management of Fluid & electrolytes disturbances.pptx

Fluid & Electrolytes Disturbances
Haythem M. G. Ahmed
MBBS, MRCSed, MSc. Human anatomy

Introductory questions:
1. What is the normal specific gravity (SG) of urine in a
normal adult?
2. What is the normal urine PH in a normal adult?
3. What is the normal volume of the ECF in a normal adult?
4. What is the definition of the third space in the fluid
compartments?
5. What is the normal urine output per hour in a normal
adult?
6. How much Sodium is present in 1 L of 0.9% NaCl?

Intended learning outcomes (ILO);
• By the end of this session audience are expected to be able to:
1. Mention the different fluid compartments & their volumes.
2. Describe the basic physiological concepts of fluid homeostasis.
3. Calculate the daily maintenance & deficit of fluid & electrolytes.
4. Discuss the causes, presenting symptoms & signs of the commonly
encountered electrolyte disturbances.
5. Illustrate the best clinical practice in managing fluid & electrolytes
disturbances.

Contents:-
• Basic physiology
• Daily maintenance & fluid balance
• Correction of fluid deficit
• Correction of electrolytes disturbances
 Hyper/hyponatremia
 Hyper/hypokalemia

Basic physiology:
• 60% of the total body weight in a 70 kg young adult male is
composed of water.
• That is TBW = 60/100 x 70 = 42 L
• 2/3 of this volume is in the ICF compartment = 28 L
• 1/3 of this volume is in the ECF compartment = 14 L
- which is further subdivided into =>
 ISF = ¾ of the ECF = 10.5 L
 IVF = ¼ of the ECF = 3.5 L

Tintinalli’s Emergency Medicine 8th edition, page 93

The third space :
• Is a collection of ECF which though present within the body
• It is not functional (always pathological).
• Examples include:
- Intestinal fluid collection in intestinal obstruction
- Ascites
- pleural effusion
- Pericardial effusion

Fundamentals for fluid balance:
1. Electrolyte free water.
2. Sodium together with the water needed for its iso-osmotic so
lution.
3. Potassium.
4. Other electrolytes (Acid-Base adjustment).

To have the ideal situation two assumptions
are made:
I. The patient is a typical 70 kg of body weight.
II. The renal function is adequate =>
a. The patient is able to concentrate proteins and glucos
e in urine to a specific gravity of 1.016 or higher
b. He is able to acidify urine to a PH of 5.8 or lower.

ECF conc. of the most important electrolytes;
Na+ 135 - 145 mmol/L
K+ 3.5 – 4.5 mmol/L
Chloride 85 - 115 mmol/L
Bicarbonate 22 - 28 mmol/L
Ca++ 2.2 – 2.6 mmol/L
4.4 – 5.5 mEq/ L
9 – 11 mg / dL
Mg++ 0.75 – 1 mmol/L
1.5 – 2.5 mEq/ L

Indication for IV fluid therapy:
A. Maintenance
• Examples:
1. Patients who are put NPO as
in the pre or post-operative
period.
2. Patients with acute
abdomen under observation
e.g. intestinal obstruction,
pancreatitis, ….etc
B. Deficit
• Excessive fluid loss due to
any pathology; Examples:
- Vomiting
- Diarrhea
- Burns
- Bleeding.

Fluid balance
Daily fluid intake Daily fluid output
Drinking 1.3 L Urine 1.5 L
Food 0.9 L Sweating &
insensible losses
0.9 L
Metabolism 0.3 L Stool 0.1 L
Total 2.5 L Total 2.5 L
* N.B: The above values may vary greatly in various physiologic & pathologic
conditions.

Daily requirements of fluids & electrolytes;
• Water = 30 - 35 ml/kg/day = 2 - 3 liters per day
• Sodium = 1 - 2 mmol/kg/day = 75 - 150 mmol/day
 0.9% NaCl drips contain 154 mmol of Na+ / 1 L
• potassium = 1 mmol/kg/day = 60 - 80 mmol/day
 Each ampule of KCl contains 20 mmol of K+

In short for a 70 kg male pt. we need;
 3 liters of water
 150 mmol of Na+
 60 mmol of K+

The composition of commonly used IV fluids in mmol/L:
Solution Na K Cl HCo3
Ringer lactate 138 4 109 28
Normal saline
0.9%
154 0 154 0
5% Dextrose 0 0 0 0

So our maintenance plan for a 70 kg pt. will be;
• 1 L of normal saline per day (NaCl 0.9%)
• 2 L of D5% per day (D5%)
• 60 mmol of K+ per day
• 1 L of NaCL 0.9% => in the morning
• 1L of D5% => in the afternoon
• 1L of D5% => in the evening
• With 20 mmol of KCl in each shift

The rule of 4 :-
1. Drip that contains K+ should run over 4 hours
2. A maximum dose of 40 mmol/drip
3. Urine output > 40 ml/hour
4. Serum K+ < 4 mmol/L

Maintelyte solution for infusion
Content of electrolytes per 1000 ml:
• Na
+
= 40 mmol
• K
+
= 20 mmol
• Mg
2+
= 1.5 mmol
• CH3COO
-
= 23 mmol
• Cl
-
4 = 40 mmol
• Glucose = 50 gram

Contraindications of Maintelyte:
The solution is contra-indicated in patients presenting:
• Hyperkalaemia
• Severe renal insufficiency (with oliguria/anuria)
• Uncompensated cardiac or pulmonary failure
• The solution is also contraindicated in case of uncontrolled
diabetes, other known glucose intolerances, hyperosmolar
coma, hyperglycaemia, hyperlactataemia.

Correction of fluid deficit
• Ringer lactate/Hartman’s solution/Plasmalyte is always
superior to NaCl 0.9% in correcting fluid deficit because it
has the same electrolytes concentration found in the
plasma.
• The rule is always replace like with like.
• Any contraindication for ringer lactate use? Why?
• What to use instead?

Hypernatremia
• Defined as serum sodium > 145 mmol/L
• Intense thirst may be present initially.
• The hypertonicity of the plasma leads to shrinkage of
neuronal cells resulting in the following symptoms:
- Dizziness
- Confusion
- seizures
- ultimately coma and death.

Classification of hypernatremia
S. W. Kim, Hypernatemia: Successful Treatment, Electrolyte & Blood Pressure 4: page 68, 2006

Correction of Hypernatremia
• The water deficit in the hypernatremic patient can
be estimated from the following formula:
• CBW refers to estimated current body water.

Correction of Hypernatremia
• For example:
 A 70 kg elderly with a plasma sodium concentration of 170
mEq/L.
- Calculate the water deficit?
- Which fluid to use?
- what is the rate of correction?

Hyponatremia
• Defined as serum sodium < 135 mmol/L.
• The hypotonicity of the plasma leads to swelling of neuronal
cells ( if hyponatremia develops rapidly) resulting in the
following symptoms & signs:
- Nausea & vomiting
- headache
- Confusion & Low GCS
- seizures
- ultimately coma and death
(High ICP)

Classification of
hyponatremia

Correction of Hyponatremia
• In patients with acute symptomatic hyponatremia (Seizures
or Coma) the best approach is:
 Infuse 100 mL bolus of 3% hypertonic saline IV over 10–15
min.
 Measure serum sodium level after each bolus.
 Repeat 100 mL of 3% hypertonic saline up to three total
doses, or a total of 300 mL IV of 3% hypertonic saline.
 Stop infusion when symptoms improve, or a target of 5
mEq/L (range 4–6 mEq/L) is achieved.

• In asymptomatic patients or after the relieve of symptoms in
symptomatic patients correction is continued with the
following formula:
 Sodium deficit = (desired sodium – current sodium)xCBW
• CBW refers to estimated current body water

• For a 70 kg elderly male with a serum Na of 110 mmol/L?

= (140 – 110) x0.5x70 = 30x35 = 1050 mmol

= (140 – 110) x0.5x70 = 30x35 = 1050 mmol
• Infusion rate =(1050x1000)/(500x72)= 29.16 ml/hour (of 3%)

= (140 – 110) x0.5x70 = 30x35 = 1050 mmol
• Infusion rate =(1050x1000)/(500x72)= 29.16 ml/hour (of 3%)
• Infusion rate =(1050x1000)/(154x72)= 94.7 ml/hour(of 0.9%)

Contents;
• Basic physiology
• Daily maintenance & fluid balance
• Correction of fluid deficit
• Correction of electrolytes disturbances
 Hyper/hyponatremia
 Hyper/hypokalemia

Hyperkalemia
• Defined as serum K > 4.5 mmol/L.
• A plasma potassium >6.5mmol/L is an emergency &
needs urgent treatment.
• The worry is of myocardial hyper-excitability leading
to VF & death.

Causes of Hyperkalemia
1. Oliguric renal failure
2. K+ sparing diuretics
3. Rhabdomyolysis, burns
4. Metabolic acidosis (DM)
5. Excess K+ therapy
6. Addison's disease
7. Massive blood transfusion
8. Drugs, e.g: ACE inhibitors,
suxamethonium
9. Artefact:
- Hemolysis of sample
- Delay in analysis (K+ leaks out
of RBCs).
- Thrombocythaemia (K+ leak
out of platelets during clotting).

Signs & symptoms include:
 Chest pain
 palpitations
 Lightheadedness.
 Muscle weakness.
 Fast irregular pulse.
 Cardiac arrhythmias & Sudden death.

ECG changes:
 Tall tented T waves;
 small P wave;
 prolongation of the PR interval
 wide QRS complex
 Sine wave
 Ventricular fibrillation.

Correction of hyperkalemia
 If moderate elevation and no ECG changes =>
a. Increase excretion (resin or diuretics)
b. Decrease intake
 If severe hyperkalemia (K >6.5) or ECG changes =>
a. Immediate stabilization of the heart
b. Rapid shifting of potassium to the ICF
c. Total body potassium elimination.
d. Discontinue any exogenous sources of potassium

Correction of hyperkalemia
 IV Ca gluconate 10 ml of 10% solution over 2 – 3 min
 IV insulin 5 IU + IV glucose (50 ml of D50%)
 Inhaled salbutamol
 IV sodium bicarbonate (if acidotic)
 Dialysis

Hypokalemia
• Defined as serum K < 3.5 mmol/L.
• If K < 2.5 mmol/L urgent treatment is required (IV
correction).
• Hypokalemia exacerbates digoxin toxicity.

Causes of Hypokalemia
1. Diuretics
2. Vomiting and diarrhea
3. Pyloric stenosis
4. Villous adenoma rectum
5. Intestinal fistulae
6. Conn's syndrome
7. Alkalosis
8. Cushing's syndrome,
steroids, ACTH
9. Purgative and liquorice
abuse
10.Renal tubular failure

Signs & symptoms:
 Muscular weakness
 Hypotonia, hyporeflexia
 Cramps
 Constipation (Paralytic ileus)
 Palpitations
 Light headedness (Arrhythmias)

ECG changes in hypokalemia:
• STUPID 
 S => ST segment depression
 T => shallow / inverted T wave
 U => U wave prominence
 P => peaked P wave
 I => Increased PR interval
 D => De Hypokalemia  ..

Correction of hypokalemia
• Start IV correction only if serum K < 2.5
• For e.g. if a 70 kg elderly male has serum K of 2 mmol/L
• K deficit = (desired conc. – current conc.)x wt. x 0.5

Correction of hypokalemia
• Start IV correction only if serum K < 2.5
• For e.g. if a 70 kg elderly male has serum K of 2 mmol/L
• K deficit = (desired conc. – current conc.)x wt. x 0.5
= (4– 2) x 70 x 0.5 = 2 x35 = 70 mmol of K+

Assessment questions:
1. What is the normal specific gravity (SG) of urine in a
normal adult?
2. What is the normal urine PH in a normal adult?
3. What is the normal volume of the ECF in a normal adult?
4. What is the definition of the third space in the fluid
compartments?
5. What is the normal urine output per hour in a normal
adult?
6. How much Sodium is present in 500 ml of 0.9% NaCl?

Conclusion
• Be aware of what you are treating (Maintenance/Deficit).
• Always remember the daily fluid & electrolyte requirement
when prescribing IV fluids.
• Hyperkalemia is dangerous !!

References
1. Tintinalli’s Emergency Medicine 9th edition
2. Oxford Handbook of Medicine 9th edition
3. Baiely Bailey & Love’s Short Practice of Surgery 26th edition
4. S. W. Kim, Hypernatemia: Successful Treatment, Electrolyte & Blood
Pressure 4:66-71, 2006.

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