Fluid Therapy

Question 1

Define hemorrhagic shock.

Answer 1

Impairment of DO2 due to whole blood loss.

Question 2

What are the 3 key points of rapid management of hemorrhagic shock?

Answer 2

1. Hemorrhage control
2. Restore adequate DO2
3. Mange secondary consequences of hemorrhagic shock

Question 3

How can you determine if hemorrhage has been controlled?

Answer 3

1. Through spontaneous resolution of the hemorrhage due to effective coagulation or cessation of hemorrhage via a procedure (ex. bandage placement).
2. If the hemorrhage site is not visualized (ex. body cavity), cardiovascular stability and maintenance of Hb/PCV/HCT

Question 4

How can you determine if hemorrhage is uncontrolled?

Answer 4

1. When ongoing hemorrhage cannot be immediately stopped.
2. Cardiovascular instability despite blood volume expansion and a falling Hb/PCV/HCT.

Question 5

What are the 5 major sites of hemorrhage sites?

Answer 5

1. External (ie., epistaxis, wounds, etc.)
2. Thoracic cavity
3. Abdominal cavity
4. Gastrointestinal tract
5. Fracture site

Severe urinary tract, mediastinal, pulmonary, or retroperitoneal hemorrhage can also cause significant enough bleeding.

Question 6

What patients are at risk of developing hemorrhagic shock in the ICU?

Answer 6

Question 7

What are the six physical examination perfusion parameters to assess the severity of perfusion impairment?

Answer 7

1. Heart rate
2. Pulse quality
3. MM color
4. Capillary refill time
5. Peripheral temperature
6. Mentation

Question 8

What are some confounding factors that can decrease the reliability of perfusion parameters?

Answer 8

1. Pain
2. Hyperthermia
3. Sedation
4. Underlying cardiac disease
5. Drugs (and their effects on HR and vascular tone)
6. Vasodilation from systemic inflammation

Question 9

Patients with an arterial catheter (especially those receiving positive pressure ventilation) with a pulse pressure variation greater than _______ will likely benefit from an increase in preload to improve stroke volume.

Answer 9

10-15%

Question 10

What are some essential monitoring and triggers for intervention for patients at risk of hemorrhage?

Answer 10

Question 11

What are the three components of the lethal triad?

Answer 11

1. Coagulopathy
2. Acidosis
3. Hypothermia

Hypothermia and acidosis can worsen coagulopathy, which can perpetuate hemorrhage and lead to worsening hypothermia and acidosis.

Question 12

Why might coagulopathies be more pronounced in patients with major trauma?

Answer 12

Due to the direct anticoagulant, profibrinolytic, and consumptive processes that occur with trauma - aka acute coagulopathy of trauma

Question 13

What are some things that can contribute to acidosis in trauma?

Answer 13

1. Anaerobic metabolism and lactate production
2. Hyperchloremic metabolic acidosis from saline resuscitation
3. Respiratory acidosis

Question 14

What does management of the controlled hemorrhage typically consist of?

Answer 14

1. Isotonic balanced crystalloids for restoration of preload
   - 0.9% NaCl can cause hyperchloremic metabolic acidosis and contribute to AKI
   - Some clinicians avoid acetate containing crystalloids (Plasma-lyte) as they may cause vasodilation, although not proven in a hemorrhagic shock model
2. Blood transfusion if necessary

Question 15

Why is the use of synthetic colloid fluids for stabilization considered controversial (what are the pros and cons)?

Answer 15

Pros:
1. May allow for stabilization with a smaller volume
2. May mitigate interstitial overhydration

Cons:
1. They can contribute to dilutional coagulopathy
2. Directly cause platelet dysfunction, hypocoagulability, and enhanced fibrinolysis
3. May cause acute kidney injury

Question 16

Define massive transfusion.

Answer 16

Transfusion of blood products totaling 1. Estimated entire blood volume in 24 hours
2. 50% of blood volume in 3-4 hours
3. Administration at 1.5mL/kg/min for 20 minutes

Question 17

What is the transfusion trigger in the case of a massive transfusion?

Answer 17

Recognition that the patient has uncontrolled hemorrhage coupled with severe shock.

Question 18

What is the ideal product for massive transfusion?

Answer 18

Fresh whole blood

Question 19

What can occur if PRBCs alone are used in massive transfusion?

Answer 19

PRBCs alone can lead to dilution coagulopathy, hypofibrinogenemia, and thrombocytopenia.

This contributes to the lethal triad.

Question 20

What is the ratio of plasma, platelets, and pRBCs units typically recommended for transfusion?

Answer 20

One unit of plasma and one unit of platelets for every one to two units of pRBCs

Question 21

What are the electrolyte derangements seen in patients receiving a massive transfusion

Answer 21

Ionized hypocalcemia and hypomagnesemia due to chelation by citrate anticoagulant

Ex. Dogs receiving a rapid 20mL/kg bolus of blood developed a moderate ionized hypocalcemia

Question 22

Should ionized hypocalcemia following a blood transfusion be treated?

Answer 22

Traditionally recommended if clinical signs are present. However, it can contribute to coagulation impairment and decrease myocardial contractility and vascular tone. Therefore, treatment of ionized hypocalcemia should be considered in a hemodynamically unstable patient.

Question 23

Why should the administration of calcium solutions be administered through a separate IVC to blood products?

Answer 23

Because calcium may initiate coagulation ex vivo if administered concurrently.

Question 24

Should ionized hypomagnesemia following a blood transfusion be treated?

Answer 24

Rarely administered as the benefit is unclear

Question 25

What are effects of overzealous crystalloid resuscitation on coagulation?

Answer 25

1. Dilution of coagulation factors 2. Low blood viscosity

Question 26

What are effects of overzealous crystalloid resuscitation on the heart?

Answer 26

1. Ventricular arrhythmias 2. Disruption of cardiac contractility 3. Decreased cardiac output (think starling’s myocardial performance curve when beyond a designated point of the curve, increases in end-diastolic volume cause a decreases in cardiac output)

Question 27

What are the consequences of GI edema?

Answer 27

1. Decreased motility 2. Increased intestinal permeability and bacterial translocation 3. Increased risk for abdominal compartment syndrome

Question 28

What are the consequences of overzealous crystalloid resuscitation?

Answer 28

Organ edema because crystalloids redistribute into the interstitium.

Question 29

Perel et al., compared peripheral perfusion parameters and normalization of lactate found that ______

Answer 29

Peripheral perfusion parameter normalization was associated with less organ dysfunction at 72 hours, but there was no significant difference in mortality.

Question 30

What is one of the main pitfalls of utilizing lactate-targeted fluid resuscitation?

Answer 30

The potential for non-perfusion related hyperlactatemia that can occur with various disease states.

Question 31

What physiologic targets does the most recent Surviving Sepsis Campaign recommend?

Answer 31

- Initial MAP target of 65mmHg - No other physiologic guidelines outlined - Instead recommend additional IVF therapy based on reassessment of hemodynamic status - Recommend the use of dynamic variables over static variables when possible (ex. passive leg raise, pulse pressure variation)

Question 32

What do the most recent Surviving Sepsis Guidelines recommend regarding crystalloid administration?

Answer 32

Administer at least 30ml/kg of crystalloids within the first 3 hours of presentation to treat sepsis-induced hypotension.

Question 33

According to the Surviving Sepsis Guidelines, early goal directed should be instituted within ________.

Answer 33

The first 3 to 6 hours of presentation.

Question 34

List resuscitation end points:

Answer 34

Physical exam 1. Improved hear rate 2. Improved pulse quality 3. Improved Capillary refill time 4. Improved temperature of extremities 5. Mentation Bloodwork 1. Improved lactate 2. Improved central venous oxygen saturation Point-of-care 1. Assessment of dynamic intravascular volume (improved CVCCI)

Question 35

What are alternative forms of achieving vascular access when a peripheral catheter cannot be placed in volume depleted patients? Which routes are not recommended for fluid resuscitation?

Answer 35

1. Jugular catheter (can start with a short catheter and transition to long one later) 2. Cut-down 3. Intraosseous catheter Routes not recommended: 1. Subcutaneous 2. Intraperitoneal

Question 36

What is the best type of catheter for fluid resuscitation?

Answer 36

Largest gauge and shortest IV length appropriate for the size of the patient.

Question 37

Rapid abnormalization of blood pressure is associated with ______ survival-to-discharge in hypotensive dogs.

Answer 37

Greater. JVECC Silverstein 2012; Effectiveness IV fluid resuscitation in the ER for treatment of hypotension in dogs

Question 38

Which isotonic crystalloid has been most commonly associated with alterations of the inflammatory cascade?

Answer 38

All isotonic crystalloids, particularly LRS

Question 39

Describe the two racemic mixtures in LRS formulations.

Answer 39

1. L-lactate stereoisomer - rapidly metabolized by the liver, associated with a decrease in inflammation secondary to pancreatitis in humans 2. D-lactate stereoisomer - associated with an increase in neutrophil stimulation

Question 40

What are the potential consequences of intravascular administration of low osmolar solution?

Answer 40

Cellular swelling, which then stimulates the production and release of TNF alpha Activation of phospholipids A2 and consequently prostaglandins, lipoxygenase, leukotrienes, epoxyeicosatrienoic acid Increased levels of proinflammatory cytokines (IL-6, IL-8, IL-10).

Question 41

Describe synthetic colloids.

Answer 41

Large molecules (>10,000 Daltons) of varying sizes that do not readily cross diffusion barriers across normal blood vessels the way crystalloids do. They increase the colloid osmotic pressure of serum, creating a force that counteracts hydrostatic pressure and allows for volume retention in the intravascular space. Colloids infused into the intravascular space tend to stay there (rather than redistribute into the interstitium)to allow for a more sustained intravascular expansion effect.

Question 42

How are starch molecules (synthetic colloids) cleared from the intravascular space?

Answer 42

It depends on the rate of absorption by the tissues, uptake by the reticuloendothelial system, clearance through urine and bile, and enzymatic degradation to small particles by serum amylase. Alpha-amylase-mediated hydrolysis can reduce the molecular weight of a colloid to <72kDa. The degree of hydroxyl substitution is the primary determinant of how long they survive in the blood.

Question 43

What is the recommended volume of administration for synthetic colloids?

Answer 43

Dogs — 5 to 20mL/kg IV over 10-20 min Cats — 2.5 to 10mL/kg IV over 10-20 min

Question 44

What are the adverse effects associated with synthetic colloids?

Answer 44

- High molecular weight starches have been associated with AKI in human sepsis patients - In dogs HMWS have been associated with an increased risk of AKI development, increase in the grade of AKI proportional to the duration of starch therapy, and association with mortality - Marginally increased markers of both tubular injury and renal inflammation in dogs - Some studies disagree with the above but a RCT has not been performed - AKI or mortality rates with the use of these products has not been studied in cats - Can cause a decrease in vWf activity, and its associated factor VIII and ristocetin cofactor (proven in humans, dogs, cats) - Can cause a degree of platelet dysfunction (proven in humans, dogs, cats) - There are mostly dog studies; one cat study showed now difference in TEG tracings when high-molecular weight starches were used. - Hetastarch doses of 20ml/kg have shown to cause coagulation derangements. Tetrastarch has fewer effects on coagulation and usually doses of 40mL/kg can be administered

Question 45

Define hypertonic crystalloid solution.

Answer 45

Any saline solution with an effective osmolarity exceeding that of normal plasma.

Question 46

What are the benefits of utilizing hypertonic saline for volume resuscitation?

Answer 46

- Causes intravascular volume expansion in excess of the amount of volume administered due to the osmotic gradient generated by the increase in plasma osmolarity. - Immunomodulatory effects - decreased neutrophil activation and adherence, stimulation of lymphocyte proliferation, inhibition of proinflammatory cytokine production by macrophages - Improves rheologic properties of circulating blood - Reduces endothelial cell swelling - Reduces intracranial pressure - May improve myocardial function and cause coronary vasodilation, therefore improving overall cardiac function

Question 47

What is the dose of hypertonic saline for small volume resuscitation?

Answer 47

Hypertonic saline 7% or 7.5% 3-5mL/kg IV over 10-20 minutes

Question 48

How long do the effects of hypertonic saline last?

Answer 48

Typically redistributes into the interstitium within 30min and can cause polyuria

Question 49

What is a turbostarch?

Answer 49

The combination of 23.4% hypertonic saline and 6% hydroxyethyl starch using a 1:2 ratio to arrive at a total volume of 3-5 mL/kg and ultimately making a 7.5% solution. Done in an effort to increase intravascular expansion time.

Question 50

What are the adverse effects of administering hypertonic saline?

Answer 50

- Hypernatremia (usually transient) - Risk for hypernatremia-induced osmotic demyelination syndrome (in patients with preexisting chronic hyponatremia) - Increase in intravascular volume and hydrostatic pressure may lead to volume overload and pulmonary edema in patients with pre-existing cardiac and pulmonary abnormalities - Can cause significant interstitial (and intravascular) volume depletion, especially in patients that are already volume depleted, if not followed by additional fluid therapy

Question 51

What are the effects of albumin on the body?

Answer 51

1. Maintenance of colloid osmotic pressure 2. Maintains endothelial integrity 3. Wound healing 4. Metabolic and acid-base functions 5. Coagulation 6. Free radical scavenging

Question 52

Why do critically ill patients suffer from hypoalbuminemia?

Answer 52

1. Loss 2. Vascular leak 3. Third-spacing 4. Decreased production as a result of shifting of hepatic production toward acute-phase proteins

Question 53

Define hypotensive resuscitation.

Answer 53

A conservative resuscitation strategy used in the acute setting during active hemorrhage to restore a lower than normal systolic blood pressure (80-90 mmHg) to facilitate controle of hemorrhage and reduce the risk of rebleeding, but at the same time ensure preserved blood flow to vital organs such as the kidney and GI tract.

Question 54

Define a fluid challenge.

Answer 54

The administration of fluids to patients that are hemodynamically unstable in order to assess their response to fluid therapy and guide further treatment decision. Allows for subjective and objective assessment of cardiovascular response. Factors that should be considered include: - Fluid type - Rate of fluid administration - End points - Safety of fluid challenge

Question 55

What is the dose of albumin?

Answer 55

- Dose albumin (g) 10 x (2.0 g/dl - patient albumin g/dl) x BW (kg) x 0.3 - 5%, 10%, 16% albumin so far without reported acute or delayed hypersensitivity reactions - Historically 25% human albumin was used but has been associated with significant adverse effects