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204 Cards in this Set
- Front
- Back
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what percent of total body weight (TBW) is water in men?
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60%
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what percent of total body weight (TBW) is water in women?
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55%
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what percent of total body weight (TBW) is water in the elderly?
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46 - 52%
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what percent of total body weight (TBW) is water in infants?
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70 80%
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what percent of total body weight (TBW) is water in obese individuals?
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fat contains less water, so obese people have a lower percent water for body weight
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fluid distribution - how much intracellular vs extracellular
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2/3 intracellular, 1/3 extracellular
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what is the fluid distribution of the extracellular fluid
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3/4 interstitial, 1/4 intravascular
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when we give a bolus of fluid intravascularly, it redistributes
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to the same ratios as it should be (2/3 intracellular...etc.)
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fluid administration can impact anything and everything
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electrolytes, protein concentration, blood viscosity, change RBC concentration, interstitial volume, intracellular space, pH, enzymatic reactions, drug distribution (fat soluble vs water soluble drugs)
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osmole defined as
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# of impermeable particles in a solution which determines the osmotic pressure
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osmolality defined as
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# of osmoles per Kg of solvent
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osmolality of plasma is
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290 - 300 mosmoles/kg
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osmolarity definition is
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# of osmoles per liter of solvent
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tonicity is defined as
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the ability of a solution to exert an osmotic force across a membrane (hypertonic, hypotonic, isotonic)
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oncotic pressure is
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the pressure produced by proteins (ex. as dissolved in the plasma)
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1 Liter of water has a mass of
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1 Kg
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goals of fluid and electrolyte management are
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homeostasis - maintenance of physiologic balance of fluid volume and electrolytes, maintaining acid/base balance
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if you maintain homeostasis in fluid and electrolyte manage you get
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a reduction in patient morbidity and mortality
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preoperative influences on fluid balance
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NPO, vomiting, diarrhea, GI suction, fever, sepsis, dialysis, burns, bowel preps
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intraoperative influences on fluid balance
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blood loss, evaporative loss, third spacing, mechanical ventilation, vasodilation, increased ADH, absorption of irrigation fluid
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what surgeries do you tend to absorb irrigation fluids
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TURPs and hysteroscopies
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third spacing means
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fluid moving out of the intravascular space to anywhere else
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fever increases both
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sensible and insensible water loss
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toxins associated with sepsis cause
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an increase in capillary permeability causing leaking of plasma proteins into the intravascular space causing edema formation by changing the oncotic pressure gradient. Patients will be intravascularly depleted, but have edema everywhere
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dialysis before surgery
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removes excess fluids and electrolytes that accumulate in renal failure leaving a patient that can be volume depleted
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damage to what can produce large volume shifts
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damage to the skin and capillary beds
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debridement procedures can lead to
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large amounts of blood loss, plasma loss, and evaporative loss
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evaporative loss on burns is proportional to
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the total surface area burned
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patients who have had bowel preps should have
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electrolytes drawn before surgery
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intraoperative fluid requirements are calculated by including what factors
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hourly rate, replacing the NPO deficit, maintenance rate, surgical loss replacement, insensible and sensible loss
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the hourly requirement is calcuated using what rule
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4-2-1 rule
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describe the 4-2-1 rule
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for 1 - 10 kg you need 4 ml/kg/hr
for 11 - 20 kg you need 2 ml/kg/hr for >21 kg you need 1 ml/kg/hr |
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if a baby weighs 5 kg, the hourly rate should be
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20 ml/hr
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if a child weighs 14 kg the hourly rate should be
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48 ml/hr
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if a person weighs 40 kg then the hourly rate should be
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80 ml/hr
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the NPO deficit is calculated by
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the hourly rate x the number of NPO hours
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what ultimately dictates how fast fluid is replaced
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the patient's history and coexisting diseases
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if you have 2 hours to replace the NPO deficit,
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divide the volume in half and give half each hour (basically divide evenly over 2 or 3 hour surgeries)
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a patient with CHF, replace fluids
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more slowly
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a healthy person with hypotension, replace fluids
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more quickly
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calculate NPO deficit for a 20 Kg child NPO for 8 hours
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480 ml deficit
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calculate NPO deficit for a 250 kg pt, NPO for 12 hours
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3480 ml deficit
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calculate NPO deficit for 700 gm neonate, no NPO deficit
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2.8 ml/hr
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calculate NPO deficit for 70 Kg adulat, NPO 20 hours
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2200 ml deficit
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shortcut for calculating hourly rate is
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weight in Kg + 40 ml (for everything over 20 kg)
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maintenance fluid attempts to compensate for
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evaporative loss and fluid redistribution out of intravascular compartments
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maintenance fluid for minimal tissue trauma/exposure
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2-4 ml/kg/hr
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maintenance fluid for moderate tissue trauma/exposure
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4 - 6 ml/kg/hr
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maintenance fluid for sever tissue trauma/exposure
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6 - 8 ml/kg/hr
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maintenance fluid for an open chest or abdominal surgery
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8 or more ml/kg/hr
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all surgeries will trigger
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inflammatory response which will cause fluid loss
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crystalloid replacement for blood loss is
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3 ml of crystalloid for every 1 ml of blood loss
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choices of crystolloid fluid to replace for blood loss
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LR or .9 (typically LR even if slightly hypotonic)
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remember, blood loss should always be replaced with
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isotonic solutions (watch for patients on D5W maintenance fluids)
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if you lose 300 ml of blood, how much crystalloid to replace
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900 ml
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maintenance fluid rate for complex laceration repair to the hand
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2-4 ml/kg/hr
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maintenance fluid rate for lap appy
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2 - 4 ml/kg/hr
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maintenance fluid rate for total hip
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4 - 6 ml/kg/hr
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maintenance fluid rate for colectomy, tumor removal, and colostomy formation
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6 - 8 ml/kg/hr
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maintenance fluid rate for GSW with exploration
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8+ ml/kg/hr
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maintenance fluid rate for craniotomy
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2 - 4 ml/kg/hr (run cranies on the dry side)
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calculate values for hourly rate, NPO deficit, mainenance fluid, and surgical loss for this scenario
78 y/o female, total hip, 50 kg, NPO 10 hr, 1st hour 300 ml blood loss, 2nd hour 200 ml blood loss, 3 hour surgery |
hourly rate 90 ml/hr
NPO - 900 ml total maintenance - 300 ml/hr blood replacement - 900 ml then 600 ml then 0 |
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calculate values for hourly rate, NPO deficit, mainenance fluid, and surgical loss for this scenario
40 y/o man, 150 kg, NPO 8 hr, spinal fusion, blood loss 1st hour 100 ml, 2nd hour 800 ml, 3rd hour 200 ml, 3 hour surgery |
hourly rate - 190 ml/hr
NPO - 1520 total Maintenance - 300 ml/hr blood replacement - 300, 2400, 600 |
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calculate values for hourly rate, NPO deficit, mainenance fluid, and surgical loss for this scenario
1 kg neonate for gastroschesis, no NPO, blood loss 1st hour 3 ml, 2nd hr 5 ml, 3 hr surgery |
hourly rate - 4 ml/hr
NPO - 0 Maintenance - 8 ml/hr surgical loss replaced - 9 ml then 15 ml then 0 ml |
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insensible water loss is different than sensible water loss because
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insensible water loss does not contain solutes (free water) whereas sensible water loss does contain solutes
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types of insensible water loss
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water loss via skin, water loss via respiratory tract, evaporative loss via incision
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types of sensible water loss
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mucous, tears, urine,stool, sweat
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how much insensible water loss a day
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700 ml/day
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how much insensible water loss a day through the skin
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300 ml/day
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how much insensible water loss a day through the respiratory tract
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400 ml/day
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how can anesthesia reduce insensible water loss in the or
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keep flow rates at a minimum, humidification of ventilated air
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why does ventilated air increase insensible water loss
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we use cold dry air in the ventilators - so water is loss from the body to warm and humidify the air from the ventilator - and the heat is carried away with the evaporative moisture loss
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insensible water loss in the neonate is approximately
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40 ml/kg/day
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factors affecting insensible water loss in the neonate are
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prematurity, tachypnea/RDS, phototherapy, radiant warmer, increased temp, major skin defects, increased ambient humidity, saran wrap/ inner shield
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the amount of insensible water loss in the neonate that is premature
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inversely proportional to gestational age
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the amount of insensible water loss in the neonate that is tachypnic
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+ 20 ml/kg/day
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the amount of insensible water loss in the neonate that need phototherapy
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+ 20 ml/kg/day
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the amount of insensible water loss in the neonate that is in a radiant warmer
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+ 20 ml/kg/day
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the amount of insensible water loss in the neonate that has an increased temperature
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+ 40 - 80 ml/kg/day
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the amount of insensible water loss in the neonate that has a major skin defect (gastroschisis)
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+ 120 ml/kg/day
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the amount of insensible water loss in the neonate that has an increase in ambient humidity
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- 12 ml/kg/day
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the amount of insensible water loss in the neonate that is saran wrapped
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- 4 - 12 ml/kg/day
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sensible water loss increases how much for every degree above 38
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10% or by 100 - 150 ml/hr for every degree over 37 (based on a 70 kg)
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make sure to account for sensible and insensible water loss in what patients
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neonates, infants, and febrile
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rate to account for sensible and insensible loss
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2 ml/kg/hr by some providers
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why do some anesthesia providers not account for sensible and insensible water loss
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the slop factor of the maintenance fluid is usually enough to compensate for it
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osmolality of D5W
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253 mosmoles/kg
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osmolality of .9
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308 mosmoles/kg
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osmolality of LR
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273 mosmoles/kg
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a hypotonic IV solution will cause RBC to
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swell and lyse
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a hypertonic IV solution will cause the RBC to
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crenate
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how much glucose in D5W
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500 mg/dl, or 50 g/L
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why is LR called a balanced salt solution
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because it contains an electrolyte profile similar to plasma
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.9 contains how much NaCl
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154 (no other electrolytes)
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LR contains what electrolytes
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Na - 130
K - 4 Cl - 109 mmol/L Lact - 28 Ca - 3 |
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D5 LR compares to regular LR
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the same electrolyte distribute, but contains 500 mg/dl of glucose
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D5.22 contains
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500 mg/dl glucose and 38.5 NaCl
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D5.45 contains
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500 mg/dl glucose and 77 NaCl
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hypertonic IV solutions
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D5LR, D5.22, D5.45
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hypotonic IV solutions
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D5W, (LR)
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isotonic IV solutions
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LR, .9, normosol
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normosol IV contains
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Na - 140
K - 5 Cl - 98 acetate - 27 gluconate - 23 |
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advantage of normosol
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pH balanced
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disadvantage of .9
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high salt content
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pH of all IV solutions except normosol
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quite acidotic (LR is closer - 6.7, and normosol is 7.4)
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which IV solution is considered to be free water
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D5W - because the glucose is metabolized by the body and then there is nothing else left in it
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what about dextrose containing solutions
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rarely used in nondiabetic patients because causes hyperglycemia, used for hypoglycemic patients, used for neonates
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what should you ask a DM patient in your preop assessment
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how much and last dose of insulin and what type of insulin
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how much insulin should you tell DM patients to take the morning of their surgery
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half their normal dose
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evaporative loss is aka
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free water loss
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the most common intraoperative fluid is
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LR
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LR provides how much free water per liter
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100 ml - which compensates nicely for evaporative free water loss
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if need large volumes of crystalloid, what iv solution is recommended
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LR
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how is lactate metabolized
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70% via gluconeogenesis in the liver to glucose, and 30% via oxidation to bicarbonate
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the intravascular half life of LR
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20 - 30 minutes
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If a diabetic, what IV solution should you consider not giving
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LR - because of future increase in blood glucose
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.9 is the iv solution of choice for what patients
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neurological injuries, DM, ESRD
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.9 is also good because
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can be used with blood
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drawback of .9
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may cause hyperchloremic acidosis - as chloride ions increase, bicarb ions decrease
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intravascular half life of .9
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15 - 20 minutes
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why avoid LR in head injuries
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blood glucose > 200 mg/dl extends neuronal injury no matter the type of head injury - and increases mortality
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mechanism of hyperchloremic acidosis
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not fully understood - as the Cl ion increases, the kidneys begin to dump bicarb, a lose of bicarb leads to acidosis (determined by anion gap analysis)
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a fluid challenge (bolus) is calculated by
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10 - 20 ml/kg of isotonic fluid
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a fluid bolus for a 70 kg male should be
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700 - 1400 ml
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a fluid bolus for a 800 gm neonate should be
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8 - 16 ml
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what to remember about iv fluids and neonates
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only use PRESERVATIVE FREE solutions - otherwise can produce apnea
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types of colloids
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albumin, dextran, hetastarch
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what affects oncotic pressure
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the number of particles in solution, not the size of the particles
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why are colloids big particles
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so they stay in the vascular system longer creating a pull to keep fluid in the intravascular system
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half life of most colloids
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more than 3 - 4 hours
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colloids also function by
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improving the intravascular half life of crystalloids
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remember that colloids are
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prepared in .9 so you do have a risk for hyperchloremic acidosis
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when do you use colloid replacement
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when crytalloid replacement exceeds 3 - 4 liters
as an adjunct while waiting for blood pt with severe protein loss (burns) to replace blood loss (1:1) |
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colloid replacement for blood loss is in a ratio if
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1:1
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the most common plasma protein
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albumin
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albumin is responsible for what % of the oncotic pressure
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70 - 80%
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how much of albumin is in the extravascular space
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60%
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how much of albumin is in the intravascular space
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40%
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albumin functions in the plasma include
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binding and transporting drugs, hormones, fatty acids, and enzymes
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albumin is given in what cases
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ARDS, bacterial peritonitis, toxic bilirubin levels in infants with hemolytic disease
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a drug that binds to albumin and the free drug relationship
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if albumin levels are high then the free drug levels are reduced (inverse relationship)
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drug doses may need to be adjusted for
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albumin levels
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some drugs compete for
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albumin binding sites
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elevated bilirubin levels in infants is dangerous so we give
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albumin to bind the bilirubin and reduce the free toxic bilirubin
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a bound drug acts as a
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reservoir of that drug
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albumin is prepared by
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heating to 60 degrees C for 10 hours (a pooled blood product)
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albumins half life
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15 - 20 days
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for each 2.5 g/dl decrease in albumin, risk of death increases
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24 - 56%
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some linking of Mad Cow disease to
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albumin
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albumin is less popular now because
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2x more expensive than hespan, 10x more expensive than crystalloid, no increased benefit (actually demonstrated 6% increase in mortality in critically ill children receiving albumin), creutzfeldt-jakob risk
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dextran 70 vs dextran 40
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difference in molecular weight
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dextran 70 is aka
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macrodex
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dextran 40 is aka
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rheomacrodex
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dextran can cause
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mild to sever anaphylactic or toid reactions
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prevent anaphylactic reactions to dextran by giving
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dextran 1 (aka Promit) to bind antibodies
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side effect of dextran
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infusions > 20 ml/kg/day can interfere with blood typing and prolong bleeding time
decreases blood viscosity b/c coats platelets making it difficult to bind fibrin disrupting platelet aggregation |
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in what cases do they like dextran and why
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microvascular cases because of the reduced clotting risk
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hetastarch is eliminated by
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the kidneys after being broken down by amylase
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advantage of hetastarch
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less expensive than albumin
nonantigenic |
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side effect of high dose hetastarch
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coag and bleeding times effected with doses greater than 1/2 to 1 liter
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maximum dose of hetastarch per anethesia texts and per manufacturers
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anesthesia texts say 20 ml/kg/d
manufacturers say 35 ml/kg/d |
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key to estimating blood loss in the or
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pay attention!
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a fully soaked 4x4 contains how much blood
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10 ml
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a fully soaked lap contains how much blood
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100 ml
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a fully soaked and dripping lap contains how much blood
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150 ml
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when weighing sponges, 1 ml of blood weighs
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1 gm
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where do you look to account for blood loss
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soaked 4x4, laps,
suction canisters floor, drapes, under the sheets chest tubes cell saver |
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weigh soaked pads for
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NICU patients
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in C-section patients, remember that blood loss
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may be mixed with amniotic fluid so more difficult to estimate
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what about old blood
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make note of it on record, but not necessary to replace
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why is tracking blood loss important - other than the obvious patient well being
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affects surgeon's career
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quick calculation of Hgb from Hct
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Hgb is approximately 1/3 of the Hct
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a dehydrated patient's Hct will be
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falsely elevated
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a patients just bolused two liters Hct will be
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falsely lowered
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is blood usually over or under estimated by anesthesia and surgeons
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underestimated
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Hgb/Hct are useful for
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baselines and trending
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blood volume and blood loss calculations are based on a patient's
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actual body weight (not the ideal body weight)
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total blood volume of a neonate
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90 ml/kg
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total blood volume of an infant
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85 ml/kg
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total blood volume of a child
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80 ml/kg
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total blood volume of an adult male
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75 ml/kg
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total blood volume of an adult female
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65 ml/kg
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total blood volume of an obese adult
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55 ml/kg
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total blood volume of a 60 kg woman is
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3900 ml
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total blood volume of a 13 kg 4 yr old is
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1040 ml
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total blood volume of a 145 kg woman
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7975 ml
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total blood volume of a 700 gm neonate
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63 ml
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allowable blood loss can be ballparked by
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EBV x 20%
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use ballpark method of ABL for patients that ____________ but not for patients with ________
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are healthy and have no Hgb/Hct available - but not large blood losses or comorbidities
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CO =
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HR x SV
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compensation for blood loss in healthy patients occurs down to a Hgb of
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7 - 8 g/dl (21 - 24% Hct)
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for elderly patients, or pts with cardiac and pulmonary diseases, the Hgb transfusion target is set at
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10 g/dl
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carrying capacity forumula
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CaO2 = (SaO2 x Hgb x 1.34) + .003(PaO2)
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crystalloids and colloids cannot improve
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oxygen carrying capacity
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healing doesn't occur as well with
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a low Hgb
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at what point do you give blood
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when the O2 carrying capacity is no longer adequate to meet body demands
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compensation for decreased carrying capacity goes something like
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decreased carrying capacity, cell metabolism switches to anaerobic metabolism, ATP stores deplete, enzymatic reactions slow down, SNS increases heart rate and stroke volume
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increased SNS affects the heart by
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increasing heart rate and increasing inotrope
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normal Hct for a preemie (acceptable)
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40 - 45 (35)
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normal Hct for a newborn (acceptable)
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45-65 (30-35)
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normal Hct for 3 months (acceptable)
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30 - 42 (25)
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normal Hct for 1 year (acceptable)
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34 - 42 (20-25)
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normal Hct for 6 years (acceptable)
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35 - 43 (20 - 25)
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how do you calculate ABL
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EBV x Hct% = ERCMV
EBV x acceptable Hct% = ARCMV subtract one from the other and multiply x 2 for when to start thinking about replacing with blood or x 3 for when blood is definitely needed by |
