Fluids Flashcards
Body fluid distribution?
Intracellular: 40% 24 L
Interstitial: 16% 9.6 L
Plasma: 4% 2.4 L
How to assess for fluid volume status
Skin turgor Mucous membrane Edema Lung sounds Vital signs Urine output HCT Urine specific gravity BUN/Creatinine
Sources of intraoperative fluid requirements
Maintenance
Fluid deficit
Blood loss
Evaporative loss (3rd space loss)Insensible loss sources?
the respiratory tract
perspiration
urine and feces
GI fluids
Maintenance fluid calculation?
4-2-1 rule
4cc/kg/hr for 1st 10kg
2cc/kg/hr for 2nd 10kg
1cc/kg/hr for each additional kg
What is fluid deficit?
The maintenance requirement multiplied by the number of hours patient NPO
If patient receiving maintenance IV fluids there is no NPO deficit but consider other losses
If baseline hypovolemia exists consider overall deficit larger than just NPO deficit
fluid should be replaced to restore mean arterial pressure , heart rate, and filling pressures prior to induction.
Normal urine output is also desirable
Fluid deficit replacement strategy?
Replacement strategy
½ deficit replaced in 1st hour of surgery
¼ deficit replaced in 2nd hour of surgery
Remaining ¼ replaced in 3rd hour of surgery
What is allowable blood loss?
Determines how much blood you can lose to reach a particular HCT
Helps anesthetist design appropriate plan and time to transfuse patient
ABL= EBV x (pts HCT – allowable HCT)
pts HCT
Evaporative loss and 3rd space loss?
Evaporative loss related directly to surface area of surgical wound and duration of exposure
3rd space loss due to massive fluid shifts and intravascular volume deficit caused by redistribution of fluids
Trauma, infection, burns
Replacing evaporative/3rd space loss: Minimal, moderate, severe, emergency?
Minimal (eye cases, lap chole : 0-2ml/kg/hr
hernia, knee scope)
Moderate (open cholecystectomy): 3-5ml/kg/hr
appendectomy
Severe (bowel surgery, THR): 6-9ml/kg/hr
Emergency (gun shot, MVC): 10-15ml/kg/hr
Blood loss replacement strategy
replace 3:1 crystalloid
Replace 1:1 blood
Name the crystalloids and their osmolarity
- Hypotonic solutions (253)
Replaces water loss, called maintenance fluids examples: D5W - Isotonic solutions (300)
Replaces water and electrolyte loss, called replacement fluids examples: LR, NS - Hypertonic solutions
For hyponatremia or shock examples: D51/2NS (432), 3% NS (1026) - LR
Describe the characteristics of LR
Isotonic, provides 100cc free water per liter of solution, tends to lower Na+
Lactate converted to bicarbonate
Most physiologic solution (most similar to ECF)
Avoid in ESRD as contains K+
Describe LR and its electrolyte contributions
Sodium130 meq/liter Potassium4 meq/liter Calcium2.7 meq/liter Chloride110 meq/liter Lactate27 meq/liter
Describe NS
0.9% NS
Isotonic solution
In large volumes produces high Cl- content dilutional hyperchloremic acidosis
Preferred solution for diluting PRBCs
Describe D5W
D5W
Hypotonic solution
Has little place perioperatively (except as 2nd line- DM Rx with insulin)
Causes free water intoxication and hyponatremia
Describe albumin?
Blood colloid Obtained from fractionated human plasma Does not contain coagulation factors or blood group antibodies Available as 5% or 25% solution 5% solution common in OR
Describe Dextran
Synthetic colloid solution Water soluble glucose polymers Enzymatically degraded to glucose Dextran 70 used for volume expansion Dextran 40 used for prevention of thrombosis Side effects include anaphylactoid reaction, platelet inhibition, noncardiac pulm edema Interference with crossmatching
Describe Hetastarch
Synthetic colloid solution
(hespan 6%)
As effective as albumin for volume expansion
Nonantigenic
Less expensive than albumin
Stored in the reticuloendothelial system for several hours and renally excreted
Coagulopathy d/t dilutional thrombocytopenia
Crystalloids vs. Colloids
Crystalloids:
Crystalloids equally effective as colloid in restoring intravascular volume if given in sufficient amounts
Support u/o better
Less likely to cause pulmonary edema, colloids associated with coagulation and antigenic problems
Inexpensive
Colloids:
Colloids better at restoring severe intravascular volume deficits by maintaining plasma oncotic pressure
Intravascular half life is 3-6 hours for colloid 20-30 minutes for crystalloid
Fluid of choice with hypoproteinemia
More tissue edema occurs with crystalloids
What are the 4 blood components?
PRBC
Platelets
Fresh frozen plasma
Cryoprecipitate
ASA guidelines for blood transfusion
Rarely indicated if HBG >10g/dl and almost always indicated if HGB
Indications for blood transfusion
- Expand intravascular volume
- Increase oxygen carrying capacity
- Hemoglobin and hematocrit
Clinical judgment based on certain factors Cardiovascular status Age Anticipated blood loss Arterial oxygenation Cardiac output and blood volume
PRBCs
Type specific ABO and Rh factor alone is sufficient in 98.9% of patients (incompatibility seen in 1 in 1000)
Further testing if antibodies present or patient has had numerous blood products
1 unit PRBC increase HGB 1gm/dL
HCT of one unit of PRBC is 70%
Autologous Unit
Reconstituted with 0.9%Normal Saline 5% dextrose in 0.4%saline 5%dextrose in 0.9% saline Normosol-R (ph of 7.4)
Citrate toxicity
Hypocalcemia
Monitor ionized calcium
