Flashcards in fluid and blood product management Deck (105)
what is the major component of the body?
water (50-70% of body weight)
what is water percentage influenced by?
-age (decreases with age; water babies vs. dry elderly)
-tissues (fat holds less water than lean tissue; thin person has more water than obese person)
describe intracellular fluid volume
-2/3 of total body water (28 L in a 70 kg male; 40% total body weight)
-fluid inside all cells, aqueous medium
-most of the potassium is here
describe extracellular fluid volume (ECF)
-1/3 of total body water (14 L in 70 kg male; 20% total body weight)
-fluid outside cells in cardiovascular system, organs, and interstitial spaces
-most of sodium is here
-two compartments: plasma volume (PV) and interstitial fluid volume
*compartment that is replaced with fluid management
describe plasma volume (PV)
-1/4 of ECF (3.5 L)
-intravascular fluid, but outside the erythrocytes
-8-9% of total body water
describe interstitial fluid (ISF)
-3/4 of ECF (10.5 L)
-extravascular, interstitial fluid, extracellular
-separated from the plasma volume by the walls of the blood vessels
-very little in the form of free fluid (increased clinically is edema)
*lymph, cavity fluid (peritoneal, pericardial, pleural), transcellular fluids (salivary, hepatic, biliary, pancreatic, dermal, mucosal, etc.)
what happens continuously between the different fluid compartments?
there is a continuous exchange of water between the different fluid compartments
what forces influence the movement of fluid between the compartments?
what is hydrostatic pressure?
the pressure within the capillaries from the weight of the blood and the pressure from the cardiac pumping mechanics
what results from hydrostatic pressure?
-small amounts of intravascular plasma volume moving into the interstitial fluid compartment
*typically, this water returns to the venous capillaries from the interstitial fluid compartment maybe through the lymph
what is osmotic pressure?
the hydrostatic pressure that must be applied to the solution of greater concentration to prevent water movement across the membrane
*forces wanting to keep fluid in; "pulls" on fluid
how does osmotic pressure work?
when two compartments are separated by a semipermeable membrane with aqueous solutions of unequal concentrations, the water will move from the more dilute to the more concentrated solution in an effort to equalize the concentrations
which end of the capillary has a net loss (fluid moving out)?
*more loss on arterial end than gain on venous end
which end of the capillary has a net gain (fluid coming back in)?
what does the solutions that exist in the compartments contain that accounts for osmotic forces?
-Na+: plasma, interstitial (extracellular)
what is the purpose of fluid management?
maintain tissue perfusion
what is tonicity?
compares osmolality of solutions; the effect of a solution on the cell volume
-osmolality of solution is the same (isoosmotic) as that of body fluids
-nothing happens to the cell
*NS, LR, plasmalyte
*plasmalyte is very similar to normal plasma
*NS is isotonic but is different and too much can create acidosis
-osmolality of solution is higher than body fluids causing water to move out of cells
*5% NS, 10% Mannitol
*neuro use; helps shrink cerebral edema or shrinks cerebral tissue to allow surgeon easier access to site and closure of cranium
-have a lower osmolality than body fluids causing absorption of water by cells
-cell swells (bursts)
-rarely ever want this to happen
*1/2 NS, D5W (starts off isotonic but the metabolism of glucose causes to become hypotonic and absorb water
*avoid in neuro patients (increases swelling)
*avoid with any ischemia (glucose products increase damage)
what contributes to volume deficit?
-prolonged NPO time
-excessive blood drawn
what clinical signs may be seen with volume deficit?
-blood pressure: orthostatic hypotension; > 20 mmHg indicates a deficit of 6-8% (w/o vasodilation); decreased BP with inspiratory gas flow (PPV decreases VR)
-heart rate: increases with hypotension; r/o medication related
-mucous membrane moisture: dry
-skin turgor: poor
-urine output: decreased
what is considered mild dehydration?
-less than 5% wt loss
-dry mouth, malaise, decrease UOP
-normotensive, normal cap refill
May be d/t vomiting or diarrhea
what is considered moderate dehydration?
5-10% reduction in body weight
-lethargy, loss of appetite, thick mucous membranes, oliguria, eyes sunken, depression of anterior fontanelle (in infants up to 6 months)
-normotensive, HR increased, capillary refill slowed to 3 seconds
what is considered severe dehydration?
> 10% decrease in body weight
-hypotension less than 60 mmHg, tachycardia, mottled cool skin, cap refill greater than 3 sec., anuria
*if suspected, give 10-20 ml/kg bolus (caution with CHF)
what contributes to volume excess?
-excessive fluid administration
-cirrhosis of the liver
what procedures put the pt. at risk for fluid excess?
transurethral resection of the prostate (TURP) and hysteroscopy
-both open up sinuses which absorb irrigation fluid
*best option is a regional with these procedures since Na+ changes are easily indicated with CNS changes which can not be assessed with GA
*know pre op Na+ levels
what clinical signs would indicate volume excess?
-edema: scleral, conjunctiva, pulmonary edema if severe
-diuresis: > 100 ml/hr
-initially HTN, progresses to hypotension if cardiac failure
**if in CHF, treatment should be completed before selective anesthesia; unless surgery is a matter of death, delay and consult cardiology
how does volume deficit influence sodium concentration?
-electrolyte free water is lost, serum sodium and serum osmolality increase
-d/t inadequate water intake, fever, loss of fluid from burns
how does volume excess influence sodium concentration?
-when water is present in body fluids in excess, the serum sodium and serum osmolality decrease
when is hyponatremia seen with hypovolemia?
when electrolyte rich fluids are lost and replaced with water
-vomitus, diarrhea, fistula drainage
*treatment: replacement fluids with electrolytes (LR)
when is hyponatremia seen with normovolemia?
when kidneys fail to conserve sodium
when is hyponatremia seen with hypervolemia?
absorption of fluids from TURP, if D5W used to replace volume deficit
what are crystalloids?
-intravascular half life 20-30 minutes
-LR, NS, plasmalyte
-choice based on fluids being replaced
-more physiologic than NS in large volumes
-contains sodium (103), chloride (109) potassium (4), calcium (3), and lactate (28)
-if give massive blood transfusion, not good to run with LR since Ca+ eventually binds with the citrate in the blood
-large volumes produce dilutional hyperchloremic acidosis (bicarb decreases as chloride concentration increases)
*preferred for transfusing PRBCs
*best option for renal failure since no potassium
-no electrolytes but isotonic osmolality
-more similar to plasma
-doesn't contain Ca+ so can give with blood
-if giving a lot of volume, doesn't alter pH like LR or NS
what are colloids?
-fluids with a higher molecular weight than crystalloids
-contain large osmotically active substances (proteins, glucose, etc.) giving greater osmolality (10% Dextran > 25% albumin > 6% Dextran > 6% Hetastarch > FFP = 5% albumin)
-intravascular half life 3-6 hours
*risk for anaphylaxis
*may develop coagulopathy
what are indications for colloid use?
-severe hypovolemia (corrects more rapidly than crystalloids)
*may preload with a colloid if extreme blood loss is expected
*no O2 carrying capacity so must replace RBCs
-from pooled donor plasma (increased risk of contracting infection)
-heated to 60 degrees C to reduce viral infections, hepatitis v. blood products
-high molecular weight proteins
-25% in small volume (50cc) = hypertonic
-5% with volume expanded with NS to 250-500 cc = isotonic
-dextrose starches: Macrodex, Rheomacrodex
-improves micro-circulation by decreasing blood viscosity and platelet effects
*can have significant effect on coagulation
*if more than 1.5 gms/kg given, bleeding times need to be checked
-potential for anaphylactic reaction
*Dextran 1 acts as hapten, binds with antibodies to prevent reaction (give prior to running fluid)
*must use a pump
describe Hespan (hetastarch)
-synthetic: plant starch
-dilutional effect of coagulation
*inhibits platelets/clot formation (impairing von Willebrand factor and factor VIIIc)
*20 ml/kg (500-1000 ml) is the max to infuse to avoid coagulopathy
-no antigenic effect; rare anaphylaxis
-hydroxyethyl starch (tetrastarch)
-allows 50 ml/kg per day
-more rapidly metabolized, higher clearance (20-30x higher), minimal tissue storage
-equivalent to hetastarch d/t higher number at a lower molecular weight; no decrease in osmotically active particle
what is the recommended ratio when replacing fluids with a crystalloid?
replace with 3x fluid loss
ex: lost 200 ml, replace 600 ml
what is the recommended ratio when replacing fluids with a colloid?
ex: lost 200ml, replace 200 ml
what are the advantages of crystalloid use?
-promotes urinary flow
-restores 3rd space loss
-used for extracellular fluid replacement
-used for initial fluid resuscitation
what are disadvantages of crystalloid use?
-dilutes plasma proteins
-causes reduction of capillary osmotic pressure
-causes peripheral edema
-has a transient effect
-has potential for pulmonary edema
what are advantages of colloid use?
-causes sustained increase in plasma volume
-requires smaller volumes for resuscitation
-causes less peripheral edema
-tends to remain intravascular
-more rapid resuscitation
-useful in conditions of altered vascular permeability
what are disadvantages of colloid use?
-can cause coagulopathy (dextran > hetastarch > hextend)
-can cause anaphylactic reaction (dextran)
-decreases Ca++ (albumin)
-can cause renal failure (dextran)
-can cause osmotic diuresis
-can cause impaired immune response (albumin)
what are 4 requirements of fluid management?
-maintenance fluid infusion
-correction of pre existing volume deficit
-replacement of ongoing fluid losses
-adjustment of amount and composition of fluids
*normothermic, normal metabolic rate replace 1.5 ml/kg/hr
describe maintenance fluids
-greater fluids required for decreasing size (smaller or younger require more)
-there is a deficit association between metabolic rate and water requirements
*smaller size has greater metabolic rate requiring more fluid
*1 ml of water is required for every kcal expended
explain the 4-2-1 rule
-for the first 10 kg of weight start rate of 4 ml/kg/h
-for the next 10 kg (10-20 kg) add 2 ml/kg/hr
-for each kg above 20 kg add 1 ml/kg/hr
ex: 25 kg child maintenance fluid requirements
first 10 kg = 4 ml/kg/hr; next 10 kg (from 10-20kg) add 2 ml/kg/her; for remaining 5 kg add 1 ml/kg/hr (40 + 20 + 5 = 65 ml/hr)
using the 4-2-1 rule for maintenance fluid requirements, what is the rate required for a 70 kg pt.?
first 10 kg = 40 ml/hr
next 10 kg = 20 ml/hr
remaining 50 kg = 50 ml/hr
total rate = 110 ml/hr
describe replacement of fluid deficits
-pre op deficits
-calculate maintenance fluid rate
*multiply by the number of hours NPO
**administer 1/2 over the first hour, then 1/4 each over the next two hours
*also assess for volume deficits
ex: 7 hrs NPO, 70 kg pt.: maintenance rate of 110 ml/hr multiplied by 7 hrs = 770 ml
describe replacement of ongoing fluid loss
-intra op blood loss
-with initial blood loss, ISF and extravascular fluid are transferred to the intravascular space, which maintains PV
*if replacing blood loss with crystalloid, they must be given 3x blood loss (replenishes intravascular and ISF)
*if colloids used to replace blood loss, usually given 1:1 since they remain intravascular
*when risk of anemia is > than risk of transfusion, give PRBCs 1:1
*even if RBCs don't need to be replaced, always replace volume (decreased N/V, shorter post op stay)
describe third spacing
-the distributional change of isotonic solution from a functional fluid compartment to a nonfunctional space
-caused by surgical trauma, muscle injuries, burns, peritonitis, or ascites (all cause tissue damage)
*starts with incision during surgery
*difficult to assess the degree of surgical trauma so look at procedure and use most restrictive fluid replacement plan if only minimal third spacing
describe evaporative losses
-air turnover in operative suite
-skin, wound, airway loss
*skin and airway: 0.5-1 ml/kg/hr loss
give examples of procedures and estimated third spacing and evaporation along with recommended fluid replacement
-minimal (herniorrhaphy, lap chole): 0-2 ml/kg
-moderate (open cholecystectomy, not involving bowel): 2-4 ml/kg
-severe (bowel resection): 4-8 ml/kg
when should you give a blood transfusion?
-Hct 25 if pathophysiology can tolerate
-Hct 29 if elderly
*individual pt. decision depending on if pathology requires maximization of O2 carrying capacity
what are estimated blood volumes for adults?
-men: 75 ml/kg
-women: 65 ml/kg
(avg 70 ml/kg)
how is allowable blood loss calculated?
estimated blood volume (EBV) x (Hct start - Hct allowed) all divided by Hct start
(if use Hgb or 8 g/dl or 10 g/dl in elderly or cardiac/pulmonary disease)
how is estimated red cell mass (ERCM) calculated?
-EBV x Hct
how is acceptable red cell loss (ARCL) calculated?
ERCM - ERCM at target Hct
*ERCM at target Hct = EBV x target Hct, so ERCM(25) = EBV x 25
how is acceptable blood loss (ABL) calculated?
ARCL x 3
what are the antigens on the erythrocytes' membranes that determines blood type?
A, B, Rh (D)
*no antigen is O Type
what antigens are in the plasma?
-anti-A and anti-B form in the plasma naturally to which ever antigens that are not present
ex: Type A has A antigens and antibodies against B antigens
*D antibodies only form when exposed to the antigen (- mom w/ + baby)
describe blood Type A
-A antigen on RBC
-anti-B antibodies in serum
-compatible with A, O
describe blood Type B
-B antigen on RBC
-anti-A antibodies in serum
-compatible w/ B, O
describe blood Type AB
-A and B antigens on RBC
-compatible w/ AB, A, B, and O
describe blood Type O
-no antigens on RBC
-anti-A and anti-B antibodies in serum
-compatible w/ O only
describe Rh positive blood
-D antigen on RBC (in addition to A or B if present)
-no antibodies against D antigen present in serum
-compatible with Rh + and Rh -
describe Rh negative blood
-no D antigen on RBC
-anti-D if sensitized present in serum
-compatible with Rh - only
what happens during the typing procedure?
donor blood is exposed to serum of known antibodies and observed for antigen antibody reaction
*confirmation of the result is by mixing the donor serum with erythrocytes of a known antigen
what happens with ABO incompatibility?
hemolysis of RBCs (can lead to renal failure)
which antigen is the most common?
D antigen, appearing on 85% of patient's RBCs (Rh +)
-double checks ABO and Rh type (5 min)
-Major: donor's RBCs (cell's antigens from the bag) with recipient's plasma (serum with antibodies)
-Minor: recipient's RBCs with donor's plasma (not much plasma in donor PRBCs)
-check for IgE antiboides (Kell, Kidd)
**crossmatch does an in vitro check of what is to occur in vivo
describe type and screening
-check ABO and Rh type of recipient
-not unit specific, just screened for antibodies in general
-indicated if blood loss is a possibility, but no likely
-stored blood is available to more than one pt.
how quick can type specific blood and O negative blood be available?
-type specific: 5 minutes
-O negative: immediately
what are the chances of reaction between crossmatching, type and screening, type specific, and O negative?
-crossmatch: 1: 100,000
-type and screen: 1: 10,000
-type specific: 1: 1,000
-O negative: 1: 500
describe transfusion of O negative blood
-no antigens on RBCs
-Rh negative has no D antigen
-small amount of plasma in PRBCs of O neg (2 units) can contain sufficient amounts of anti-A and anti-B antibodies to result in hemolysis
**once O negative is given, have to stick with O negative
(better to start with crossmatch, then type and screen, then type specific and save O negative as last resort)
describe blood storage
-CPD (citrate-phosphate-dextrose) or CPD-A (adenine) preservative added
-stored at 1 to 6 degrees Celsius
-last 21 days for CPD
-lasts 35 days for CPD-A
*over time blood changes
*K+ is 3.9 at day one; 21 at day 21
*pH at day 1 is 7.1; 6.9 at day 21
*PCO2 is 48 at day 1; 140 at day 7
*viable platelets is 10% at day 1; 0 at day 7
*factor V, VII 70% day 1; 20% day 7
**fresh blood is better
describe packed red blood cells
-volume 250-300 ml
-indication: anemia associated with acute blood loss; to increase oxygen carrying capacity of blood
-reconstitute with crystalloid (NS, Plasmalyte) 50-100 ml (decreases viscosity and can give faster; don't use too much or will dilute Hgb)
-less plasma than whole blood (only used with blood loss > 1500)
how does PRBCs increase Hct?
for every 1 ml of PRBCs transfused per kg of body weight, Hct should rise about 1%
how much should each unit of PRBCs raise Hct?
based on average blood volume of 5000 ml, each PRBC unit should raise the Hct by 3-4%
with pediatrics, how does transfusion raise Hct and Hgb?
10ml/kg will increase Hct by 10% or Hgb by 3%
-indications: tx of thrombocytopenia w/o giving unnecessary blood
-one unit increases plt. count 10,000 to 20,000 mm3 one hour after
-half-life approx. 24 hrs.
-risks: sensitization to HLA antigens on cell membranes; transmission of viral disease d/t multi donors (may give Tylenol before)
when should platelets be giving during a spleenectomy?
-spleen is chewing up platelets
*start when artery to spleen is clamped so new platelets wont be used up
*surgery will start with a low platelet count
describe fresh frozen plasma
-plasma protein form a unit of whole blood that is frozen within 6 hours of collection (must be thawed so plan ahead)
-contains coagulation factors except platelets (may need to give both)
-indication: treatment of coagulation factors (may be diluted out); if no response from heparin
-single unit (250 ml) should raise levels by 7-8%
-risks: transmission of viral diseases and allergic reactions
-primary source of von Willebrand factor; also contains factor VIII, fibrinogen, and fibronectin
-indications: treating hemophilia; DIC w/ fibrinolysis
-risks: transmission of viral diseases and allergic reactions
describe a febrile transfusion reaction
-temperature rarely increases above 38 degrees C
-treat by slowing transfusion and giving antipyretics and maybe Benadryl
describe an allergic transfusion reaction
-fever, pruritus, and urticarial
-treat by admin. antihistamines
-in severe cases, discontinue blood
-look for hgb in the urine to r/o hemolytic reaction
-usually r/t to plasma products
describe hemolytic transfusion reaction
-d/t ABO incompatibility
-primarily occurs when a human error leads to admin. of ABO incompatible blood
*even if everything checks out, if see signs, treat! (error usually in lab)
what are signs of hemolytic reaction?
-first sign under GA is hypotension
-free hgb in the urine also a sign (acute renal failure is caused by precipitation of contents of hemolyzed RBCs in the distal renal tubules)
*flush with fluid to prevent tubules clogging
-DIC is initiated by material released from hemolyzed RBCs (again, flush with fluids)
*volume of RBCs transfused determines severity of reaction so STOP
what is the treatment for hemolytic transfusion reaction?
-infuse crystalloid (NS)
-administer mannitol or Lasix or dopamine
-administer sodium bicarb to alkalinize the urine and increase the solubility of products in the renal tubules
-confirm hemolysis (send to lab)
-return unused portion of donor unit to blood bank
-treat coagulopathy with platelet and coagulation factors (FFP and platelets)
**alert surgeon and anesthesiologist
what are the chances of infectious disease with transfusions?
-HIV: 1: 1,400,000
-hepatitis C: 1: 1.9 million
-1: 10,000 transfused pts. will develop chronic hepatitis leading to liver failure or hepatocellular cancer (out of the chance of catching hepatitis C)
*everyone is immune suppressed with transfusion
-formed in storage by platelets and leukocytes and increases with time in storage
-associated with pulmonary dysfunction
-fewer in PRBCs than whole blood
-administer blood through 40 micron filters
*standard blood filter is 170 micron filter
what are the risks with large volume transfusions?
-hypothermia: cardiac irritability (v fib) shivering, increased VO2 (*must warm blood)
-hyperkalemia: K+ content increase with time storage; transfusion of one unit every 5 min. causes increase; if see peak T wave consider CaCl
-acid-base changes: pH of stored blood becomes more acidic the longer it is stored; preservative has pH 5-6.5
*citrate metabolism to bicarb may contribute to metabolic alkalosis
-citrate binds calcium resulting in hypocalcemia (rare)
*supplement Ca++ if transfusion rate > 50 ml/min, hypothermia or liver disease interferes with metabolism of citrate, or neonate
describe dilutional thrombocytopenia risk with transfusions
-platelets abent from stored blood after 24 hrs
-platelet level below 100,000 associated w/ increased bleeding
describe dilution of factors V and VIII with transfusions
-only 5-20% of normal level are necessary for normal clotting
-rare that this is a problem
*if needed, give FFP (usu. if need to try anything)
describe DIC with transfusions
-activation of the coagulation system with consumption of platelets and coagulants
-remove the cause and administer platelets and FFP
what are alternatives to blood transfusions?
describe autologous blood transfusions
-pt. donates own blood
-collection started 4-5 weeks prior to surgery
-donation allowed if Hct is 34%
-may be given iron supplements
-minimum of 72 hrs b/w donations to allow plasma volume to normalize
-not complication free: clerical errors, allergic reactions to ethylene oxide
describe cell saver
-blood salvage and reinfusion
-used during cardiac, vascular, and orthopedic cases
-suction with heparin solution to collect
*when sufficient amount is collected, RBCs are concentrated and washed to remove debris and anticoagulant and reinfused
-hematocrit usually 50-60%
-best if blood loss exceeds 1000-1500 ml (peds may not be an option)
-contraindications: septic wound, malignant tumor
*for anticipated significant blood loss
describe normovolemic hemodilution
-blood is removed from the patient just prior to surgery and replaced with crystalloid or colloid to achieve a Hct of 21-25% (must be a healthy pt.)
-stored in a CPD bag until the end of surgery (6 hrs.) or end of blood loss (better), if possible to keep hemodynamically stable until stopped (individual based)
*principle is that the number of RBCs lost in a dilute blood loss is reduced; yet CO is maintained by the normovolemic state