Fluid and Blood Therapy Flashcards
Why is hypovolemia common in patients scheduled for surgery?
NPO status
surgical trauma
evaporation
dry anesthetic gases
Why complications can result from hypovolemia that cause a significant increase in postoperative morbidity and mortality?
Ranges from PONV to serious complications such as organ dysfunction and prolongation of hospital stay
What are the goals of fluid therapy?
Avoid or correct a hypovolemic state
Restore intravascular volume
Maintain oxygen-carrying capacity of the intravascular volume
**Maintain adequate tissue perfusion
How is total body water (TBW) determined?
Percentage of body weight, varies with age, gender, and body habitus
What is the TBW of the average 70 kg adult male?
60%
What is the TBW of the average 70 kg adult female?
55%
What is the TBW of premature infants?
80-90%
What is the TBW of term infants?
75%
What is the TBW of the elderly?
50-55%
What are the different body fluid compartments and their volume?
TBW = 42 L (60%)
ECF = 15 L (20%) ICF = 27 L (40%)
- Plasma = 3 L (4%)
- Interstitial fluid = 12 L (16%)
How does water move between the ICF and ECF?
Osmotically active particles attract water across semipermeable membranes until equilibrium is attained
What is the ratio of plasma to interstitial fluid across the capillary membrane?
1:4
What is osmosis?
water moving across a membrane from solution of low concentration to a solution of high concentration
Will a higher concentration solution have a lower or higher osmotic pressure than a lower concentration solution?
higher - more osmotically active particles
What is osmolality?
Number of osmotically active particles per kilogram of water
What is osmolarity?
Number of osmotically active particles per liter of solution
How is osmolality calculated?
Osmolality = (serum Na+ x 2) + blood glucose + blood urea (mmol/kg)
What is tonicity?
measure of particles which are capable of exerting an osmotic force, used to describe osmolality of a solution relative to plasma
What does isotonic mean?
2 solutions with the same osmolarity (no osmotic pressure generated across cell membranes)
What is a hypotonic solution?
solution with a lower osmolarity than plasma
What is a hypertonic solution?
solution with a higher osmolarity than plasma
How does water move between the plasma and ISF?
Colloid oncotic pressure
Starling forces
What are the different Starling forces?
Capillary hydrostatic pressure
ISF hydrostatic pressure
ISF colloid osmotic pressure
Plasma colloid osmotic pressure
What is the colloid osmotic pressure?
Osmotic pressure exerted by the macromolecules (colloid molecules), prevents fluid from leaving the plasma and exerts a “pull” from the interstitial space
How does plasma colloid oncotic pressure maintain plasma volume?
Proteins
Albumin
Gamma globulins
How much crystalloid is required to expand the IV compartment 1 L?
3-4 L of crystalloid
What are dextrose solutions used for?
to replace daily water requirement or replace water deficits
What are dextrose solutions not suitable for?
resuscitation or rapid volume replacement
Are dextrose solutions hypo or hypertonic?
Hypo, glucose initially osmotically active but then is rapidly metabolized leaving free water with/without electrolytes
How much D5W would be required to replace 500 mL plasma volume?
7L D5W
What is the most commonly used crystalloid fluid?
LR
What is the tonicity of LR?
Slightly hypotonic with osmolarity of 273, 100 mL free water/L
What electrolyte abnormality does LR cause?
Hyponatremia, tends to lower serum Na to 130 mEq/L
In LR, lactate is converted by ____ into _______.
Liver, bicarbonate
Which fluid is the most physiologic?
LR, has least effect on ECF
What patient population would you want to avoid giving LR?
renal patients due to potassium content in LR
What is the only fluid acceptable to use with blood transfusions?
NS
What is the osmolality of NS?
308
What can large volumes of NS cause?
Dilutional hyperchloremic metabolic acidosis due to chloride content in NS
(bicarb concentration decreases as chloride concentration increases)
What electrolyte abnormality would indicate the administration of hypertonic crystalloids?
Severe hyponatremia
With what clinical conditions would hypertonic crystalloids be useful?
resuscitation of severe hypovolemic shock or burn patients
What are some undesired effects of hypertonic crystalloids?
Hyperchloremia
Hypernatremia
Cellular dehydration
Limited intravascular duration
Should you administer hypertonic crystalloids fast or slow?
SLOW
What are colloids?
Solutions that contain large molecules that are retained in the intravascular space (“plasma expanders”)
What does colloid duration in the vasculature depend on?
Size of the molecules, their overall oncotic effect, and plasma 1/2 lives
What are some adverse effects of colloids?
Effects on platelets and coagulation
Anaphylaxis
Action in reticulo-endothelial system
What is the molecular weight of endogenous albumin?
69,000
What is the degradation 1/2 life of endogenous albumin?
18 days
How much albumin is synthesized a day by hepatocytes to maintain normal plasma concentration of 40 g/L?
9-12 g/day
How much of the plasma colloidal oncotic pressure is attributed to endogenous albumin?
60-80%
What determines the concentration of endogenous albumin in the ISF?
capillary permeability
How is albumin in the ISF return to circulation?
lymphatic system
How are blood-derived colloids prepared to minimize hepatitis/viral disease transmission?
heated to 60 degrees Celsius for 10 hours
What is the molecular weight of 5% and 25% albumin solutions?
66,000-69,000
What are clinical benefits of giving albumin 5% and 25%?
Provides high colloid osmotic pressure
Expands IV volume up to 5 x’s volume given by drawing fluid in from ISF
How much of the albumin 5% or 25% infused escaped from the IV space/hour?
4-5%
What is the plasma half-life of albumin 5% and 25%?
16 hours
What is plasma protein fraction 5%?
5% solution of selected proteins prepared from human blood, serum, or plasma
What is plasma protein fraction 5% composed of?
Mixture of proteins, but mostly albumin in a concentration of >/= 83% of total protein composition
What is an adverse effect of plasma protein fraction 5%?
allergic reaction resulting in hypotension
What are the synthetic colloids?
Dextran and Hydroxyethyl starch
What is the molecular weight of Hydroxyethyl starch 6%?
450,000
What is Dextran composed of?
Highly branched polysaccharide molecules
What is a benefit to administering Dextran 70?
Better volume expander
What is a benefit to administering Dextran 40?
Improves blood flow through microcirculation; reduced red cell and platelet sludging
Volume expansion
Hemodilution-induced reduction in blood viscosity
With what type of surgery will you most likely use Dextran 40?
Vascular surgeries
What is an adverse effect of Dextrans?
Can be antigenic; anaphylactoid/anaphylactic
What are benefits to giving HES?
Less expensive than albumin and non-antigenic
Highly effective plasma expander
What is the duration of HES?
approximately 24-36 hours
What other colloid is HES comparable to?
5% albumin
How is HES metabolized and excreted?
Large molecules broken down by amylase; small molecules eliminated by kidneys; primarily excreted by the kidneys
What is a common adverse effect after HES administration?
Pruritis
What are crystalloids generally used for?
maintenance fluid for insensible losses and as replacement for body fluid deficits
What are colloids generally used for?
Fluid replacement and shock resuscitation
Which type of fluid is ideal for initial management of ECF losses?
Crystalloids
What can large volumes of crystalloids cause?
Hemodilution and decreased plasma colloidal oncotic pressure –> edema and transudates
How much does an infusion of 500 mL albumin or HES 6% expand plasma volume?
500 mL
How much do colloids expand plasma volume per gram of colloid?
Expands plasma volume 20 mL
What are perioperative goals for fluid management?
**Enhance microvascular blood flow so that oxygen is delivered to tissues Meet basal fluid requirements Replace losses Restore/maintain hemodynamic stability Maintain aerobic cellular metabolism
What is the formula to determine oxygen delivery to the tissues?
DO2 (oxygen delivery) = CI (cardiac index) x CaO2 (arterial oxygen content)
What things must you consider when calculating oxygen delivery to the tissues?
- cardiac status; ability to increase cardiac output to meet DO2 demands
- Pulmonary status; ability to maintain SaO2
- Ability of O2 delivery to meet O2 demands
What is the average normal water metabolic rate for a normothermic 70 kg patient? (how much water is gained and lost in a day)
2500 mL water/day (gain 400 mL from metabolic water; net hypothetical loss of 2000 mL/day)
How can you calculate maintenance fluid requirements?
4-2-1 rule
weight in kg + 40
How can you calculate NPO deficits?
hours fasted x maintenance requirements
What are some examples of obligatory losses?
- evaporation (most apparent with large wounds and directly proportionate to surface area exposed and duration of exposure)
- internal redistribution of body fluids (Third spacing; can be massive resulting in severe intravascular depletion)
What is third space sequestration?
Traumatized, inflamed, or infected tissue (burns, surgery, peritonitis) can sequester large amounts of fluid in interstitial space, translocate fluid across serosal surfaces (ascites), translocate fluid into bowel lumen
What do you need to know to calculate the third space loss?
Type of procedure
Degree of exposure
Amount of surgical manipulation
What is the additional fluid requirement for minimal trauma?
1-2 mL/kg/hr
What is the additional fluid requirement for moderate trauma?
4-7 mL/kg/hr
What is the additional fluid requirement for severe trauma?
8-10 mL/kg/hr
What is the primary reason to administer blood?
maintain O2 carrying capacity
How much blood loss can most adults tolerate?
10% of EBV
When would you want to check a Hgb?
After 15-20% loss of EBV ( in healthy patients, earlier if comorbidities present)
What Hgb and Hct do healthy patients tolerate?
Hgb of 6-7 g/dL and Hct 18-21%
You would maintain normovolemia with crystalloid or colloid until what point?
Danger of anemia outweighs risk of transfusion
How much crystalloid do you infuse for every mL of blood loss?
3 mL crystalloid: 1 mL blood lost hourly
How much colloid do you infuse for every mL of blood loss?
1 mL colloid: 1 mL blood lost hourly
What is the systematic approach to a fluid plan?
maintenance needs + deficit + 3rd space + blood loss = systematic approach
What is the total blood volume (TBV) composed of?
RBC volume (2L) Plasma volume (3L)
What tends to increase blood volume?
Muscularity and physical activity
What tends to decrease blood volume?
Obesity, inactivity, and chronic disease
As you get older, your estimated blood volume increases or decreases?
decreases
What is the EBV for an adult male?
75 mL/kg
What is the EBV for an adult female?
65 mL/kg
What is the EBV for a geriatric male?
65 mL/kg
What is the EBV for a geriatric female?
60 mL/kg
What is the EBV for children?
75 mL/kg
What is the EBV for infants?
80 mL/kg
What is the EBV for neonates?
premature - 95 mL/kg
full term - 85 mL/kg
What formula can you use to calculate allowable blood loss?
ABL = 3[(EBV x Hct preop) - (EBV x Hct allowable)]
How much will 1 unit PRBC increase Hgb and Hct?
Increases Hgb by 1 g/dL and Hct 2-3% in adults
How much of a RBC transfusion will increase Hgb by 3 g/dL and Hct by 10%?
10 mL/kg transfusion
How can you estimate how much blood is lost?
Suction canisters
Sponges
Watch the surgical field
Scale weight
How much blood does a 4x4 sponge hold?
10 cc
How much blood does a Ray-tech sponge hold?
10-20 cc
How much blood do lap pads hold?
100 cc
How much blood do wet sponges hold?
20-30% of dry value
How do you split up the NPO deficit if the surgery is to last 3 hrs?
1/2 NPO deficit the 1st hour, then 1/4 the 2nd hour, and the last 1/4 the 3rd hour
What is type specific compatibility testing?
ABO-Rh typing only; 99.8% compatible
What is a type and screen?
ABO-Rh type and screen for specific antibodies commonly associated with non-ABO hemolytic reactions; 99.94% compatible
What is a type and crossmatch?
Confirms ABO-Rh typing
Detects antibodies to other blood groups
Detects antibodies in low titers
How long does it take to do a type and crossmatch?
Can take up to 45 mins, not ideal for someone who is actively hemorrhaging
What is the universal donor for someone with an unknown blood type?
O negative
How long does it take to get ABO specific units?
5 minutes
What is the probability that someone will have an unexpected antibody to ABO specific units?
1:1000
If you are infusing O negative blood to someone with an unknown blood type, how long should you continue to give O negative blood?
If 4 units or less used of O negative, switch to cross matched blood when available; if greater than 4 units of O negative blood used, stick with O negative
How much volume is in whole blood, how is it stored, and when is it used?
450 mL
Fresh storage for 24 hours
Rarely used unless there is mass casualty or other military situations; also used for >25% EBV loss with ongoing active bleeding
How much volume is in PRBC, what is the Hct, and when are PRBC used?
250-350 mL volume
Hct 70%
Used to replace RBC, but not volume
How much does one unit of platelets increase the platelet count?
5000-10000
How much volume is in a single donor bag and a multiple donor bag of platelets?
single - 10-25 mL/bag
multiple - 50-70 mL/bag
When are platelets given?
To treat thrombocytopenia or dysfunctional platelets
- <10,000-20,000 = increased risk of spontaneous hemorrhage
How are platelets stored and how long do they last?
Stored at room temperature and survive 7 days post transfusion
How much volume is in FFP and what does it contain?
250 mL/bag
Contains all clotting factors except for platelets
What are some indications for FFP?
- Isolated factor deficiency
- Reversal for warfarin therapy (5-8 mL/kg)
- Correct of coagulopathy or microvascular bleeding
- Massive transfusion (large volumes of crystalloid/colloid depletes clotting factors)
What is the initial dose of FFP?
10-15 mL/kg
What is cryo used for?
Correct specific coagulopathies (used for factor VIII deficiency and hemophilia A)
What is one major risk factor of giving cryo?
Carries greatest infectious risk from hepatitis since it is pooled from more than one donor
What are some complications of transfusions?
- immune hemolytic reactions
- immune non-hemolytic reactions
- infections (hepatitis, HIV)
- metabolic complications (decreased pH and lactate production or increased potassium with cell lysis, increased with storage)
What are some clotting complications of transfusions?
- coagulopathy (usually occurs after massive transfusion >10 units)
- dilutional thrombocytopenia (responds well to platelet transfusion)
- low factors V and VIII (stored blood factors may be 15-20% of normal)
- DIC (activation of clotting system –> microvascular fibrin deposition –> activation of fibrinolysis)
What is TRALI?
Transfusion Related Acute Lung Injury
- leading cause of transfusion related death in US
- Noncardiogenic pulmonary edema
- Thought to be secondary to donor leukocyte antibodies and recipient leukocytes
What are some s/s of TRALI?
Hypoxia Cyanosis Fever Dyspnea Fluid in ETT Hypotension
What is the treatment for TRALI?
Supportive treatment such as PEEP, increased FiO2, and vasopressors
What is a massive transfusion?
Replacement of pt’s total blood volume in 1/2 the patient’s estimated blood volume in 3 hours or less
Transfusion of more than 10 units of whole blood
What is citrate toxicity?
- CItrate preservative (used as anticoagulant in stored blood) may bind to and chelate calcium
- Empiric administration of calcium is not warranted unless ionized calcium levels are low
- Clinically significant hypocalcemia resulting in cardiac depression does not occur in most normal patients unless the transfusion rate exceeds 1 unit every 5 minutes
What are some transfusion alternatives?
- Autologous donation and transfusion (pt donates blood before procedure)
- Donor-directed transfusion
- Autotransfusion
- Perioperative blood salvage (cell saver)
- Intraoperative isovolemic hemodilution
- Substitute products for replacement of plasma and blood volume
What are proper transfusion practices?
Warm the blood
Use a filter (170 micrometer filter)
Reconstitute with NS (Calcium in LR may cause blood to clot by reversing anticoagulant effect of citrate)
What clinical signs can show you adequate perfusion?
Urine output Capillary refill Skin color Temperature Pulse rate Acid-base status Oxygen consumption Mixed venous O2 saturation BP
