elspeth ferguson st4 paediatrics september 2011 fluid & electrolyte balance
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Elspeth FergusonST4 PaediatricsSeptember 2011
Fluid & Electrolyte balance
Learning objectives
Maintenance fluid requirementsDeficit & Supplemental fluid requirementsGrades of dehydrationTypes of dehydrationFluid & Electrolyte management Scenarios
How are children different?
15 % turnover of body fluids (adults 5%)
Limited access to fluidsEasier to give inappropriate fluids
Maintenance requirements
Based on calorie requirements and fluid losses from the body
Insensible losses 1/5th
Essential urine output 1/5th
Normal urine output 3/5th
Maintenance requirements (Child)
Body Body weight weight (kg)(kg)
FluidFluid
(ml/kg/d)(ml/kg/d)NaNa
(mmol/kg/(mmol/kg/d)d)
KK
(mmol/kg/(mmol/kg/d)d)
ProteinProtein
(g/kg/d)(g/kg/d)EnergyEnergy
(kcal/kg/d)(kcal/kg/d)
<10 <10 100100 33 22 2.52.5 100100
10-2010-20 +50+50 +1.5+1.5 +1+1 +1.5+1.5 +75+75
>20>20 +20+20 +0.75+0.75 +0.4+0.4 +1+1 +30+30
Maintenance requirements (Neonates)
Day of lifeDay of life Fluid(ml/kg)Fluid(ml/kg) TypeType
11 6060 10% 10% dextrosdextrosee
22 9090 Na 3 mmol/kgNa 3 mmol/kg
K 2 mmol/kgK 2 mmol/kg
10% dextrose10% dextrose
+ additives+ additives33 120120
44 150150
55 180180
Deficit
Deficit = abnormal lossesAbnormal losses
vomitingdiarrheafevertachypneahot weatherDKA3rd space losses
% dehydration x 10 = ml/kg deficit
Supplemental
Supplemental = ongoing abnormal lossesComposition of body fluids (mmol/l)
Na K Cl Bicarb
diarrhoea 50 40 40 40gastric 50 15 150 40small bowel 130 15 110 30
Dehydration
HistoryAgeIntakeOutputSystemic illness
Pre-illness weight comparisonRehydrated wt estimate
= admission wt (kg) x 100100 - % dehydration
Grades of dehydration
1(symptoms) 1(symptoms) 5%5%
2(signs) 7%2(signs) 7% 3(shock) 10%3(shock) 10%
Clinical Clinical conditioncondition
Thirsty alert Thirsty alert restlessrestless
Lethargic Lethargic irritable drowsyirritable drowsy
Floppy Floppy comatosecomatose
PulsePulse NormalNormal FastFast FeebleFeeble
RespirationRespiration NormalNormal DeepDeep Deep & RapidDeep & Rapid
FontanelleFontanelle NormalNormal SunkenSunken Very sunkenVery sunken
Systolic BPSystolic BP NormalNormal Postural dropPostural drop LowLow
CRTCRT NormalNormal >2 seconds>2 seconds > 3 seconds> 3 seconds
EyesEyes NormalNormal SunkenSunken Very sunkenVery sunken
Mucous membMucous memb MoistMoist Dry Dry Very dryVery dry
Urine outputUrine output NormalNormal ConcentratedConcentrated AnuriaAnuria
Deficit (ml/kg)Deficit (ml/kg) 5050 7070 100 100
Types of dehydration
Hyponatremic (< 135 mmol/l)greater loss of Na relative to waterdeficit exaggerated by hypotonicityseizures may occur
Isonatremic (135-150 mmol/l)equal losses of Na and water
Hypernatremic (>150 mmol/l)difficult to estimate the degree of dehydrationcorrect over 48 hoursNa fall should be < 10 mmol/day
Types of fluids
FluidFluid NaNa
(mmol/(mmol/l)l)
KK
(mmol/l)(mmol/l)ClCl
(mmol/l)(mmol/l)CaloriesCalories
(kcal/l)(kcal/l)
0.9% Saline0.9% Saline 150150 00 150150 00
0.45% Saline 0.45% Saline
+ 5% dextrose+ 5% dextrose7575 00 7575 200200
10% dextrose10% dextrose 00 00 00 400400
0.45% Saline 0.45% Saline
+ 5% dextrose+ 5% dextrose
+ KCl+ KCl
7575 4040 7575 200200
Principles of fluid therapy
Fluids are drugs : Check calculations !Add K when U&Es are back ( 40 mmol/l)Rehydration usually corrects metabolic
acidosisMonitor U&Es closely
To admit or not?
> 5 % dehydrationPersistent vomitingNeed for IV therapyFailure of outpatient managementDiagnosis is not clear
Which route?
Oral when possibleDioralyteRehidrat
Nasogastric fluidsIV fluids
persistent vomitingsevere ongoing lossesShockOral therapy fails
Which fluid?
Use 0.9% saline as bolusUse 0.45% saline + 5 % dextrose for all types
of dehydration initiallyThen fluid composition is guided by U&Es
How much fluid?
Hourly rate =
Maintenance + Deficit + Ongoing losses24
Monitoring
IntakeOutputWeightCRTPulseBPConscious levelU&Es
Case 1
A previously healthy 11 month old infant isreferred to CAU with a 3 day history of diarrhoeaand vomiting with a poor urine output
She has sunken eyes, sunken fontanelle and drymucous membranes. The pulse is rapid and easilyfelt. She vomits all her feeds
Calculate her fluid requirements over the next24 hours
Case 2
A 10 year old girl has been brought by ambulancein a semi-comatose state. She is found to have anon-blanching rash over her trunk, neck stiffnessand an axillary temperature of 39.5°C. Hercapillary return time is 7 seconds and her systolicBP is 90 mm/HG.
How will you manage her fluids in the emergencysetting and subsequently?
Case 3
A 6 year old boy has been referred by his GP for being unwell and wetting his bed lately. His mothers says that he has been losingweight since he came back from Pakistan 4 weeks ago. His urine shows 4+ glucose and “large” ketones and a lab blood sugar is 32.
On examination he is found to be lethargic with a capillary return time of 5 seconds. He is afebrile with a dry mouth and a pulse of 120/min.Blood pressure is 110/70.
What is your diagnosis?How will you write up the fluids for this child?
Case 4
A 6 month old infant of a drug addict is brought to the Children’s Ward with a history of vomiting and excessive drowsiness. The Health Visitor accompanying the infant fears that the mother may have made up the feeds wrongly over the past few days.
The infant is found to have a sunken fontanelle and has not passed urine for a few hours. The S. Na+ is 165, S. K+ is 3.5, Urea is 8, Creatinine is 70.
How will you manage this infant?
Case 5
A 6 week old male infant who was born at 38 weeks gestation is referred by his GP on a Saturday for non bilious vomiting after most feeds for the last two weeks. His birth weight centile was the 10th but now is is less than the 3rd.
On examination he is alert and hungry. He looks thin and has a capillary return time of 4-5 seconds. Abdomen palpation reveals no abnormality but you notice that his nappy is wet.
The lab results area as follows:Na+ 132K+ 3.2C1- 96HCO3 32pH 7.45
How will you manage the fluid and electrolyte needs of this infant?
Case 6
A 5 day old baby who was a planned home birth is seen by theCommunity Midwife who feels that the baby’s genitalia are odd. The
baby isseen in the clinic and has an underdeveloped phallus and scrotum. No
testesare palpable in the scrotum.
The baby has a poor perfusion and weak cry. It is admitted from clinic.Dextrostix is 2.
The lab results are back urgently:S. Na+ 125S. K+ 7.5 (non-haemolysed sample)Blood sugar 1.8
How will you manage this neonate’s fluids?
Summary
Maintenance fluid requirementsDeficit & Supplemental fluid requirementsGrades of dehydrationTypes of dehydrationFluid & Electrolyte management Scenarios
Questions