3928768 Fluids and Electrolytes

8/13/2019 3928768 Fluids and Electrolytes

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Fluids and Electrolytes

By

Chirag Jain



Objectives

Learn to calculate maintenance fluids

Learn maintenance electrolyte needs

Learn the signs and symptoms ofdehydration

Learn to calculate replacement fluids for

isonatremic/hyponatremic/hypernatremicdehydration

Oral Rehydration Therapy



“Just Start Maintenance”…

Maintenance fluid provide the water andelectrolytes equal to those lost simply forbeing alive and having a basal metabolic rate

Metabolism makes heat and solute that youneed to get rid of to maintain homeostasis – Insensible fluid loss – dissipates heat by evaporation

of water from skin and URT (50% of maintenance

needs) – Soluble waste is excreted in urine (50% of

maintenance needs)



Some Conversions

1 mL = 1 cc30 cc = 1 ounce



Calculating Maintenance Fluids

The Holliday-Segar Formula(Burn these numbers into your mind)

100-50-20

4-2-1




The Holliday-Segar Formula

Based on calorie expenditure

1 mL of water needed for each kcal usedWeight (kg) kcal/d or mL/d kcal/h or mL/h

0 to 10 kg 100/kg/d 4/kg/h

11 to 20 kg (1000) + 50/kg/d

For each kg > 10

(40) + 2/kg/h

For each kg >10

>20 kg (1,500) + 20/kg/d

For each kg > 20

(60) + 1/kg/h

For each kg > 20





Case #1

An 32 kg girl is admitted for elective surgery

and is NPO. She has normal renal

function, no diarrhea and no fever. Whatwould her maintenance fluids be?





First 10 kg 100 ml/kg/day x 10 = 1000 ml

Second 10 kg 50 ml/kg/day x 10 = 500 ml

Last 12 kg 20 ml/kg/day x 12 = 240 ml

________________________________________

Total 32 kg 1740 ml/dayor

72.5 ml/hr





First 10 kg 4 ml/hr x 10 = 40 mlSecond 10 kg 2 ml/hr x 10 = 20 ml

Last 12 kg 1 ml/hr x 12 = 12 ml

___________________________________

Total 32 kg 72 ml/hr



Maintenance Electrolytes

Electrolyte loss can all be considered

urinary

Sodium 3 mEq/100 ml

Potassium 2 mEq/100 ml

Chloride 2 mEq/100 ml



We all need some Sugar…

Glucose is added to:

– Prevent ketosis

– Limit protein catabolism

20% of caloric need made up of glucose is

sufficient to prevent severe catabolism

– 5 grams glucose for every 100 cal

– D5W (5% dextrose water) is an appropriate

base for electrolyte solutions



Putting it Together

Maintenance IVF will need: – Water

– Glucose

– Sodium – Potassium

– Chloride

Your choices:

– D5 0.2 NS with 20 mEq KCl/L (<18 month old) – D5 0.45 NS with 20 mEq KCl/L

(PEARL – Do not add KCl until after first void andpotassium level is known)



Dehydration

Any combination of abnl intake and/or abnl

losses can lead to dehydration

– Most common cause in pediatrics is diarrhea

Types of dehydration:

– Isonatremic

– Hyponatremic

– Hypernatremic



Taking the History

Vomiting

Diarrhea

Urine output (number of wet diapers)

Decreased po intake

Weight changes (acute)

Fever

Length of illness







Degree of Dehydration

Clinical Signs Mild Moderate Severe↓ in body weight 3-5% 6-10% 11-15%

Fontenelle/Skin

turgor/Eyes

Normal (+/-) ↓ ↓↓

Skin Color Normal Pale Grey

Mucus

Membranes

Normal to Dry Dry Parched

Cap Refill 2-3 seconds 3-4 seconds > 4 seconds

Heart Rate Normal ↑ ↑↑

Blood Pressure Normal Postural changes Hypotension

Urine Output Normal to slight ↓ Oliguria Severe oliguria or

anuria

Tears ↓ ↓↓ to absent Absent

Urine Spec Grav >1.020 ↑↑ ↑↑↑ or anuria



How dry are you?

Only with accurate weights can you beprecise – how often does that happen?

Level of dehydration can be estimated

using the H&P and labs



A Case of Dehydration

A 10 kg infant has had severe diarrhea for

the past 2 days, decreased formula intake,

a sunken fontenelle, no tears and oliguria.

How dehydrated is this infant?

What laboratory values do you want toobtain?

How do you want to manage this infant?



Management of Dehydration

Step 1 – Determine the presence anddegree of dehydration

Step 2 – Obtain appropriate laboratory

data (iso/hypo/hyper-natremia)Step 3 – Bolus 20 mL/kg of NS (isotonicand will stay in the intravascular space)

Step 4 – Determine patient’s needs fornext 24 to 48 hours

Maintenance + Deficit + On-going losses




This infant is ~10% dehydrated given the

history and PE findings

Na 140, K 3.7, Cl 107, HCO3 22

Bolus 20 mL/kg NS improved urine

output

Still refusing po intake and still stooling ata rate of 20 mL/hr

Now what?




PEARL 1000 mL (1L) = 1000 gm (1 kg)

Maintenance = 1000 mL (100 mL/kg/day)Deficit = 1000 mL (10% of a 10 kg infant)

1000 mL – 200 mL (bolus given) = 800 mL remains

to be given

On-going losses = 20 mL/hr 480 mL/day




For isonatremic and hyponatremic

dehydration

Give HALF of Maintenance and Deficit in first 8

hours and remainder over the next 16 hours

(Maintenance + Deficit) – Bolus = 1800 mL

Therefore: Run 900 mL over 8 hours at 112 mL/hrThen, 900 mL over 16 hours at 56 mL/hr



Hypernatremic Dehydration

Total body water losses in excess of

sodium losses

Hypernatremia must be corrected

SLOWLYHyperosmolality causes cells to shrink – especially

in the CNS

Correcting too quickly will cause fluid to be rapidlydrawn into brain cells

Cerebral edema is BAD




A Case

A 5 kg infant presents with a 5 day history ofviral syndrome with fever, vomiting and

diarrhea. Signs and symptoms reveal an

infant who is 10% dehydrated. Laboratory

data reveals a Na of 160.




Hypernatremic dehydration is corrected EVENLY

over 48 hours

Bolus 20 mL/kg to restore intravascular volume

Maintenance = 100 mL/kg x 5 kg = 500ml/day48 hours of maintenance = 1000 mL

Deficit = 0.5 kg = 500 mL500 mL – 100 mL (bolus given) = 400 mL remain to be given

Total fluids over a 48 hour period is 1400 mL or

29 mL/hr




Indications

– <10% dehydrated

– Following initial volume resuscitation

Contraindications

– >10% dehydrated/circulatory instability

– Severe vomiting

– Abdominal distention/ absent bowel sounds

– Severe hypo- or hypernatremia




Examples – Pedialyte, Infalyte, WHO

rehydration solution

Administration

– 25 mL/kg/hr of deficit over the first 6 hours

– Then 10 mL/kg/hr over the next 6 hours (if

needed)

– When repleted then maintenance volumescan be given



ANY QUESTIONS ??

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3928768 Fluids and Electrolytes