This document discusses water and electrolyte balance, which is important for homeostasis and maintained by the kidneys. Changes can occur pre, intra, and postoperatively or with trauma/sepsis. Total body water is about 60% of body weight, with two thirds being intracellular fluid and one third extracellular fluid. Electrolytes like sodium, potassium, and calcium are also discussed in relation to their distribution and role in fluid balance.

2.  Water & electrolyte balance is important for
body hemostasis & is one of the most
protected physiological mechanism in body
 A critical role of kidney is to maintain
circulating volume, plasma osmolality &
electrolyte hemostasis within relatively
narrow limit
 Changes in both fluid volume & electrolyte
composition occur preoperatively,
intraoperatively & postoperatively, as well
response to trauma or sepsis

3. •Varies with age, gender and body habitus

4. Total body water (TBW)
(70kg man )
42L
ECF
1/3 of TBW
14 L
ICF
2/3 of TBW
28L
Interstitial fluid
¾ of ECF
11 L
Plasma
¼ of ECF
3L
TBW =0.6X Body Weight

7. • ECF
• Intravascular fluid: within blood vessels (5%)
• Interstitial fluid: between cells - blood vessels
(15%)
• Transcellular fluid: cerebrospinal, pericardial,
synovial
• ICF
• Inside cell
• Most of body fluid here - 40% weight
• Decreased in elderly

8. • Electrolyte :
• …is a substance capable of conducting
electric current in solution.
• They exist in ions
• > Cations : Na+, K+, Ca++ etc.
• > Anions : Cl-, HCO3
-

9. Component ECF ICF
Na+ High Low
K+ Low High
Ca++ Low Low (higher
than ECF)
Proteins High High

10. • DIFFUSION: movement of solute particles along
concentration gradient.
• OSMOSIS: movement of solvent across a
semipermeable membrane into regions of higher
solute concentration.
• Osmolarity = solute/(solute+solvent)
• (normal 280-310mosm/L)

11.  OSMOLALITY: = solute/solvent (285-290mosm/kg)
Plasma osmolality= 2x(Na) + (Glucose/18) + (Urea/2.8)
• TONICITY: effective osmolality with respect to a
semipermeable membrane.
Plasma tonicity = 2 x (Na) + (Glucose/18)
Important in determining distribution of fluids across a cell
membrane and sensed by hypothalamic osmoreceptors.

12. Renal sympathetic nerves
Renin-angiotensin-
aldosterone system
Atrial natriuretic peptide (ANP)

14. 1. Correction of existing fluid abnormalities
 Fluid resuscitation
 Sepsis (sepsis bundle) – 30 ml/kg
 Burn = TBSA(%) x 4 x body weight (kg) – Parkland’s formula
2. Maintenance of daily requirement
 Normal ongoing loss – Sensible & insensible
3. Replacement of ongoing abnormal losses
4. Reassess the patient ( clinical and laboratory
parameter eg. blood pressure, urine output,
central venous pressure )

15.  Enteral
 Parenteral
◦ Crystalloids
◦ Colloids
◦ Blood products

16.  Crystalloid solutions –
 clear fluids made up of water and electrolyte
solutions; Will cross a semi-permeable
membrane e.g Normal, hypo and hypertonic
saline solutions; Dextrose solutions; Ringer’s
lactate and Hartmann’s solution.

17.  Colloid solutions –
 Gelatinous solutions containing particles
suspended in solution. These particles will not
form a sediment under the influence of gravity and
are largely unable to cross a semi-permeable
membrane. e.g. Albumin, Dextrans, Hydroxyethyl
starch [HES]; Haemaccel and Gelofusine

18. 1. Blood derived Human albumin.
2. Synthetic
* Starches.
* Gelatins.
*Dextrans.

19.  5% (isotonic) and 25% (hypertonic) in NS.
 Uses:
Abnormal protein loss. e.g peritonitis.
Severe burns.
 Expensive.
 No risk of viral infection.
 Rare allergic reactions.
 No effct on coagulation.

20.  Hetastarch 6% Pentastarch 10% in NS.
 More effective than 5% albumin,gelatins and
dextrans.
 Non antigenic;no effect on crossmatching.
 Lower cost than albumin.
 Cleared by the kidneys.
 Disadvantages:
Coag.abnormalities if >1.5L.
Rare anaphylactic reactions.
Elevated serum amylase.

21.  Haemagel
 Relatively cheap.
 No effect on coagulation or on
crossmatching.
 High incidence of allergic reactions.

22.  Dextran 40 and 70 in NS or 5% dextrose.
 Anti-thrombotic effects.
 Dextran 70 is preferrd (12h.).
 Dextran 40 improves blood flow in
microcirculat.
 Uses:
*plasma expander.
*To prevent thromboembolism
* To improve blood flow to isch.limb
(dextran 40).

23.  Disadvantages:
1- Bleeding tendency.
2- Interfere with biood grouping and
crossmatching.
3- Rare anaphylactic reactions.
4- Dextran 40 can precipitate in renal
tubules leading to RF.

24. CRYSTALLOID COLLOID
DEFINITION Balanced salt solution,
administered intravenously
Plasma expander containing
larger insoluble molecules
ADVANTAGES • Cheaper
• Easily available
• More shelf life
• Not disturb coagulation
• Less risk of APO
• Ratio of replacement 1:1
DISADVANTAGES • Ratio replacement 1:3
• More risk of APO
• Expensive
• Disturb coagulopathy

26. (1) 0.9% Normal Saline – Think of it as ‘Salt and
water’
 Principal fluid used for intravascular resuscitation and replacement
of salt loss e.g diarrhoea and vomiting
 Contains: Na+ 154 mmol/l, K+ - Nil, Cl- - 154 mmol/l; But K+ is
often added
 IsoOsmolar compared to normal plasma
 Distribution: Stays almost entirely in the Extracellular space
Of 1 litre – 750ml Extra cellular fluid; 250ml intravacular fluid
 So for 100ml blood loss – need to give 400ml N.saline [only 25%
remains intravascular]

27. (2) 0.45% Normal saline = ‘Half’ Normal
Saline = HYPOtonic saline
 Reserved for severe hyperosmolar states E.g. severe
dehydration
 Leads to HYPOnatraemia if plasma sodium is normal
 May cause rapid reduction in serum sodium if used in excess
or infused too rapidly. This may lead to cerebral oedema and
rarely, central pontine demyelinosis ; Use with caution!
(3) 1.8, 3.0, 7.0, 7.5 and 10% Saline =
HYPERtonic saline
 Reserved for plasma expansion with colloids
 In practice rarely used in general wards; Reserved for high
dependency, specialist areas
 Distributed almost entirely in the ECF and intravascular
space. This leads to an osmotic gradient between the ECF and
ICF, causing passage of fluid into the EC space. This fluid
distributes itself evenly across the ECF and intravascualr
space, in turn leading to intravascular repletion.
 Large volumes will cause HYPERnatraemia and IC
dehydration.

28. (1) 5% Dextrose (often written D5W) – Think of it
as ‘Sugar and Water’
 Primarily used to maintain water balance in patients
who are not able to take anything by mouth; Commonly
used post-operatively in conjuction with salt retaining
fluids ie saline; Often prescribed as 2L : 1L N.Saline
[‘Physiological replacement’ of water and Na+ losses]
 Provides some calories [ approximately 10% of daily
requirements]
 Regarded as ‘electrolyte free’ – contains NO Sodium,
Potassium, Chloride or Calcium
 Distribution: <10% Intravascular; > 66% intracellular
 When infused is rapidly redistributed into the
intracellular space; Less than 10% stays in the
intravascular space therefore it is of limited use in fluid
resuscitation.
 For every 100ml blood loss – need 1000ml dextrose
replacement [10% retained in intravascular space
 Common cause of iatrogenic hyponatraemia in surgical
patient

29. (2) Dextrose saline – Think of it as ‘a bit
of salt and sugar’
 Similar indications to 5% dextrose;
Provides Na+ 30mmol/l and Cl- 30mmol/l
Ie a sprinkling of salt and sugar!
 Primarily used to replace water losses
post-operatively
 Limited indications outside of post-
operative replacement – ‘Neither really
saline or dextrose’; Advantage – doesn’t
commonly cause water or salt overload.

30.  PREOPERATIVE:
◦ DIRECT INTRAVASCULAR DEPLETION
◦ LOSS FROM GI TRACT
◦ INFLAMMATION RELATED REDISTRIBUTION
◦ FLUID SEQUESTRATION IN THIRD SPACE LOSSES
 INTRAOPERATIVE:
◦ ALTERED DISTRIBUTION OF INTRAVASCULAR
VOLUME.
◦ DIRECT LOSS OF INTRAVASCULAR VOLUME.
◦ INSENSIBLE LOSSES.

31. ◦ INFLAMMATION RELATED REDISTRIBUTION.
◦ RENAL OUTPUT
 POSTOPERATIVE :
◦ INFLAMMATION AND IMMUNE RESPONSE (IL1, TNF
ALPHA, IL6, SIRS)
◦ CATABOLIC METABOLISM
◦ REGULATION OF SALT AND WATER BALANCE WITH
ADH RELEASE

32.  QUANTITY OF FLUID :
◦ TARGETTING OVERALL FLUID BALANCE
◦ GOAL DIRECTED THERAPY: based on
measurements as follows
 pulmonary arterial catheter,
 esophageal doppler monitoring and
 other targets like arterial waveform analysis, cvp,
lactate, echocardiography, oxygen extraction &venous
saturation or central venous saturation etc.

33. 1. Urine Output: at least 1.0 ml/kg/hr
2. Vital Signs: BP and HR normal.
3. Physical Assessment: Skin and mucous
membranes no dry; no thirst in an awake
patient.
. Laboratory tests: periodic monitoring of
hemoglobin and hematocrit.

34. The following factors must be taken into
account:
1- Maintenance fluid requirements
2- NPO and other deficits: NG suction, bowel
prep
3- Third space losses
4- Replacement of blood loss
5- Special additional losses: diarrhea

35. • “4-2-1 Rule” HOLIDAY SEGAR FORMULA
- 4 ml/kg/hr for the first 10 kg of body weight
- 2 ml/kg/hr for the second 10 kg body weight
- 1 ml/kg/hr subsequent kg body weight
- Extra fluid for fever, tracheotomy, denuded surfaces

36. • NPO deficit = number of hours NPO x
maintenance fluid requirement.
• Bowel prep may result in up to 1 L fluid loss.
• Measurable fluid losses, e.g. NG suctioning,
vomiting, ostomy output, biliary fistula and
tube.

37. • Isotonic transfer of ECF from functional body
fluid compartments to non-functional
compartments.
• Depends on location and duration of surgical
procedure, amount of tissue trauma,
temperature, room ventilation
• Superficial surgical trauma: 1-2 ml/kg/hr
• Minimal Surgical Trauma: 3-4 ml/kg/hr
- head and neck, hernia, knee surgery
• Moderate Surgical Trauma: 5-6 ml/kg/hr
- hysterectomy, chest surgery
• Severe surgical trauma: 8-10 ml/kg/hr (or more)
- Nehprectomy

38. • Replace 3 cc of crystalloid solution per cc of
blood loss (crystalloid solutions leave the
intravascular space)
• When using blood products or colloids
replace blood loss volume per volume

39.  PAEDIATRIC:
◦ Modification in preoperative fasting ( allowing
carbohydrate containing fluids upto 2 hours).
◦ Glucose free balanced crystalloid solutions to be
used intraoperatively.
◦ Avoid hypotonic fluids.
◦ Maintenance fluid using ½ to 2/3 of calculated 4-2-
1 formula
◦ Return to oral fluids as soon as possible.
◦ Maintenance and ongoing losses to be replaced
seperately.

40.  Decrease in total body water
 Decrease in GFR
 Decrease in urinary concentrating ability
 Increase in antidiuretic hormone (ADH)
 Increase in atrial natriuretic peptide (ANP)
 Decrease in aldosterone
 Decrease in thirst mechanism
 Decrease in free-water clearance

41. ◦ The British Consensus Guidelines on Intravenous
Fluid Therapy for Adult Surgical Patients (GIFTASUP)
for fluid management recommends that “when
crystalloid resuscitation or replacement is indicated
balanced salt solution Ringer’s lactate/acetate or
Hartmann’s solution should replace 0.9% normal
saline, except in cases of hypochloremia for
example from vomiting or gastric drainage.”
◦ If colloids are indicated and used, lower-
molecular-weight colloids that can maintain
adequate oncotic pressure should be considered.

42. Goals :
◦ maintaining baseline blood volume and cerebral
perfusion
◦ avoid significant decrease in serum sodium and
osmolality and oncotic pressure.
 Situations requiring specific management:
◦ Raised ICP- increasing serum osmolarity with
mannitol, hypertonic saline.
◦ Cerebral vasospasm – triple H( hypervolemia,
hemodilution, hypertension).
◦ Intacranial pathologic condition associated with
cerebral salt wasting, diabetes insipidus

43.  ORGAN FAILURE:
◦ HEART FAILURE: goals –
 Preserve cardiac output with limited preload.
 Minimise cardiac work . Avoid hypovolemia.
 Optimisation of electrolyte and fluid disturbances.
◦ Renal failure:
 Avoid both hypo- and hypervolemia.
 Dialysis day before surgery for euvolemia.
 Avoid large boluses of isotonic saline.
 Fluids available- potassium free HCO3- buffered
dialysis solution>potassium containing balanced
crystalloids.
 Colloids- volume effect and potential toxicities
exaggerated.

44. ◦ HEPATIC FAILURE
RELATIVE intravascular volume depletion with salt
and water retention.
◦ Careful assesement of volume status along with
cardiac output monitoring.
◦ Replace losses with isotonic crystalloids, colloids
or blood.
◦ Avoid salt and water retention due to excessive
volumes of saline.
◦ Metabolism of lactates and other buffered
solutions is slowed.
◦ Hypertonic saline may be used in hepatic
encephalopathy.

45.  INITIAL RESUSCITATION (<6 HRS) Prefer
crystalloids over colloids.

46. ◦ APPROACH- permissive hypovolemia with
fluids targetted to achieve cerebration rather
than normotension.
◦ Early replacement with blood and blood
products.
◦ After Clot stabilisation, now restore normal
circulating volume and tissue perfusion.

47.  BURNS :
◦ I.V. FLUIDSinstituted for burns >15% BSA(adults),
>10% BSA( children)
◦ Prefer crystalloids over colloids.

48.  Reduced plasma volume in contrast to
volume expansion as in normal pregnancy.
 Hypoalbuminemia and endothelial
dysfunction.
 Management
◦ Restricted volume of crystalloid including drug
diluents.
◦ Blood loss in peripartum or perioperative period to
be replaced with appropriate volumes of blood,
colloids & crystalloids.
◦ Invasive monitoring required.
◦ Oliguria in presence of normal renal function not to
be treated with fluid boluses.

49.  Fluid and electrolyte abnormalities:
dehydration, hypochloremic metabolic
alkalosis with paradoxically acid urine and
hypocalcaemia.
 Correction: gradual rehydration with normal
saline and potassium supplementation.
 Surgery to treat gastric outlet obstruction to
be scheduled after correction of acid base
status.

50.  Compensatory IV volume expansion.
 Normal maintenance requirements.
 Pre-existing deficits.
 Surgical fluid losses:
Blood.
Other fluids.

51.  factors that need to be considered in the
peri-operative period:
-Patient (age, physiological reserve, pre-op
status)
-Clinical context (magnitude of surgery,
blood loss, etc.)
-Existing deficit
-Stress response - causes salt and water
retention.
-Anticipated losses( Fever Respiratory rate
Drain/NG losses, Third space)

52. 5-7 ml/kg of crystalloid before anaesthesia.
This to compensate for vasodilatation and
cardiac depression by anaesth. drugs.

53.  For the first 10 kg: 4 ml/kg/h.
 For the next 10-20 kg: 2 ml/kg/h.
 For each kg above 20 kg: add 1 ml/kg/h.
Example:
Maintenance fluid needs for a 25 kg child:
40+20+5= 65ml/hour.

54.  Water: as maintenance.
 Potassium: 1 mmol/kg/day.
 Sodium: 1-1.5 mmol/kg/day.

55. The deficit can be estimated by multiplying the
normal maintenance rate by the length of the
fast.

56.  Usually, patients who are eating require “supplemental”
fluids (i.e., inadequate oral intake) will only require small
amounts of fluid. In general, intravenous potassium
replacement is not required for these patients (even if they
are hypokalaemic, you can usually use oral supplementation).
 Try to calculate the amount of water actually required. For
example, if they need 1L of water in addition to oral intake,
then only give 1 litre in a day (as normal saline or dextrose
solution). If no other intravenous access is required and
intravenous access is difficult, consider a subcutaneous line
(generally a maximum rate of fluid at about 80 mL/h). Do not
put a dextrose solution subcutaneously.

57.  Blood loss
Continuous monitoring and accurate
estimation of blood loss is v. important.
for each 1 ml loss replace 3 ml crystalloids or
1 ml colloids.
 Other losses
Evaporation from large exposed wounds.
Third space losses.

58. 1- Short large-bore I.V. cannula.
2- The consequences of hypovolemia carry
high mortality and must be treated promp.
3- Do not give inotropes to hypovol. pt.
4- For old,cardiac,hepatic or renal pt,replace
gradually.Only half . deficit is given
initially.CVP is mandatory.

59. 5- Crystalloids,when given in sufficient
amounts are just as effective as colloids.
3-6 times.
6- Severe deficits correct by colloids.
7- Rapid large amounts of crystalloids(>5L) is
more freq. associated with tissue edema
8- Simple monitoring

60.  Clinical
 Markers of perfusion
◦ Capillary refill time
◦ Urine output
 Observations (Pulse-BP-CVP)
 CVP if central venous access present (5-12cmH2O)
 Patient thirst
 Response to fluid challenge
 Investigations
E(Na&K)/Hb /urine out put more than 0.5ml/kg/h.
 ABG -CXR

61. Water imbalance.
Water depletion
Causes
1-lack of intake
2-Diabetes insipidus
3-increased out put( fever-osmotic diuresis)
C/P
Intense thirst&weakness-decreased skin turgor-
oliguria with incr specific gravity
TTT
Initialy increase in serum Na3mmol=1L
water deficit
Na free water e.g,IV5%glucose

62.  Causes(iatrogenic)
 Most common cause over infusion of IV5%glucose in post
operative patients
 Colorectal washout with plain water instead of saline before
colonic surgery
 Excessive uptake of water during TURP
 Moderate asymptomatic(increased urine volume-incr body weight
(no pitting edema)-decr Na&Heamatocrit)
 Marked(Na below120meq/L)
 Edema of brain cells
 Nausea&vomiting of clear fluid
 TTT Mildwater excess require restriction
 SEVERE induction of diuresis by Mannitol+careful infusion of5%NaCl

63. Hyponatremia
Causes
1-abnormal GIT losses(suction,vomiting,diarrhea)as in obstruction of small
bowel
2-loss of ECF externally(burn-marked sweating)internallyas athird space
3-excessive urine Na wastage(diuretics,salt wasting nephritis,adrenal
failure)
4- blood loss 5-decrease intake 6-addision disease
C/P eyes sunken&face drawn&skin dry&wrinkled&tongue dry
Peripheral veins contracted hypovolaemia (tachycardia & orthostatic
hypotention & shock)
Low CVP
decrease urine
TTT NaCl0.9% blood loss replaced by blood

64.  Causes
 If patientsgiven excessive amount of 0,9%NaCl during Early
post operative(some degree of Na retention is to be expected
 Hyperaldosteronism ( Conn,s disease-liver cirrhosis)
 Cushing syndrome
 C/P puffiness of the face is the only early sign –only reliable
sign Oedema-weight gain-HTN
 Serum Na is usually normal
 TTT Na restriction & diuretics

65.  Since serum K small amount of total body K small reduction in its
serum level may reflect large body losses of K
 CAUSES
 Excessive vomiting e,g. pyloric stenosis-intestinal obstuction-
paralytic illeus –prolonged gastro duodenal aspiration with fluid
replcement by IV NaCl
 External alimentary fistulae
 Diarrhoea & Diuretics as furosemide
 Alkalosis (shift of K intra cellular) & Hyperaldosteronsim
 C/P most patient asymptomatic –early sign of K
depletion,malaise& weakness
 Paralytic illeus&distention-muscular paresis
 ECG prolonged QT-Tachycardia-St segment depression-U wave
appearance
 TTT 1meq of K =35 ampoules
 SAFE rule is rule of 40

66.  Causes
 Life-threatening k excess usually withRenal failure
 Acidosis lead to shift of K out side the cells
 C/P arryhythmia,bradycardia,hypotention,cardiac
arrest
 ECG wide QRS&peaked Twave
 TTT IV Ca gluconate&IV
NaHCO3&glucose,insulin&if previous fail ion
exchange resins&the end Dialysis

67.  Hypocalcemia
 Latent e,g. hypoparathyriodism following thyriod surgeryC/P
(Circumoral tingling,numbness&+ve chvosteks sing)
 Symptomatic hypocalcemia in permanent
hypoparathyroidism,acute pancreatitis&acute
alkalosisC/P(hyperactive deep tendon
reflexes,muscle&abdominal cramps,carpopedal spasm
 ECG prolonged QT interval
 TTT IV Ca gluconate or Ca Cl2
 Chronic hypocalcaemia vit D, oralCa& AL(OH)3 bind
phosphate in the intestine

68.  Metabolic Acidosis
 Causes
 Over production of organic acid DKA-Lactic acidosis
of sepsis and shock[ HIGH ANION GAP ]
 Renal failure(acute-chronic)
 Excessive loss of HCO3(diarrhea,pancreatic or small
intestinal fistula,uretro sigmoidostmy [ NORMAL
ANION GAP ]
 C/P increased rate&depth of breathing
 TTT mild to moderate ttt of cause
 Sever (IV HCO3 causes (1/2body weight X (15-
HCO3))

69.  PH more than 7.45
 Causes
 Gastrointestinal losses of H due to vomiting,suction(pyloric
stenosis)
 Hypokalemia lead to H movement into the cells(extracellular
alkalosis&paradoxical intracellular acidosis)
 HCO3 retention(NAHCO3 administration,milk alkali syndrome)
 C/P Chyne-Stoke & apnea-Tetany
 TTT replacement of CL
 In mild cases saline NaCl is sufficient associated hypokalemia ttt
by IV KCl
 Sever: IV ammonium chloride NHCL or hydrogen cholride HCl
very slowly
 TETANY ttt by slow IV10ml Ca gluconate

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