NUR 837 Exam 3 Hemotherapy Study Guide PDF

NUR 837 Exam 3 HEMOTHERAPY Evaluation of Intravascular Volume • pt hx, physical exam, labs, hemodynamic monitoring techniques • multiple modalities—one method isn’t specific enough Physical Exam • indications of hypovolemia: o abnormal skin turgor o dehydrated mucous membranes o thready peripheral p...

NUR 837 Exam 3 HEMOTHERAPY Evaluation of Intravascular Volume • pt hx, physical exam, labs, hemodynamic monitoring techniques • multiple modalities—one method isn’t specific enough Physical Exam • indications of hypovolemia: o abnormal skin turgor o dehydrated mucous membranes o thready peripheral pulses o increased resting HR o BP changes from supine to sitting or standing (orthostatic changes) o decreased urinary flow rate • indications of hypervolemia: o pretibial pitting edema in the ambulatory patient o presacral pitting edema in the bedridden patient o late signs of hypervolemia: CHF, tachycardia, tachypnea, elevated jugular pulse pressure, pulmonary crackles, wheezing, cyanosis, pink and frothy pulmonary secretions Laboratory Evaluation • serial hematocrit, arterial blood pH, urine specific gravity or osmolality, urine serum sodium or chloride concentration, ser um sodium, BUN-to-creatinine ratio are surrogate measures of intravascular volume. o INDIRECT measures—may be altered by perioperative factors • lab signs of dehydration— o rising hematocrit and hemoglobin o progressive metabolic acidosis (including lactic acidosis) o urine specific gravity > 1.010 o urine sodium < 10 mEq/L o urine osmolality > 450 mOsm/L o hypernatremia o BUN-to-creatinine ratio > 10:1 • hemoglobin and hematocrit are UNCHANGED in acute hypovolemic patients – not enough time for extravascular fluid to shift into the intravascular space • ultrasound will show nearly collapsed vena cava or incompletely filled cardiac chambers Hemodynamic Measurements • central venous pressure (CVP) monitoring used when volume status is hard to assess o must use trends, not isolated measurements • pulmonary artery pressure (PAP) monitoring is used when CVP readings don’t match the clinical assessment or when patient has primary or secondary RV dysfunction • pulmonary artery occlusion pressure (PAOP) < 8 mmHg indicates hypovolemia in patients with normal LV compliance o PAOP < 15 mmHg indicates relative hypovolemia in patients with impaired LV compliance • PAOP > 18 mmHg → elevated → LV volume overload • PAOP is measured at END EXPIRATION • echocardiography is more accurate at determining cardiac filling pressures than is PA pressure measurements. • during spontaneous ventilation, BP decreases on inspiration. • during positive pressure ventilation, BP increases on inspiration. Intravenous Fluids • crystalloid solutions: aqueous solutions of ions (salts) with or without glucose o rapidly equilibrate with and distribute throughout the entire extracellular fluid space • colloid solutions: solutions with high molecular weight proteins or large glucose polymers o help maintain plasma colloid oncotic pressure o mostly remain intravascular • Crystalloid Solutions: o intravascular half-life: 20-30 min o initial resuscitation fluid in patients with hemorrhagic and septic shock, burns, head injury (to maintain cerebral perfusion pressure), undergoing plasmapheresis and liver resection o if loss primarily involves water → replace with hypotonic solution o if loss is water and electrolytes → replace with isotonic electrolyte solution o glucose is provided to maintain tonicity, prevent ketosis and hypoglycemia o most intraoperative fluid losses are isotonic → normal saline (NS), lactated Ringers (LR), PlasmaLyte o NS in large volumes → hyperchloremic metabolic acidosis ▪ high chloride content with no bicarbonate o D5W used to replacing pure water deficits or as maintenance fluid for those with salt restrictions o administer hypotonic solutions slowly to prevent hemolysis. • Colloid Solutions: o stay in the intravascular space o intravascular half-life: 3-6 hrs o indications for colloid use: ▪ fluid resuscitation wit patients with severe intravascular fluid deficits (ex.: hemorrhagic shock) prior to the arrival of blood for transfusion ▪ fluid resuscitation in the presence of severe hypoalbuminemia or conditions where lots of protein is lost, like burns o albumin is a blood-derived colloid. o dextran: volume expander ▪ reduces blood viscosity, von Willebrand factor antigen, platelet adhesion, and RBC aggregation ▪ infusions > 20 mL/kg/day → interfere with blood typing, increase bleeding time, more bleeding complications ▪ AKI, anaphylaxis o hetastarch: plasma expander ▪ decreases von Willebrand factor antigen levels ▪ prolongs PTT ▪ associated with hemorrhagic conditions ▪ potentially nephrotoxic Perioperative Fluid Therapy • replacing normal losses (maintenance requirements). preexisting deficits, surgical wound losses including blood loss Normal Maintenance Requirements Preexisting Deficits • deficit is proportional to the fast • normal maintenance rate x hours fasting • for a 70-kg patient fasting for 8 hours, (40 + 20 + 50) mL/hr x 8 hours = 880 mL • abnormal fluid losses that contribute to preexistin deficits: o preoperative bleeding o vomiting o NG suctioning o diuresis o diarrhea • increased insensible losses from sweating, fever, hyperventilation Surgical Fluid Losses • Blood Loss o measure from suction canister, sponges TBW: male—60% female—50% elderly—will be a little less (elderly male—50%; decreased muscle mass, increased adipose) newborn—80% neonate--closer to 90% Describe the functionally distinct compartments of body water. • Total Body Water (TBW) is 57% of IBW. The remaining 43% is Solids (27%) and Adipose Tissue (15%). • Intracellular Fluid (ICF) compartment comprises about 2/3 of TBW. • Extracellular Fluid (ECF) compartment comprises 1/3 TBW. o Interstitial Fluid (ISF) ¾ of ECF o Plasma ¼ of ECF ▪ About 5 L ▪ Plasma, plasma proteins, formed blood elements ▪ Plasma proteins generate colloidal osmotic pressure (distribution of water between ISF and BV compartments. • Colloid osmotic pressure=oncotic pressure • Exerted by proteins in plasma that pulls blood/liquid into the circulatory system • Fluid exchange occurs at the capillary. Describe the dynamics of the distribution of fluids between the intravascular and interstitial fluid compartments. • ECF o ISF and BV are in dynamic equilibrium. o Governed by hydrostatic and osmotic forces. o Starling’s law o Capillary Hydrostatic Pressure (Cp) on arterial side=outward filtration of fluid. o Capillary Osmotic Pressure causes reabsorption on venous side. o Slight disequilibrium = slight excess in the net filtration of fluid o Returned to circulation through lymphatics o Application: IV crystalloids distribute throughout the entire ECF within minutes ▪ some stays in, some filters out. net excess → lymphatics o o Hydrostatic pressure on arterial side—forces fluid out Oncotic pressure—reabsorption Distribution of Fluids • Forces determining outward filtration of ECF: o Mean capillary hydrostatic pressure (mmHg) 17.3 o Negative ISF pressure o ISF colloid osmotic pressure o Totals (mmHg) • Forces promoting reabsorption o Plasma colloid osmotic pressure (mmHG) 3.0 8.0 28.3 28.0 danger of increased interstitial fluid: • pulmonary edema • acidosis (limiting O2/CO2 exchange at the basement membrane) • healing impedance (edematous tissue hinders healing) don’t want hypervolemic state goal: maintain pt’s optimal CO UOP is not a good indicator of fluid status. BP alone is not a good indicator of fluid status. plasma proteins keep fluid in vessels vascular tone—decreased by volatile agents PPV—affects heart, preload heart pumping ability—CAD, CHF think of fluid balance as a pump system -maintain CO, perfuse tissues, deliver O2 How are fluid requirements determined? • Preoperative loss replacement + • Maintenance fluid replacement + • Surgical Loss Replacement + • Blood Loss Replacement = • Total Perioperative Fluid Replacement __________________________________________________________________________________________ • preop-loss replacement: how long has pt been NPO? o replace this volume over a period of time o hourly requirement x # hrs NPO • maintenance fluid replacement • surgical loss replacement—evaporative loss from wound o open abdomen o insensible losses (evaporation) • blood loss replacement o what kind of fluid are we giving? crystalloids, colloids, blood __________________________________________________________________________________________ • • • • • Related to metabolic rate Caloric requirements and oxygen consumption are both measures of metabolic rate. Daily fluid requirement: o 4-2-1 o Hourly requirement ▪ 4 ml/kg for first 10 kg ▪ 2 ml/kg for second 10 kg ▪ 1 ml/kg for remainder of weight o Example for 70 kg patient Goal: euvolemia (goal-directed therapy) o goal-directed fluid therapy: uses stroke volume, cardiac output, cardiac index, mean arterial blood pressure to determine volume responsiveness and to guide fluid administration by bolus Want CO to be what’s needed to deliver O2 to tissues Anticipated surgical fluid loss? • Add: o Minimal tissue trauma (exp. Hernia repair): o Moderate tissue trauma (exp. cholecystectomy): o Severe tissue trauma (exp. Bowel resection): 2-4 ml/kg/hr 4-6 ml/kg/hr 6-8 ml/kg/hr Describe a proper preoperative evaluation of volume status. 1. History and clinical context • NPO status • Administered fluids (if inpatient, will likely be on fluids) o delete NPO status, unless it doesn’t match their calculated maintenance rate • Vomiting, diarrhea, diaphoresis, diabetes (mellitus or insipidus), alcohol ingestion o GI pts—colonoscopy, very volume down • Review of medication, especially diuretic use o last time taken? o if they held it → elevated • Bowel preparations (2-4 L of volume loss) • Emergency operations for conditions associated with hypovolemia o ileus, peritonitis, bleeding, burns, trauma, large bone fractures, febrile illness 2. Physical assessment o Skin turgor, mucous membranes, cap refill, edema (chronic vs. acute), pulmonary edema ▪ skin turgor—tenting ▪ edema does not always mean hypervolemia (acute v. chronic) ▪ mucus membranes—should be shiny, moist ▪ cap refill ▪ pulm. edema ▪ CO estimation: VS, but look at them together not in isolation ▪ pulse pressure via art line ▪ stroke volume 3. Vital signs and hemodynamic measurements o Pulse rate, pulse pressure, blood pressure, respiratory rate o Orthostatic changes in pulse and blood pressure o Central filling pressures 4. Urine output o Oliguria (less than 0.5 ml/kg/hr) o Adequate adult output = 0.5-1.0 ml/kg/hr o Children greater output than adults o Neonates = 2.0 ml/kg/hr o Alcohol and anesthetics may alter 5. Laboratory determinations o Hgb, Hct, BUN, creatinine, proteins (albumin), urine osmolality, specific gravity, and sodium concentration ▪ be able to pick out abnormals ▪ know hgb, hct, bun, Cr, albumin normal values Describe the progression of signs and symptoms with un-replaced acute blood loss and their correlation with volume loss. • 10% → Thirst, vasoconstriction • 20% → Sweating, increase HR, decrease BP, decrease UOP • 30% → Tachycardia, hypotension, high degree vasoconstriction, cool, clammy, pale, anuria o large symptomatic shifts at 30% loss • 40% → Severe hypotension, tachycardia, mental confusion • 50% → Coma, near death • No big symptomatic changes until 30% loss due to compensatory mechanisms • In mechanically ventilated pts, won’t see symptoms until 20-30% What are the goals in the resuscitation of hypovolemic patients? What is the preferred initial resuscitation fluid? How does it distribute? • Primary goal is restoration of microcirculation (tissue perfusion) and reversal of hypovolemic state. • Restore ECF volume (BV and ISF). • Fluid of choice is balanced salt solution that will distribute quickly into both BV and ISF compartments. • Crystalloid: 1/3 intracellular and 2/3 interstitial o NS, LR o if pt loses blood, for every 1 cc of blood lost, replace with 3 cc crystalloid. (3:1 ratio) • Blood loss must be replaced 3:1 with fluids; 1:1 with PRBCs • Colloid replacement is 1:1 (1cc blood lost, give 1cc colloid) • • PRBCs 1:1 Initial resuscitation may result in compensated shock. o Diminished CO, high SVR (they’re vasoconstricted), tissue hypoperfusion o Persisting hypoperfusion, blood loss, declining Hct, age of patient, coexisting disease, extent of injury, expected future losses suggest a need for blood transfusion. What is meant by third-space losses? What are the effects of such losses? • ECF = BV + ISF • Patients develop fluid requirements not explained by measurable losses. • EXP: Major intra-abdominal procedures, hemorrhagic shock, burns, sepsis • Internal losses, temporary sequestration of ECF into a functionless third-space • Necessitates further infusions to maintain intravascular volume, adequate cardiac output, and perfusion. • inside of vascular blood vessel cells—glycocalyx • fx: hold in proteins to maintain filtration & reabsorption (hydrostatic & oncotic pressures) • if damaged → proteins leak out; less colloid pressure in vessels • damage to glycocalyx by: heart peptide • heart can release a peptide, when it thinks there’s too much fluid on board (BNP or ANP??). this fluid damages the glycocalyx and lets proteins leak out, so fluid leaks out. • third-spacing can cause massive fluid shifts and severe intravascular depletion in patients with peritonitis or burns. • traumatized, infected, or inflamed tissue can sequester a large amount of fluid in the interstitial space and can translocate fluid across serosal surfaces (ascites) or into the bowel lumen. What are the determinates of perioperative fluid requirements? 1. Basal requirements 2. Preoperative deficits (calculate using 4-2-1) 3. Blood loss (Calculate using lap sponges, suction canisters, surgical field) 4. Third space losses and evaporation losses 5. Transcellular fluid losses (ascites, effusions, fistulas) 6. Effects of anesthesia o General anesthesia unmasks hypovolemia, vasoactive substances may be used, fluid administration usually improves status 7. Frequently the best determinate is satisfactory urine output. 8. Procedures with major fluid losses can be monitored with CVP, PA cath for central pressures and cardiac output. o arterial line What can I give? • Crystalloids (3:1 replacement for blood loss) o Solutions contain salts and electrolytes for intravascular volume expansion o Lactated Ringers o Normal Saline o 3-4x what’s lost • Colloids (1:1 replacement for blood loss) o Solutions containing large molecules, provide oncotic pressure in addition to intravascular expansion o Albumin (protein) o Dextran (non-protein) o Hespan (Hetastarch) → not favored anymore • Blood (1:1 replacement for blood loss) What is the average human blood volume? • Total intravascular blood volume: o 3 Liters of Plasma o 2 Liters of Red Cells o Varies with age, weight, sex, and body habitus • Females have greater percentage of adipose tissue, which is less vascular than other tissues • Neonates: o premature: 95 mL/kg blood volume o full-term: 85 mL/kg blood volume • Infants: 80 mL/kg blood volume • Adults: o men: 75 mL/kg blood volume o women: 65 mL/kg blood volume What is a normal Hgb/Hct? • Hgb: o oxygen carrying portion of red blood cell o Normal for males: 14-18 g/dl o Normal for females: 12-16 g/dl o below a hemoglobin concentration of 7 g/dL, resting cardiac output increases to maintain normal oxygen delivery • Hct: o Volume of red cells compared to total blood volume o Normal for males: 40-54% o Normal for females: 36-48% o If hematocrit is normal, transfuse when losses are greater than 10-20% of blood volume. What are the physiologic adaptations to acute normovolemic anemia? • During surgery, blood loss is replaced with crystalline solutions, resulting in acute normovolemic anemia. • Compensatory changes: o Increased cardiac output (reduced blood viscosity (thinner), increased venous return and venomotor tone, increased sympathetic nervous system activity) o Redistribution of blood to tissues that are oxygen supply dependent (heart, brain) o Increased oxygen extraction ▪ oxyhemoglobin curve ▪ dec RBCs, so will take more from what’s available What is an acceptable minimum preoperative hematocrit? • Focus is on maintenance of adequate hematocrit during perioperative period. • Decision to transfuse based on initial Hct, age, general health, drugs, disease increasing oxygen demands, prediction of ongoing blood loss. (if diseased, do they compensate well for it?) • Patients with co-existing disease and impaired cardiac function are less tolerant of decreased Hct. • In the absence of CV instability, perioperative transfusion should be considered at: o Healthy patients 18% o Patients with well-compensated systemic disease 24% o Patients with symptomatic cardiac disease 30% How is blood loss estimated? • 60 kg man with preoperative HCT 42% • Estimated TBV o TBV (ml)= Wt (kg) x EBV (ml/kg) o 60 kg x 75 ml/kg = 4500 ml o Rough estimate (Adult man = 75 ml/kg, Adult woman = 65 ml/kg) • Estimate RBCV (red blood cell volume) at preop HCT (RBCVp): o RBCVp (ml)= TBV (ml) X (preop HCT/100) o 4500 ml X 0.42 = 1890 ml • EBV: o Male 75 ml/kg o Female 65 ml/kg o Infants 80 ml/kg o Neonates 85 ml/kg o Premature Neonates 96 ml/kg • Estimate RBCV at HCT of 30% (RBCV30): o RBCV30 (ml) = TBV X 0.30 o 4500 X 0.3 = 1350 ml • Final condensed formula for allowable blood loss for a HCT 30 o (TBV x (RBCVp – RBCV30))/ RBCVp o (4500 x (42-30))/ 42 = 1,285 ml • RBCVp = present RBC vol How do I estimate blood loss in the OR? • Suction canisters o surgeon or tech will tell you when irrigating o tape by numbers to serve as a marker • Surgical field o suctioned up or use sponges to soak up o sometimes rolls into pockets on surgical drapes • Sponge Saturation 4x4 gauze → holds 10 mL blood Ray-tech → line shows up on x-ray Holds 10-20 mL blood **calculate EBL on test For what is donor blood screened? • Syphilis • Viral Hepatitis o Hep B o Hep C o Alanine aminotransferase (nonspecific marker of liver infections) • Retroviruses o HIV assay o T cell lymphotrophic virus assay What types of red cell products are available? • Red blood cells (300-350 ml, 75-80% Hct, anticoagulant) • Red blood cells deglycerolized o Frozen, rare types, prolonged storage o Used for more rare blood types • Leukocyte reduced red blood cells o Previous febrile transfusion reactions • Washed red blood cells o Previous severe allergies • Whole blood o Rarely used, symptomatic deficit in oxygen-carrying capacity, preserving components • If allergic rxn to blood transfusion previously, use leukocyte reduced OR washed RBC’s (severe) What is the difference between a type and screen and a crossmatch? • Type and screen o ABO ▪ presence of absence of A or B RBC surface antigens ▪ type A has A surface antigen ▪ type B has B surface antigen ▪ type AB has both A and B surface antigens ▪ type O has neither antigen o Rh ▪ have D Rhesus antigen = Rh positive ▪ no D Rhesus antigen = Rh negative o Antibodies ▪ indirect Coombs test: mix patient’s serum with red cells of known antigenic composition o Usually about 45 minutes • Crossmatch o Antibody screen negative- abbreviated mix (5 minutes) o Antibody screen positive- more extensive crossmatch (45 minutes) o Donor’s red cells are mixed with recipient’s serum. o 3 functions of crossmatching: ▪ confirms ABO and Rh typing ▪ ▪ detects antibodies to other blood group systems detects antibodies in low titers or those that do not agglutinate easily What type of blood should be used in an emergency? Type O negative What are some complications of massive blood transfusion? • Coagulopathy o dilutional thrombocytopenia o lack of factors 5 & 8 o DIC (very high risk) • Metabolic problems o hyperkalemia o citrate toxicity o acidosis o hypothermia o impaired O2 carrying capacity (d/t reduced 2,3 DPG concentration) By how much will transfusing one unit of PRBCs increase the hematocrit? • Average adult: o 2-3% Hct o 1 g/dL Hgb What are the clinical manifestations of hemolytic blood reaction? • Fever, chills • Chest, flank, back pain • Nausea • Oliguria or anuria • Hemoglobinuria • Diffuse bleeding • If asleep → T, BP, UOP indicators How is a hemolytic transfusion reaction managed? 1. stop transfusion and remove blood tubing 2. alert blood bank; send specimens 3. treat hypotension aggressively with IV fluids, pressors 4. maintain UOP (IVF, mannitol, diuretics, dopamine) 5. monitor K+ (RBC lysis → releases K+ into bloodstream) 6. perform coagulation studies; monitor for DIC a. bleeding time: gold standard for testing platelet function What are alternatives to homologous blood transfusion? • Autologous transfusion → collection and re-infusion of own blood o collection of blood 4-5 weeks before surgery o wait 72 hours between donations to make sure plasma volume is normal. • Perioperative blood salvage (CellSaver) o blood aspirated into reservoir and mixed with heparin o red cells are concentrated, washed, reinfused o requires blood loss > 1,000-1,500 to be effective o contraindications: infection, sepsis, malignancy • Intraoperative hemodilution → withdrawal and replacement o rare, lots of issues o 1-2 units of blood removed and replaced with crystalloids and colloids to maintain Hct 21-25% o reinfused after blood lost from surgery • Use of substitute products—not as effective How do you hang PRBCs in the OR? • Y-tubing • NS • filter • hand pump → no air‼ • warmer if needed • need 20 g IV or bigger • central line/cordis if lots of blood products ____________________________________________________________________________________________________________ euvolemia measuring CO → most accurate for assessing volume status look at arterial BP waveform • pulse pressure is the difference btwn systolic and diastolic BP • if > 12% → hypovolemia • for accuracy, need 8 mL/kg Vt (might be too large) • why would there be a difference btwn inspiration and expiration? • inspiration: dec volume in R side of heart (dec preload), will eventually affect LV stroke volume • look at pleth on sat (make sure pt doesn’t have dec perfusion) Fresh Frozen Plasma (FFP) • contains all plasma proteins including most clotting factors • indications for FFP administration: o treatment of isolated factor deficiencies o reversal of warfarin o correction of coagulopathy associated with liver dz • 1 unit increases level of clotting by 2-3% in adults Platelets • transfuse when platelet count < 10,000 • for surgery, transfuse when platelet count < 50,000 • 1 unit of platelets will increase count by 5,000-10,000 • transfused platelets only survive 1-7 days after transfusion