Body Fluids

• Total Body Water = Extracellular Fluid (ECF) + Intracellular Fluid (ICF)

• ECF = Plasma + Interstitial Fluid• Total Body Water expressed in terms of %

bodyweight (adolescent or adult):• ICF (30-40%) • Interstitial(15%)• Plasma5% & Infants- 8%

Change in Body Composition

Change in Body Composition

dehydration

• Child: Mild- 5% weight lossModerate 1015-severe or shock

• 3%/6%/9% old child & adults

dehydration

• Mild: thirsty, minimal clinical picture• Moderate: tachycardia, sunken eyes, dry

mucous membranes, depressed fontanel, decreased urination (???- only 20% of "oliguric" patients have dehydration!), ± prolonged capillary refill

• Severe: blood pressure drop

dehydration

• Isotonic dehydration• hypertonic (Na≥150)• hypotonic (Na≤130)

dehydration

• Acute< 3 days75-100% of fluids losses is from ECF

(primarily Na loss, less K loss)• Subacute or chronic> 3 days

65-70% of losses from ECF and 30% from ICF with greater level of potassium loss

Treatment of dehydration

• Fluids!!!!!• Etiologic treatment

Treatment of dehydration

• Rout of fluids administration:enteral and parenteral

Treatment of dehydration

• Oral/PZ- preferable & most physiologic type–Hypotonic type: ORS by 40-60meq Na/20

meq K and 2.5D for non choleric patients–Medium type: 70meq Na–High solute type: 60-90Na for cholera 1

cc/kg for mild and 2cc/kg for moderate dehydration for 4 h every 5 minutes

Dehydration treatment

Oral rehydration contraindications: • intractable vomiting• impaired consciousness• aspirations risk• bowel obstruction

Treatment of dehydration

• Parenteral:– Subcutaneous with recombinant

hyaluronidase adjuvant– IV/io for failed ORS or Moderate-Severe

dehydration

IV dehydration correction

• 3 phases– Emergent–Corrections–Maintenance and ongoing losses

Emergent phase of fluid replacement

correction of perfusion failure and intravascular deficit by bolus of isotonic fluids

0.9 NaCl±D5 or Ringer lactate20ml/kg (previous mass!)• Bolus- within minutes!• Repeat boluses until stable

Emergent phase

• Patient with decreased oncotic pressure (nephrotic syndrome, protein-loosing entheropathy, burns, cirrhosis)- may give 5% albumin

• DKA- start 10 ml/kg• Premature and small newborns- 10 ml/kg• Suspected cardiogenic shock – 10ml/kg

Second phase- deficits correction

Deficits: H2O+ Na+ K± Ca

Deficits correction

• Assess degree of dehydration• Assess type of dehydration• Assess length of dehydration

Deficits correction

• FIRST - calculate the amount of fluid you need• NEXT - calculate how much sodium and

potassium you need• FINALLY - pick a fluid based upon what is

commercially available if you can

Deficits correction

Persistent deficits= previous loss- bolusesMost accurate method of water deficit estimation- weight lossOther method: Calculated previous weight- current weightCalculated weight= current+ estimated fluid lossEstimated fluid loss- by percent of dehydration

Isotonic dehydration

• Water deficit- weight loss or estimated weight loss

• Sodium deficit

Isotonic dehydrationsodium deficit

total body water(normal)*140meq/l- current TBW*current [Na]= Na deficit

Isotonic dehydration

• Normal TBW= normal body mass*Kk~0.75 neonates, 0.65 toddlers, 0.6w &0.5m

• ??????Really Current TBW~ current mass (k- estimated percent of dehydration/10)

10 kg infant with 10% dehydration- 1l lossSodium deficit= 1*140 meq/mlSodium maintenance= 3meq/100 ml of water*daily fluids

Isotonic dehydration

• Replacement and maintenance by isotonic or ½ NS based fluids

• Give 100-70% of deficit at 1st day• Give 1st half of day fluids amount at 1st 8h and

rest at 16h• New recommendations- to give NS based

fluids to prevent iatrogenic hyponatremia

Ongoing Repletion and Maintenance Therapy

• Once the patient is stable

Persistent deficits+ ongoing losses+ maintenance fluids

Fluid maintenance: Holliday Segar formula

• 1st 10kg- 100 ml/kg• 2nd 10kg- 50ml/kg• Others- 20ml/kg

• ~400 ml/m²/d+ renal sensible loss

Caloric (energy) maintenance• The daily fluid requirement is the same as the

daily caloric requirement (e.g., if a child requires 1000 cc fluid, he also requires 1000 Kcalorie

• In terms of fluids, calories most often provided as dextrose (glucose)

• Difficult to provide total daily caloric requirement intravenously unless using TPN

• Most often, it is sufficient to provide 20% of total daily caloric requirement intravenously so as to prevent ketosis

Ongoing loses

• Sensible: diuresis and diarrhea (rectal tube)• Insensible: feces, skin, respiration• 10ml/kg for each diarrhea• Burns- Parkland formula: BSA*4*mass for

>20% of TBS of 2nd degree and > • Tachypnea: 5-10ml/kg/10resp> normal• Hyperthermia: 5-10 ml/kg/1°>38• Vomiting:5-10 ml/kg/event

Decreased maintenance

• SIADH• Ventilated children• Inactive/hypothermic children

Example of isotonic dehydration

• 1y boy with moderate dehydration

• Water and sodium (Na) deficitssimple calculation: loss of 1 l of isotonic fluidsWater deficit: 10 kg × 10% = 1 LNa deficit: 1 L × 140 mEq/L = 140 mEq

• Emergent fluid repletion with NS or D5% NS20 mL/kg × 10 kg = 200 mL (200 mL water and ≈30 mEq sodium)

Ongoing repletion and maintenance requirementsRemaining water deficit: 1,000 mL - 200 mL = 800 mLDaily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day800 mL + 1,000 mL = 1,800 mL/24 h = 75 mL/hRemaining Na deficit: 140 mEq - 30 mEq = 110 mEqMaintenance sodium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day110 mEq + 30 mEq = 140 mEq/24 h140 mEq/1,800 mL ≈ 0.45% sodium chloride (½ NS)

Maintenance potassium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day30 mEq/1,800 mL ≈15–20 mEq/LIntravenous fluid based upon deficit calculations:D5% 1/2 NS with 20 mEq/L KCl at 75 mL/h

Ongoing lossesExtrarenal losses should be replaced mL-for-mL if volumes are significant.The sodium content of the fluid lost should be estimated or measured in order to select the appropriate replacement fluid.

Hyponatremic (125) dehydration example

Water and sodium deficitsWater deficit: 10 kg × 10% = 1 LSodium deficit: [TBW(n) × 140 mEq/L] - [TBW(c) × 125 mEq/L]TBW(n) = 10 kg × 0.65 = 6.5 LTBW(c) = TBW(n) - water deficit = 6.5 L - 1 L = 5.5 LSodium deficit: (6.5 L × 140 mEq/L) - (5.5 L × 125 mEq/L) ≈ 220 mEq

Emergent fluid repletion with NS or D5%NS20 mL/kg × 10 kg = 200 mL (200 mL water and ≈30 mEq sodium)

Ongoing repletion and maintenance requirements

Remaining water deficit: 1,000 mL - 200 mL = 800 mLDaily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day800 mL + 1,000 mL = 1,800 mL/24 h = 75 mL/hRemaining Na deficit: 220 mEq - 30 mEq = 190 mEqMaintenance Na requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day190 mEq + 30 mEq = 220 mEq220 mEq/1,800 mL ≈120 mEq/L

Maintenance potassium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day30 mEq/1,800 mL ≈15–20 mEq/L KClIntravenous fluid based upon deficit calculations:D5% with 120 mEq/L Nacl and 20 mEq/L KCl at 75 mL/hD5%NS with added potassium could be provided for the initial half of the total volume and completed with D5%1/2 NS with added potassium

Hypernatremic dehydration example

Total Fluids loss= free water losses+ isotonic fluids lossesFreeH2O deficit = TBW(c) × [(serum Na/140) - 1]Total fluid deficit- free water deficit= isotonic losses

• Water and sodium deficitsTotal water deficit: 10 kg × 10% = 1 LTBW(c) = TBW(n) - 1L = (10 kg × 65%) - 1 L = 5.5LFree water deficit: TBW(c)[(155/140) - 1] = 5.5[(155/140) - 1] = 0.59 LIsotonic deficit = total water deficit - free water deficit = 0.41 LSodium deficit: 0.41 L × 140 mEq/L ≈ 60 mEq

• Emergent fluid repletion with NS or D5%NS20 mL/kg × 10 kg = 200 mL (200 mL water and ~30 mEq sodium)

Ongoing repletion and maintenance requirementsRemaining total water deficit: 1,000 mL - 200 mL = 800 mL, plan to replace over 36–48 h or 400 mL/day × 2 daysDaily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day1,000 mL + 400 mL = 1,400/24 h or ≈60 mL/hRemaining sodium deficit: 60 mEq - 30 mEq = 30 mEqMaintenance sodium requirement: 3 mEq/100 mL of water intake × 1,000 mL/day = 30 mEq/dayTotal sodium requirement: 30 mEq + 30 mEq = 60 mEq60 mEq/1,400 mL or ≈0.225% sodium chloride

• Maintenance potassium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day30 mEq/1,400 mL ≈20 mEq/L KClD5% 1/4 NS with 20 mEq/L KCl at 60 mL/h for ~36–48 h

• Correct sodium 10-12 mEq/l per 24 h• Acute states- rate may be higher• Chronic state- decrease the rate of correction• Estimate the rate of correction by planning of

free water deficit replacement

Sodium

• Predominant solute of extracellular space• Concentration inversely related to total body water• Osmotic gradient• Membrane potential• Normal measured concentration: 135-145• Measured Na ( +0.016 *serum glucose (mg/dL)=

Corrected serum Na• Other pseudohyponatremias- hyperlipidemia &

paraproteinemia

sodium

• Normal intake: 2-3 meq/kg/d

Signs of hypernatremia

• 145- 150-158- mild/moderate signs– Intense thirst– restlessness

Severe hypernatremia

• 158–160 mmol/l• severe signs due to rupture of brain vessels

especially in rapid developed hypernatremia due to brain volume fall with subsequent brain separation from meninx

Severe hypernatremia

– Absent thirst– altered mental status– anorexia– muscle weakness– nausea– vomiting– lethargy– irritability– Stupor or coma– vascular rupture with cerebral bleeding and

subarachnoid hemorrhages

• Chronic hyperNa- minimal neurological symptoms due to neuronal adaptation by osmolytes (amino acids and carbohydrates) production within 72 h- don’t repair rapidly to prevent brain edema

correction

• 1st step- correct intravascular volume depletion by bolus

• A & B stabilisation• For acute hypernatremia- acute correction 1

mmol/h• For hypernatremia of longer or unknown

duration- slow correction 0.5 mmol/h till145

• Anorexia• Headache• Nausea• Vomiting• Irritability• Disorientation• Weakness & cramps- rhabdomyolisis• Seizures and coma due to cerebral edema in case of

rapidly progressive hyponatremia• Death

1st tx step- volume replacement by isotonic fluids especially in hemodinamically unstable patient + A& B stabilization including intubation and seizures control

• Correction: 8–12 mmol/l/d for chronic hyponatremia to prevent demyelination

• Mechanism of demyelination: rapid osmolarity repair→ fluid efflux from brain blood barrier endothelium→ endotheliocytes constriction→ opening pores in BBB→ plasma inflammatory substances (TNF & interferon) attack of glya

• Acute tx for acute severe hyponatremia (symptomatic): start after hemodynamic stabilization 4-6 ml/kg NaCl3% bolus

• Water restriction and loop diuretics+ salt supplements in neurologically intact or hypervolaemic patient without fluid resuscitation

• Water restriction in euvolaemia

Signs

Muscular:• Usually ascending• doesn’t involve respiratory muscles- DD with hypo

K• appears then K>8• Fatigue• Weakness• Paresthesia• muscular paralysis/tetany

Cardiac: • Peaked T- earliest ECG sign• 2nd- flat P• prolonged PR/QRS, BBB, VF, asystole

• The rapider K rises the severer clinical picture• Hyponatremia, acidosis, hypoCa- more rapid

and sever clinical picture• Pseudo hyperkalemia: serum K- plasma K> 0.3

mmol

treatment

• Ca to prevent arrhythmia• Insulin +D• Bicarbonate• Ventoline• Key oxalate• diuretics

signs

• Mild 3.0-3.5 mmol/l- arrhythmia in cardiac patients

Moderate 3- 2.5:

• ascending muscle weakness & diaphragmatic paralysis

• hypertension• paralytic ileus• flat or inverted T; ST depression• prominent U-waves• atrial tachycardia± block• atrioventricular dissociation• VT/F/SVT especially on digitalis

Severe< 2.5:• Myopathy• Rhabdomyolysis• ascending paralysis• respiratory failure• myocardial necrosis• constipation• urinary retention and voiding dysfunction