid Example Calculations Calculate the maintenance fluids in mL/day and mL/hr for the following patient weights: • 25kg • 4kg • 16kg Electrolyte Maintenance Requirements Sodium 2 - 3 mEq/kg/day Potassium 1 - 2 mEq/kg/day Chloride 3 - 5 mEq/kg/day • Chloride needs are generally met by meeting sodium and potassium requirements with NaCl and KCl 7
  8. 8. What is the usual maintenance fluid for a child?• 28 kg, well-hydrated child - What fluid would you recommend?• FIRST - calculate the amount of fluid you need• NEXT - calculate how much sodium and potassium you need• FINALLY - pick a fluid based upon what is commercially available if you can Increased Maintenance Requirements• Fever• Vomiting• Hyperventilation• Hypermetabolic states• High environmental temperature• Intestinal losses• Burns Decreased Maintenance Requirements• Increased environmental humidity• Hypothermia• Hypometabolic states 8
  9. 9. Dehydration Clinical Signs of Dehydration • Weight loss • Babies - sunken – Weigh children fontanelle frequently • Decreased urine • Thirst production • Decreased skin turgor • Increased urine • Dry mucous membranes specific gravity • Lack of tears • Increased heart rate • Decreased blood pressure What are the implications of dehydration for drug therapy? Anterior Fontanellehttp://commons.wikimedia.org/wiki/Image:Human_anterior_fontanelle_1_month_dscn1449.jpg 9
  10. 10. Degree of Dehydration • Need to accurately monitor patient weights frequently • Fluid deficit (L) = PIW (kg) – IW (kg) – PIW = Pre-illness weight – IW = Illness weight • % Dehydration = PIW (kg) – IW (kg) x 100% PIW (kg) Degree of Dehydration Mild Moderate Severe Older 3% 6% 9% Child (30 mL/kg) (60 mL/kg) (90 mL/kg) 5% 10% 15% Infant (50 mL/kg) (100 mL/kg) (150 mL/kg) Degrees of Dehydration Clinical Signs Mild Moderate SevereWeight Loss (%) 5 10 15 Hyperirritable toBehavior Normal Irritable lethargicThirst Slight Moderate IntenseMucous May be Dry Parchedmembranes normalTears Present ± AbsentAnterior Flat ± SunkenFontanelle 10
  11. 11. Degrees of DehydrationClinical Signs Mild Moderate SevereEyes Normal Deepset SunkenSkin Turgor Normal ± IncreasedBlood Normal Normal DecreasedPressureSkin color Normal Pale Gray / mottled Full, normalPulse Rapid Rapid, weak rate MarkedlyUrine output Decreased Anuria decreased Types of Dehydration • Isotonic – Serum Na = 130-150 mEq/L – 80% of dehydrated patients • Hypertonic – Serum Na > 150 mEq/L – 15% of dehydrated patients • Hypotonic – Serum Na < 130 mEq/L – 5% of dehydrated patients Dehydration – Developing a Plan of Action 1. Estimate the degree of dehydration 2. Determine the type of dehydration • This will lead you to your Plan! • Plan will have 3 phases 11
  12. 12. Phase I – Rapid phase• Goal: Restore circulation, reperfuse brain, kidneys• Mild-Moderate – 10 – 20 mL/kg bolus given over 30 – 60 minutes• Severe – May repeat bolus as needed• Fluids – something isotonic such as NS or lactated ringers (LR) Hypotonic / Isotonic Dehydration Phase 2 – Replacement Phase• Goal: Replace deficit of fluids and electrolytes• Amount: – 1/3 daily maintenance + ½ deficit• Fluids: – D5 ½ NS + 20-30 mEq KCl • Add KCl only if patient has voided• Time: Over 8 hours Hypotonic / Isotonic Dehydration Phase 3 – Stabilization Phase• Goal: Transition to maintenance fluids• Amount: – 2/3 daily maintenance + ½ deficit• Fluids: – D5 ¼ NS + 20-30 mEq KCl• Time: Over 16 hours 12
  13. 13. Hypertonic Dehydration Phase 2 – Replacement Phase• Goal: Replace deficit of fluids and electrolytes and daily maintenance• Amount: – Deficits + daily maintenance• Fluid: – D5 ¼NS + 20-30 mEq/L KCl• Give over 24-48 hours• IMPORTANT: Lower serum Na by no more than 10-12 mEq/L/day Hypertonic Dehydration Phase 3 – Replacement Phase• Goal: Replace ongoing losses and transition towards maintenance fluid therapy• Amount: – Replacement + daily maintenance• Fluid: – D5 ¼NS + 20-30 mEq/L KCl Acute Severe Hyponatremia• Serum Na < 120, CNS symptoms• Administer 3% saline• Total volume = – [(130 - serum Na)(0.6)(wt in kg)] x 2• Give 1/2 total in < 1 hr and remainder over the next 2 hours if symptoms persist 13
  14. 14. Oral Rehydration • Effective, safe, inexpensive • Indications – Replacement fluid for mild dehydration – Following Phase I volume resuscitation in moderate dehydration • Contraindications – Severe dehydration – Electrolyte abnormalities – Ileus or gastric obstructionwww.rehydrate.org Rehydration Solutions Recommendation: Glucose 2 - 2.5 g/dL Sodium 50-75 mEq/L Glucose Sodium Potassium (g/dL) (mEq/L) (mEq/L) Pedialyte 2.5 45 20 Gatorade 5.9 21 2.5 Apple Juice 11.9 0.4 26 Milk 4.9 22 36 Water 3 0.5http://almostgirl.coffeespoons.org/?p=1131http://www.yummy.com/subcategorylist.aspx?cGw8n4AckUu5BAvSiFaUNV n9hS91DEsEXmQyGJauVHM= Oral Rehydration • Patient vomiting – 5-10mL Q 5-10 minutes and increase as tolerated • Mild Rehydration – Deficit replacement: 50 mL/kg over 4 hours • Moderate Rehydration – Deficit replacement: 100 mL/kg over 4 hours 14
  15. 15. Hyperkalemia • Can cause life-threatening arrhythmias – Bradycardia – Ventricular dysrhythmias • First determine why the serum level might be high – Heel stick? – KCl in fluids? Blood Collection in Newbornshttp://health.state. ga. us/programs/nsmscd/screening_form.asphttp://www.nlm.nih.gov/medlineplus/ency/imagepages/2961.htm Hyperkalemia • Treatment – Calcium – Bicarbonate – Insulin (with glucose) – Albuterol 15
  16. 16. Case #3• JW, a 16 month old boy (11kg), is brought into your pharmacy by his mother. JW’s mom says that he had a mild bout of diarrhea a few days ago, and she is still noticing fewer wet diapers. Otherwise, he has no symptoms. JW’s mother would like to know what she should do. What do you recommend? Case #4• DR is a 4 year old girl (16kg) who presents to the emergency room with fatigue, headache, generalized malaise, and severe gastrointestinal distress. The ER team gets a chem-7 and discovers her sodium to be 118. They would like to give 3% NS and ask you for a recommendation on how much to give, and at what rate. Case #5• LM is a 4 month old, 7kg (preillness) girl who presents to the ER with a sunken fontanelle, dusky skin, lethargy, and is not crying. She has not urinated in several hours. Current weight is 6kg. Her sodium is 137. What type and degree of dehydration does she have? How do you recommend treating her? 16
  17. 17. Case #5• How do I double-check my answer? It’s easy! Just add up all the fluid you gave. It should equal the deficit + the daily maintenance requirement. 17

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