This document discusses total body water and fluid compartments. It notes that total body water makes up 50-70% of body weight and is divided into intracellular fluid and extracellular fluid. Intracellular fluid makes up the largest proportion and contains potassium and magnesium as principal ions. Extracellular fluid contains sodium and chloride as principal ions and exists in both interstitial and intravascular spaces. The document then discusses daily water intake and losses, causes and signs of fluid volume and composition changes, and electrolyte abnormalities involving potassium, calcium, and magnesium. It concludes with sections on preoperative, intraoperative, and postoperative fluid therapy.

1. Dr. Muhammad Saifullah
HOUSE SURGEON (SU-III)

2. Total Body Water
Intracellular Fluid
Extracellular Fluid

3. constitutes 50-70 % of total body weight
fat contains little water, the lean individual
has a greater proportion of water to total
body weight thanthe obese person
total body water as a percentageof total
body weight decreases steadily and
significantly with increasing age

4. %of Body Weight %of Total Body Water
Body Water 60 100
ICF 40 67
ECF 20 33
Intravascular 4 8
Interstitial 16 25

5. largest proportion in the skeletal muscle
potassium and magnesium arethe
principal cations
phosphates and proteins the principal
anions

6. interstitial fluid: two types
functional component (90%) - rapidly equilibrating
nonfunctioning components (10%) - slowly
equilibrating
connective tissue water and transcellularwater
called a “third space” or distributionalchange
sodium is the principal cation
chloride and bicarb theprincipal anions

7. Water Exchange
Salt Gain &Losses

8. daily water gains
normal individual consumes 2500mL
water per day
approximately 2000-2200 mL taken by
mouth…half in Solid food!!!
rest is extracted from food as the product
of oxidation, about 300-500 mL

9. daily water losses
60-150 mL in stools, 1500 mL in urine, and 600 mL as
insensible loss
total losses ~ 2.2 liters
Insensible loss: skin (75%) and lungs(25%)
increased by hypermetabolism, hyperventilation, and fever
250 mL/day per degree offever
unhumidified tracheostomy with hyperventilation=
insensible loss up to 1.5L/day

10. Minimum of 400mLurine per24hrs
required to excrete the products of
protein catabolism

11. daily salt intake varies 3-5 gm asNaCl
kidneys excretes excess salt: can vary from < 1to> 200
mEq/day
Volume and composition of various typesof
gastrointestinal secretions
Gastrointestinal losses usually are isotonic orslightly
hypotonic
should replace by isotonic saltsolution

12. Volume Changes
Concentration Changes
Composition Changes
Potassium Abnormalities
Calcium Abnormalities
Magnesium Abnormalities

13. If isotonic salt solution is added to or lost from
the body fluids, only the volume of the ECF is
changed, ICF is relatively unaffected
If water is added to or lost from the ECF, the conc.
of osmotically active particles changes
Water will pass into the intracellular space until
osmolarity is again equal in the two compartments

14. BUN level rises with an ECF deficit ofsufficient
magnitude to reduce GFR
creatinine level may not incr. proportionally in young
people with healthy kidneys
hematocrit increases with an ECF deficit and decreases
with ECF excess
sodium is not reliably related to the volume status of
ECF
a severe volume deficit may exist with a normal,
low, or high serum level

15. ECF volume deficit is most common fluid loss in
surgical patients
most common causes of ECF volume deficit are: GI
losses from vomiting, nasogastric suction,diarrhea,
and fistular drainage
other common causes: soft-tissue injuries and
infections, peritonitis, obstruction,
and burns

16. signs and symptoms of volumedeficit:
CNS: sleepy, apathy – stupor, coma
GI: dec food consumption –N/V
CVS: orthostatic, tachy, collapsed veins
- hypotension
Tissue: dec skin turgor, small tongue –
sunken eyes, atonia

17. Iatrogenic or Secondary to renalinsufficiency,
cirrhosis, or CHF
signs &symptoms of volume excess:
CNS: none
GI: edema of bowel
CVS: elevated CVP, venous distension –
pulmonary edema
Tissue: pitting edema –anasarca

18. Na+ primarily responsible for ECFosmolarity
Hyponatremia and hypernatremia s&s often occurif
changes are severe or occurrapidly
The concentration of most ions within the ECF can be
altered without significant osmolality change, thus
producing only a compositional change
Example: rise of potassium from 4 to 8 mEq/L would
significantly effect the myocardium, but not the effective
osmotic pressure of the ECF

19. acute symptomatic hyponatremia (<130)
hypertension can occur &is probably induced by therise in
intracranial pressure
signs &symptoms:
CNS: twitching, hyperactive reflexes – inc ICP,
convulsions, areflexia
CVS: HTN/brady due to incICP
Tissue: salivation, watery diarrhea
Renal: oliguria - anuria

20. Hyponatremia occurs when water is given to replace
losses of sodium-containing fluids or when water
administration consistently exceeds water losses
Hyperglycemia: glucose exerts an osmotic force in the
ECF and causes the transfer of cellular water into the
ECF, resulting in a dilutional hyponatremia

21. The only state in which dry, sticky mucous membranes are
characteristic
sign does not occur with pure ECF deficit alone
signs &symptoms:
CNS: restless, weak - delirium
CVS: tachycardia - hypotension
Tissue: dry/sticky muc membranes – swollentongue
Renal: oliguria
Metabolic: fever – heat stroke

22. Potassium Abnormalities
Calcium Abnormalities
Magnesium Abnormalities

23. normal daily dietary intake of K+ is approx. 50to
100 mEq
majority of K+ is excreted in the urine
98% of the potassium in the body is located in ICF
@150mEq/L and it is the major cation of
intracellular water
intracellular K+ is released into the extracellular
space in response to severe injury or surgical stress,
acidosis, and the catabolicstate

24. signs &symptoms:
CVS: peaked T waves, widened QRS
complex, and depressed ST segments
Disappearance of T waves, heart block,
and diastolic cardiac arrest
GI: nausea, vomiting, diarrhea
(hyperfunctional bowel)

25. K+ has an important role in the regulation of acid-base
balance
alkalosis causes increased renal K+/H+ excretion
signs &symptoms:
CVS: flatten T waves, depressed STsegments
GI: paralytic ileus
Muscular: weakness - flaccid paralysis, diminished to
absent tendon reflexes

26. majority of the 1000 to1200g of calcium in the
average-sized adult is found in the bone
Normal daily intake of calcium is 1to 3gm
Most is excreted via the GI tract
half is non-ionized and bound to proteins
ionized portion is responsible forneuromuscular
stability

27. signs &symptoms (serum level < 8):
numbness and tingling of the circumoral region and the
tips of the fingers and toes
hyperactive tendon reflexes, positive Chvostek's sign,
muscle and abdominal cramps, tetany with carpopedal
spasm, convulsions (with severe deficit), and
prolongation of the Q-T interval on the ECG

28. causes:
acute pancreatitis, massive soft-tissue
infections (necrotizing fasciitis), acute
and chronic renal failure, pancreatic
and small-bowel fistulas, and
hypoparathyroidism

29. signs &symptoms:
CNS: easy fatigue, weakness, stupor, and
coma
GI: anorexia, nausea, vomiting, and
weight loss, thirst, polydipsia, and
polyuria

30. two major causes:
hyperparathyroidism and cancer
bone mets
PTH-like peptide in malignancies

31. total body contentof magnesium 2000 mEq
about half of which is incorporated in bone
distribution of Mg similar to K+, the major
portion being intracellular
normal daily dietary intake of magnesium is
approximately 240 mg
most is excreted in the feces and the remainder in
the urine

32. causes:
starvation, malabsorption syndromes, GI
losses, prolonged IV or TPN with
magnesium-free solutions
signs &symptoms:
similar to those of calciumdeficiency

33. Symptomatic hypermagnesemia, although rare, is
most commonly seen with severe renal insufficiency
signs &symptoms:
CNS: lethargy and weakness withprogressive loss of
DTR’s – somnolence, coma, death
CVS: increased P-R interval, widened QRS complex, and
elevated T waves (resemble hyperkalemia) – cardiac
arrest

35. Preoperative Fluid Therapy
Intraoperative Fluid Therapy
Postoperative Fluid Therapy

36. Correction of Volume Changes: Volume deficits result
from external loss of fluids or from an internal
redistribution of ECF into a nonfunctional compartment
nonfunctional because it is no longer able to participate in the
normal function of the ECF and may just as well have been lost
externally
Correction of Concentration Changes: If severe
symptomatic hypo or hypernatremia complicates the
volume loss, prompt correction of the concentration
abnormality to the extent that symptoms are relieved is
necessary

37. replace losses &supply amaintenance:
open abdomen losses: 8 cc/kg/hr
NGT &urine output
Blood loss x 3
Replace with isotonic salt solution (LR orNS)
unwise to administer potassium during the first 24 h,
until adequate urine output has been established even a
small quantity of potassium may be detrimental
because of fluid shifts

38. Postoperative fluids:
1Dextrose saline will produce hyponatraemia in a
postoperative patient.
2Alternate bags of saline and dextrose saline with
supplementary potassium give the best balance.
Fluids distribute into:
1Colloid(blood, albumin or gelatine solution ) stays in the
vascular compartment.
2Saline stays in the extracellular compartment.
3-Dextrose eventually goes to all compartment