fromfrom

Total body fluids = 600ml/kg Total body fluids = 600ml/kg in men(60%) and 500ml/kg in in men(60%) and 500ml/kg in women (50%).women (50%).

Whole blood = 66ml/kg in men Whole blood = 66ml/kg in men and 60ml/kg in womenand 60ml/kg in women

Plasma= 40ml/kg in men and Plasma= 40ml/kg in men and 36ml/kg in women36ml/kg in women

Erythrocytes = 26ml/kg in Erythrocytes = 26ml/kg in men and 24 ml/kg in womenmen and 24 ml/kg in women

Body Water Body Water CompartmentsCompartments

• Intracellular water: 2/3 of Intracellular water: 2/3 of TBWTBW

• Extracellular water: 1/3 Extracellular water: 1/3 TBWTBW

April 10, 2023 6

Body WaterBody Water

60%60%

ICF=28LICF=28L InterstitialInterstitial= 9L= 9L

RBCRBCss

Plasma Plasma

Intracellular VolumeIntracellular Volume

Extracellular VolumeExtracellular Volume

Interstitial VolumeInterstitial Volume

Plasma VolumePlasma Volume

Total Body WaterTotal Body Water 60%60% 42L42L

40%40% 28L28L

20%20% 14L14L

16%16% 9L9L

4%4% 3L3L

How is fluid lost?How is fluid lost? Failure of intakeFailure of intake

Excessive excretionExcessive excretion eg diarrhoea, polyuria, sweating, eg diarrhoea, polyuria, sweating,

bleedingbleeding

Sequestration into body cavities Sequestration into body cavities eg effusions in peritoneal /pleural eg effusions in peritoneal /pleural

cavity, rupture of the urinary tract cavity, rupture of the urinary tract “third space”“third space”

Where is the fluid lost Where is the fluid lost from?from?

Extracellular fluidExtracellular fluid vascular compartment (effective vascular compartment (effective

circulating volume)circulating volume) interstitialinterstitial water in GI tract and other body water in GI tract and other body

spacesspaces lymphlymph

Intracellular fluidIntracellular fluid

Preoperative EvaluationPreoperative Evaluationof Fluid Statusof Fluid Status

• Factors to Assess:Factors to Assess:- mental statusmental status- intake and outputintake and output- blood pressure: supine blood pressure: supine andand standing standing- heart rateheart rate- skin turgorskin turgor- urinary outputurinary output- serum electrolytes/osmolarityserum electrolytes/osmolarity

• Systolic blood pressure Systolic blood pressure decreasedecrease of of greater than 20mmHg from supine greater than 20mmHg from supine to standing Indicates fluid to standing Indicates fluid deficitdeficit of of 6-8% body weight6-8% body weight

-- Heart rate should increase as a Heart rate should increase as a compensatory measurecompensatory measure

-- If no increase in heart rate, may If no increase in heart rate, may indicate autonomic dysfunction or indicate autonomic dysfunction or antihypertensive drug therapyantihypertensive drug therapy

Perioperative Fluid Perioperative Fluid RequirementsRequirements

the following factors must be taken the following factors must be taken into account:into account:

• Maintenance fluid requirementsMaintenance fluid requirements• NPO and other deficits: NG suction, NPO and other deficits: NG suction,

bowel prepbowel prep• Third space lossesThird space losses• Replacement of blood lossReplacement of blood loss• Special additional lossesSpecial additional losses

Maintenance Fluid Maintenance Fluid RequirementsRequirements

• Insensible losses such as evaporation of Insensible losses such as evaporation of water from respiratory tract, sweat, feces, water from respiratory tract, sweat, feces, urinary excretion..urinary excretion..

• Adults: approximately 1.5 ml/kg/hrAdults: approximately 1.5 ml/kg/hr““4-2-1 Rule”4-2-1 Rule”

-- 4 ml/kg/hr for the first 10 kg of body 4 ml/kg/hr for the first 10 kg of body weightweight

-- 2 ml/kg/hr for the second 10 kg body 2 ml/kg/hr for the second 10 kg body weightweight

-- 1 ml/kg/hr subsequent kg body weight 1 ml/kg/hr subsequent kg body weight-- Extra fluid for fever, tracheotomy, Extra fluid for fever, tracheotomy, denuded surfacesdenuded surfaces

NPO and other deficitsNPO and other deficits

• NPO deficit = number of hours NPO NPO deficit = number of hours NPO x maintenance fluid requirement.x maintenance fluid requirement.

• Bowel prep may result in up to 1 L Bowel prep may result in up to 1 L fluid loss.fluid loss.

• Measurable fluid losses, e.g. NG Measurable fluid losses, e.g. NG suctioning, vomiting, ostomy output.suctioning, vomiting, ostomy output.

Third Space LossesThird Space Losses

• Isotonic transfer of ECF from Isotonic transfer of ECF from functionalfunctional body fluid compartments body fluid compartments to to non-functionalnon-functional

compartments.compartments.• Depends on location and duration of Depends on location and duration of

surgical procedure, amount of tissue surgical procedure, amount of tissue trauma, ambient temperature, room trauma, ambient temperature, room ventilation.ventilation.

Replacing Third Space Replacing Third Space LossesLosses

• Superficial surgical trauma: 1-2 ml/kg/hrSuperficial surgical trauma: 1-2 ml/kg/hr• Minimal Surgical Trauma: 3-4 ml/kg/hrMinimal Surgical Trauma: 3-4 ml/kg/hr

- - head and neck, hernia, knee surgery head and neck, hernia, knee surgery• Moderate Surgical Trauma: 5-6 ml/kg/hrModerate Surgical Trauma: 5-6 ml/kg/hr

-- hysterectomy, chest surgery hysterectomy, chest surgery• Severe surgical trauma: 8-10 ml/kg/hr Severe surgical trauma: 8-10 ml/kg/hr

(or more)(or more)

-- AAA repair, nehprectomy AAA repair, nehprectomy

Blood LossBlood Loss

• Replace Replace 3 cc3 cc of crystalloid solution of crystalloid solution per cc of blood loss (crystalloid per cc of blood loss (crystalloid solutions leave the intravascular solutions leave the intravascular space)space)

• When using blood products or When using blood products or colloids replace blood loss volume colloids replace blood loss volume per volumeper volume

Type of fluid requiredType of fluid required

Same or similar to the type of fluid lostSame or similar to the type of fluid lost Polyionic crystalloid solutionsPolyionic crystalloid solutions

Hartmanns’Hartmanns’ Lactated Ringers Lactated Ringers

ColloidsColloids pentastarchpentastarch

PlasmaPlasma

CrystalloidsCrystalloids Crystalloid solutions contain low molecular Crystalloid solutions contain low molecular

weight salts or sugars which dissolve weight salts or sugars which dissolve completely in water and pass freely between completely in water and pass freely between the intravascular and interstitial compartmentsthe intravascular and interstitial compartments

Normal SalineNormal Saline: Good for Fluid Boluses, : Good for Fluid Boluses, compatible with blood products, most drugs. compatible with blood products, most drugs. 0.9% NaCl has an osmolarity of 308 0.9% NaCl has an osmolarity of 308 mOsm/liter, slightly greater than that of plasmamOsm/liter, slightly greater than that of plasma

Lactated RingersLactated Ringers: Good for fluid boluses but : Good for fluid boluses but is mildly hypo-osmolar when compared to is mildly hypo-osmolar when compared to plasma, resulting in approximately 114 ml of plasma, resulting in approximately 114 ml of free water per liter of LR free water per liter of LR

D5WD5W: Mainly for Hypoglycemia in : Mainly for Hypoglycemia in the stable pt or for infants.the stable pt or for infants.

Dextrose containing solutionsDextrose containing solutions should not be used for boluses as should not be used for boluses as they will likely cause Hyperglycemia they will likely cause Hyperglycemia which is associated with poor which is associated with poor neurological outcomes.neurological outcomes.

ColloidsColloids ColloidColloid refers to a liquid that exerts refers to a liquid that exerts

osmotic pressure due to large MW osmotic pressure due to large MW (greater than 30,000) particles in (greater than 30,000) particles in solution. A variety of colloid solutions solution. A variety of colloid solutions are seen for in hospital use: are seen for in hospital use:

Hydroxyethyl starch :Hydroxyethyl starch : hetastarch can cause hetastarch can cause a coagulopathy, through hemodilution of a coagulopathy, through hemodilution of clotting factors, inhibition of platelet function clotting factors, inhibition of platelet function and reduction of the activity of factor VIIIand reduction of the activity of factor VIII

Pentastarch :Pentastarch :Pentastarch differs from Pentastarch differs from hetastarch in that it has a lower mean MW. hetastarch in that it has a lower mean MW. Preliminary studies also suggest that Preliminary studies also suggest that pentastarch may have fewer adverse effects pentastarch may have fewer adverse effects on coagulation than hetastarch.on coagulation than hetastarch.

Dextran solutions (dextran 40 and Dextran solutions (dextran 40 and dextran 70): dextran 70): Similar osmotic pressure Similar osmotic pressure to plasma. Dextrans interfere with to plasma. Dextrans interfere with normal coagulation partly by normal coagulation partly by hemodilution of clotting factors and hemodilution of clotting factors and partly by “coating” platelets and the partly by “coating” platelets and the vascular endothelium. May promote vascular endothelium. May promote renal failure. renal failure.

5% Human serum albumin5% Human serum albumin: Protein : Protein based solution, based solution,

Several times more crystalloid than Several times more crystalloid than colloid is required to achieve the colloid is required to achieve the same degree of vascular filling, and same degree of vascular filling, and because crystalloid solutions move because crystalloid solutions move rapidly into the interstitial rapidly into the interstitial compartment, a side effect of compartment, a side effect of crystalloid resuscitation is more crystalloid resuscitation is more interstitial oedema than in colloid interstitial oedema than in colloid treated patients. treated patients.

Routes of Fluid Routes of Fluid AdministrationAdministration

Subcutaneous: Subcutaneous:

- not for sever dehydration or shock- not for sever dehydration or shock

- not if potential vasoconstriction- not if potential vasoconstriction

- crystalloids only- crystalloids only

- no dextrose- no dextrose

- K- K++ is painful is painful

- aseptic technique- aseptic technique

Enteral: Enteral: - limited by patients ability to handle - limited by patients ability to handle - can use to prevent gut-atrophy - can use to prevent gut-atrophy - trickle feeding- trickle feeding- can combine with other methods (NG - can combine with other methods (NG tube, etc.)tube, etc.)

Intraperitoneal:Intraperitoneal:- fairly rapid adsorption- fairly rapid adsorption- aseptic technique- aseptic technique- warm fluids- warm fluids

Intraosseous:Intraosseous:- similar to IV- similar to IV- useful especially in neonates and small - useful especially in neonates and small patientspatients

Intravenous:Intravenous:- peripheral vs. central line- peripheral vs. central line- moderate/severe dehydration, shock- moderate/severe dehydration, shock- cutdowns (20G needle technique)- cutdowns (20G needle technique)- change catheters every 72 hours- change catheters every 72 hours- CVP- CVP

Determining Appropriate Determining Appropriate IVFIVF

Step 1: Assess volume status Step 1: Assess volume status What is the volume status of my patient? What is the volume status of my patient? Do they have ongoing losses?Do they have ongoing losses? Can my patient take PO safely? Can my patient take PO safely? Are the NPO for a reason?Are the NPO for a reason?

Step 2: Determine Access Step 2: Determine Access Peripheral IVPeripheral IV Central lineCentral line IO line IO line

Step 3: Select Type of Fluid Step 3: Select Type of Fluid

Hypovolemic Patient Hypovolemic Patient Always use Normal SalineAlways use Normal Saline for goal of for goal of

volume resuscitation volume resuscitation Normal saline is almost isotonic with Normal saline is almost isotonic with

blood so it is the best choice!blood so it is the best choice!On surgery or if going to administer more On surgery or if going to administer more

than 3-4L often use LR. (Addition of than 3-4L often use LR. (Addition of

lactate that is metabolized to bicarbonate lactate that is metabolized to bicarbonate

to help buffer acidosis) to help buffer acidosis)

Hypervolemic Patient Hypervolemic Patient Avoid additional IVF Avoid additional IVF

NPO Patient now euvolemic NPO Patient now euvolemic Administer maintenance fluids. Goal is to Administer maintenance fluids. Goal is to

maintain input of fluids to keep up with ongoing maintain input of fluids to keep up with ongoing

losses and normal fluid needslosses and normal fluid needsFor average adult NPO for more than 6-12 For average adult NPO for more than 6-12

hours, consider D5/2NS at 75-100cc/hr hours, consider D5/2NS at 75-100cc/hr Consider pt co-morbidities Consider pt co-morbidities Don’t give fluids blindly i.e.: if the patient is Don’t give fluids blindly i.e.: if the patient is

pre-procedure but is old (predisposed to fluid pre-procedure but is old (predisposed to fluid

overload because of stiff LV) or has history of overload because of stiff LV) or has history of

CHF, be CAREFUL! CHF, be CAREFUL! No need for fluids if they are taking PO without No need for fluids if they are taking PO without

problems!problems!

Step 4: Determine Rate Step 4: Determine Rate If you are trying to fluid resuscitate that If you are trying to fluid resuscitate that

patient, you might be giving fluids “wide patient, you might be giving fluids “wide open” or 500 cc/hr.open” or 500 cc/hr.

The hypovolemic pt may need multiple The hypovolemic pt may need multiple 1L bolus to reestablish intravascular 1L bolus to reestablish intravascular volumevolume

If you are just giving fluids to the If you are just giving fluids to the average patient, give fluids at 75-100 average patient, give fluids at 75-100 cc/hr. Adjust for individual patient cc/hr. Adjust for individual patient

To meet maintenance requirements, To meet maintenance requirements, patients should receive sodium 50-patients should receive sodium 50-100 mmol/day, potassium 40-80 100 mmol/day, potassium 40-80 mmol/day in 1.5-2.5 litres of water by mmol/day in 1.5-2.5 litres of water by the oral, enteral or parenteral route the oral, enteral or parenteral route (or a combination of routes). (or a combination of routes). Additional amounts should be given to Additional amounts should be given to correct deficit or continuing losses. correct deficit or continuing losses. Careful monitoring should be Careful monitoring should be undertaken using clinical undertaken using clinical examination, fluid balance charts and examination, fluid balance charts and regular weighing, when possible. regular weighing, when possible.