Download ppt - Basic Fluid Management …with references to the Harriet Lane (because you have it with you) Julie Story Byerley, MD, MPH

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


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


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


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


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





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





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





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