4Total body fluids = 600ml/kg in men(60%) and 500ml/kg in women (50%). Whole blood = 66ml/kg in men and 60ml/kg in womenPlasma= 40ml/kg in men and 36ml/kg in womenErythrocytes = 26ml/kg in men and 24 ml/kg in women
5Body Water Compartments Intracellular water: 2/3 of TBWExtracellular water: 1/3 TBW
6Body Water ICF=28L 60% 42L 40% 28L 20% 14L 16% 9L 4% 3L 60% RBCs Intracellular VolumeExtracellular VolumeInterstitial VolumePlasma VolumeTotal Body Water60%42L40%28L20%14L16%9L4%3L60%ICF=28LInterstitial= 9LRBCsPlasma25 March 2017
7How is fluid lost? Failure of intake Excessive excretion eg diarrhoea, polyuria, sweating, bleedingSequestration into body cavitieseg effusions in peritoneal /pleural cavity, rupture of the urinary tract “third space”
8Where is the fluid lost from? Extracellular fluidvascular compartment (effective circulating volume)interstitialwater in GI tract and other body spaceslymphIntracellular fluid
9Preoperative Evaluation of Fluid Status Factors to Assess:mental statusintake and outputblood pressure: supine and standingheart rateskin turgorurinary outputserum electrolytes/osmolarity
10Systolic 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
11Perioperative Fluid Requirements the following factors must be taken into account:Maintenance fluid requirementsNPO and other deficits: NG suction, bowel prepThird space lossesReplacement of blood lossSpecial additional losses
12Maintenance 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
13NPO and other deficitsNPO 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.
14Third Space LossesIsotonic transfer of ECF from functional body fluid compartments to non-functionalcompartments.Depends on location and duration of surgical procedure, amount of tissue trauma, ambient temperature, room ventilation.
15Replacing Third Space Losses Superficial surgical trauma: 1-2 ml/kg/hrMinimal Surgical Trauma: 3-4 ml/kg/hr- head and neck, hernia, knee surgeryModerate Surgical Trauma: 5-6 ml/kg/hr- hysterectomy, chest surgerySevere surgical trauma: 8-10 ml/kg/hr (or more)- AAA repair, nehprectomy
16Blood LossReplace 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
17Type of fluid required Same or similar to the type of fluid lost Polyionic crystalloid solutionsHartmanns’Lactated RingersColloidspentastarchPlasma
18CrystalloidsCrystalloid solutions contain low molecular weight salts or sugars which dissolve completely in water and pass freely between the intravascular and interstitial compartmentsNormal 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 plasmaLactated 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
19D5W: 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.
20ColloidsColloid 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 VIIIPentastarch :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.
21Dextran 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,
22Several 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.
23Routes of Fluid Administration Subcutaneous:- not for sever dehydration or shock- not if potential vasoconstriction- crystalloids only- no dextrose- K+ is painful- aseptic technique
24Enteral:- 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
25Intraosseous:- similar to IV- useful especially in neonates and small patientsIntravenous:- peripheral vs. central line- moderate/severe dehydration, shock- cutdowns (20G needle technique)- change catheters every 72 hours- CVP
26Determining Appropriate IVF Step 1: Assess volume statusWhat 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 AccessPeripheral IVCentral lineIO line
28Hypovolemic Patient Hypervolemic Patient Always use Normal Saline for goal of volume resuscitationNormal 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 PatientAvoid additional IVF
29NPO Patient now euvolemic Administer maintenance fluids. Goal is to maintain input of fluids to keep up with ongoing losses and normal fluid needsFor average adult NPO for more than 6-12 hours, consider D5/2NS at cc/hrConsider pt co-morbiditiesDon’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!
30Step 4: Determine RateIf 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 volumeIf you are just giving fluids to the average patient, give fluids at cc/hr. Adjust for individual patient
31To 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.