Water and sodium deficits

Report
Body Fluids
• Total Body Water = Extracellular Fluid (ECF) +
Intracellular Fluid (ICF)
• ECF = Plasma + Interstitial Fluid
• Total Body Water expressed in terms of %
body
weight (adolescent or adult):
• ICF (30-40%)
• Interstitial)15%(
• Plasma 5% & Infants- 8%
Change in Body Composition
Change in Body Composition
dehydration
• Child:
Mild- 5% weight loss
Moderate 10
15-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 days
75-100% 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
perfusion failure and
intravascular deficit by bolus of
correction of
isotonic fluids
0.9 NaCl±D5 or Ringer lactate
20ml/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: H O+ Na+ K± Ca
2
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- boluses
Most accurate method of water deficit
estimation- weight loss
Other method: Calculated previous weightcurrent weight
Calculated weight= current+ estimated fluid loss
Estimated fluid loss- by percent of dehydration
Isotonic dehydration
• Water deficit- weight loss or estimated weight
loss
• Sodium deficit
Isotonic dehydration
sodium deficit
total body water(normal)*140meq/l- current
TBW*current [Na]= Na deficit
Isotonic dehydration
• Normal TBW= normal body mass*K
k~0.75 neonates, 0.65 toddlers, 0.6w &0.5m
• ??????Really Current TBW~ current mass (kestimated percent of dehydration/10)
10 kg infant with 10% dehydration- 1l loss
Sodium deficit= 1*140 meq/ml
Sodium 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
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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) deficits
simple calculation: loss of 1 l of isotonic fluids
Water deficit: 10 kg × 10% = 1 L
Na deficit: 1 L × 140 mEq/L = 140 mEq
• Emergent fluid repletion with NS or D5% NS
20 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
mL
Daily maintenance water requirement: 100
mL/kg/day × 10 kg = 1,000 mL/day
800 mL + 1,000 mL = 1,800 mL/24 h = 75 mL/h
Remaining Na deficit: 140 mEq - 30 mEq = 110 mEq
Maintenance sodium requirement: 3 mEq/100 mL
water × 1,000 mL/day = 30 mEq/day
110 mEq + 30 mEq = 140 mEq/24 h
140 mEq/1,800 mL ≈ 0.45% sodium chloride (½ NS)
Maintenance potassium requirement: 3
mEq/100 mL water × 1,000 mL/day = 30
mEq/day
30 mEq/1,800 mL ≈15–20 mEq/L
Intravenous fluid based upon deficit
calculations:
D5% 1/2 NS with 20 mEq/L KCl at 75 mL/h
Ongoing losses
Extrarenal 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 deficits
Water deficit: 10 kg × 10% = 1 L
Sodium deficit: [TBW(n) × 140 mEq/L] - [TBW(c)
× 125 mEq/L]
TBW(n) = 10 kg × 0.65 = 6.5 L
TBW(c) = TBW(n) - water deficit = 6.5 L - 1 L =
5.5 L
Sodium deficit: (6.5 L × 140 mEq/L) - (5.5 L × 125
mEq/L) ≈ 220 mEq
Emergent fluid repletion with NS or D5%NS
20 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
mL
Daily maintenance water requirement: 100
mL/kg/day × 10 kg = 1,000 mL/day
800 mL + 1,000 mL = 1,800 mL/24 h = 75 mL/h
Remaining Na deficit: 220 mEq - 30 mEq = 190 mEq
Maintenance Na requirement: 3 mEq/100 mL
water × 1,000 mL/day = 30 mEq/day
190 mEq + 30 mEq = 220 mEq
220 mEq/1,800 mL ≈120 mEq/L
Maintenance potassium requirement: 3 mEq/100
mL water × 1,000 mL/day = 30 mEq/day
30 mEq/1,800 mL ≈15–20 mEq/L KCl
Intravenous fluid based upon deficit calculations:
D5% with 120 mEq/L Nacl and 20 mEq/L KCl at 75
mL/h
D5%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 losses
FreeH2O deficit = TBW(c) × [(serum Na/140) - 1]
Total fluid deficit- free water deficit= isotonic
losses
• Water and sodium deficits
Total water deficit: 10 kg × 10% = 1 L
TBW(c) = TBW(n) - 1L = (10 kg × 65%) - 1 L =
5.5L
Free water deficit: TBW(c)[(155/140) - 1] =
5.5[(155/140) - 1] = 0.59 L
Isotonic deficit = total water deficit - free
water deficit = 0.41 L
Sodium deficit: 0.41 L × 140 mEq/L ≈ 60 mEq
• Emergent fluid repletion with NS or D5%NS
20 mL/kg × 10 kg = 200 mL (200 mL water and
~30 mEq sodium)
Ongoing repletion and maintenance requirements
Remaining total water deficit: 1,000 mL - 200 mL = 800
mL, plan to replace over 36–48 h or 400 mL/day × 2 days
Daily maintenance water requirement: 100 mL/kg/day ×
10 kg = 1,000 mL/day
1,000 mL + 400 mL = 1,400/24 h or ≈60 mL/h
Remaining sodium deficit: 60 mEq - 30 mEq = 30 mEq
Maintenance sodium requirement: 3 mEq/100 mL of
water intake × 1,000 mL/day = 30 mEq/day
Total sodium requirement: 30 mEq + 30 mEq = 60 mEq
60 mEq/1,400 mL or ≈0.225% sodium chloride
• Maintenance potassium requirement: 3
mEq/100 mL water × 1,000 mL/day = 30
mEq/day
30 mEq/1,400 mL ≈20 mEq/L KCl
D5% 1/4 NS with 20 mEq/L KCl at 60 mL/h for
~36–48 h
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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
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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
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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

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