Week 11 Handout Flashcards
What is the importance of fluid and blood management?
Maintenance of:
* Intravascular Volume
* Fluid Exchange
* Oxygen Delivery
These components are crucial for ensuring adequate perfusion and preventing complications during surgical procedures.
What are the risks associated with fluid and blood management?
Where we can go wrong:
* Under-resuscitation
* Over-resuscitation
* Complications
* Surgical Risks and Considerations
Both under-resuscitation and over-resuscitation can lead to serious complications.
What factors increase surgical risks?
Factors Increasing Surgical Risks:
* Emergency Surgery
* Surgeries with Expected High Blood Loss
* Long Surgeries with Large Fluid Shifts
These factors can complicate fluid management and recovery.
What are examples of high-risk procedures?
Examples of High Risk Procedures:
* Open Aortic Surgery
* Peripheral Vascular Surgery
* Neurosurgery
* Thyroid Surgery
* Prostatectomy
These procedures often involve significant blood loss and fluid shifts.
What are examples of moderate risk procedures?
Examples of Moderate Risk Procedures:
* Liver Biopsies
* Most Surgical Procedures
Moderate risk procedures typically have fewer complications related to fluid management.
What are examples of low-risk procedures?
Examples of Low Risk Procedures:
* Endoscopy
* Bronchoscopy
* Cataract Extraction
These procedures generally have minimal impact on fluid balance.
Define Intracellular Volume (ICV).
Intracellular Volume (ICV) is the volume of fluid contained within the cells of the body.
It is a key component of total body water.
Define Extracellular Volume (ECV).
Extracellular Volume (ECV) is the volume of fluid outside the cells, further broken down into:
* Intravascular (Plasma) Volume
* Interstitial (Tissue) Volume
* Transcellular Fluids (e.g., CSF, synovial, GI Secretions)
ECV plays a crucial role in maintaining overall fluid balance.
What factors keep fluid balance in the body?
Four components:
* Capillary Hydrostatic Pressure
* Interstitial Fluid Pressure
* Plasma Oncotic Pressure
* Interstitial Oncotic Pressure
These forces govern the movement of fluids between capillaries and interstitial spaces.
What is Capillary Hydrostatic Pressure (Pc)?
Capillary Hydrostatic Pressure (Pc) is the pressure within the capillaries generated by the heart pumping blood.
It influences fluid movement out of capillaries into surrounding tissues, particularly in conditions like heart failure.
What is Interstitial Fluid Pressure (Pif)?
Interstitial Fluid Pressure (Pif) is the pressure exerted by the fluid in the interstitial space, typically helping to push fluid back into capillaries.
Increased Pif can occur in conditions like compartment syndrome.
What is Plasma Oncotic Pressure (πp)?
Plasma Oncotic Pressure (πp) is the osmotic pressure exerted by proteins, primarily albumin, in the blood.
A decrease in πp can lead to fluid leakage into tissues, causing conditions such as edema.
What is Interstitial Oncotic Pressure (πif)?
Interstitial Oncotic Pressure (πif) is the osmotic pressure exerted by proteins in the interstitial fluid.
Increased πif can worsen tissue edema by drawing fluid out of capillaries.
What is the Starling Equation?
Jv = Kf × ((Pc - Pif) - σ(πp - πif))
* Jv = net fluid movement (positive means filtration, negative means absorption)
* Kf = permeability of capillaries
* σ = reflection coefficient
This equation describes the fluid movement across capillary membranes.
What does an upward/leftward shift of the Frank-Starling Curve indicate?
UPWARD/LEFTWARD SHIFT indicates:
* ↑ Contractility / ↑ Performance
* Positive inotropes (e.g., dobutamine, epinephrine)
* Sympathetic stimulation
* Decreased afterload
* Mild exercise in a healthy heart
This shift reflects improved cardiac output.
What does a downward/rightward shift of the Frank-Starling Curve indicate?
DOWNWARD/RIGHTWARD SHIFT indicates:
* ↓ Contractility / ↓ Performance
* Negative inotropes (e.g., beta blockers)
* Myocardial ischemia or infarction
* Heart failure
* Acidosis
* Hypoxia
* Increased afterload
This shift reflects reduced cardiac output and efficiency.
What are the types of intravenous fluids?
Types of Intravenous Fluids:
* Crystalloids
* Colloids
Each type has distinct properties and uses in fluid resuscitation and management.
What are crystalloids?
Crystalloids are isotonic solutions commonly used for:
* Resuscitation
* Perioperative fluid replacement
Examples include Normal Saline and Lactated Ringer’s.
What are the advantages of crystalloids?
Advantages of Crystalloids:
* Readily available
* No allergenic potential
* Easily metabolized and renally cleared
* Restore both intravascular volume and hydration
They are often the first-line treatment for fluid resuscitation.
What are the disadvantages of crystalloids?
Disadvantages of Crystalloids:
* Dilution effect requiring large volumes
* Transient plasma expansion
* Risk of hyperchloremic metabolic acidosis
Overuse can lead to complications, especially in critical patients.
What are colloids?
Colloids contain high-molecular-weight substances that exert oncotic pressure, reducing transcapillary filtration.
They help retain fluid intravascularly, making them effective for plasma volume expansion.
What are the advantages of colloids?
Advantages of Colloids:
* Longer intravascular half-life than crystalloids
* More efficient for restoring intravascular volume
* Useful in severe intravascular deficits
Colloids can be critical in situations like hemorrhagic shock.
What are the disadvantages of colloids?
Disadvantages of Colloids:
* Higher cost than crystalloids
* Potential for complications like pulmonary edema
* Safety concerns with synthetic colloids
Risks include renal injury and coagulopathy, particularly with certain types.
What is the normal daily water loss?
Normal Daily Water Loss averages: 2500 mL per day
This includes losses from urine, sweat, and respiration.
What is the 4-2-1 Rule for calculating fluid requirements?
The 4-2-1 Rule:
* First 10 kg: 4 ml/kg/hr
* Next 10 kg: 2 ml/kg/hr
* Remaining weight: 1 ml/kg/hr
This rule helps estimate fluid needs based on weight.
What accounts for about 25% of heat loss?
Fluid loss
Fluid loss is significant in maintaining body temperature.
What is the 4-2-1 Rule for calculating fluid requirements?
First 10 kg: 4 ml/kg/hr, Next 10 kg: 2 ml/kg/hr, Remaining weight: 1 ml/kg/hr
This rule helps in estimating fluid needs based on body weight.
Calculate the fluid requirement for a 100 kg patient using the 4-2-1 Rule.
Total: 140 ml/hr
Calculation: First 10 kg = 40 ml, Next 10 kg = 20 ml, Remaining 80 kg = 80 ml.
Calculate the fluid requirement for a 14 kg patient using the 4-2-1 Rule.
Total: 48 ml/hr
Calculation: First 10 kg = 40 ml, Remaining 4 kg = 8 ml.
What is the formula for calculating NPO fluid deficit?
NPO fluid deficit = Hours NPO x Hour fluid requirement
This formula is crucial for determining fluid needs during fasting.
What percentage of NPO deficit should be replenished in the first hour?
50%
This is part of a strategy to gradually restore fluid balance.
What is the percentage of NPO deficit to be replenished in the 2nd and 3rd hours?
25% each
This ensures a steady approach to fluid replacement.
What are evaporative losses primarily due to?
Evaporation and internal redistribution of body fluids
These losses are significant in surgical settings.
What factors influence evaporative losses?
- Surface area exposed * Duration of surgical procedure
Larger wounds and longer surgeries increase fluid loss.
What is the evaporative loss range for superficial trauma?
1 to 2 mL/kg/hr
This is a common measurement in fluid management.
What is the evaporative loss range for severe trauma?
4 to 6 mL/kg/hr
Severe cases require higher fluid management.
What are the consequences of under-resuscitation?
- Hypovolemia * Decreased microvascular perfusion * Reduced tissue perfusion * End-organ complications * PONV * Renal dysfunction * Myocardial ischemia * Hemoconcentration
These issues highlight the importance of adequate fluid management.
What are the consequences of over-resuscitation?
- Vascular overload * Microvascular congestion * Decreased DO2 * Endothelial glycocalyx disruption * Decreased tissue oxygenation * Altered coagulation * Hemodilution
Over-resuscitation can lead to serious complications.
What is the goal of fluid and blood management?
Euvolemia
Achieving euvolemia is critical for patient stability.
What does GDFT stand for?
Goal Directed Fluid Therapy
What was the origin of GDFT?
Studies showing improved survival in critically ill patients when tissue oxygen delivery was optimized
What do traditional fixed-volume formulas, like the 4-2-1 rule, fail to account for?
Individual variability, increasing the risk of fluid imbalance
What are some benefits of GDFT according to meta-analyses?
- Reduces perioperative complications (e.g., acute kidney injury)
- Shortens hospital stays in major surgeries
- May improve bowel recovery after abdominal procedures
What are the monitoring techniques used in GDFT?
- Pulse contour analysis (e.g., FloTrac, LiDCO)
- Esophageal Doppler for real-time LV function
- TEE/TTE for global hemodynamic assessment
- Dilution techniques (e.g., thermodilution via PACs or PiCCO)
- Noninvasive monitors (e.g., ClearSight, CNAP)
What is the role of the Plethysmography Variability Index (PVI) in GDFT?
To assess fluid responsiveness
Fill in the blank: GDFT protocols guide ______ based on real-time data.
fluid administration
What does GDFT aim to avoid?
Excessive fluid administration seen in liberal fluid strategies
What is the relationship between GDFT and Enhanced Recovery After Surgery (ERAS) protocols?
ERAS protocols integrate GDFT to optimize perioperative outcomes
What are the challenges in GDFT research?
Results vary based on surgical type and GDFT implementation
What is the importance of accurate estimation of blood loss?
Guides fluid resuscitation and transfusion decisions
What are common techniques used for estimating blood loss?
- Suction canisters
- Visual estimation (e.g., soaked sponges, laparotomy pads)
What is a limitation of visual estimation for blood loss?
Highly subjective and varies between providers
What does sponge weighing indicate in blood loss estimation?
1 gram difference = 1 mL blood loss
What are hematocrit and hemoglobin considered in blood loss estimation?
Indirect, lagging indicators affected by fluid shifts and IV replacement
What is the difference between Estimated Blood Loss (EBL) and Quantitative Blood Loss (QBL)?
EBL is quicker but less accurate than QBL
What is a critical component of hemodynamic monitoring?
Watch for changes in HR, BP, SpO₂, Pulse Pressure Variation
What is the recommended fluid replacement ratio for crystalloids?
Replace at a 1:1 ratio
According to the ASA Taskforce on Blood Transfusion, when is transfusion almost always indicated?
When hemoglobin concentration is less than 6 g/dL, especially in acute anemia
What is the blood volume for a premature infant at birth?
90–105 mL/kg
What is the Allowable Blood Loss (ABL) equation?
ABL = (HCTinitial – HCTallowable) x EBV/HCTinitial
What does blood transfusion enable?
Targeted replacement of deficient components: RBCs, platelets, coagulation factors, or plasma volume
What is the volume of whole blood?
~500–515 mL
What are the risks associated with whole blood?
- Hyperkalemia
- Infectious disease transmission
- Transfusion reactions
What does one unit of PRBCs raise Hgb and Hct by?
- Hgb by ~1 g/dL
- Hct by 2–3%
What are leukocyte-reduced PRBCs indicated for?
To reduce the risk of febrile reactions, alloimmunization, CMV transmission
What is the shelf life of frozen RBCs?
Stored in glycerol for 10 years
What are the indications for platelet transfusion?
- plt <50,000/μL
- For high-risk procedures, keep plt >75,000–100,000/μL
- Prophylactic: plt <10–20,000/μL in at-risk patients
What does Fresh Frozen Plasma (FFP) contain?
All clotting factors, albumin, globulins, complement
What is the volume of FFP?
~200–600 mL
What is the goal when administering FFP?
Achieve 30% normal factor activity
What is the goal of factor replacement therapy?
Achieve 30% normal factor activity
What are the indications for using factor replacement therapy?
- Multiple factor deficiencies
- Warfarin reversal (if PCC unavailable)
- Liver disease coagulopathy
- TTP (with plasmapheresis)
- Massive transfusion protocols
What is the typical dose for factor replacement therapy?
10–15 mL/kg
What does cryoprecipitate contain?
- Fibrinogen
- Factor VIII
- Factor XIII
- vWF
- Fibronectin
What is the volume and dose for cryoprecipitate?
- Volume: 10–20 mL/unit
- Dose: 1 unit/10 kg → ↑ fibrinogen by ~50 mg/dL
What are the indications for using cryoprecipitate?
- Hypofibrinogenemia (<80–100 mg/dL)
- Massive transfusion
- Congenital fibrinogen disorders
- Von Willebrand disease (unresponsive to DDAVP)
- Factor XIII deficiency
What is Prothrombin Complex Concentrate (PCC) used for?
Vitamin K-dependent factor replacement for urgent warfarin reversal
What is the last-resort option for life-threatening bleeding?
Recombinant Factor VIIa
What is the dose for recombinant Factor VIIa?
15–20 µg/kg
What is the purpose of TEG/ROTEM in transfusions?
To guide transfusions where available
What are the key components of blood donor screening?
- Medical history review
- Antibody screening
- Infectious disease screening
- ABO and Rh typing
- Bacterial contamination monitoring
- Leukocyte reduction
- CMV screening
What does an indirect Coombs test detect?
Non-ABO antibodies associated with hemolytic transfusion reactions
What are the infectious diseases screened in blood donation?
- Hepatitis B
- Hepatitis C
- Syphilis
- HIV (anti-HIV-1 and anti-HIV-2 antibodies)
What is the purpose of leukocyte reduction in blood transfusions?
To reduce febrile reactions, immunosuppression, and CMV transmission
What is the function of a Cell Saver Machine?
Collects, filters, and washes shed surgical blood for reinfusion
What is the role of a blood warmer during transfusions?
Warms blood to 37°C to prevent hypothermia and associated complications
What is Acute Normovolemic Hemodilution (ANH)?
Blood removed and replaced with crystalloids/colloids preoperatively, then reinfused
What are the pharmacologic interventions for blood conservation?
- Antifibrinolytics (e.g., tranexamic acid)
- Desmopressin (DDAVP)
- Factor concentrates
What is the purpose of monitoring hemoglobin and hematocrit?
Standard monitoring of coagulopathy
What does hyponatremia indicate?
Na⁺ < 135 mEq/L
What are the classifications of hyponatremia?
- Hypovolemic (e.g., diuretics, GI losses)
- Euvolemic (e.g., SIADH, hypothyroidism)
- Hypervolemic (e.g., CHF, cirrhosis)
What is a key clinical manifestation of hyponatremia?
Neurological symptoms due to cerebral edema
What is the treatment for hypovolemic hyponatremia?
Isotonic saline
What defines hypernatremia?
Na⁺ > 145 mEq/L
What are the classifications of hypernatremia?
- Hypovolemic (e.g., GI or renal losses)
- Euvolemic (e.g., diabetes insipidus)
- Hypervolemic (e.g., hypertonic saline administration)
What are the clinical manifestations of hypernatremia?
Neurologic symptoms due to cellular dehydration
What is the treatment for hypernatremia?
Gradual correction over 48 hours to prevent cerebral edema
What defines hypokalemia?
K⁺ < 3.5 mEq/L
What are the clinical manifestations of hypokalemia?
- Muscle weakness
- Hyporeflexia
- Ileus
- ECG changes (flattened T waves, U waves, arrhythmias)
What is the treatment for symptomatic or severe hypokalemia?
IV K⁺ with central line use and ECG monitoring if >10 mEq/h
What defines hyperkalemia?
K⁺ > 5.5 mEq/L
What are the causes of hyperkalemia?
- Intercompartmental shifts (e.g., acidosis)
- Decreased renal excretion (e.g., renal failure)
What is the definition of hyperkalemia?
K⁺ > 5.5 mEq/L
Hyperkalemia can lead to serious cardiac complications.
What are the causes of hyperkalemia?
- Intercompartmental shifts (e.g., acidosis, trauma, succinylcholine)
- Decreased renal excretion (e.g., renal failure, hypoaldosteronism, RAAS inhibitors)
- Rarely, excessive intake
Consider ruling out pseudohyperkalemia.
What are the hallmark signs of hyperkalemia?
- Neuromuscular weakness
- Life-threatening cardiac arrhythmias
ECG changes can progress significantly in hyperkalemia.
What ECG changes are associated with hyperkalemia?
- Peaked T waves
- Widened QRS
- Sine wave pattern
These changes may lead to ventricular fibrillation or asystole.
What should be evaluated in the diagnosis of hyperkalemia?
- Renal insufficiency
- Medications
- Acidosis
- Sources of cell lysis
Confirm true hyperkalemia by rechecking plasma levels.
What is the initial treatment for hyperkalemia?
Stabilize myocardium with IV calcium
Additional treatments involve shifting K⁺ into cells and removing K⁺.
What should be avoided in anesthetic considerations for hyperkalemia?
Avoid succinylcholine and potassium-containing fluids
Monitor ECG closely during anesthesia.
What is the definition of hypocalcemia?
Ionized Ca²⁺ < 4.0 mg/dL or Total Ca²⁺ < 8.5 mg/dL
Hypocalcemia can lead to severe clinical manifestations.
What are the causes of hypocalcemia?
- Hypoparathyroidism
- Vitamin D deficiency
- Hyperphosphatemia (CKD)
- Calcium chelation (e.g., citrate, pancreatitis, rhabdomyolysis)
- Alkalosis
- Sepsis
- Certain medications
Ionized calcium is the physiologically relevant form for diagnosis.
What are the clinical manifestations of hypocalcemia?
- Paresthesia
- Tetany (Chvostek and Trousseau signs)
- Seizures
- Laryngospasm
- Bronchospasm
- Prolonged QT interval
- Decreased contractility
- Hypotension
- Bradycardia
Symptoms can vary significantly.
What should be assessed in the diagnosis of hypocalcemia?
- Ionized calcium
- Total calcium corrected for albumin
- Associated hypomagnesemia
- Hyperphosphatemia
- Renal dysfunction
- Recent transfusion or albumin administration
Accurate diagnosis is critical for appropriate treatment.
What is the treatment for acute/symptomatic hypocalcemia?
IV calcium (chloride or gluconate), ideally via central line
Avoid co-administration with bicarbonate/phosphate solutions.
What is the definition of hypercalcemia?
Ionized Ca²⁺ > 5.3 mg/dL or Total Ca²⁺ > 10.5 mg/dL
Hypercalcemia can have serious cardiac and renal implications.
What are common causes of hypercalcemia?
- Hyperparathyroidism
- Malignancy (PTHrP, bone metastases)
- Granulomatous disease (vitamin D sensitivity)
- Immobilization
- Milk-alkali syndrome
- Certain drugs (thiazides, lithium)
Ionized calcium reflects true severity and should be corrected for albumin.
What are the clinical manifestations of hypercalcemia?
- Nausea
- Vomiting
- Weakness
- Polyuria
- Confusion
- Coma
- Shortened QT interval
- Sinus bradycardia
- AV block
- Ventricular dysrhythmias
Severe cases can lead to renal failure and pancreatitis.
What is the initial treatment for hypercalcemia?
IV saline hydration followed by loop diuretics
Bisphosphonates or calcitonin may be used for moderate to severe cases.
What is Goal Directed Fluid Therapy (GDFT)?
A fluid management approach that tailors fluid administration based on real-time hemodynamic variables
Aims to optimize oxygen delivery and prevent both over- and under-resuscitation.
What hemodynamic variables are considered in GDFT?
- Stroke volume (SV)
- Cardiac output (CO)
- Cardiac index (CI)
- Mean arterial pressure (MAP)
GDFT is particularly important in perioperative and critically ill patients.
