Fluid & Elyte

Case Discussion

Hooman N

IUMS

2013

Objectives

• Know maintenance water and electrolyte

requirements.

• Assess hydration status.

• Determine replacement fluids (oral and iv)

• Know how to approach to dyskalemia

Approach to Fluid Calculations

1. Maintenance: Determined by a ‘system’:

a. Caloric expenditure method

b. Holliday-Segar method

c. Surface area method

2. Deficit: Determined by acute weight

change or clinical estimate

3. Ongoing losses: Determined by measuring

GOAL OF MAINTANANCE FLUIDS

• Prevent dehydration

• Prevent electrolyte disorder

• Prevent ketoacidosis

• Prevent protein degradation

Maintenance Fluids

• Holliday-Segar Method

– Estimates caloric expenditure from weight, assuming that for each 100 calories metabolized, 100 ml H20 are required.

Body Weight Water

ml/kg/day ml/kg/hr

First 10 kg 100 4

Second 10 kg 50 2

Each additional kg 20 1

Example: 8 year-old weighing 25kg

• ml/kg/day

– 100 (for 1st 10 kg) x 10 kg = 1000 ml/day

– 50 (for 2nd 10 kg) x 10 kg = 500 ml/day

– 20 (per remaining kg) x 5 kg = 100 ml/day

1600 ml/day

A 6 kg child needs 600 ml/day, which equals 25 ml/hr

A 35 kg child needs 1800 ml/day,which equals 75 ml/hr

A 14 kg child needs 1200 ml fluids with:

Na 36 mEq (3 mEq/100 cal)

K 24 mEq (2 mEq/100 cal)

Cl 48 mEq (4 mEq/100 cal)

Examples

Maintenance Electrolytes

Electrolyte mEq/100 ml H2O

Na+ 3 (2-4)

K+ 2 (2-3)

Cl- 4

Modifications

Increase Decrease

Fever (12% for each oC Renal failure

above 37 oC ) Heart failure

High ambient temperature Inappropriate secretion

Diabetes mellitus of ADH

Diabetes insipidus High-humidity respiratory

Vigorous exercise therapy

Acute Renal Failure

Meticulous management of fluids and

electrolytes is required, including twice daily

weights, strict I/O’s and close laboratory

monitoring

Oligo-anuric patients should receive fluid

intake equal to their total output; output

must include insensible losses

Insensible losses should be replaced with

D5W (or D10W)

Assessing Hydration Status

• History

– Volume of liquid intake

– Frequency of wet diapers/urination

– Frequency/quantity of diarrhea

– Recent weight (if known)

• Labs

– BMP if admitting the patient

• Serum sodium

Deficit

Tenting

Normal

moderate

severe

Urine output

Vital Sign

Sign & Symptoms Mild Moderate Severe

Wt loss 3-5% 6-9% >10%

General condition Alert, Restless Thirsty, lethargic Cold,sweaty,limp

Pulse Normal rate,

volume

Rapid,weak Rapid,feeble

Respiration Nr Deep,rapid Deep,rapid

Ant.fontanelle Nr Sunken Very sunken

SBP Nr Nr/ low OH Low/ unrecordable

Skin turgor Nr Decreased Markedly decreased

Eyes Nr Sunken,dry Grossly sunken

Mucus membrane Moist Dry Very dry

Urine output Adequate Less,dark Oliguria, anuria

Capillary refill Nr <2 sec > 3 Sec

Estimated deficit 30-50ml/kg 60-90ml/kg 100ml/kg

%100)/( xPIWILPIW

% Dehydration

ECF and ICF Percentage of

Loss

% fluid of deficit % fluid of deficit

Duration of illness from ECF from ICF

<3 days 80 20

>3days 60 40

Na K Cl HCO3

Gastric juice 20-80 15 125 0

Small-intestinal juice 100-140 15 155 40

Diarrhea 10-90 40 40 40

Sweat normal 10-30 10 25 0

Sweat CF 50-130 15 75 0

Electrolytes in Body Fluids (mEq/L)

Normal saline 154 0 154 0

½ Saline 77 0 77 0

Ringer Lactate 130 4 109 28

Third-spaced fluid

– 18 -24 H: Sequestration of fluid

• Fluid is isotonic, Check urine output

Surgical trauma Type of surgery Fluid

replacement

Minimal Inguinal hernia

repair1-2

ml/kg/h

Moderate Ureteral implantation 4ml/kg/h

Severe Scoliosis, bowel

obstruction>6ml/kg/h

Oral vs. IV Replacement

• Oral rehydration therapy (ORT) is preferred for mild – moderate dehydration unless

– emesis is intractable

– stool losses > 10 cc/kg/hr

– consciousness is impaired

IV Emergency Replacement – AKA “Boluses”

• What fluid?

– Isotonic fluid

• 0.9% NS, Lactated Ringers

• NO dextrose-containing fluids

• How much fluid?

– 20 cc/kg over 20-30 minutes.

• Patients with congenital heart disease or renal insufficiency - ~10 cc/kg over 30-60 minutes.

• How many boluses?

– Enough (although consider pressors if you’re needing more than 60-80 cc/kg)

IV Maintenance Fluids

• 3 important components

– Dextrose

• D5 for most children; D10 in the NICU

– Potassium (except for patients with decreased urine output or renal insufficiency)

• Usually add 20 mEq/L

– Sodium

Common IV Fluids

Fluid Na (mEq/L)

D5W 0

0.9% NaCl (NS) 154

0.45% NaCl (1/2 NS) 77

0.2% NaCl (1/4 NS) 34

Lactated Ringers 130

ORT

Which fluid do I choose?

• Consider the patient’s daily free water and sodium needs.– 5 kg infant

• FW: 5 kg x 100 cc/kg/day = 500 cc/day

• Na+: 5 kg x 3 mEq/kg = 15 mEq/day

• 15 mEq/500 cc = 30 mEq/L D5 0.2 NS

– 20 kg child• FW: (10 kg x 100 cc/kg/d) + (10 kg x 50 cc/kg/d) =

1500 cc/day

• Na+: 20 kg x 3 mEq/kg = 60 mEq/day

• 60 mEq/1500 cc = 40 mEq/L D5 0.45 NS

A 2 year old has a 4-day history of gastroenteritis,

poor fluid intake and infrequent urination. On exam

you find dryness of the mucous membranes, sunken

eyes with mild tenting of the skin. The serum sodium

is 137 mEq/L.

The weight is 10 kg.

You determine the child is suffering from about 10%

dehydration.

What are the fluid and electrolyte requirements?

Case 1

Isonatremic Dehydration

Patient is dehydrated and Na+ is 135-145 mEq/L

Determine fluid deficit as percentage of weight based on clinical findings

Determine which parts of deficit come from ICF versus ECF compartments based on duration of illness

ECF Na+ loss = ECF Fluid deficit (L) X 145

ICF K+ loss = ICF Fluid deficit (L) X 150

H2O Na K Cl

(ml) (mEq) (mEq) (mEq)

Maintenance

Total deficit = 1000 ml

Extracellular fluid deficit

(60% of total)

Intracellular fluid deficit

(40% of total)

Total

1000 30 20 40

600 87 - 60

400 - 60 -

2000 117 80 100

Isonatremic Dehydration

Phase Approach

PHASE 1– Emergency restoration of circulation if patient is hypovolemic

– 10-20 ml/kg of isotonic fluids only 40ml/kg

– No response 10ml/kg albumin/plasma/blood

PHASE 2– Replacement of ½ of the fluid loss (deficit and maintenance) in

first 8 hours

– Replacement of ongoing loss

PHASE 3– Replacement of remaining ½ of the fluid loss (maintenance

and remaining deficit) in next 16 hours

– Replacement of potassium after voids

Case 2

• 3 m infant

• Loose watery stools

x3days

• Vomiting X4 during

last 12 hours

• No urine for 10 hours

• Wt : 5 kg , PR: 160

/min , RR= 60/min

• BP: 90/85

• Fontanels & eye

sunken

• Extremities cold , skin

mottled

• Loss of skin turgor

• No tear , weak cry

• Capillary refill time 3

sec

• Good sensorium

• Deficit 10% ? ml/kg

• Calculate the first day fluid therapy

Wt = 5kg Water Sodium Potassium

Maintenance

Deficit

Ongoing loss

case 7

• A 7 year old boy presented with at least a weeks

history of abdominal pain and vomiting and

polyuria . He was mildly confused. BP= Nr., wt=25

kg

– PH=7.52 Na=137

– PCO2=44.6 K= 2.2

– HCO3= 38 Cl=91

– How do you approach to this patient?

– How do you treat ?

– What is the cause of hypokalemia?

Wt =9 kg Water Sodium Potassium

Maintenance

Deficit

Ongoing loss

• Treatment

– Oral

• Safest, although solutions may cause diarrhea

– IV

• Peripheral: do not exceed 40-50 mEq/L potassium - Avoid

temptation to rapidly bolus

• Central: 0.5 -1 mEq/kg over 1-3 hours, depending on

severity

– Replace magnesium also if low

• (25-50 mg/kg MgSO4)

3.5-5.5 >2

2

1

Case Study #8

• HPI:

– An eight month old infant with autosomal recessive

polycystic kidney disease presents with irritability.

She is on nightly peritoneal dialysis at home. The lab

calls a panic potassium value of 7.1 meq/L. The tech

says it is not hemolyzed.

What do you do now?

Cardiac Monitor

• What is this rhythm?

What is the immediate

treatment?

1- Calcium Gluconate

2- Hypertonic Saline

3- Insulin infusion for 4 H

4- Albuterol inhaler

The goals of therapy, in chronologic order

1. Antagonize the effect of K on excitable cell

membranes.

2. Redistribute extracellular K into cells.

3. Enhance elimination of K from the body.

Rapid treatment

Elimination

J Am Soc Nephrol 21: 733–735, 2010.

Clin J Am Soc Nephrol 5: 1723–1726, 2010

After infusing calcium gluconate , ECG showed sinus

rhythm, what is the next step of therapy?

1- Sodium Bicarbonate

2- Furosemide

3- hemodialysis

4- peritoneal dialysis

5- Kayexelate

Any Question?