fluid and electrolytes (introduction) and sodium imbalance

8/10/2019 Fluid and Electrolytes (Introduction) and Sodium Imbalance

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Fluid and electrolyte management are

paramountto the care of the surgical patient.

Changes in both fluid volume and electrolyte

composition occur preoperatively,

intraoperative, and post operatively, as wellas in response to trauma and sepsis.

Fluid and Electrolytes in Surgical PatientsIntroduction (1)


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Fluid and Electrolytes BalanceNormal Anatomy and Physiology

Total Body Water (60% body weight)Lesser in

obesity(Adipose tissues

less water)

ExtracellularFluid(20%b

ody

weight) Active

NA

Pump


Micropores

allow

escape and

returning of

ALBUMIN

(5%/hr)

Sodium and

potassiumto maintain

electrical

neutrality


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External fluid and electrolyte balance between body and its

environment is defined by intake of fluid & electrolytes with

the output from kidney, GI tracts, skin and lungs (insensible

loss).

Modified and may not be the same, if there are excessive

loss due to diseases, changes in climate and etc.

Intake (in ml) Output (in ml)

Water from beverages 1200 Urine 1500

Water from solid food 1000 Insensible losses from skin and

lungs

900

Metabolic water from oxidation 300 Faeces 100

2500 2500


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Normal Maintenance Requirement

Calculated approximately from an estimation of insensible

(lungs, skin) and obligatory losses.

Typical daily maintenance fluid regimen consists 5% dextrose witheither Hartmannsor normal salineto a volume of 2 liters.

Replacement fluids required to correct pre-existing deficienciesand supplemental fluids required to compensate for anticipatedadditional intestinal or other loses.

Water 25 -35 ml /kg/day

Sodium 0.91.2 mmol/kg/day

Potassium 1 mmol/kg/day


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Solution NA K Ca Cl Lactate Colloid

Hartmanns 131 5 2 111 29

Normal Saline(0.9% NaCl) 154 154

Dextrose Saline(4% Dextrose in 0.18% saline)

30 30

Gelofusine 150 150 Gelatin

in 4 %

Haemcael 145 5.1 < 1 145 Polygelin(75g/L)

Hetastarch Hydroxyethyl starch

(6%)


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Fluid and Electrolytes in Surgical PatientsElectrolytes Imbalance: Sodium Hyponatremia

INTRODUCTION

Defined as a serum sodium concentration lower than135 mmol/L.

It can result from a particular laboratory technique or fromimproper blood collection, excessively high water intake, or,most commonly, an inability of the kidneys to excrete freewater.

Causes by

(a) Sodium depletion

(b) Sodium dilution


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CAUSE 1 : SODIUM DEPLETION1. Decrease intake

(a) Low Na diet(b) Enteral feeds

2. Increase loss(a) Gastrointestinal Losses like vomiting, prolonged NGT

suctioning, and diarrhea(b) Renal Losses due to diuretics and primary renal disease

3. Dehydration (loss fluids and loss electrolytes)


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CAUSE 2 : SODIUM DILUTION

1. Due to excess extracellular water

(a) Intentional: excessive oral intake

(b) Iatrogenic: Intravenous

2. Drugs like antipsychotics, Tricyclic antidepressants andAngiotensin-converting enzyme inhibitors

3. Hyperosmolar like Mannitol and Hyperglycemia


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Establishing Type of Hyponatremia

BP, JVP, Skin Turgor

DecreasesBP, JVP, Skin Turgor

Increases


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Clinical Presentation

CNS symptom show when Na


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Management

Calculate the deficit of Na by the formula below:

Na+deficit (mEq) = (140 Naserum) x 0.6 x Kg

Correct sodium to above 120 mEq/dl

NaCl + 40 mEq/L KCl

3% Saline

serial electrolytes

be prepared to handle seizures

Replace potassium

Cl should correct itself


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Treatment Strategies

Hypovolemic Hyponatremia

expand intravascular volume

0.9% NS or 3% Hypertonic Saline

Hypervolemic Hyponatremia

water restriction

treat medical condition

hemodialysis

Euvolemic Hyponatremia SIADH

restrict fluid: 7-10 ml/kg/d

demeclocycline antagonizes vasopressin


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Central Pontine Myelinosis

Results from overcorrection of sodium

Acute correction limit 25 mEq /day Chronic correction limit 10 mEq/day

In hyponatremia, brain adjust their osmolytes to fall, then

they will absorb free water from surrounding.

If too rapid correction, causes ECF to be hypertonic, free waterwill then move out from cells, brain appear to shrink.

Manifest as paralysis, dysphagia, dysarthria


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Fluid and Electrolytes in Surgical PatientsElectrolytes Imbalance: Hypernatremia

Hypernatremia

High level of sodium

Due to increase sodiumor decrease in water

Plasma sodium more

than 145 mEq/L

Water moves from ICFto ECF

Cell dehydrates/shrink


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Hypernatremia

Volume Status

Normal

Nonrenal water loss

Skin

Gastrointestinal

Renal water loss

Renal disease

Diabetes insipidus

High

Iatrogenic sodium

administration

Mineralocorticoid excess

Aldosteronism

Cushings disease

Congenital adrenal

hyperplasia

Low

Nonrenal water loss

Skin

Gastrointestinal losses

Renal water losses

Diabetes insipidus

Adrenal failure


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Presentation

Thirst

Neurologic symptoms like confusion,neuromuscular excitability, seizures, coma

due to osmotic shift of water out of brain cells

(brain cell shrinkage)


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Diagnosis

Clinically and measuring of serum Na

Determine underlying disorders


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Treatment

Normal saline in hypovolemic patients

Hypotonic fluid (D/w 5%, D/W 5% in or normal saline,

or entral water)

The formula used to estimate the amount of water

required to correct hypernatremia:

140Water deficit (L)= Serum sodium - 140 TBW

fluid and electrolytes (introduction) and sodium imbalance

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