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Basic Fluid ManagementBasic Fluid Management…with references to the Harriet …with references to the Harriet
LaneLane (because you have it with you)(because you have it with you)
Julie Story Byerley, MD, MPHJulie Story Byerley, MD, MPH
Why does fluid management Why does fluid management matter?matter?
It’s basic pediatrics.It’s basic pediatrics. Pediatricians are supposed to be the Pediatricians are supposed to be the
experts of fluid management.experts of fluid management. It matters to just about every inpatient.It matters to just about every inpatient. Fluid is often extremely effective therapy.Fluid is often extremely effective therapy. Incorrect fluid management can seriously Incorrect fluid management can seriously
hurt patients.hurt patients. It’s not always as simple as you might It’s not always as simple as you might
think – but you think – but you cancan make it simple. make it simple.
OutlineOutline
Maintenance requirementsMaintenance requirements Management of dehydrationManagement of dehydration
NormonatremicNormonatremic HyponatremicHyponatremic HypernatremicHypernatremic
A few little pearlsA few little pearls
Maintenance requirementsMaintenance requirementsChapter 10, Harriet Lane, p. 233Chapter 10, Harriet Lane, p. 233
The two functions of maintenance fluids includeThe two functions of maintenance fluids include Solute excretion in urine Solute excretion in urine Heat dissipation through insensible losses of Heat dissipation through insensible losses of
waterwater Insensible losses are about 2/3 skin and 1/3 lungsInsensible losses are about 2/3 skin and 1/3 lungs
Each can be considered as about 50% when Each can be considered as about 50% when maintenance needs are exactly met and urine maintenance needs are exactly met and urine concentration is 1.010concentration is 1.010
The kidneys are usually smart – insensible losses The kidneys are usually smart – insensible losses come first (less adjustable) and the kidneys can come first (less adjustable) and the kidneys can then adjust how much water is in the urinethen adjust how much water is in the urine
Maintenance RequirementsMaintenance Requirements
Caloric Expenditure MethodCaloric Expenditure Method Holliday-Segar MethodHolliday-Segar Method Body Surface Area MethodBody Surface Area Method
Remember that maintenance Remember that maintenance requirements are over about 24 requirements are over about 24 hours, and don’t have to be given hours, and don’t have to be given evenly divided over each hourevenly divided over each hour
Caloric Expenditure MethodCaloric Expenditure Method
Water and electrolyte needs parallel Water and electrolyte needs parallel caloric needscaloric needs
Caloric needs depend on activityCaloric needs depend on activity For each 100 For each 100 kcalskcals, ,
100-120 cc water, 100-120 cc water, 2-4 MEq Na, and 2-4 MEq Na, and 2-3 MEq K are needed2-3 MEq K are needed
Average Caloric NeedsAverage Caloric NeedsSee page 436 in Harriet Lane (table 20-1)See page 436 in Harriet Lane (table 20-1)
At normal activityAt normal activity Infants approx. 100 kcal/kg/dInfants approx. 100 kcal/kg/d 4-6yo approx. 90 kcal/kg/d4-6yo approx. 90 kcal/kg/d 7-10yo approx. 70 kcal/kg/d7-10yo approx. 70 kcal/kg/d Teens approx. 50 kcal/kg/dTeens approx. 50 kcal/kg/d
Caloric needs are based on resting energy expenditure and Caloric needs are based on resting energy expenditure and activity activity
Resting energy expenditure (REE) is based on sizeResting energy expenditure (REE) is based on size Energy needs increase with injury, fever, growth, etc.Energy needs increase with injury, fever, growth, etc.
See p. 435 in Harriet Lane See p. 435 in Harriet Lane REE (Resting Energy Expenditure) REE (Resting Energy Expenditure)
+ REE X (Mtn + Injury + Activity + Growth)+ REE X (Mtn + Injury + Activity + Growth) Don’t memorize it, just get the conceptDon’t memorize it, just get the concept
Example, Caloric Expenditure Example, Caloric Expenditure MethodMethod
10 yo boy with injuries and fever, 30kg10 yo boy with injuries and fever, 30kg = REE + REE x (Mtn + Activ + Fever + Inj + = REE + REE x (Mtn + Activ + Fever + Inj +
Growth)Growth) = 40 + 40 x(0.2 + 0.1 + 0.13 + 0.4 + 0.5)= 40 + 40 x(0.2 + 0.1 + 0.13 + 0.4 + 0.5) = 40 + 40 x(1.33)= 40 + 40 x(1.33) = 93 kcal/kg/d = 2790 kcal/d= 93 kcal/kg/d = 2790 kcal/d Therefore, he needs 2790 cc water per dayTherefore, he needs 2790 cc water per day
water needs parallel caloric needswater needs parallel caloric needs 3 MEq Na/(100 kcals) = 84 MEq Na total per day3 MEq Na/(100 kcals) = 84 MEq Na total per day 2 MEq K/(100 kcals) = 56 MEq K total per day2 MEq K/(100 kcals) = 56 MEq K total per day
The Math – what fluid?The Math – what fluid? D5 is standard D5 is standard 2790 cc of D5 has only 474 kcals 2790 cc of D5 has only 474 kcals
only 16 kcal/kg/d only 16 kcal/kg/d people are malnourished when they only people are malnourished when they only
receive IVF!receive IVF! 84 MEq Na/ 2790 cc = X / 1000; X = 3084 MEq Na/ 2790 cc = X / 1000; X = 30 Quarter NS = 38.5 MEq Na/LQuarter NS = 38.5 MEq Na/L 56 MEq K/ 2790 cc = Y / 1000; Y = 2056 MEq K/ 2790 cc = Y / 1000; Y = 20 Try D5 quarter NS with 20 KCl at 116 cc/hourTry D5 quarter NS with 20 KCl at 116 cc/hour More fluid than using the 4:2:1 rule (70cc/h); More fluid than using the 4:2:1 rule (70cc/h);
necessary because of injuries and fever necessary because of injuries and fever
Holliday-Segar MethodHolliday-Segar Method
Estimates caloric and fluid needs from Estimates caloric and fluid needs from weight aloneweight alone
Can over-estimate fluid needs for Can over-estimate fluid needs for infants and under-estimate fluid infants and under-estimate fluid needs in fever and injuryneeds in fever and injury
Method we tend to use most Method we tend to use most commonlycommonly
4,2,1 rule4,2,1 rule
Holliday-Segar MethodHolliday-Segar Method
WeightWeight cc/kg/dcc/kg/d cc/kg/hcc/kg/h
First 10 kg First 10 kg 100100 44
Second 10 kgSecond 10 kg 5050 22
Each Each additional kgadditional kg
2020 11
Ex: 25 kgEx: 25 kg 1600 cc/d 1600 cc/d (1000+500+100)(1000+500+100)
65 cc/h 65 cc/h
Holliday-Segar MethodHolliday-Segar Method
Electrolyte RequirementsElectrolyte Requirements Na – 3 MEq per 100 cc waterNa – 3 MEq per 100 cc water K - 2 MEq per 100 cc waterK - 2 MEq per 100 cc water
Example, 25 kg kid, 1600 cc/dExample, 25 kg kid, 1600 cc/d 48 Meq Na, 32 Meq K48 Meq Na, 32 Meq K 48/1600 = X/1000; X = 30 48/1600 = X/1000; X = 30 (Remember that quarter NS has 38.5 MEq/L Na)(Remember that quarter NS has 38.5 MEq/L Na) 32/1600 = Y/ 1000; Y= 2032/1600 = Y/ 1000; Y= 20 D5 quarter NS with 20 MEq/L KCl (as Cl is your anion to D5 quarter NS with 20 MEq/L KCl (as Cl is your anion to
fill with)fill with)
SodiumSodium Since the ratio of electrolytes needed to amount Since the ratio of electrolytes needed to amount
of water does not change, the Na concentration of water does not change, the Na concentration in MIVF does not need to change based on in MIVF does not need to change based on weightweight
Often people use D5 ¼ NS for small babies and Often people use D5 ¼ NS for small babies and D5 D5 11//22 NS for bigger kids and adults NS for bigger kids and adults This can give adults more sodium than neededThis can give adults more sodium than needed This error is based on the fact that fluid needs This error is based on the fact that fluid needs
decrease as size increasesdecrease as size increases Na should be calculated based on kcals, (therefore cc’s Na should be calculated based on kcals, (therefore cc’s
not kg) not kg) We decrease water needs as weight increases (the 4,2,1 We decrease water needs as weight increases (the 4,2,1
rule), but we tend to calculate Na needs as 3 MEq per kg rule), but we tend to calculate Na needs as 3 MEq per kg per day. Na needs are not linear. They should decrease per day. Na needs are not linear. They should decrease like water needs do.like water needs do.
Many argue that D5 ¼ NS with 20 K is an Many argue that D5 ¼ NS with 20 K is an appropriate maintenance fluid for all people.appropriate maintenance fluid for all people.
Body Surface Area MethodBody Surface Area Method
Method not used as frequently, but Method not used as frequently, but often taught in nephrologyoften taught in nephrology
More difficult to use with small More difficult to use with small childrenchildren
To calculate the BSA you need to To calculate the BSA you need to know heightknow height
Maintenance requirements are about Maintenance requirements are about 1500 ml/m2/day1500 ml/m2/day
DehydrationDehydration
BackgroundBackground
Dehydration complicates many Dehydration complicates many acute illnessesacute illnesses
Accurate assessment is importantAccurate assessment is important Consequences of under-Consequences of under-
estimationestimation Consequences of over-estimationConsequences of over-estimation Practice guidelines for evaluation Practice guidelines for evaluation
and managementand management
DehydrationDehydration
Initial resuscitation Initial resuscitation Determining deficitDetermining deficit Adding in maintenanceAdding in maintenance Ongoing losses (don’t forget!)Ongoing losses (don’t forget!)
Estimating degree of Estimating degree of dehydration…traditional dehydration…traditional
teachingteaching Recent weight changesRecent weight changes Physical exam findingsPhysical exam findings
Dehydration Mild (5%) Moderate (10%) Severe (15%) Turgor Normal Tenting None Cap refill Brisk (< 2 sec) 2-4 sec >4 sec Mucus membranes Moist Dry Parched/cracked Eyes Normal Deep set Sunken Tears Present Reduced None Fontenelle Flat Sunken CNS Consolable Irritable Lethargic/obtunded Pulse Regular Slight increase Increase Urine output Normal Decreased Anuric
Caveats…traditional Caveats…traditional teachingteaching
The previous chart applies to babies. For The previous chart applies to babies. For adults it should be scaled back to 3%, 6%, adults it should be scaled back to 3%, 6%, and 9%.and 9%. Older kids show symptoms at a lower % Older kids show symptoms at a lower %
dehydrationdehydration Hyponatremic dehydration looks worse Hyponatremic dehydration looks worse
clinically – exaggerated hemodynamic clinically – exaggerated hemodynamic instabilityinstability
Hypernatremic dehydration looks better Hypernatremic dehydration looks better clinically – circulation maintained at the clinically – circulation maintained at the expense of expense of intracellular volumeintracellular volume
Systematic Review of the Systematic Review of the Published Data on History, Published Data on History,
PE, and Labs in PE, and Labs in DehydrationDehydration
Mike Steiner, Darren DeWalt, Julie Mike Steiner, Darren DeWalt, Julie Byerley, 2002-3Byerley, 2002-3
Historical FactorsHistorical Factors
Previous visit to PCP, or previous trial Previous visit to PCP, or previous trial of clears provided minimal but some of clears provided minimal but some increase in the likelihood of increase in the likelihood of dehydrationdehydration
Physical exam signs less helpful than Physical exam signs less helpful than previously taughtpreviously taught
Delayed Capillary RefillDelayed Capillary Refill
LimitationsLimitations::
Inter-rater agreement only slight to fairInter-rater agreement only slight to fair Kappa 0.01-0.35Kappa 0.01-0.35
Site of application, lighting and ambient Site of application, lighting and ambient temperaturetemperature
Sensitivity Specificity LR Positive LR Negative
0.60 (0.30-0.91)
0.85 (0.72-0.98)
4.1(1.7-9.8)
0.6(0.4-0.8)
Abnormal Skin TurgorAbnormal Skin Turgor
LimitationsLimitations:: Inter-rater agreement fair to moderateInter-rater agreement fair to moderate
Kappa 0.36-0.55Kappa 0.36-0.55 Hypernatremia increases false negativesHypernatremia increases false negatives
Sensitivity Specificity LR Positive LR Negative
0.58(0.40-0.75)
0.76(0.59-0.93)
2.5(1.5-4.2)
0.7(0.6-0.8)
Abnormal RespirationsAbnormal Respirations
LimitationsLimitations:: Inter-rater agreement of only chance to fairInter-rater agreement of only chance to fair
Kappa –0.04 to 0.40Kappa –0.04 to 0.40 Varying measurements and definitionsVarying measurements and definitions
Sensitivity Specificity LR Positive LR Negative
0.43(0.3-0.6)
0.79(0.7-0.9)
2.0(1.5-2.7)
0.7(0.6-0.9)
Less Useful SignsLess Useful SignsSign Comment
Sunken Eyes Pooled LR of 1.7Dry MM Pooled LR of 1.7Weak Pulse LR ranged from not significant to 3.1
sensitivity low (0.04-0.25), specificity high (0.89 to 1)
Cool Extremity LR ranged from not significant to 18.8
Absent tears Pooled LR CI crosses 1.0
Abnormal overall appearance
Pooled LR CI crosses 1.0
Tachycardia Pooled LR CI crosses 1.0
Weak Cry CI for LR crosses 1.0.
Sunken fontanelle LR actually below one, CI crosses 1.0
Combinations of SignsCombinations of Signs
Vega evaluated the standard dehydration Vega evaluated the standard dehydration table table ‘‘Severe’ classificationSevere’ classification
LR 3.4 for 5% dehydrationLR 3.4 for 5% dehydration ‘‘Mild or ‘Moderate’ classificationMild or ‘Moderate’ classification
No increase in likelihood of dehydrationNo increase in likelihood of dehydration
Gorelick found an LR of 4.9 when 3/10 Gorelick found an LR of 4.9 when 3/10 signs of dehydration presentsigns of dehydration present
Results: Laboratory TestsResults: Laboratory Tests
BUNBUN Study of hospitalized patients with gastroenteritisStudy of hospitalized patients with gastroenteritis
BUN >45, specificity: 1.00, LR positive of 46.1BUN >45, specificity: 1.00, LR positive of 46.1 BUN cutoffs of 8, 18, and 27 yielded mixed results in BUN cutoffs of 8, 18, and 27 yielded mixed results in
four other studiesfour other studies AcidosisAcidosis
One study found no statistical increase in likelihoodOne study found no statistical increase in likelihood Four studies found significant positive LRs between Four studies found significant positive LRs between
1.5 and 3.51.5 and 3.5
DiscussionDiscussion
Poor to moderate inter-observer agreement Poor to moderate inter-observer agreement History and parental report have limited History and parental report have limited
valuevalue Best individual testsBest individual tests
Prolonged capillary refillProlonged capillary refill Abnormal skin turgorAbnormal skin turgor Abnormal respirationsAbnormal respirations
Groups of positive signs are helpful Groups of positive signs are helpful Extremely abnormal lab tests are helpfulExtremely abnormal lab tests are helpful
ImplicationsImplications
Focus on symptoms and signs with Focus on symptoms and signs with proven utilityproven utility
Ability to estimate exact degree of Ability to estimate exact degree of dehydration is limiteddehydration is limited
Support change to ‘none, some, or Support change to ‘none, some, or severe’ classification scheme severe’ classification scheme
Oral RehydrationOral Rehydration
Recommended by the AAP, WHO, Recommended by the AAP, WHO, and CDCand CDC
Appropriate for mild-moderate Appropriate for mild-moderate (some) dehydration(some) dehydration
Goal is 50-100 cc/kg over 4 hours for Goal is 50-100 cc/kg over 4 hours for mild-moderate dehydrationmild-moderate dehydration
5 cc every 1-2 minutes5 cc every 1-2 minutes Solution containing 40-60 MEq/L NaSolution containing 40-60 MEq/L Na
The Fluid Used MattersThe Fluid Used Matters
Solution CHO (g/dL) Na (mEq/L) K (mEq/L) mOsmPedialyte 2.5 45 20 250Rehydralyte 2.5 75 (1/2/NS) 20 310WHO 2 90 20 310Gatorade 5.9 21 2.5 377Apple juice 12 0.4 26 700Gingerale 9 3.5 .1 565Coke 11 4 .1 656
Fluid Management in ShockFluid Management in Shock
Initial boluses of 20 cc/kg over 30 minInitial boluses of 20 cc/kg over 30 min 20 cc/kg is 2% of body weight – therefore it 20 cc/kg is 2% of body weight – therefore it
should take a 10% dehydrated baby to only 8% should take a 10% dehydrated baby to only 8% drydry
One bolus is One bolus is not enoughnot enough when someone is 15% when someone is 15% dry dry
Use isotonic solutions (NS, LR)Use isotonic solutions (NS, LR) Consider blood, other fluids and/or pressors Consider blood, other fluids and/or pressors
in special circumstancesin special circumstances Trauma or blood lossTrauma or blood loss Nephrotic syndromeNephrotic syndrome Septic and cardiogenic shockSeptic and cardiogenic shock
Fluid CompositionFluid Composition
FluidFluid CHO CHO g/100cg/100ccc
Cal/LCal/L NaNa KK ClCl CO3CO3 CaCa
D5WD5W 55 170170
NS NS (0.9% (0.9% NaCl)NaCl)
154154 154154
LRLR 0-100-10 0-0-340340
130130 44 109109 2828 33
RehydrationRehydration
First resuscitate out of shock – restore First resuscitate out of shock – restore perfusionperfusion
Calculate maintenance, including ongoing Calculate maintenance, including ongoing losses, and deficitlosses, and deficit
Run maintenance as usualRun maintenance as usual Replace ongoing lossesReplace ongoing losses Typical is to replace deficit over 24 hoursTypical is to replace deficit over 24 hours
Half in first 8 hours Half in first 8 hours Other half over 16 hoursOther half over 16 hours
Where the dehydration comes Where the dehydration comes from…traditional teachingfrom…traditional teaching
In a brief duration of illness (<3 days), In a brief duration of illness (<3 days), 80% of the deficit is typically from the ECF80% of the deficit is typically from the ECF
More than 3 days of illness and the deficit More than 3 days of illness and the deficit from the ICF increases to about 40% from the ICF increases to about 40% (therefore 60% from ECF)(therefore 60% from ECF)
This matters because ECF contains a lot of This matters because ECF contains a lot of sodium (135-145 mEq), and intracellular sodium (135-145 mEq), and intracellular fluid contains a lot of potassium (150MEq)fluid contains a lot of potassium (150MEq)
But remember…“No walls, no sparks”But remember…“No walls, no sparks”
Example Calculations, Example Calculations, normal normal NaNa
(See table 10-7 in Harriet Lane on page 237.) (See table 10-7 in Harriet Lane on page 237.) 7 kg infant with 10% dehydration that accumulated over >3d.7 kg infant with 10% dehydration that accumulated over >3d.24 Hours24 Hours H2OH2O NaNa KKMaintenance Maintenance (Hol.-Seg.)(Hol.-Seg.)
700700 2121 1414
Deficit Deficit
(10% of 7 kg)(10% of 7 kg)700700
ECF ECF (60%)(60%)
420420
6161(145MEq/L (145MEq/L x 0.42L)x 0.42L)
ICF (40%)ICF (40%)
2802804242(150MEq/L (150MEq/L x 0.28L)x 0.28L)
TotalTotal 1400c1400ccc
82ME82MEqq
56MEq56MEq
First 8 hoursFirst 8 hours
MIVF for 8 hours plus 50% of the deficitMIVF for 8 hours plus 50% of the deficit
583/8=73 cc/h; 38/0.583=65MEqNa/L = 583/8=73 cc/h; 38/0.583=65MEqNa/L = 0.42NS (65/154); 26/0.583=45MEqK/L 0.42NS (65/154); 26/0.583=45MEqK/L
Roughly D5halfNS plus 40 KCl at 75 cc/hRoughly D5halfNS plus 40 KCl at 75 cc/h
H2OH2O NaNa KK11//3 3 MaintMaint 233233 77 55
½ Deficit½ Deficit 350350 3131 2121
TotalTotal 583583 3838 2626
Next 16 hoursNext 16 hours
MIVF for 16 hours plus other 50% of the MIVF for 16 hours plus other 50% of the deficitdeficit
817/16=51 cc/h; 44/0.817=54MEqNa/L = 817/16=51 cc/h; 44/0.817=54MEqNa/L = 0.35NS (54/154); 30/0.817=37MEqK/L 0.35NS (54/154); 30/0.817=37MEqK/L
Roughly D5halfNS plus 40 KCl at 50 cc/hRoughly D5halfNS plus 40 KCl at 50 cc/h
H2OH2O NaNa KK22//3 3 MaintMaint 467467 1414 99
½ Deficit½ Deficit 350350 3030 2121
TotalTotal 817817 4444 3030
Simplified – what fluid, normal Simplified – what fluid, normal Na (Roberts’ method)Na (Roberts’ method)
Usually after boluses with NS or LR, Usually after boluses with NS or LR, D5halfNS is an appropriate rehydration fluidD5halfNS is an appropriate rehydration fluid
After urine output is assured, give K as 20 After urine output is assured, give K as 20 MEq/L MEq/L That is usually safeThat is usually safe Often you don’t need to fully replete K losses Often you don’t need to fully replete K losses
acutelyacutely Watch the rate of fluids regarding K and don’t Watch the rate of fluids regarding K and don’t
give more than 1 MEq/kg/hgive more than 1 MEq/kg/h
Simplified – what rateSimplified – what rate (Roberts’ method) (Roberts’ method)
If a child is 10% dehydrated - If a child is 10% dehydrated - Give a 20 cc/kg bolus of NS Give a 20 cc/kg bolus of NS
Restores hydration 2%Restores hydration 2% Next give 10 cc/kg/h of D5halfNS with 20 Next give 10 cc/kg/h of D5halfNS with 20
KCl for 8 hoursKCl for 8 hours Restores hydration 8%Restores hydration 8%
Next give 1.5 times MIVF using Next give 1.5 times MIVF using D5quarterNS with 20KCL for 16 hoursD5quarterNS with 20KCL for 16 hours That day’s maintenanceThat day’s maintenance
Example, the Robert’s Example, the Robert’s methodmethod
7kg child with 10% dehydration7kg child with 10% dehydration Bolus of 140 cc NSBolus of 140 cc NS 70 cc/h of D5halfNS with 20 KCL for 8 70 cc/h of D5halfNS with 20 KCL for 8
hours, thenhours, then 40 cc/h of D5quarterNS with 20 KCL 40 cc/h of D5quarterNS with 20 KCL
for 16 hoursfor 16 hours
HyponatremiaHyponatremia
Always measure the sodium.Always measure the sodium.
Hyponatremic patients look more Hyponatremic patients look more dehydrated than they probably dehydrated than they probably
are.are.
Example calculation, Example calculation, hyponatremia hyponatremia (7kg with 10% (7kg with 10% dehydration, Na 115, >3 d duration)dehydration, Na 115, >3 d duration)
Table 10-8 on p. 238Table 10-8 on p. 238 Fluid deficit – same as beforeFluid deficit – same as before
10% of 7 kg=700 ml 10% of 7 kg=700 ml totaltotal fluid deficit fluid deficit 60% from ECF, 40% from ICF 60% from ECF, 40% from ICF
Na deficit (from dehydration) – same as beforeNa deficit (from dehydration) – same as before ECF Na x 60% of total fluid deficitECF Na x 60% of total fluid deficit 145 mEq/L x .6 x .7L = 61mE145 mEq/L x .6 x .7L = 61mE
ExcessExcess Na deficit (because hyponatremic)Na deficit (because hyponatremic) (Desired Na – Actual Na) x distribution factor x wt(Desired Na – Actual Na) x distribution factor x wt (CD-CA) x fD x weight(CD-CA) x fD x weight (135-115)MEq/L x (135-115)MEq/L x 0.6L/kg0.6L/kg x 7kg = 84 mEq Na x 7kg = 84 mEq Na Replace excess Na deficit over 24 hoursReplace excess Na deficit over 24 hours Replace Na faster if symptomaticReplace Na faster if symptomatic
K deficit (same as before)K deficit (same as before) ICF K x 40% of total fluid deficitICF K x 40% of total fluid deficit 150mEq/L x 0.4 x 0.7L=42 mEq150mEq/L x 0.4 x 0.7L=42 mEq
Make a table!Make a table!
Component H2O (mL)
Na (mEq)
K (mEq)
Mainenance Na=3mEq/100ml K=2mEq/100ml
700 21 14
Deficit 700 60% ECF x 700
= 420 61
40% ICF x 700 = 280
42
Excess Na deficit
(135-115) x .6 x 7kg
84
24 hour totals
1400 166 56
First 8 hours, hyponatremiaFirst 8 hours, hyponatremia
MIVF for 8 hours plus 50% of the deficitMIVF for 8 hours plus 50% of the deficit
583/8=73 cc/h; 80/0.583=137MEqNa/L = 583/8=73 cc/h; 80/0.583=137MEqNa/L = 0.89NS (137/154); 26/0.583=45MEqK/L 0.89NS (137/154); 26/0.583=45MEqK/L
Roughly D5halfNS plus 40 KCl at 75 cc/hRoughly D5halfNS plus 40 KCl at 75 cc/h
H2OH2O NaNa KK11//3 3 MaintMaint 233233 77 55
½ Deficit½ Deficit 350350 7272 2121
TotalTotal 583583 8080 2626
Next 16 hours, Next 16 hours, hyponatremiahyponatremia
MIVF for 16 hours plus other 50% of the MIVF for 16 hours plus other 50% of the deficitdeficit
817/16=51 cc/h; 86/0.817=105MEqNa/L = 817/16=51 cc/h; 86/0.817=105MEqNa/L = 0.68NS (105/154); 30/0.817=37MEqK/L 0.68NS (105/154); 30/0.817=37MEqK/L
Roughly D5halfNS plus 40 KCl at 50 cc/hRoughly D5halfNS plus 40 KCl at 50 cc/h
H2OH2O NaNa KK22//3 3 MaintMaint 467467 1414 99
½ Deficit½ Deficit 350350 7272 2121
TotalTotal 817817 8686 3030
Practical Interpretation, Practical Interpretation, HyponatremiaHyponatremia
In adults, rapid correction of hyponatremia In adults, rapid correction of hyponatremia may be associated with central pontine may be associated with central pontine myelinoysis. myelinoysis.
Correct the Na fast only if the patient is Correct the Na fast only if the patient is symptomatic (seizing or particularly irritable) symptomatic (seizing or particularly irritable)
For asymptomatic patients, the goal should be For asymptomatic patients, the goal should be to increase the Na no faster than 1 MEq/L per to increase the Na no faster than 1 MEq/L per hourhour
Start with NS boluses and then D5NS or Start with NS boluses and then D5NS or D5halfNSD5halfNS
Follow Na carefullyFollow Na carefully
HypernatremiaHypernatremia
Always measure the sodiumAlways measure the sodium
HypernatremiaHypernatremia
In hypernatremia, rehydrate more slowly to avoid In hypernatremia, rehydrate more slowly to avoid fluid shifts that could cause cerebral edema or fluid shifts that could cause cerebral edema or intracranial bleedingintracranial bleeding
Remember that the hypernatremic patient Remember that the hypernatremic patient doesn’t always look as dry as they are because doesn’t always look as dry as they are because the intravascular volume is protectedthe intravascular volume is protected
The hypernatremic dehydrated patient is still The hypernatremic dehydrated patient is still sodium depleted, but in addition has lost free sodium depleted, but in addition has lost free waterwater
Free water losses must be calculated and Free water losses must be calculated and subtracted from total deficit to calculate the subtracted from total deficit to calculate the solute deficitsolute deficit
Example calculation, Example calculation, hypernatremia hypernatremia (7kg with 10% (7kg with 10% dehydration, Na 155, >3 d duration)dehydration, Na 155, >3 d duration)
Table 10-9 on p. 239Table 10-9 on p. 239 Same fluid deficit, maintenance fluid and electrolytes as before, in Same fluid deficit, maintenance fluid and electrolytes as before, in
isotonic dehydration exampleisotonic dehydration example FW deficitFW deficit
=(measured Na – ideal Na)x 4cc/kg x wt=(measured Na – ideal Na)x 4cc/kg x wt FW def = (155-145) x 4 x 7 = 280 ccFW def = (155-145) x 4 x 7 = 280 cc Replace free water deficit evenly over 48 hReplace free water deficit evenly over 48 h
Give only half of FW deficit in first dayGive only half of FW deficit in first day Drop Na less than 15 MEq/L/dayDrop Na less than 15 MEq/L/day Follow lytes closely – every 4 hours at firstFollow lytes closely – every 4 hours at first Subtract the free water deficit from the total Subtract the free water deficit from the total
deficit to determine Na deficitdeficit to determine Na deficit
Chart for Hypernatremia, first Chart for Hypernatremia, first 24 h24 h
H2OH2O NaNa KK
MIVFMIVF 700700 2121 1414
Free water Free water deficit = deficit = 280cc/2 days280cc/2 days
140140
Def remaining Def remaining (solute) (solute) =420cc=420cc
(700-(700-280=420)280=420)
ECF (60%)ECF (60%)
ICF (40%)ICF (40%)
252252
1681683737
2525
Total, 24 hrTotal, 24 hr 12601260 5858 3939
Fluid choice, HypernatremiaFluid choice, Hypernatremia
Need in 24 hours, Need in 24 hours, 1260 cc water1260 cc water 58 Meq Na 58 Meq Na 39 MEq K 39 MEq K
1260/24 = 52.5 cc/h 1260/24 = 52.5 cc/h 58/1.260 = 46 MEqNa/L = 0.3 NS (46/154)58/1.260 = 46 MEqNa/L = 0.3 NS (46/154) 39/1.260 = 31MEqK/L 39/1.260 = 31MEqK/L Roughly D5halfNS with 30KCl at 50 cc/h – Roughly D5halfNS with 30KCl at 50 cc/h –
could also use D5quarterNS – half is more could also use D5quarterNS – half is more conservativeconservative
Practical Interpretation, Practical Interpretation, HypernatremiaHypernatremia
Still bolus the hypernatremic patient with Still bolus the hypernatremic patient with NS if neededNS if needed
You want to lower the Na slowly so you You want to lower the Na slowly so you can start with D5halfNS and remeasurecan start with D5halfNS and remeasure
The calculations almost always come out The calculations almost always come out to something near quarter NS, and you to something near quarter NS, and you should not give more dilute fluid than that, should not give more dilute fluid than that, so that is also a reasonable starting pointso that is also a reasonable starting point
The important thing is to follow the sodium The important thing is to follow the sodium carefully and adjust as necessarycarefully and adjust as necessary
Practical Approach, Practical Approach, Replacing the DeficitReplacing the Deficit
Isotonic dehydrationIsotonic dehydration 1/2 NS1/2 NS
Hyponatremic dehydrationHyponatremic dehydration 3/4 or NS3/4 or NS
Hypernatrmic dehydrationHypernatrmic dehydration 1/4 NS1/4 NS
Follow I/O’s, weights, lytes carefully – Follow I/O’s, weights, lytes carefully – q 4 hours, you can follow on VBGsq 4 hours, you can follow on VBGs
Even Easier…Run Even Easier…Run Maintenance and Deficit Maintenance and Deficit
SeparatelySeparately Maintenance (calculate using Holliday-Segar) Maintenance (calculate using Holliday-Segar) Y in Deficit Y in Deficit Ongoing losses (calculate by shift or Ongoing losses (calculate by shift or
anticipate)anticipate)
Use the same calculations as above to Use the same calculations as above to calculate the deficit, but hang different fluidscalculate the deficit, but hang different fluids
Generally easier to manage than having Generally easier to manage than having unusual fluids mixed by pharmacy unusual fluids mixed by pharmacy
Ongoing lossesOngoing losses
Don’t forget losses into third Don’t forget losses into third spacesspaces
Pay attention to In-Out sheetsPay attention to In-Out sheets Replace shift to shift if output is Replace shift to shift if output is
largelarge Check electrolytes on output prnCheck electrolytes on output prn
Ongoing losses!Ongoing losses!
Usually replace GI losses with half normalUsually replace GI losses with half normal Radiant losses are usually just waterRadiant losses are usually just water
See table 10-11, p.240, for other specific See table 10-11, p.240, for other specific situationssituations
Fluid Na K ClGastric 20-80 5-20 100-150Illeostomy 45-135 3-15 20-115Diarrhea 10-90 10-80 10-110Burns 140 5 110
Special situationsSpecial situations
Symptomatic hyponatremia (sz’s)Symptomatic hyponatremia (sz’s) 10-12mL/kg of 3% saline over 60 10-12mL/kg of 3% saline over 60
minutesminutes Increased insensible lossesIncreased insensible losses When the kidneys are not smarter When the kidneys are not smarter
than you!than you! Electrolyte abnormalitiesElectrolyte abnormalities
THE ENDTHE END
Other Equations, Anion GapOther Equations, Anion Gap
Anion gap = Na – (Cl + HCO3)Anion gap = Na – (Cl + HCO3) Normal gap 12 +/- 4Normal gap 12 +/- 4 AG increased in acid production or AG increased in acid production or
decreased acid excretiondecreased acid excretion Ketones, lactic acidosis, inborn errors of Ketones, lactic acidosis, inborn errors of
metabolismmetabolism Renal failureRenal failure
AG normal in hyperchloremic acidosisAG normal in hyperchloremic acidosis GI loss of bicarbGI loss of bicarb Renal loss of bicarbRenal loss of bicarb
Other Equations, OsmolalityOther Equations, Osmolality
Osmolality is number of particles per Osmolality is number of particles per literliter
Approximated by:Approximated by: 2(Na) + (glu/18) + (BUN/2.8)2(Na) + (glu/18) + (BUN/2.8) Where glucose and BUN are in mg/dlWhere glucose and BUN are in mg/dl Normal is 285-295Normal is 285-295
A Pearl about Blood A Pearl about Blood TransfusionTransfusion
See p. 319 in Harriet Lane (table 15.7)See p. 319 in Harriet Lane (table 15.7) Vol PRBC needed to transfuse = Vol PRBC needed to transfuse =
EBV (cc) multiplied by (desired EBV (cc) multiplied by (desired HCT – actual HCT)/ HCT of PRBCsHCT – actual HCT)/ HCT of PRBCs
Ex: Transfuse a 6 mo old with HCT 20% Ex: Transfuse a 6 mo old with HCT 20% with 87.5 cc to get their HCT to 30%with 87.5 cc to get their HCT to 30%
cc PRBC = 75cc/kg(7kg)(.10)/0.60cc PRBC = 75cc/kg(7kg)(.10)/0.60