FLUID AND ELECTROLYTE MANAGEMENT Houssam Fayad , MD

COMPOSITION OF BODY FLUIDS Water is the most plentiful component of human body Total body water (TBW): constitutes 50-75% of total body mass, depending on age, sex and fat content.

TBW -Fetus has a very high water content -TBW decreases to 75% in a full term neonate -During 1 year of life TBW content decreases to 60% and remains same until puberty.

FLUID COMPARTMENTS ICF 40% In newborn ECF>ICF By 1 year of age ratio of ICF to ECF approaches the adult level. INTERSTITIAL 15% ECF 20% PLASMA 5%

ELECTROLYTE COMPOSITION ECF ICF Na + CI - K + Phos - HCO3 - Prot - K + Prot - Na + Ca + HCO3 - Other Mg + Mg + Phos - CI -

OSMOLALITY ICF and ECF are in osmotic equilibrium Change in osmolality in one of the compartments leads to water shift through the cell membranes to normalize equilibrium Plasma osmolality: 285-295 mosm/kg Calculated based on formula: 2xNa+glucose/18+BUN/2.8

REGULATION OF OSMOLALITY

MAINTENANCE AND REPLACEMENT THERAPY Therapy of fluid and electrolyte disorders directed toward: Providing maintenance fluids and electrolyte requirements Replenishing prior losses Replace persistent abnormal losses

MAINTENANCE AND REPLACEMENT THERAPY Maintenance fluid requirement take into account: Normal insensible water losses skin and lungs: 35% Urine: 60% Stool 5% Assuming that patient is afebrile and relatively inactive

MAINTENANCE AND REPLACEMENT THERAPY Maintenance fluids are used when a child cannot be fed orally. Replacement therapy needed when patient has excessive ongoing losses from NG tube, ongoing diarrhea or vomiting or high urine output due to nephrogenic diabetes insipidus. Deficit therapy corrects dehydration or prior losses

COMPOSITION OF MAINTENANCE FLUIDS Water Glucose Sodium Potassium

GOALS OF MAINTENANCE FLUIDS Prevent dehydration Prevent electrolyte disorders Prevent starvation ketoacidosis Prevent protein degradation

MAINTENANCE WATER 1 ml of water needed for each calorie expended Body Weight (kg) Kcal/kg mL of Water/kg 3-10 100 11-20 1000 kcal + 50 Kcal/kg for each kg > 10 kg 1000 mL + 50 mL/ Kg for each kg > 10 kg > 20 1500 kcal + 20 Kg > 20 1500 mL + 20 mL/kg for each Kg > 20 kg

GLUCOSE IN MAINENANCE FLUIDS How much glucose is required in maintenance fluids? Why? What % glucose solution will cover this requirement?

GLUCOSE IN MAINENANCE FLUIDS 20% of patient’s true caloric requirements needed to prevent starvation ketosis and limit protein catabolism. Example: 10 kg baby will need 1000 kcal/day 20% ----200 kcal/day from glucose 1 g glucose provides 4 kcal X g glucose provides 200 kcal X =50 g 50 g glucose in 1000 ml=> 5% glucose

MAINTENANCE ELECTROLYTES SODIUM: 2-3 mEq/kg/24 hr or 3 meq/100cc POTASSIUM: 1-2 mEq/kg/24 hr or 2 meq/100cc

COMPOSITION OF IV SOLUTIONS FLUIDS SODIUM CONCENTRATIONS SODIUM CHLORIDE 0.9% NaCL 154 mEq ½ NS 77 mEq 1/3 NS 52 mEq ¼ NS 38 mEq

SELECTION OF SODIUM CONCENTRATION IN IV MAINTENANCE FLUIDS Based on Na requirement/kg/day 10 kg baby needs 1000 cc of fluids and 30 meq/L Na=> ¼ NS 20 kg baby needs 1500 cc of fluids Na requirements=3meq x 20 kg=60 meq 60 meq to be given in 1500 cc X meq to be given in 1000 cc=> and 40 meq/L Na=> ¼NS-1/3 NS 30 kg baby needs 1700 cc of fluids and 90 meq of Na to be given in this volume of fluids=> 53 meq/L=>1/3 NS-1/2 NS

CALCULATION OF KCL REQUIREMENTS IN IV FLUIDS Calculate maintenance water requirements Calculate KCL requirement/kg/day Adjust KCL per liter of fluids EXAMPLE: 25 kg child needs 1600 cc of maintenance water 25kgx1-2mEq/kg/24 hr=25-50 mEq/24hr of KCL 1600 cc of water contains 25-50 mEq of KCL 1000 cc of water contains X mEq of KCL X=15.63- 31.25 mEq=> 20 mEq

REMEMBER! Maintenance fluids do not provide adequate calories. Patient will lose 0.5-1% of weight each day. TPN should be started for children who can not be fed enterally for more than a few days Certain conditions increase or decrease maintenance requirements. Examples? For each 1 degree increase in temperature above 38-maintenance requirements are increased by 10%

REPLACEMENT FLUIDS Diarrhea is often associated with loss of potassium and bicarbonate leading to metabolic acidosis and hypokalemia. Concurrently, volume depletion leads to hypoperfusion and lactic acidosis.

ADJUSTING FLUID THERAPY IN DIARRHEA Average composition of diarrhea: Sodium: 55 meq/L Potassium: 25 meq/L Bicarbonate: 15 meq/L

APPROACH TO REPLACEMENT THERAPY GI losses can be measured Replace losses as they occur every 2-6 hours depending on the rate cc by cc Use appropriate solution close in composition to electrolytes being lost Child should receive appropriate maintenance therapy in addition to replacement therapy Daily BMP

LOSS OF GASTRIC FLUID Can occur via emesis or NG suction What electrolytes are lost with gastric fluids? Sodium 60 meq/L Chloride 90 meq/L Potassium 10 meq/L What metabolic disturbances it can cause? hypokalemia and metabolic alkalosis

THIRD SPACE LOSSES Occur after abdominal surgery Results in shift of fluid from intravascular space into interstitial space Isotonic loss- best replaced by NS or RL Cannot be quantitated Replacement is based on continuing assessment of intravascular volume status

DEHYDRATION-the most frequent reason for hospitalization INCREASE LOSSES DECREASED INTAKE Vomiting: AGE Pyloric stenosis Pyelonephritis Increased ICP Abdominal obstruction Appendicitis Pancreatitis, etc Diarrhea: Malabsorption milk-protein allergy, IBD DKA, DI, burns Gingivostomatitis Pharyngitis Fever Altered mental status Physical restriction Dependence on caregiver

CLINICAL SIGNS OF DEHYDRATION Symptom/Sign Mild Dehydration Moderate Dehydration Severe Dehydration Level of consciousness* Alert Lethargic Obtunded Capillary refill* 2 Seconds 2-4 Seconds Greater than 4 seconds, cool limbs Mucous membranes* Normal Dry Parched, cracked Tears* Decreased Absent Heart rate Slight increase Increased Very increased Respiratory rate Increased and hyperpnea Blood pressure Normal, but orthostasis Pulse Thready Faint or impalpable Skin turgor Slow Tenting Fontanel Depressed Sunken Eyes Very sunken Urine output Oliguria Oliguria/anuria

DEHYDRATION SCORING SYSTEM Decreased skin elasticity Capillary refill>2 sec Ill appeared(tired, somnolent, “washed out”) Absent tears Abnormal respirations Dry mucous membranes Sunken eyes Abnormal radial pulse Tachycardia Decreased urine output (parental report)

DEHYDRATION SCORING SYSTEM Score 0- no dehydration Score 1-2- mild Score 3-6-moderate Score 7-10- severe

LABORATORY FINDING IN DEHYDRATION-BMP Disproportionate increase of BUN with little or no change of Creatinine due to increase passive reabsorption of urea in proximal tubule due to appropriate conservation of Na and water

LABORATORY FINDINGS IN DEHYDRATION What changes in urinalysis may be present in dehydration? Elevation of spesific gravity Proteinuria 30-100 mg/dL Few WBC and RBC Hyaline and granular casts

APPROACH TO DEHYDRATION Acute intervention to restore intravascular volume and improve perfusion NS bolus 20 cc/hr over 20 min Deficit correction : Total amount of fluids includes maintenance and deficit fluid Bolus is subtracted from the total volume Half of total fluids given over the first 8 hr, reminder half-over the last 16 hr

ORAL DEHYDRATION THERAPY Best used in the absence of shock When poor perfusion is present isotonic fluid bolus can restore perfusion, then oral rehydration can proceed. Glucose is actively absorbed and Na is co-transported across gut mucosa optimal glucose transport at concentrations: glucose 2-2.5gm/L Na 45-90 mEq/L higher glucose concentration will exacerbate diarrhea and Na loss

ORAL REHYDRATION THERAPY Aim is to replace fluid deficit over 4-6 hours Calculate total volume to be given over 4 hours: MILD=50 cc/kg MODERATE=100 cc/kg Calculate 5 min. aliquot volume: Administer aliquot over 5 min period Increase volume as tolerated Maintenance: 100 mL of ORS/kg/24

ESTIMATED FLUID DEFICIT Severity Infants (weight <10 kg) Children (weight >10 kg) Mild dehydration 5% or 50 mL/kg 3% or 30 mL/kg Moderate dehydration 10% or 100 mL/kg 6% or 60 mL/kg Severe dehydration 15% or 150 mL/kg 9% or 90 mL/kg

EXAMPLE 7 y.o. boy is admitted with 2-day hx of vomiting and diarrhea. He is estimated to be 7% dehydrated and vomited all attempts at oral dehydration in ER. He was given 20 cc/kg of NS bolus prior to transfer to the floor. His weight is 23 kg

EXAMPLE Maintenance water: 1560 cc=>65 cc/hr Maintenance Na= 2-3 meq x 23 kg=46-69meq Maintenance K=1-2 meq x 23=23-46 meq Total fluid deficit=23kg x 0.07 x 1000cc/kg=1610 cc Previous replacement=23 kg x 20cc/kg=460cc Balance fluid deficit= 1610-460=1150cc=>1/2 is given over the first 8 hr=72 cc/hr; another ½ over the last 16 hr=36 cc/hr

QUESTIONS You are called to the ER to see a 4 month old baby boy for admission as he has been having nasal congestion and cough with decreases oral intake of one day duration. Wet diapers decreased in the past 24 hours. Vital signs as follow: HR of 160, RR of 50, O2 sat =95%, temp = 100.7, weight = 17 Ibs. Normal physical examination. What percentage of dehydration is he? How do you manage his fluids Bolus Maintenance fluids

QUESTIONS You are the resident in the pediatric floor and your fellow resident left you with an admission. The patient is a 5 year old male with sickle cell whom is being admitted as he has fever (Tmax 103F) x 2 days, vomiting x 2 days (1 to 2 episoded per day), pain all over and decreased po. Vital signs: pulse = 180, RR= 60, stable BP, O2 sat = 88% and. Weight = 44 Ibs. Physical examination shows crackles, dry mucous membranes, cap refill 3 sec and he is in obvious distress as he is crying in pain Percentage of dehydration Fluid management and type of fluid

QUESTIONS You are assessing a 4 year old female for diarrhea x 7 days, fever x 4 days with Tmax of 101F, decreased po intake and sleeping more than usual. Vital signs: T=102F, Pulse = 130, RR= 20, O2 sat =100%and BP = 60/50. Weight =35 Ib Physical examination pertinent for a girl that is lethargic but arousable to speech and touch, cap refil is 4 sec 1) What is the percentage of dehydration ? 2) What type of fluid are you going to use 3) What is your management for her fluids

QUESTIONS A one week old infant present to the ER with vomiting x 3 days, diarrhea x 3 days, not feeding well, decreased wet diapers x 2 days with no urine x 24 hours. Vital signs: Pulse = 180, RR= 80, Bp= 40/30, sat = 78% Weight = 7 Ibs Physical examination: lethargic, depressed anterior fontanelle, doghey skin, dry mucous memebranes and cap refil is 4 sec. What is the percentage of dehydration What type of fluid would you use for a bolus What is her fluid management?

QUESTIONS This is a one year old female presenting to the ER s/p tonsillectomy 3 days ago as she is in pain, not eating or drinking well and with a fever. Decrease wet diapers x 1 day. Vital signs P=100, RR=22, BP= xx, sat =100% Weight =24 Ibs Physical examination: she is irritable with examination but consolable, cries with tears, cap refill 2 sec, tonsillar bed with whitish tissue, rest of exam normal 1) Percent of dehydration 2) What type of fluids are you going to use 3) Would you give her a bolus? What about maintenace fluids.

QUESTIONS This is a 6 year old male with hx of asthma whom is presenting to the ER with c/o breathing fast, SOB, and wheezing x 1 day. Mother ran out of his medaications. Vital signs: P= 140, RR= 55, BP = xx, O2 sat = 85% Weight = 55 Ibs Physical examination pertinent for subcostal and intercostal retractions, expiratory wheezing and decrease air entry. Would you bolus him? If so with what? Type of fluids? Fluid management?