Perioperative Fluid Management Flashcards
What are the goals of perioperative fluid management?
Provide appropriate amount of parental fluid to maintain adequate intravascular fluid volume, left ventricular filling pressure, CO, systemic BP, and O2 delivery to tissues
In the average adult, the extracellular fluid volume represents approximately ___ % of total body water.
33%
The major components of the extracellular compartment are:
Interstitial fluid and plasma volume
Blood volume at rest is normally distributed as __% arterial and __% venous
15
85
The primary gradient that helps maintains intravascular fluid may be best described as:
oncotic pressure
The recommended duration of preoperative fasting from clear liquids is:
2 hours
Approximately 20 to 40 minutes following parenteral administration of crystalloid solutions, ___ % of the crystalloid remains intravascular.
33%
Balanced salt solutions (LR, Plasma-lyte) in respect to sodium are (slightly hypotonic, isotonic, or slightly hypertonic).
slightly hypotonic
The buffer in LR is metabolized in vivo to generate:
bicarbonate
Which crystalloids are appropriate for diluting PRBCs?
Normal saline, plasma-lyte
Name 3 situations where normal saline is preferred over LR.
Brain injury
Hypochloremic metabolic acidosis
Hyponatremia
What is the 1/2 life of albumin under normal circumstances?
16 hours
What is the recommended max dose of Dextran 70 in the initial 24 hours?
How does it increase bleeding time (keep it simple)?
20ml/kg/day (in the first 24 hours), then 10ml/kg/day
Decreases platelet adhesiveness
Calculate fluid maintenance rate for a 15Kg patient.
10kg * 4ml/kg = 40
5kg * 2ml/kg = 10
50ml/hr maintenance fluid
What is the maintenance fluid rate for an 80kg pt?
120ml/hr
How is fluid deficit calculated?
Preoperative fluid deficit = Maintenance fluid rate x hours NPO
If your 80kg pt was NPO for 14 hours, what would his fluid deficit be?
1680 ml
80kg = 120ml/hr * 14 hr = 1680 ml
To address a patient’s fluid deficit, how much should be infused in the first hour? Second hour? Third hour?
50%
25%
25%
Why is dextrose solutions typically not used for volume maintenance during surgery?
Dextrose metabolized, leaving only water. The water can dilute other plasma substrates.
For every 1ml of blood loss, ___ ml of crystalloid can be given.
3ml
Define third spacing
Movement of extracellular fluid to the interstitial space, an area where the body cannot use fluid in the intravascular space to move O2 and other essential nutrients to tissues.
Under what conditions should fluids be restricted?
CHF ESRD Liver resection Pulmonary surgery patients Abdominal surgery
Soaked sponge holds __ ml of blood.
Soaked laparotomy pad holds __ to __ ml of blood.
10
100 to 150ml
How do you calculate estimated blood volume (EBV)?
EBV = 60-70ml/kg in adults * weight
80ml/kg in children
90ml/kg in infants
100ml/kg in infants
How do you calculated allowable blood loss (ABL)?
ABL = [EBV * (Hi - Hm)]/Hi
i.e. [4900 * (40-25)]/40
What is the most common cause of bleeding following a massive blood transfusion?
Dilutional thrombocytopenia
What is the only reason for blood transfusion?
To increase O2 carrying capacity
Why do males have more total body weight of water than females?
Increased adipose tissue in females (60% males vs 50% females)
Plasma volume is what percent of total body weight?
4% (20% of ECF, which is 20% of TBW)
Why may a transfusion of LR only temporarily increase blood volume intravascularly?
LR is slightly hypotonic. Infusing this will dilute intravascular volume of Na and plasma proteins, shifting excess water intracellularly and to interstitial space. This leaves less water intravascularly.
At what degree of hyponatremia do seizures occur?
<120
What are some EKG changes associated with hypokalemia?
flattened or inverted T wave
U wave
Prolonged QT interval