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Flashcards in FEN: Fluid Management Deck (35)
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1
Q

Describe distribution of total body fluid (TBF)

A
  1. TBF = 60% lean body weight in men and 50% in women (about 42 L)
  2. 60% TBF is IntraCellular, 40% is ExtraCellular
  3. 75% of EC is InterStitial, 25% of EC is IntraVascular
  4. This means 10% of TBF is IntraVascular
2
Q

Describe distribution of Normal Saline, Lactated Ringer and Normosol-R and Plasma-Lyte

A
  1. 100% of Infused Volume stays in the ExtraCelular space
  2. The volume distributes evenly across capillary membrane in the EC compartment. Na and Cl do not freely cross into cells.
  3. 25% of EC is Intravascular
  4. 1L infusion = 250 mL volume expansion
3
Q

Describe distribution of 5% dextrose

A
  1. 5% dextrose in metabolized into free water and carbon dioxide
  2. Free water distributes evenly across capillary AND cell membranes
  3. 10% of total body fluid is intravascular
  4. 1L infusion = 100 mL volume expansion
4
Q

Describe distribution of most colloids (packed red blood cells, pooled human plasma, semisynthetic glucose polymers (dextran), and semisynthetic hydroxyethyl starch (hetastarch)

A
  1. Colloids are too large to cross capillary membranes, so they remain in intravascular space
  2. Albumin 25% is a special case that does not follow this rule
  3. 500 mL infusion = 500 mL volume expansion
5
Q

Describe distribution of albumin 25%

A
  1. 25% albumin has an oncotic pressure about 5-fold that of normal plasma
  2. This pulls water from other side of capillary, moving fluid from IS space to IV space
  3. 100 mL infusion = 500 mL volume expansion
6
Q

What are components/amounts of total blood volume

A
  1. Total blood volume is about 5 L
  2. 3 L is plasma, which is EC fluid in intravascular space
  3. 2 L is intracellular fluid within red blood cells
7
Q

What are the contents of Sodium chloride 0.9% (NS) (mEq/L of each component and total osmolarity)

A
  1. Na 154
  2. Cl 154
  3. Osmolality: 308
8
Q

What are the contents of Lactated Ringer (LR) (mEq/L of each component and total osmolarity)

A
  1. Na 130
  2. Cl 109
  3. K 4
  4. Ca 3
  5. Lactate 28
  6. Osmolality: 273
9
Q

What are the contents of Normosol-R (mEq/L of each component and total osmolarity)

A
  1. Na 140
  2. Cl 98
  3. K 5
  4. Mg 3
  5. Acetate 27/Gluconate 23
  6. Osmolality: 295
10
Q

What are the contents of D5W (grams of dextrose and kcal)

A
  1. 5 g of dextrose per 100 mL of water

2. This is about 17 kcal/100 mL

11
Q

D5W has the net effect of administering “free water.” What is a safety concern about it crossing into cells?

A
  1. Many experts avoid adminsitering D5W whenever possible in patients with neurologic injury and elevated intracranial pressure (ICP) because it can cross into cerebral cells causing further elevation in ICP.
12
Q

Describe three safety concerns with hydroxyethyl starch (hetastarch)

A
  1. Increased mortality in critically ill patients
  2. Coagulopathy
  3. Acute kidney injury
13
Q

Describe two safety concerns with dextran products

A
  1. Coagulopathy

2. Kidney impairment

14
Q

List two causes of intravascular fluid depletion

A
  1. Hypovolemic shock

2. Distributive (septic) shock

15
Q

List two complications of intravascular fluid depletion

A
  1. Reduced cardiac function

2. Organ hypoperfusion

16
Q

When do signs or symptoms of intravascular fluid depletion typically occur?

A
  1. When about 15% of blood volume is lost (e.g. hemorrhage) or shifts out of the intravascular space (e.g. sepsis)
  2. Blood volume = 5 L, so 15% = 750 mL of blood volume.
17
Q

List 9 signs or symptoms of intravascular volume depletion

A
  1. Tachycardia (HR > 100 bpm)
  2. Hypotension (SBP < 80 mmHg)
  3. Orthostatic changes in HR or BP
  4. Increased BUN/SCr ratio > 20:1
  5. Dry mucous membranes
  6. Decreased skin turgor
  7. Reduced urine output
  8. Dizziness
  9. Improvement in HR and BP after a 500-1000mL fluid bolus
18
Q

When is fluid resuscitation indicated?

A

Patients with signs or symptoms of intravascular volume depletion

19
Q

What is the goal of fluid resuscitation?

A

Restore intrasvascular volume depletion and prevent organ hypoperfusion

20
Q

What is a common fluid resuscitation strategy?

A
  1. In sepsis: 30 ml/kg
  2. 500-1000 mL fluid bolus of NS or LR
  3. Reevaluate and repeat as long as signs and symptoms are improving
21
Q

Describe differences between crystalloids and colloids in time to achieve fluid resuscitation and patient outcomes

A
  1. Colloids have not been shown to be superior

2. Colloids are associated with higher cost and some adverse effects (e.g. coagulopathy, kidney impairment)

22
Q

What is a reasonable role for colloids in fluid resuscitation

A
  1. When fluid resuscitation with crystalloid (usually 4-6L) has failed to achieve hemodynamic goals OR
  2. Clinically significant edema limits the further administration of crystalloid
23
Q

When should albumin be considered in the setting of fluid resuscitation

A

Albumin can be considered in patients:

  1. Who have required a large volume of resuscitation fluids (e.g. crystalloids)
  2. and have a low albumin concentration
24
Q

How to use albumin 25% in setting of clinically significant edema?

A
  1. Patients who do not require fluid resusictation but may benefit from redistribution of fluid (ascites, pleural effusions, pulmonary edema causing respiratory failure)
  2. Low albumin concentration
  3. In conjunction with appropriately dosed diuretics that are ineffective alone
25
Q

What fluids are recommended for first line fluid resuscitation in HYPOVOLEMIA?

A

NS or LR are equal

26
Q

What fluids are recommended first line fluid resuscitation in surgery and trauma patients?

A
  1. NS or LR

2. Historically LR is preferred in surgery and trauma but no evidence suggests superiority over NS

27
Q

Can LR be used in metabolic acidosis?

A
  1. Lactate is metabolized to bicarbonate
  2. However, lactate metabolism is impaired during shock
  3. Therefore LR may be an ineffective source of bicarbonate
28
Q

Describe chloride-restrictive fluid resuscitation strategies in critically ill patients

A
  1. NS has 154 mmol/L chloride while LR has 109 mmol/L, which is closer to normal physiologic (i.e. balanced)
  2. In ICU patients, balanced fluids have lower rate of any cause of death, new renal replacement therapy and persistent renal dysfunction.
  3. In non-ICU patients, there was no difference found in hospital-free days. A secondary outcome still showed better renal outcomes with balanced fluids.
29
Q

When are maintenance fluids indicated

A

When patients are unable to tolerate oral fluids

30
Q

What is the goal of maintenance fluids

A

Prevent dehydration and maintain a normal fluid and electrolyte balance

31
Q

What is a typical strategy for administering maintenance IV fluids?

A
  1. Calculate daily volume requirement

2. Administer as a continuous infusion through a peripheral or central catheter

32
Q

Roughly how much water is required for an adult

A

20-40 mL/kg/day (adults only)

33
Q

What is the 4-2-1 method for daily volume requirement?

A
  1. Administer 100 mL/kg/ for first 10 kg, followed by 50 mL/kg for the next 10 kg (i.e. 1500 mL for the first 20 kg), plus 20 mL/kg for every kg greater than 20 kg
  2. It’s called 4-2-1 because you can divide into hourly rates, i.e. 4 ml/kg/hr for first 10 kg, followed by 2 ml/kg/hour for next 10 kg, plus 1 ml/kg/hr for every kg after 20.
34
Q

What is the most common maintenance IV fluid

A
  1. D5W with 0.45% NaCl plus 20-40 mEq of potassium chloride per L (adjusted for the individual patient)
  2. e.g. “D5W in 1/2 NS with 20 KCl”
35
Q

When an infusion of 150 mEq of Sodium bicarbonate is required, should it be added to NS?

A
  1. 150 mEq of Sodium bicarbonate added to 850 mL of NS results in 1.6% sodium chloride.
  2. Instead it is recommended to add the sodium bicarb to D5W or sterile water for injection instead of NS.