Fluid Management Flashcards
anion gap
difference between cations and anions
Na+-(Cl-+HCO3-)
Normal = <12
>12 indicates pt has metabolic acidosis
Respiratory acidosis results in…
- reduced myocardial contractility
- increased PVR
- decreased SVR
Respiratory alkalosis results in…
- hypokalemia
- hypocalcemia
- dysrhythmias
- bronchoconstriction
- cerebrovasoconstricion
- hypotension
Metabolic acisosis results in…
- reduced myocardial contractility
- increased PVR
- decreased SVR
Metabolic alkalosis results in…
- hypokalemia
- hypocalcemia
- arrhythmias
- compensatory hypoventilation/hypercarbia
- reduced tissue oxygenation
treatment of metabolic alkalosis
- expansion of intravascular volume
- administer K
- administer carbonic anhydrase inhibitor
Base excess or deficit
- Used to measure deviation from normal bicarbonate level to help determine adequacy of intravascular volume
- 0 = normal bicarbonate level
- -2 to <0 = metabolic acidosis (base deficit)
- >0 to +2 = metabolic alkalosis (base excess)
Plasma solute concentrations
- Na: 140
- K: 4.3
- Mg: 2
- Cl: 105
- HCO3-: 24
- phosphate: 2
- Protein: 1
- Total Osm: 291
- pH: 7.4
ECF solute concentrations
- Na: 140
- K: 4.3
- Mg: 2
- Cl: 105
- HCO3-: 24
- phosphate: 2
- protein: 0
- Total Osm: 290
- pH: 7.4
ICF solute concentrations
- Na: 12
- K: 120
- Mg: 40
- Cl: 5
- HCO3-: 12
- Phosphate: 100
- protein: high
- Total osm: 290
- pH: 7.2
sources of intra-op fluid requirements
- maintenance
- healthy adults require 2.5L/day over 24 hours
- fluid deficit
- Blood loss
- evaporative loss
- 3rd space loss
calculating maintenance fluids
- 4-2-1 rule
- 4 ml/kg/hr for first 10 kg
- 2 ml/kg/hr for second 10 kg
- 1 ml/kg/hr for each additional kg
Fluid deficit
- the maintenace requirement multiplied by the number of hours pt was NPO
- if receiving maintenace IVF, no NPO deficit
- if baseline hypovolemia exists, consider the overall deficit greater than just NPO deficit
- replace fluid to restore MAP, HR and filling pressures BEFORE induction
Fluid deficit replacement strategy
- 1/2 of deficit replaced during first hour of surgery
- 1/4 of deficit replaced during second hour of surgery
- 1/4 of deficit replaced during third hour of surgery
Blood loss estimations
- soaked gauze 4x4 = 10 ml
- soaked laparotomy pads = 100-150 ml
- suction containers
- floor and drapes
- consider if gauze and pads are being used wet or dry by surgeon
floor spill approximations
- 1 inch diameter = 5ml
- 2 inch diameter = 20 ml
- 3 inch diameter = 45 ml
- 4 inch diameter = 80 ml
Estimated blood volume
- neonates
- premie = 95 ml/kg
- term = 85 ml/kg
- infant = 80ml/kg
- child = 70 ml/kg
- adult
- men = 75 ml/kg
- women = 65 ml/kg
allowable blood loss
ABL = (EBV x (starting HCT - allowable HCT))/ starting HCT
*helps anesthetist plan when to transfuse patient
Evaporative loss
- evaporative loss is directly related to amount of surface area of surgical wound and duration of exposure
3rd space loss
due to fluid shifts and intravascular volume deficit caused by redistribution of fluids
Ex. trauma, infection, burns, ascites