DEHYDRATION

Dr.SOAD JABER 2010

Maintenance fluid replacement Obligatory water lossNormal fluid replacement * urine, sweat ,stool

Thirst ADH

Osmotic Hydrostatic

ECF

ICF

*Insensible water loss Aldosterone70% skin 30% lung no solute content

Some causes of dehydration

Vomiting Metabolic alkalosis HypokalemiaHyponatremic dehydration

Diarrhea Iso, hypo, hyper natremicdehydration

DKA Hyper tonic dehydration

Cystic fibrosis sweating diarrhea. Salt loss

Fever 1°C → 10% water loss

Intestinal Obstruction Prolonged gastric aspiration Hyponatremic dehydration

Diabetes Insipidus Pure water loss Hypernatremic dehydration

Renal disease Na+water loss Iso OR hyponatremicdehydration

Dehydration

Simple deficit in body water

Contraction of body fluid space

Both water and electrolyte contents

Loss of ECF ± ICF

Deficit:

Cumulative body water and electrolyte losses that occur prior to clinical presentation.

Body losses:

Absolute amount of water lost always Exceeds the amount of solute loss.

Every dehydration tend to be hypertonic ,Only kidneys prevent hypertonicity.

Types of Dehydration

Hypertonic Isotonic Hypotonic

Types

Isotonic: 70% most common. Na 135-145 meq/L (Normal level).

cont

Hypertonic:

20%.

Na 145 meq /L.

Water loss > solute.

Renal circulation impaired → kidney can't excrete solute.

? Salt intake,

May occur in well nourished obese infants follow acute process with marked anorexia and fulminant diarrhea.

CONT Hypertonic:

Signs of dehydration less than the actual degree of dehydration

Fluid shift ICF → ECF

Doughy skin Parched tongue Almost near normal B.P.

Complications: Shrinkage of brain cells:

hematoma Bleeding

Brain edema while treatment: Coma Seizure

Associated with acidosis: Hypokalemia

Hypotonic10%-

In an infant or a child with diarrhea whose intake is electrolyte free.

Weak tea,, Rice water,, diluted milk

Chronically malnourished child with bouts of mild to moderate diarrhea and poor intake.

Fluid shift ECF → ICF

Well preserved intracellular volume.

Collapse and shock with degree of dehydration,

decrease Renal flow with milder degree of dehydration.

HYPOTONIC

Complication

Convulsion due to hyponatremia.

Circulatory collapse and shock even with milder degree of dehydration. Extra cellular fluid losses.

Intra cellular fluid shift.

Volume depletion more than actual water loss.

Profound volume depletion will lead to ± Renal failure – shock.

DEGREE of Dehydration:

10% Moderate

Skin turger

elasticity

tenting

Fontanels depressed.

Oliguria .

tears OR absent.

B.P. Still well maintained.

Orthostatic B.P.

Sunken eyes : Obvious to the parents not to the physician.

Cont

Moderate - Severe

Hypovolemia due to contraction of plasma volume.

Hypotension

Cold extremities

Tachycardia

Cont

15% Severe dehydration

Circulatory collapse

B.P.

Cool cyanotic sweaty extremities

Mottled skin

Shock

Death

Severe >10%Mild <5%Mod 5-9%

Tachycardia

turgor

Sunken

Dry

Cool ,mottled

Lethargic, coma

Absent

N to

N to

Turgor

Normal

Dry

Delay capillrefill

N or lethargic

Normal

Normal

Normal

Normal

Normal

Slightly dry

Perfuse

Normal

Slightly

Blood Pressure

Pulse pressure

Heart rate

Skin

Fontanel

Mucous memo

Extremities

Mental status

Urine output

Thirst

Management of:

Fluid and electrolyte

Refeeding

Dehydration:

More severe in children.

a. greater basal fluid + elect requirement / kg

b. dependent on others for the demands.

Assess the degree of dehydration:

Clinical signs and symptoms.

Ongoing losses.

daily requirement.

Investigation: Lab: Repeat all at 6 - 12 - 24 h. 1. CBC:

Hemo concentration Hb Hct

2. Plasma osmolality. 3.Urea + electrolytes.* Na ... Type of dehydration

*Normal

*Na Acidosis Renal function

*Na with significant stool losses with severe vomiting - alkalosis with treatment with high glucosetreatment with alkali

* HCO3 loss will lead to acidosis with severe diarrhea. * Urea nitrogen & Creatinine.

Rehydration therapy

* I.V. * Oral

I.V.Initial therapy: Resuscitation fluid (10-20ml /hour).

Designed to expand extra cellular fluid volume rapidly especially plasma.

Improve circulatory and renal function. Prevention or treatment of shock.

Fluid type:Isotonic saline. 0.9%. [ 0.9% N.S. ]

Initial therapy (Continuation)

If with severe acidosis

Ringer lactate

N a 140 meq/L

K 115 meq/L

HCO3 25 meq/L

Dextrose 5%

If in shock

Plasma expander

*Alb 5% *Blood 10 ml/kg

Repeat once or twice till patient is hemo-dynamically stable.

No hypotonic saline →may lead to cerebral edema.

II. Subsequent therapy

Provision of maintenance fluid and electrolyte.

Replacement of existing deficits.

Replacement of ongoing losses.

To be re-checked at 8 hourly interval.

1)Maintenance

- Fluid requirement /kg /24 hour.

-Constant everyday.

-Maintenance calculated on daily basis regardless to deficit or ongoing losses.

II. Subsequent therapy (Maintenance)

How1-10 kgs 100 mls/kg/24 h 10-20 kgs 50 mls/kg/24 h > 20 kgs 20 mls/kg/24 h

Example:Child weight is 25 kg what is his maintenance?

1 st 10 kgs 10 x 100 = 1000 mls2nd 10 kgs 10 x 50 = 500 mls

> 20 kg 5 x 20 = 100 mls

1600 mls/24 h

2)Deficits

*Degree of dehydration:

5% dehydration (mild) 50 mls/kg

10% dehydration ( moderate) 100 mls/kg

15% dehydration (Severe) 150mIs/kg

*Type of dehydration:

According to Na level:

Rate.

Type of fluid.

A)Isotonic (Isonatremic) dehydration:

Loss of isotonic fluid from the body

-No osmotic gradient between Intra + Extra cellular fluids.

-Full deficit correction over 24 hours:

1/2 over 1 st 6-8h

1/2 over 16-18h .

Type of fluid

D5 in 0.2 N .S.

D5 in 0.45 N.S.

B)Hyponatremic dehydration:

-Na loss more than water loss. ex.* with dysentery *Treatment with low Na fluid - RateFull deficit correction over 36h ,1/2over 6-8h. . the rest over16-18hour.-Depend on

... level of Na …degree of dehydration

Type of fluids:

D5 IN 0.45 N .S.

D5 IN 0.9 N.S.

depend on Na level

Usually no need to add Na to the fluid as correction of dehydration will correct Na.

If after correction of dehydration still Na loss

Add: 6 meq/kg Na cl

Max 12ml/kg of 3% Na cl over 6 h

orCalculate Na deficit = (135 – actual Na level) x 0.3 x B. W. in kg.

C) Hypernatremic dehydration:

More serious. Fluid therapy replacement can be difficult. Severe hyper osmolality may result in cerebral damage

and Hemorrhage. Seizures occur during treatment as serum Na returning to

normal due to rapid correction, or the use of hypotonic fluid.

Treatment of convulsion: *Anti convulsant. *NaCl.

Excess movement of water into cerebral cells during rehydration with hypotonic saline ,or rapid correction will lead to → Cerebral edema.

May be irreversible or fatal

Type of fluid:

-Slow rate is more important than type of fluid.

-Na drop should not be more than 10 meq/L/ 24 hour.

-Start with D5 0.45 N .S.

Rate:Very slow. Can be done over days. Usually 48 - 72 hours.

***Example:

Child weight 30 kg with 10% dehydration What is his fluid requirement?

1)Maintenance: 30 kg 10 x 100 = 1000 10 x 50 = 500 1700 mls/ 24 h 10 x 20 = 200

2)Deficit 10% dehydration = 100 mls/kg 100 x 30 = 3000 mIs

Type and rate according to type of dehydration.

3)Ongoing losses: Continuous pathological losses

Stool - diarrhea VomitusN.G. tube

*Small amount 50 mls/time*Moderate amount 100 mls/time*Large amount 150 mls/time

To be added to deficit, calculated every 6-8h.

ORS

To all patient but:1. Severe dehydration in patient whose care giver can’t

administer fluids.

2. If ongoing losses can’t be compensated orally.

3. Severe vomiting.

Value: Rapid rehydration with rapid replacement of ongoing losses

during the first 4-6 hours.

Once rehydrated – oral maintenance solutions.

Home remedies? Decarbonated soda beverages.

Fruit juices.

Tea.

Not suitable: Inappropriate high osmolarities due to CHO

conc.

Low Na content → hyponatremia.

Inappropriate CHO to Na ratio.

Oral rehydration solution

When to use it?

Contraindication: Presistant vomiting. Comatose patient. Congenital anomalies e.g. cleft palate.

Types: (important)

WHO PedialyteNa meq/L 90 45 K meq/L 20 20 C1 meq/L 80 35 HCO5 meq/L 30 30 citrate Glucose g/dl 2% 2.7%

Rate:50 ml/kg …. within 4 hours for patient with mild dehydration100 ml/kg … within 6 hours for patient with moderate dehydration

* Small amounts + short intervals

IMPORTANT NOTES :

Goals of rehydration therapy:

1) To achieve euvolemia.

2) Maintain or restore fluid and electrolyte homeostasis.

Fluid Isotonic :

*if they have the tonicity of plasma.

*Or osmolality around 300meq/l.

Ingredient to calculate osmolarity

*Cations, Na, k-

*Anions, Cl, alkali, D-glucose.

D5 is added to buffer hypotonic solutions that may lead to acute hemolysisand to prevent short time starvation and catabolism.

Cont.

Total body water = ECF+ICF

Normal values:

*ECF: Anions: Na 140meq/l

K3.5-5meq/l

Cations: Cl 100mg/l

Bic: 25mg/l

*ICF: Cations K 150mg/l

Anion-minor Na 5mg/l

Hypernatremia High plasma osmolality ICF ECF ,

*intravascular volume and vital signs are relatively preserved.

Disadvantage

-Cell shrinkage physical reduction in the size of the brain with attended rupture of the veins bridging the cranial vault intracranial hemorrhage.

Normal urine output 1-2mls/kg/hour.

Thank You

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