# from Total body fluids = 600ml/kg in men(60%) and 500ml/kg in women (50%). Whole blood = 66ml/kg in men and 60ml/kg in women Plasma= 40ml/kg in men.

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Total body fluids = 600ml/kg in men(60%) and 500ml/kg in women (50%).
Whole blood = 66ml/kg in men and 60ml/kg in women Plasma= 40ml/kg in men and 36ml/kg in women Erythrocytes = 26ml/kg in men and 24 ml/kg in women

Body Water Compartments
Intracellular water: 2/3 of TBW Extracellular water: 1/3 TBW

Body Water ICF=28L 60% 42L 40% 28L 20% 14L 16% 9L 4% 3L 60% RBCs
Intracellular Volume Extracellular Volume Interstitial Volume Plasma Volume Total Body Water 60% 42L 40% 28L 20% 14L 16% 9L 4% 3L 60% ICF=28L Interstitial = 9L RBCs Plasma 25 March 2017

How is fluid lost? Failure of intake Excessive excretion
eg diarrhoea, polyuria, sweating, bleeding Sequestration into body cavities eg effusions in peritoneal /pleural cavity, rupture of the urinary tract “third space”

Where is the fluid lost from?
Extracellular fluid vascular compartment (effective circulating volume) interstitial water in GI tract and other body spaces lymph Intracellular fluid

Preoperative Evaluation of Fluid Status
Factors to Assess: mental status intake and output blood pressure: supine and standing heart rate skin turgor urinary output serum electrolytes/osmolarity

Systolic blood pressure decrease of greater than 20mmHg from supine to standing Indicates fluid deficit of 6-8% body weight - Heart rate should increase as a compensatory measure - If no increase in heart rate, may indicate autonomic dysfunction or antihypertensive drug therapy

Perioperative Fluid Requirements
the following factors must be taken into account: Maintenance fluid requirements NPO and other deficits: NG suction, bowel prep Third space losses Replacement of blood loss Special additional losses

Maintenance Fluid Requirements
Insensible losses such as evaporation of water from respiratory tract, sweat, feces, urinary excretion.. Adults: approximately 1.5 ml/kg/hr “4-2-1 Rule” - 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

NPO and other deficits 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.

Third Space Losses 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, ambient temperature, room ventilation.

Replacing Third Space Losses
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) - AAA repair, nehprectomy

Blood Loss 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

Type of fluid required Same or similar to the type of fluid lost
Polyionic crystalloid solutions Hartmanns’ Lactated Ringers Colloids pentastarch Plasma

Crystalloids Crystalloid solutions contain low molecular weight salts or sugars which dissolve completely in water and pass freely between the intravascular and interstitial compartments Normal Saline: Good for Fluid Boluses, compatible with blood products, most drugs. 0.9% NaCl has an osmolarity of 308 mOsm/liter, slightly greater than that of plasma Lactated Ringers: Good for fluid boluses but is mildly hypo-osmolar when compared to plasma, resulting in approximately 114 ml of free water per liter of LR

D5W: Mainly for Hypoglycemia in the stable pt or for infants.
Dextrose containing solutions should not be used for boluses as they will likely cause Hyperglycemia which is associated with poor neurological outcomes.

Colloids Colloid refers to a liquid that exerts osmotic pressure due to large MW (greater than 30,000) particles in solution. A variety of colloid solutions are seen for in hospital use: Hydroxyethyl starch : hetastarch can cause a coagulopathy, through hemodilution of clotting factors, inhibition of platelet function and reduction of the activity of factor VIII Pentastarch :Pentastarch differs from hetastarch in that it has a lower mean MW. Preliminary studies also suggest that pentastarch may have fewer adverse effects on coagulation than hetastarch.

Dextran solutions (dextran 40 and dextran 70): Similar osmotic pressure to plasma. Dextrans interfere with normal coagulation partly by hemodilution of clotting factors and partly by “coating” platelets and the vascular endothelium. May promote renal failure. 5% Human serum albumin: Protein based solution,

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

Routes of Fluid Administration
Subcutaneous: - not for sever dehydration or shock - not if potential vasoconstriction - crystalloids only - no dextrose - K+ is painful - aseptic technique

Enteral: - limited by patients ability to handle - can use to prevent gut-atrophy - trickle feeding - can combine with other methods (NG tube, etc.) Intraperitoneal: - fairly rapid adsorption - aseptic technique - warm fluids

Intraosseous: - similar to IV - useful especially in neonates and small patients Intravenous: - peripheral vs. central line - moderate/severe dehydration, shock - cutdowns (20G needle technique) - change catheters every 72 hours - CVP

Determining Appropriate IVF
Step 1: Assess volume status What is the volume status of my patient? Do they have ongoing losses? Can my patient take PO safely? Are the NPO for a reason? Step 2: Determine Access Peripheral IV Central line IO line

Step 3: Select Type of Fluid

Hypovolemic Patient Hypervolemic Patient
Always use Normal Saline for goal of volume resuscitation Normal saline is almost isotonic with blood so it is the best choice! On surgery or if going to administer more than 3-4L often use LR. (Addition of lactate that is metabolized to bicarbonate to help buffer acidosis) Hypervolemic Patient Avoid additional IVF

NPO Patient now euvolemic
Administer maintenance fluids. Goal is to maintain input of fluids to keep up with ongoing losses and normal fluid needs For average adult NPO for more than 6-12 hours, consider D5/2NS at cc/hr Consider pt co-morbidities Don’t give fluids blindly i.e.: if the patient is pre-procedure but is old (predisposed to fluid overload because of stiff LV) or has history of CHF, be CAREFUL! No need for fluids if they are taking PO without problems!

Step 4: Determine Rate If you are trying to fluid resuscitate that patient, you might be giving fluids “wide open” or 500 cc/hr. The hypovolemic pt may need multiple 1L bolus to reestablish intravascular volume If you are just giving fluids to the average patient, give fluids at cc/hr. Adjust for individual patient

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

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