This document provides an overview of fluid management in surgical patients. It discusses the body's fluid compartments and regulation, changes in fluid balance, therapeutic fluids including crystalloids and colloids, and perioperative fluid management strategies. The key goals of fluid therapy are to maintain normovolemia and minimize excess fluids and salts. Enhanced recovery after surgery protocols recommend restrictive fluid management and early enteral intake to reduce complications.

1. FLUID MANAGEMENT
IN
SURGICAL PATIENTS
Presenter: Mekonen Birhnau (1st year resident)
Moderator: Ashenafi Birhanu (Consultant General & Cardiothoracic surgeon)
UoG, Gondar Ethiopia
August 24/2022
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2. Outline
• Introduction
• Body fluid compartments
o Their composition
o Regulation of exchange & osmotic equilibrium
• Body fluid changes
• Therapeutic fluids
• Perioperative fluid management
• Hemodynamic monitoring and volume responsiveness
• Summary
• References 2

3. Introduction
• The human body is predominantly water
• The maintenance of a relatively constant volume and a stable composition of the
body fluids is essential for homeostasis
o Fluid and electrolyte management is paramount to the care of the surgical patients.
• The concept of continuous IV drip introduced in 1924 by Rudolph Matas.
• Wartime experience has helped in the evolution of fluid management.
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4. Body Fluids
Total Body Water
• Constitutes approximately:
o 50% to 60% of total bodyweight in young adult female & male respectively.
o 80% of their total body weight in newborns.
o 65% by 1 year of age.
• The precise percentage is affected by gender, body fat and age.
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5. Body Fluid Compartments
• TBW is distributed mainly between two compartments:
o The extracellular and intracellular fluid.
• The extracellular fluid is divided into the interstitial fluid and the blood plasma.
• The ECF compose about one-third of the TBW, and the ICF the remaining two-thirds.
o Plasma compose 5% of body weight
o Interstitial fluid compose15% of body weight.
o ICF compose 40% of an individual’s total body weight.
 Transcellular fluids!
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6. Body Fluid Compartments…
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Figure 1: Body fluid regulation and the compartments. The values shown are for an average 70Kg adult man.

7. Composition of Fluid Compartments
• The composition of the plasma and interstitial fluid differs only
slightly.
• Movement of ions and proteins between the various compartments is
restricted.
• But, water is freely diffusible.
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8. Composition of Fluid Compartments…
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Composition Fluid compartments
ECF ICF
Principal Cations Na+ K+, Mg2+
Principal Anions Cl-, HCO3
- HPO4
3– , SO4
2– , Proteins
Table 1: Principal ionic Composition of Fluid Compartments

9. Composition of Fluid Compartments…
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Figure 2: Chemical composition of body fluid compartments

10. Blood
• Blood contains both ECF and ICF.
o Plasma & RBC.
• It is considered to be a separate fluid compartment.
• Accounts about 7 % of body weight (5L).
• Composed of:
o Plasma – 60 % of the blood and
o Red blood cells – 40 % of the blood.
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11. Regulation of Fluid Exchange and Osmotic Equilibrium
• ECF distribution is determined by the balance of hydrostatic and colloid osmotic forces.
• Distribution between intracellular and extracellular compartments is determined by the
osmotic effect of the smaller solutes.
• The cell membranes are highly permeable to water but relatively impermeable to even
small ions.
• Therefore, water moves across the cell membrane rapidly – osmosis.
o As a result, ICF remains isotonic with the ECF.
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12. Osmolar Activity
• The physiologic activity of electrolytes in solution can be expressed as:
o Molarity: the number of particles per unit volume (mmol/L)
o Normality: the number of electric charges per unit volume (mEq/L).
o Osmolarity or Osmolality: the number of osmotically active ions per unit volume (mOsm/L or mOsm/kg).
o Osmotic pressure: determined by the osmoles. Expressed by mmHg!
o Tonicity: the fluid effect on cellular volume
• The osmolality of the ICF and ECF is maintained between 290 and 310 mOsm
• Calculated serum osmolality = 2 Sodium + (glucose/18) + (BUN/2.8) 12

13. Body Fluid Changes
Normal Exchange of Fluid
• Healthy person consumes an average of 2000 mL /day.
o 75% from oral intake and the rest extracted from solid foods.
• Daily water losses include:
o 800 to1200 mL in urine
o 250 mL in stool and
o 600 mL in insensible losses.
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14. Body Fluid Changes…
• Most fluid gains and losses are directly from the ECF.
• Disorders in fluid balance can be of 3 general categories. Disturbances in:
1. Volume
2. Concentration and/or
3. Composition
• Extracellular volume deficit is the most common
o Can be either acute or chronic.
o Acute volume deficit is associated with CVS and CNS signs
o Chronic deficits display tissue signs
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15. Volume Depletion
Etiologies:
• GI loss: most common cause in surgical patients
o From NGT, vomiting, diarrhea or enterocutaneous fistula
• Bleeding: traumatic, non traumatic, surgical
• Renal losses: secondary to:
o Diuretics, osmotic diuresis, salt-wasting nephropathies, and hypoaldosteronism
• Skin losses: secondary to:
o Sweat, burns, and other dermatological conditions
• Third-space sequestration: secondary to:
o Soft tissue injuries, burns, infection/inflammation, intestinal obstruction, or prolonged surgery.
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16. Volume Depletion…
Diagnosis:
• Clinically: symptoms and objective findings
• Laboratory:
o Decreased urine out put
o U/A
o Increased serum BUN & Cr
o Deranged electrolyte, Hct & albumin concentration
o Acid – base disturbance.
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17. Volume Depletion…
Principles of Management
• Knowing the underlying cause
• Identifying electrolyte and Acid – base disturbances
• Assessing and treating the volume deficit
 Influence the choice of fluid and rate of administration.
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18. Fluid Therapy
• There are two components to fluid therapy:
1. Maintenance therapy
o Replaces the ongoing losses under normal physiologic conditions
2. Replacement therapy
o Corrects any existing deficits OR
o Ongoing losses
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19. Maintenance therapy
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Table 3: Calculating Maintenance therapy

20. Therapeutic Fluids
Therapeutic fluids can be:
• Crystalloids
• Colloids
• Blood
• Blood substitutes
• Novel fluids
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21. Determinants of fluid choice
• The type of fluid administered depends on:
o The patient’s volume status
o The type of concentration or compositional abnormality and
o The underlying cause
o Institutional and clinician preference.
• Evidences showed lack of any significant proven benefit of one crystalloid over
another 22

22. Crystalloids
• Are acellular electrolyte solutions.
• May be isotonic, hypotonic, or hypertonic with respect to plasma.
• Examples:
o Normal saline
o Lactated ringer’s (Hartmann's solution)
o Plasma lyte
o Alternatives
• Balanced crystalloids
o AKA buffered crystalloids/chloride restrictive
o Have similar electrolyte composition to plasma with the addition of a buffer
 LR & Plasma lyte
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23. Crystalloids…
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Table 4: Crystalloids and their compositions

24. Crystalloids…
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Table 5: Crystalloids and their compositions

25. 0.9% Normal saline
• Mildly hypertonic
• Contains 154 mEq Na+ & 154 mEq Cl-
• Ideal solution for correcting volume deficits associated with hyponatremia,
hypochloremia, and metabolic alkalosis.
• Complications:
o Hyperchloremic metabolic acidosis.
o Peripheral edema
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26. Lactated Ringer’s
• Is slightly hypotonic
• Contains 130 mEq Na+, 109 mEq Cl-, 28 mEq lactate, K+ & Ca+2.
• Lactate is converted into bicarbonate by the liver.
• Complications:
o Peripheral edema
o Electrolyte disturbance
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27. Plasma-Lyte
• One of emerging most popular isotonic fluids
• Closely resembles human plasma.
• Contains a number of additional buffers in addition to the electrolytes
• Contains 140 mEq Na+, 98 mEq Cl-, 27 mEq lactate, K+, gluconate & Mg+2 .
• Complications:
o Peripheral edema
o Electrolyte disturbance
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28. Hypertonic saline
• Preparations: 3.5%, 5%, 7.5%.
• 3.5% & 5% are used for correction of severe sodium deficits.
• 7.5% has been used in closed head injuries.
• However, there have also been concerns about increased bleeding.
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29. Hypotonic saline
• Preparations: 0.45% sodium chloride
• Are useful for:
• Replacement of ongoing GI losses
• MF therapy in the postoperative period.
• DNS (5% dextrose):
• 50 g of dextrose per liter supplies 200 kcal/L, and
• Dextrose is added to maintain osmolality
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30. Colloids
• Are human plasma derivatives or semisynthetic preparations
• Major types are:
o Albumin
o Dextran
o Gelatin and
o Starch – based colloids.
• They are more of confined to the intravascular space
• More efficient transient plasma volume expanders.
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31. Colloids …
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Table 6: Colloids and their composition

32. Colloids Vs. crystalloids
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Characteristics Colloids Crystalloids
Molecular weight Large Small
Colloid oncotic pressure Yes No
Maximum volume expansion 70 – 500 % 20 – 25 %
Duration of volume expansion Several hours to days 1 – 4 hrs
Plasmatic half-life Several hours to days 30 min.
Cost Expensive Affordable
Side effects
Infection transmission, Allergic &
anaphylactic reactions, coagulopathy,
Renal dysfunction, HF…
Edema, electrolyte & acid – base
disturbance
Table 7: comparison between Colloids & crystalloids

33. Colloids Vs. crystalloids…
 Report of a systematic review of Meta-analysis of colloids versus crystalloids in critically ill,
trauma and surgical patients was published by BJS In a 2015.
• Done in 59 multicenter RCTs involving 16, 889 patients.
• Outcomes of interest were: mortality, AKI, RRT, length of ICU & hospital stay.
 Mortality: colloids did not increase mortality compared with crystalloid (23.32 Vs. 24.04 %)
 AKI/ARF: colloids increased risk of developing AKI (13.36 Vs. 11.51%)
o In critically ill patients with sepsis but not in patients with traumatic injuries or those undergoing non-trauma
surgery
 RRT: colloids increased the risk of RRT (10.46 Vs. 7.99%)
 ICU & hospital stay: colloid administration increased the length of ICU & hospital stay
• Limitations: clinical heterogeneity, difference in fluid & surgery types. 34

34. Colloids Vs. crystalloids…
Report of network meta-analysis (NMA) comparing fluid types in sepsis,
surgical, trauma, and traumatic brain injury patient was published in Taiwan in
2020.
• 58 RCTs which included 26,351 patients.
• Outcomes of interest were: mortality, fluid & transfusion volume, adverse effects (AKI, allergy).
• Seven group of fluids were used:
o Balanced crystalloids
o 0.9%Saline
o 5 colloids (iso-oncotic albumin (4%, 5%), hyperoncotic albumin (20%, or 25%), L-HES, H-HES and gelatin).
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35. Colloids Vs. crystalloids…
• Qualitative results:
o Among sepsis and surgical patients: balanced crystalloids and albumin attained lower
MR, lower risks of AKI, and less transfusion volume than did saline and L-HES.
o In TBI patients: saline and L-HES showed better mortality rates than hypotonic solutions,
including iso – oncotic albumin and balanced crystalloids.
o Balanced crystalloids required the greatest fluid resuscitation volume than all the other fluid
types.
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36. Perioperative Fluid Therapy
• Perioperative fluid management is important
• Is a major tenet of ERAS protocols
• A continuum through the preoperative, intraoperative, and postoperative phases
• Fluid Management Strategies:
o Restrictive (zero – balance) strategy
o Goal – directed fluid therapy
o Traditional liberal or fixed – volume
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37. Perioperative Fluid Therapy …
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Figure 3: Volume status affects postoperative morbidity

38. Preoperative Fluid Therapy
• The goal is to make the patient hydrated and euvolemic.
• Prolonged fasting is not recommended
• MF is all that is required in an otherwise healthy individual
• Replacement of deficit or ongoing fluid losses accordingly.
• ERAS recommends clear liquids enteral intake up to 2 hours prior to surgery.
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39. Preoperative Fluid Therapy…
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Table 8: Preoperative Fasting in pediatrics

40. Intraoperative Fluid Therapy
• The goals are to maintain central euvolemia and to minimize excess
salt and water.
• MF therapy combined with fluid challenges
o Adequate maintenance fluid therapy
o Correcting known fluid losses
o Replacing ongoing losses & third-space sequestration 41

41. Postoperative Fluid Therapy
• Early enteral intake is advised.
• Once enteral intake is established, IV administration can be discontinued
• If clinically indicated: low – sodium, low – volume fluids
o MF (balanced crystalloid )
o Any deficits & third-space losses
o Ongoing requirements
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42. Hemodynamic monitoring and volume responsiveness
Traditional static parameters:
• Can be determined invasively or non – invasively
• Can be used in spontaneously breathing or mechanically ventilated
• Less reliable
• Examples:
o BP, HR, UO, CVP, PAOP
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43. Hemodynamic monitoring and volume responsiveness…
Dynamic parameters:
• More of in invasive major surgery & large expected blood losses.
• Superior in assessment of response to a fluid challenge
• Can be computed (manually/automatically) or visually estimated.
• Change in dynamic parameters of > 10 – 15 % indicate volume responsiveness.
• Examples:
o Respiratory variations in arterial pressure (PPV, SVV, SPV, IVC )
o Transesophageal Doppler ultrasound, TEE, TTE, POCUS
o Straight Leg Raise (SLR)
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44. Strategies of fluid therapy
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Strategies Restrictive GDT Traditional liberal
Surgery Major surgery (blood loss
<500ml)
Major surgery (blood loss
>500ml)
Major surgery
Monitoring Non – invasive Invasive & advanced
medical devices
Non – Invasive
Fluid dose MF + replacement MF + fluid challenge Predetermined
Preloading No Bolus Yes
Non – anatomic "third
space" losses
Not replaced Accordingly Yes
Cryst. & Colloid to blood 1.5 : 1 & 1 :1 resp. Based on risk 3 : 1 & 1 :1 resp.
Remark Abandoned
Table 9: Fluid Management Strategies

45. GDT
• For invasive major high risk surgery with anticipated significant blood losses.
• Is to achieve a prespecified individualized goal.
• Utilizes a CO monitor, volume status & responsiveness
• Invasive dynamic hemodynamic parameters are used to assess the CO.
• Fluid administration is stopped once normovolemia has been achieved.
• May have added benefits in higher risk patients within an ERAS pathway
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46. GDT…
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Figure 4: A risk – adapted matrix to match monitoring needs to patient and surgical risk

47. Summary
• TBW constitutes approximately 50% to 60% of total body weight.
o Compartmentalized in to ECF (1/3rd ) & ICF (2/3rd ).
o Distribution within the compartments is regulated by hydrostatic & colloid oncotic pressure and osmotic effect of
electrolytes.
• Body fluid balance can be disturbed in volume, composition and/or concentration.
• Therapeutic fluids can be grouped mainly as crystalloids, colloids, blood.
• The key to treatment is evaluating patient’s initial condition and the fluid status.
• Fluid therapy can be in the form of MF or replacement therapy
• The target of fluid therapy is maintaining normovolemia
• ERAS recommends minimized perioperative fluid administration and focuses on early enteral intake.
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48. References
1. Schwartz’s Principles of Surgery 11th Edition
2. Sabiston Textbook of Surgery 20th Edition
3. UpToDate 2022
4. Guyton and Hall Textbook of Medical Physiology 13th Edition
5. Nelson Textbook Of Pediatrics 21st Edition
6. Google scholar
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49. Thank you !!!
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