Fluid, electrolytes, and acid base balance

Fluid,
Electrolytes,
and Acid
Base Balance
(8/7/2020)
Surgical Club Red Sea University SC (RSU)

Prepared by
 DR.Attia19
 DR.Zeinab 19
 DR. Khlood osman 18
 DR Esraa18
presented by
 DR. Amar yahia Ibrahim
 Registrar of general surgery
SC (RSU 8/7/2020

Composition of the body fluid
compartment
1: Total body water: is 60% of body weight in
males, 50% of body weight in females, i.e. 30 liters.
 Intracellular water—20 liters (2/3).
 Extracellular water—10 liters (1/3).
 Plasma (1/4) (2.5 liters).
 Interstitial fluid (7.5 liters).

Third space fluids
 collect outside of the functional or
“exchangeable” extracellular space (e.g.,
pleural effusions, ascites).
 Large amounts of fluid may be unavailable to
the circulation

 The abdominal peritoneum can hold up to 18 L
of third space fluids in the presence of an
inflammatory process (e.g.,peritonitis,
postoperatively).
Osmolality of body fluid:
is 290 to 300 mosm /L

Surgical Club Red Sea University SC (RSU)Surgical Club Red Sea University SC (RSU)

MineralGeneral Function
Na+Maintain blood volume
K+Responsible for RMP
Ca++Muscle contraction
Mg++Is necessary for action of
intracellular enzymes
Cl-Synthesis of HCL
-HCO3Control PH

Biomedical Importance of Water:
1. Homeostasis (CES)
 Water distribution
 PH maintenance
 Maintain Electrolyte Concentration

2. Set of Fluid Balance
Depletion (dehydration)
Intoxication (over-hydration)

Water imbalance:
 A: Water loss (volume loss)
 B: Water excess: “water intoxication”

A: Water loss (volume loss):
 It is decrease in the whole body ﬂuid volume
which includes both ECF and ICF.
 It is usually ECF loss which is more important
and Assessed

It can be:
Isotonic volume depletion
Only water loss

Causes and Features
1. Isotonic volume depletion occurs due to
diarrhea, vomiting, and excess diuresis. Here
normal or decreased sodium is observed.
Fluid loss is only of ECF and so early
intravascular volume reduction occurs.

C/F:
 thirst, weakness
 reduced tissue turgor.
 oliguria with HIGH specific Gravity.
 hypotension and decreased tissue perfusion
 dry tongue and rapid pulse
 cold clammy extremities'

 2-Only pure water loss: occurs due to poor fluid
intake and diabetes insipidus hypotension is less.
 severe thirst
 confusion
 Convulsions due to hypernatremia
 Dehydration can be mild (weight loss 5%);
moderate (10%) severe (15%).

Management:-
1-Isotonic volume depletion is corrected by
0.9% normal saline.
2- Pure water depletion is corrected by
more water intake/intravenous 5% dextrose.

3-Monitoring fluid therapy mainly by monitoring
the amount of urine out put.
4- Other modalities include skin and tongue
examination, weight gain, pulse, blood
pressure, CVP, PCWP.

B: Water excess: “water intoxication”:
 It can be divided into
1. water and salt excess
2. predominantly water excess called as
water intoxication.

Water and salt excess occurs in CCF,
cirrhosis, nephrotic syndrome,
hypoproteinemia, renal failure, excessive
saline infusion.

 2-Water intoxication
 The main cause is excess infusion of 5%
(dextrose only infusion).
 Other causes include: TURP syndrom,
colorectal washout with plain water, SIADH
secretion, psychogenic polydipsia.

It is managed by:
1. stopping fluid infusion or procedure (TURP)
2. fluid restriction
3. treating the cause.

C/F:-
1-Drowsiness, weakness
2- Convulsions and coma
3-Nausea, vomiting

4- Passage of dilute urine
5- Distended neck veins
6- Pedal edema
7- Circulatory overload—tachycardia,
pulmonary edema , hypertension

Treatment of water excess:-
1-Water and salt restriction and observation.
2-Monitoring in ICU.
3-Management of fluid and electrolyte balance.

4- Infusion of hypotonic sodium chloride.
administration of diuretics and hyper
tonic saline should be avoided.

Electrolyte Metabolism and Balance
 A/ SODIUM
 average daily intake of sodium is 1mmol/kg ;
which is about 5g/day.
 The sodium balance is largely controlled by
regulating its output which the renal tubule
reabsorb from the glomerular filtrate and the
amount of sodium excreted by the sweat
glands.

Sodium depletion
(hypo natremia)
 Sodium level less than 130 mEq/liter.
 Hypernatremia is said to be severe if serum
sodium becomes
1. lesser than 100 mEq/L in acute type
2. lesser than 115 mEq/L in chronic type.

Causes:
1/abnormal GIT loses “suction, vomiting,
diarrhea”.
2/ loss of ECF “burn, marked sweating”.
3/ excessive urine sodium wastage “diuretic, salt
wasting ,nephritis , adrenal failure”

4/ blood loss.
5/ restricted dietary intake.
6/ a adrenocortical insufficiency

Types of hyponatremia:
1. Acute—presents as neurological
manifestations.
2. Chronic—causes pontine myelinolysis. It
presents as behavioral changes, progressive
weakness, and cranial nerve palsies.

Types also may be:
1-Hypervolaemic hyponatremia:
wherein rapid absorption of fluid occurs into
intravascular compartment leading into
pulmonary and cerebral edema. It is due to
decreased osmolality causing movement of ECF
into the cells

Acute hyponatremia is corrected by fluid
restriction, hypertonic saline, loop diuretics
like furosemide.

2-Hypovolaemic hyponatremia: It is due to
hypovolemia by diarrhea, vomiting, wherein
urine sodium level is less than 20 mmol/L treated
well using isotonic normal saline

* C/F :
1/ eye swelling (face drawn in front, anterior
fontanels depressed ,dry skin, tongue coated
dry )
2/ peripheral vein contracted
3/ tachycardia , hypotension , low CVP
4/ oliguria
5/ harem concentration.

Treated by:
1/ normal saline
2/ blood loss replaced by blood.

3-Normovolaemic hyponatremia:
It may be due to renal failure or syndrome
of inappropriate ADH secretion (SIADH)

4-Pseudohyponatraemia: Plasma osmolality is
mainly achieved by serum sodium; but small
proportion, i.e. 25%of osmolality is due to other
solutes like glucose, lipids, plasma proteins, urea
which will not move easily between intracellular
and extracellular spaces

Treatment:-
 1-Intravenous infusion of normal saline as a slow
and gradual correction at a rate of 2
mEq/L/hour in acute cases and < 1mEq/L/hour in
chronic cases. Correction should not exceed
more than 20 mEq/L/day in acute cases and
more than 10mEq/L/day in chronic cases.

 Hypertonic saline of 1.6% or 3%also can be
used in severe cases. 0.9% normal saline
contains154 mEq of NaCl; 3% saline contains
500 mEq of NaCl.
 2- treatment of the underlying cause

Sodium excess (hypernatremia)
 Serum sodium level > 150 mEq/L.
 Excess infusion of normal saline causes overload
in circulating salt and water. It is usually due to
water deficit.

Causes:
1/ giving excessive amount of 0.9% saline.
2/ hyper aldosteronism.
3/ Cushing syndrome.
4/ Renal dysfunction.

 5/ Cardiac failure.
 6/Drug induced like NSAID, corticosteroids
 treated by: sodium restriction and careful use of
diuretics

* C/F:
 1/early sign is slight puffiness of the face.
 2/ total sodium excess lead to edema.
 3/ weight gain.
 4/hypertension.

 treated by:1-Initial infusion of normal saline, then
infusion of half strength saline (0.45%) and later
with 5% dextrose, i.e. Gradual controlled
correction is done. Otherwise cerebral
 edema and hyperglycemia can develop.
 2-Oral and nasogastric administration of
water/fluids

B/POTASSIUM
 Normal daily intake is 1mmol/kg
 Potassium is mainly excreted in urine and
almost equals the intake.

Potassium depletion (hypokalemia) :
*Serum potassium level less than 3.5 mEq/L.
sudden:-It occurs in patients in diabetic
Gradual

Causes:
 1/excessive vomiting.
 2/external alimentary fistula.
 3/severe diarrhea.
 4/ type of diuretics like FUROSEMIDE.
 5/alkalosis.
 6/hyper aldosteronism.

 hypokalemia raises membrane excitation
potential which make nerves and muscles LESS
excitable.

*C/F:
1/most is Asymptomatic.
2/EARLY – malaise , weakness , slow
speech.
3/paralytic ileus.
4/muscular paralysis.
5/ECG reveals prolonged QT , depressed
ST, inversion T wave.

* treated by:
1/ at normal PH in the adult: calculated of
deficit potassium(4.6 serum concentration)x100.
2/the required quantity added to the infusion
and distributed all over the day;

safe rule to added potassium is
a) urine output at least 40 ml/Lt
b) not more than 40 mmol/L not fast than
40mmol/Hour
3/ correction causes of excessive loss

Potassium excess (hyperkalemia) :
 Normal range of potassium is 4.0 to 4.5
mEq/litre.
 Hyperkalaemia manifests when potassium
exceeds 6 mEq/litre.

*causes:
1-Renal failure.
2-Rapid infusion of potassium.
3-Transfusion of stored blood.
4-Diabetic ketoacidosis.

5-Adrenal insufficiency.
6-Potassium sparing diuretics, cyclosporine, beta
blockers.
Metabolic acidosis.

7- Insulin deficiency.
8-Tissue destruction, burns, trauma, tumor necrosis,
crush injury.
9-In vitro hemolysis, thrombocytosis, tourniquet
application , exercise pseudo hyper kalaemia.
10-Familial hyper kalaemic periodic paralysis

Treated by :
 Stop exogenous K administration and treat the
underlining cause
 Reverse cardiogenic effects via: 10 gm of 10%
calcium gluconate with ECG monitoring
 glucose insulin drip 10 and insulin plus 20m of
glucose.
 rapid alkalization of ECF by lactate/Hco3.

 Cation exchange resins. Continuous ECG
monitoring is a must.
 Salbutamol nebulization or intravenously 0.5
mg in 4 ml of saline/Albuterol nebulization.

IV sodium bicarbonate—shifts potassium in
to cells.
e)if all fail : HEMODIALYSIS.

C/ CALCIUM
 The serum calcium level is likely to be modified
by vitamin D , calcitonin ,parathyroid hormone,
renal& small bowel function.

Hypocalcemia:
 causes:
1/acute pancreatitis .
 2/hypo parathyrodism.
3/soft tissue infections.

*C/f:
 Carpopedal spasm.
 Chvostek's sign.
 Trousseau’s sign.
*Treatment:
1/ treating the underling cause
2/ oral or I.V infusion of calcium gluconate.

Hypercalcemia:
*causes:
1/malignancy
2/ hyper Vit D
3/Hyperparathyrodism
.

*C/F:
Fatigue , weakness , somnolence , coma.
*Treatment:
1/ Fluid replacement
2/ Diuretics
3/ Oral or I.V inorganic phosphates
4/ I.V Na sulphate

HYPERMAGNESAEMIA
 It is rare. Serum magnesium > 2.5 mEq/litre.
 Normal serum magnesium is 1.5-2.5 mEq/L
 Magnesium is mainly deposited in bone (60%)

Causes:
 1-Advanced renal failure treated with
magnesium containing antacids, diabetic
ketoacidosis.
 2- Intentionally produced hyper magnesaemia
while treating pre-eclampsia

Clinical Features:
1- Loss of tendon reflexes (most common).
2-Neuromuscular depression.
3- Flaccid quadriplegia.
4- Respiratory paralysis.
5- Somnolence.
6-Hypotension

HYPOMAGNESAEMIA
Serum magnesium < 1.5 mEq/litre.
 Causes
1-Malnutrition, alcohol.
2-Large GI fluid loss.
3-Patients on total parenteral nutrition.

Clinical Features
1-Hyperreflexia.
2-Muscle spasm.
3- Paresthesia.
4- Tetany.
5- It mimics hypocalcaemia. It is often associated
with hypokalemia and hypocalcaemia

Treatment:-
 Two gram (16 mEq) of magnesium sulphate
slow intravenously ,in 10 minutes. Later
maintenance dose of 1 mEq/kg/day as slow
continuous infusion is given/oral magnesium is
needed.

 Phosphateb ions :- are required for bone
mineralization
 About 740g is bound in mineral salt of the
skeleton
 In plasma it is reabsorbed from tubular fluid
along PCT
 Plasma concentration is 1.8-2.9mEq/l

Hyperphosphatemia:-
Serum phosphate up to4.5mg/dl
Causes:-
 1-chronic kidney disease
 2-hypoparathyrodism
 3-metabolic and respiratory acidosis

 c/f it due to effect of hypocalcemia
 lead to tetany muscle cramp

Hypophsphoatemia:-
 is rare due malnourished
 Decrease absorb intestine
 Increased remove by kidney
 Most familial form inherited condition

c/f:-
 Muscle weakness
 Fatigue
 Appetite loss
 Slowed growth in child
 Late baby teeth

IV Fluids
Management

Crystalloid versus colloid solutions
a. Crystalloid solutions use ions in the form of
salts (e.g., NaCl) as osmotically active
particles
b. Colloid solutions use proteins,
polysaccharides, and other
macromolecules as osmotically active
particles.

1. Hetastarch
 is a synthetic solution containing polysaccharides.
2. Albumin solutions (5% or 25%)
 are made from human plasma.
 Use of albumin solutions is questioned because of
their high cost and short half-life (< 24 hours).
Colloid solutions

3. Fresh frozen plasma (FFP)
 from human donors is a colloid solution
frequently used for repletion of clotting
factors during resuscitation.
 The use of colloid solutions for volume
resuscitation has not been shown to provide
additional benefit versus crystalloid solutions.

Maintenance fluids
 provide the minimal requirements for daily
water and electrolyte balance.

Estimations for maintenance IV
fluids
1. For the first 10 kg of body weight
give 100 mL/kg divided over 24 hours.
2. For the second 10 kg of body weight
administer 50 mL/kg.
3. All weight thereafter requires 20 mL/kg
divided over 24 hours.

Replacement of additional
fluid losses
 should approximate in volume and
electrolyte concentration the fluid that is
being lost

Input and Output of the “Normal” Adult

Types of Solutions used
 Isotonic solutions
 Hypotonic solutions
 Hypertonic solutions

Isotonic solutions
Fluids with approximately close osmotic
pressure to
blood cells.
Examples :
0.9% Saline
5% Dextrose in 0.225% saline (D5W1/4NS)
Lactated Ringer’s

Hypotonic solutions
Fluids which have less Osmotic pressure than
blood cells.
Examples :
0.45% Saline (1/2 NS)
0.225% Saline (1/4 NS)
0.33% saline (1/3 NS)

Hypertonic solutions
 Fluids which have greater osmotic pressure than
 blood cells.
 Examples :
 3% Saline
 5% Saline
 10% Dextrose in Water (D10W)
 5% Dextrose in 0.9% Saline
 5% Dextrose in 0.45% saline
 5% Dextrose in Lactated Ringer’s

ACID BASE
BALANCE
(2020)

 Normal pH : 7.35-7.45
 Acidosis
 Physiological state resulting from abnormally low
plasma pH
 Alkalosis
 Physiological state resulting from abnormally high
plasma pH

 Acidemia: plasma pH < 7.35
 Alkalemia: plasma pH > 7.45

Four Basic Types of Imbalance
 • Metabolic Acidosis
 • Metabolic Alkalosis
 • Respiratory Acidosis
 • Respiratory Alkalosis

Difference between the various
types of acidosis and alkalosis

Defect COMMON CAUSES
Bicarbonate
/carbonic
acid ratio
(20/1)
▪compensation
Met
acidosis
▪Retention of
fixed acids
▪Loss of base
HCO3-
▪DIABETES, uraemia
▪Increased lactic
acid
▪Diarrhea
▪Small bowel
fistulae
•Reduced
▪Pulmonary (rapid)
▪Increased rate and depth of
breathing
▪Renal (slow)
Met
alkalosis
▪Loss of fixed
acids
▪Gain of base
HCO3-
▪Vomiting , pyloric
stenosis
•Elevated
▪Pulmonary (rapid), reduced rate and
depth of breathing.
▪Renal (slow)
Res
acidosis
▪Retention of
co2
▪(hypo-
ventilation)
▪Depression of
respiratory center
▪Obstructive
pulmonary disease
▪Reduced
▪Renal retention of HCO3- ,excretion
of H+
▪Chloride shift into red blood cells
Res
alkalosis
▪Excessive
loss of Co2
(hyper-
ventilation)
▪hyperventilation ▪Elevated
▪Renal excretion of HCO3- and
retention of H+

ARTERIAL BLOOD GAS
ANALYSIS (ABG)
 • Drawn from artery- Radial, Brachial,
Femoral
 • It is an invasive procedure

Indications of ABG
 • Assess adequacy of ventilation and
oxygenation
 • Aids in establishing a diagnosis and severity
of respiratory
 failure
 • Assess changes in acid- base homeostasis
 • Helps to guide treatment plan
 • Helps in management of ICU patients.

Components of an ABG
Normal Values
 – pH - 7.35 - 7.45
 – PaCO2 - 35-45 mmHg
 – PaO2 - 80-100 mmHg
 – HCO3 - 22-26
 – O2sat - 95-100%
 – Base Excess - +/-2 m Eq/L

References:
 General Surgery (Board Review Series) 1st Edition
 SRB's Manual of Surgery, 3rd Edition
 Schwartz's Principles of Surgery, 11edition
 Bailey & Love's Short Practice of Surgery, 27th edition
 Alkaaser Alainy

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