2. INTRODUCTION
ANATOMY OF BODY FLUIDS AND ELECTROLYTE COMPOSITION.
• Fluid physiology varies with age, sex and lean body mass.
• Total body water= about 55% in females and 60% in males.
3. Average fluid intake and output of a healthy
adult.
Intake volume Output volume
Water from beverage
(exogenous)
1200ml Urine 1500ml
Water from food
(exogenous)
1000ml Insensible losses (lungs
and skin)
900ml
Water from oxidation
(endogenous)
300ml Faeces 100ml
4. Distribution of electrolytes .
ECF:
• Major cation- sodium.
• Major anion- chloride.
ICF:
• Major cation- potassium.
• Major anions-phosphate, sulfate,
proteins.
5. Classification of body fluid changes
• Disturbances in fluid volume.
• Disturbances in concentration and composition
6. 1. Volume balance disturbance (dehydration)
• Extracellular volume deficit is most common.
• Causes:
Isotonic water loss- diarrhoea, vomiting, and excess diuresis.
• Features - dry tongue, rapid pulse, collapsed neck veins,cold
clammy extremities, sunken eyes, hypotension, oliguria, raised
blood urea, decreased urinary sodium.
Pure water loss- poor fluid intake, diabetes insipidus.
• Features —severe thirst, confusion and convulsions due to
hypernatraemia; blood pressure is relatively normal.
7. Management
• Evaluation is done by doing serum sodium, urinary sodium, and blood
urea.
• Isotonic volume depletion is corrected by 0.9% normal saline.
• Pure water depletion is corrected by more water intake/ intravenous
5% dextrose.
• Monitoring fluid therapy by skin and tongue examination, weight
gain, pulse, blood pressure, CVP.
8. Volume balance disturbance (volume excess)
Can be:
• Water and salt excess -CCF, cirrhosis, nephrotic syndrome,
hypoproteinaemia, renal failure, excessive saline infusion.
• Water intoxication-TURP, excess infusion of 5% dextrose only, SIADH
secretion, psychogenic polydypsia.
Features : Drowsiness, weakness, convulsions and coma, tachycardia,
pulmonary edema, hypertension, bilateral basal crackles, ascites,
nausea, vomiting, gain in body weight, passage of dilute urine, pedal
edema
9. Management
• Investigations- Haematocrit , UECs- low sodium level, low potassium,
low blood urea.
• Treatment
• Water and salt restriction and observation.
• Monitoring in ICU.
• Infusion of hypotonic sodium chloride.
• NB: Administration of diuretics and hypertonic saline should be
avoided- may cause neuronal demyelination
12. Management
• Investigations: UECs, urinary sodium.
• Treatment
• Intravenous infusion of normal saline as a slow and gradual
correction at a rate of 2 mEq/L/hour in acute cases and 0.5
mEq/L/hour in chronic cases.
• Correction should not exceed more than 20 mEq/L/day in acute
cases and more than 10 mEq/L/day in chronic cases.
• Hypertonic saline of 1.6% or 3% also can be used in severe cases.
• Treat the cause
13. Hypernatremia
Serum sodium concentration above 145mmol./L
• Causes
• Euvolemic - failure of water intake, high fever, diabetes insipidus,
chronic renal failure.
• Hypovolaemic- vomiting, diarrhoea, excess sweating, osmotic
diuresis by glucose/ mannitol.
• Hypervolaemic - more salt intake, excess steroids, sodium
bicarbonate/hypertonic saline infusion.
Features:
restlessness, lethargy, ataxia, irritability, tonic spasms, delirium,
seizures, coma, weakness, tachycardia, hypotension, syncope, dry,
sticky mucous membranes, decreased saliva and tears.
14. Management
• Treat the associated water deficit.
• In hypovolemic patients, volume should be first restored with normal
saline then concentration abnormality.
• The water deficit is replaced using a hypotonic fluid such as 5%
dextrose in one quarter normal saline.
16. Management of hyperkalemia
1. Reducing the total body potassium
• reduce intake.
• decrease absorption in the gut, by using a cation-exchange resin eg
Kayexalate.
• increase loss in urine e.g. loop diuretics.
2. Shifting potassium from the extracellular to the intracellular space
using glucose and insulin.
3. Protecting the cells from the effects of increased potassium using
calcium chloride or calcium gluconate.
18. Management of hypokalemia
• Oral potassium 2 g*6, 15 ml potassium chloride syrup (20 mmol of K).
• IV KCl 40 mmol/litre given in 5% dextrose or normal saline slowly,
often under ECG monitoring [Total dose is 40 mmol (0.2 mmol
/kg/hour). Maximum dose per hour is 20 mmol].
19. Calcium abnormalities
Normal serum calcium-8.5 to 10.5 mmol/L (normal ionized calcium-4.2
to 4.8mmol/L).
• Hypercalcemia- serum Ca > 10.5mmol/L or ionized Ca levels>
4.8mmol/L.
• Causes: primary hyperparathyroidism, malignancy.
• Signs and symptoms:
hypertension, cardiac arrhythmias, polyuria, polydipsia, weakness,
confusion, coma, bone pain, anorexia, nausea, vomiting, abdominal
pain.
20. Hypocalcemia
• Serum Ca level <8.5mmol/L or ionized Ca level < 4.2mmol/L.
• Causes: pancreatitis, necrotizing fasciitis, renal failure, pancreatic and
small bowel fistulas, hypoparathyroidism, parathyroidectomy, toxic
shock syndrome.
• Signs and symptoms: paresthesias of the face and extremities, muscle
cramps, carpopedal spasm, stridor, tetany, seizure, hyperreflexia,
decreased cardiac contractility and heart failure.
21. Management of calcium abnormalities
• Management of hypercalcemia- repleting the associated volume
deficit and then inducing diuresis with normal saline.
• Management of hypocalcemia- calcium supplementation.
23. Management
Hypomagnesemia
• 2g (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
24. Hypermagnesemia
• Serum Mg > 1.1mmol./L.
• Causes: excess magnesium intake, total parenteral nutrition, massive
trauma, thermal injury and severe acidosis.
• Signs and symptoms:
nausea and vomiting, weakness, lethargy, decreased reflexes,
hypotension, arrest.
Rx- restrict intake
25. Phosphate abnormalities
• Normal serum phosphate levels- 1.12 to 1.45 mmol./L.
Hypophosphatemia- serum phosphate levels < 1.12 mmol./L.
• Causes malabsorption, decreased dietary intake, respiratory alkalosis,
insulin therapy.
• Symptoms can manifest as cardiac dysfunction or muscle weakness.
26. Hyperphosphatemia
Serum phosphate levels > 1.45mmol./L.
• Causes: hypoparathyroidism, hyperthyroidism, excessive
administration from IV hyperalimentation solutions or phosphorus-
containing laxatives.
• Most patients are asymptomatic. Prolonged hyperphosphatemia can
lead to metastatic deposition of soft tissue calcium-phosphorus
complexes.
27. Acid- base disorders.
• Normal pH ranges from 7.35 to 7.45.
• pH below 7.35 indicate acidosis, pH above 7.45 indicate alkalosis.
• Normal range PaCO2 of 35-45mmHg and serum concentration of
HCO3 range of 21-28 mmol./L.
29. Acid- base disorders
Respiratory acidosis
• Causes: CNS injury, pulmonary atelectasis or increased secretions,
narcotics.
• Signs and symptoms: mental cloudiness, signs of increased
intracranial pressure such as papilledema.
• Treatment: improve ventillation
30. Acid-base disorders
Metabolic acidosis
• Causes: ketoacidosis, exogenous acid ingestion, loss of bicarbonate
ions, diarrhea.
• Signs and symptoms: increased rate and depth of breathing.
• Treatment: treat underlying cause.
31. Acid base disorders
Respiratory alkalosis.
• Causes: hyperventilation, anxiety, hypoxemia, cerebral tumors.
• Signs and symptoms: loss of consciousness, tachycardia, light
headedness
• Treatment: treat the underlying cause.
32. Acid-base disorders
Metabolic alkalosis
• Causes: GIT losses due to vomiting, bicarbonate retention as in milk-
alkali syndrome, NaHCO3 administration.
• Signs and symptoms: Cheyne-Stokes respiration, apnoea, tetany
• Treatment: replacement of chloride ions.
33. FLUID AND ELECTROLYTE THERAPY
INDICATIONS
oFluid Resuscitation- to restore intravascular volume in hypovolemic
patients.
oReplacement of ongoing losses- such as in burns, and replacement of
free water deficit- in the treatment of dehydration.
oCorrection of electrolyte imbalances.
oRoutine maintenance- for patients who cannot or are not allowed to
take fluids orally following addition of 30ml/kg/h or using 4,2, 1 rule.
34. Nature and volume of fluids are determined
by:
• Assessment of vital signs-pulse, BP.
• Clinical examination- assess hydration status (skin tugor, urine
output). Investigations- urine, serum electrolytes and hematocrit.
• Estimation of losses already incurred and their nature, through
vomiting.
• Estimation of supplemental fluids for future losses from fistulae,
nasogastric tube.
• Determination of appropriate replacement fluid from consideration of
the electrolyte composition of secretions.
35. Parenteral solutions used for therapy
Crystalloids- are aqueous solutions of
mineral salts and other water soluble
molecules.
• Isotonic solutions: Plasma-Lyte,
lactated Ringer’s solution,
normal saline.
• Hypotonic solutions: 0.45%
sodium chloride, 5% dextrose.
• Hypertonic solution: 3.5%, 5%,
7.5% hypertonic saline solutions.
Colloids- contain larger insoluble
molecules.
• Natural: Albumin (5% and 25%)
• Synthetic: dextrans (dextran 40
and 70), starch (hetastarch),
gelatins (gelofusine, plasmagel,
polygeline).
37. Differences between colloid and crystalloids
Colloids
• Have large particles (1-200nm).
• Are heterogeneous solutions.
• Replaces fluid volume for
volume.
• There is risk of anaphylactic
reactions.
• Replaces mostly extracellular
fluid volume (intravascular)
Crystalloids
• Have small particles (<1nm).
• Are homogeneous solutions.
• Replaces fluid volume 3 times
the volume needed.
• Non- allergenic.
• Replaces both intracellular and
extracellular fluid volume.
39. Colloids
ALBUMIN- protein normally synthesized by the liver.
Indications:
• Hypoalbuminemic states i.e. albumin < 2.5mg/dL (e.g. following
paracentesis, liver cirrhosis)
• If crystalloid fluid resuscitation has caused significant edema.
• Acute management of severe burns
• Spontaneous bacterial peritonitis (SBP).
40. Colloids
GELATIN- large molecular weight proteins formed from hydrolysis of
collagen.
Indications:
• Acute management of hemorrhagic hypovolemia
• Volume preloading before regional anesthesia
41. Colloids
ADVERSE EFFECTS OF COLLOIDS
• Anaphylaxis
• Volume overload
• Interference with blood grouping and cross matching
• Pruritus with prolonged use
• Nephrotoxicity.
42. Refeeding syndrome
• Occurrence of severe fluid and electrolyte imbalance in severely
malnourished individual while starting the proper feeding enteral or
parenteral nutrition.
• Common in chronic starvation, severe anorexia and alcoholic patients.
• Causes hypomagnesaemia, hypocalcaemia and hypophosphataemia
leading to:
• myocardial dysfunction, respiratory changes, altered liver
functions, altered level of consciousness, convulsions and often
death
43. Management
• Administer thiamine before initiation of feeding
• Gradual feeding
• Correction of magnesium, phosphate and calcium and other
electrolytes
• Monitor vitals, fluids balance and electrolytes
