IV Fluids: Volume, Electrolytes and Maintenance Therapy

Question 1

Volume Deficit-Clinical Types

1. What is Total Body loss?
   - Examples? 2
2. Extracellular? 3
3. Intravascular? 1

Answer 1

Total body water

1. Water loss
   - diabetes insipidus
   - osmotic diarrhea
2. Extracellular
   - Salt and water loss
   - GI tract losses
   - Third spacing
3. Intravascular
   - Acute hemorrhage

Question 2

Extracellular: What are examples of salt and water loss? 3

Extracellular: GI losses? 3

Answer 2

1. secretory diarrhea
2. ascites
3. edema
4. V/D,
5. NG Sx,
6. enteric fistulas

Question 3

1. What is “Third Space” (not intra- or extra-) loss?
2. Causes? 6
3. This situation is not normal and the fluid is derived from ___________ fluid……will always need IV fluids to prevent__________ volume depletion.

Answer 3

1. Acute sequestration in a body compartment that is not in equilibrium with ECF (isotonic)
2. Causes
   - Intestinal obstruction
   - Severe pancreatitis
   - Peritonitis
   - Major venous obstruction
   - Capillary leak syndrome
   - Burns
3. extracellular, extracellular

Not interstitial and not intravascular…non-contributory space

Question 4

Extracellular space volume loss
1. Describe the timeline of loss compared to intracellular?

2. Use your clinical parameters to judge degree of volume loss such as? 6

Answer 4

1. Loss occurs more rapidly than from the intracellular space
2. • Weight loss,
   • BP,
   • JVP,
   • urine sodium concentration,
   • urine output,
   • HCT

Question 5

Increased states of fluid loss

6

Answer 5

1. Fever
2. Burns
3. Sepsis
4. Gastric fistulas
5. Surgical drains (may or may not have high output)
6. Or other states of increased metabolic activity

Question 6

Signs of extracellular fluid depletion

Clinical findings? 9

Lab findings? 4

Answer 6

1. Clinical findings
2. Thirst
3. Decreased urine output
4. Weight loss
5. Drowsiness to coma
6. Decreased skin turgor
7. Dry mucous membranes
8. Sunken eyes
9. Tachycardia
10. Orthostatic hypotension progressing to hypotension

Lab findings

1. Increased HCT
2. Elevated BUN/Creat
3. Elevated urine sodium
4. Urine SG less than 1.020

Question 7

Clinical signs to monitor for ECF depletion?

Answer 7

1. Watch hemodynamic parameters
2. Urine output
3. Patient daily weights
4. Daily labs

Question 8

1. Whats normal urine output?

2. Which daily labs for ECF depletion? 3

Answer 8

1. Normal > 30 ml/hr
2. • HCT
   • BMP
   • Serum sodium may be helpful

Question 9

Compare the signs of hypovolemia to hypervolemia

Volume depletion? 8

Volume overload? 9

Answer 9

Volume depletion

1. Orthostatic hypotension
2. Tachycardia
3. Flat neck veins
4. Decreased skin turgor
5. Dry mucosa
6. Supine hypotension
7. Oligouria
8. Organ failure

Volume overload

1. Hypertension
2. Tachycardia
3. Increased JVP
4. Gallop
5. Edema
6. Pleural effusion
7. Pulmonary edema
8. Ascites
9. Organ failure

Question 10

Severe hypovolemia and hypovolemic shock

2

Answer 10

1. 1-2 L of isotonic saline (0.9% NS) bolus/rapid infusion

2. Continue until clinical signs of hypovolemia begin to improve

Question 11

Severe hypovolemia and hypovolemic shock:

Continue until clinical signs of hypovolemia begin to improve. Which would be? 3

Answer 11

1. low blood pressure,
2. low urine output,
3. and/or impaired mental status

Question 12

Severe hypovolemia and hypovolemic shock:

• Type of replacement fluid
  1. If bleeding?
  2. Otherwise?

Answer 12

1. If bleeding: use blood to get HCT up to 35%

2. Otherwise crystalloid vs. colloid

Question 13

Replacement solution for severe hypovolemia

Describe how crystalloids and colloids differ in treating severe hypovolemia?

Answer 13

Crystalloid saline solutions are equally effective in expanding the plasma volume as colloids but need to use 1.5-3 X as much because of extravascular distribution

Question 14

Replacement solution for severe hypovolemia
1. Albumin advantages over isotonic saline? 2

2. Disadvantage? 2

Answer 14

1. Albumin advantages over isotonic saline
   - More rapid plasma volume expansion (remains in the intravascular space)
   - Lesser risk of pulmonary edema due to dilutional hypoalbuminemia

Disadvantages:

1. cost,
2. not as readily available

Question 15

Replacement solution for severe hypovolemia: What about other colloids like hyperoncotic starches?

Answer 15

Associated with increased risk of acute kidney injury and in some studies increased mortality

Question 16

May need buffer therapy or to replace other electrolytes
1. Large volume resuscitation with isotonic saline may be associated with the development of what?

2. If acidotic add what?

Answer 16

1. hyperchloremic metabolic acidosis
   - Isotonic saline (NaCl) is hyperchloremic compared to plasma
2. If acidotic add sodium bicarbonate to the infusate

Question 17

Mild to Moderate Hypovolemia
1. Rapid fluid resuscitation is not necessary in patients with what?

2. To avoid worsening of the volume deficit, the rate of fluid administration must be ________ than the rate of continued fluid losses
3. What are our continued fluid losses? 3

Answer 17

1. mild to moderate hypovolemia
2. greater
3. equal to the
   - urine output plus estimated
   - insensible losses (usually 30 to 50 mL/hour)
   - plus any other fluid losses (eg, gastrointestinal losses) that may be present

Question 18

Mild to Moderate Hypovolemia

Consider administration of fluid at a rate that is how much greater than estimated fluid losses?

Answer 18

50 to 100 mL/hour greater

Question 19

What type of replacement fluids?

4

Answer 19

1. Hypotonic solutions should be used in hypernatremia
2. Isotonic or hypertonic saline should be used in hyponatremia
3. Isotonic saline and/or blood should be used in patients with blood loss
4. Potassium or bicarbonate may need to be added in patients with hypokalemia or metabolic acidosis

Question 20

1. Maintenance: Electrolytes
   How are electrolytes lost?
2. Thus, anuric patients have no maintenance what needs?
   Always be careful with the renal patient

Answer 20

1. No significant amount of electrolytes are lost in sweat or exhaled water vapor; all electrolyte losses are urinary
2. sodium or potassium

Question 21

Disorders of Sodium
1. Serum Sodium = what? 2

2. Regulated by what? 3
3. A disruption in water balance is manifested as what?

Answer 21

1. Osmolality = Water
2. • thirst,
   • ADH &
   • renal water handling
3. abnormality in serum sodium

Question 22

1. Sodium is a functionally impermeable solute, so it contributes to what? 2
2. Hypernatremia = what kind of dehydration?
3. Hyponatremia = what kind of dehydration?

Answer 22

1. • tonicity and
   • induces water movement across membranes
2. hyperosmolar (hypertonic)
3. hyposmolar (hypotonic)

Question 23

Sodium:
1. Hypernatremia is usually due to what?

2. Can calculate the what to help?
3. Loss of free water …increase in what?
4. Always be careful when correcting hyper or hyponatremia… why? 2

Answer 23

1. water loss
2. the free water deficit
3. ECF osmolarity (serum sodium)
4. • cerebral edema or
   • central pontine myelinosis

Question 24

Hypernatremia: Management
Slow Correction
1. Prudent in patients with what?

2. Correct sodium by how?
3. Others suggest adding the calculated fluid deficit to what requirements and giving over ___ hours

IVF
4. Only ________ fluids are appropriate unless frank circulatory collapse exists

5. The more hypotonic the infusate, the ______ the required volume to correct the hypertonicity, and the lower the what?

Answer 24

1. hypernatremia of longer or unknown duration
2. 0.5 mEq/L/hr or 10 mEq/L with goal of 145 mEq/L
3. maintenance fluid , 48
4. hypotonic
5. lower, risk of cerebral edema

Question 25

Hypernatremia: Management
1. Rate of infusion is calculated using the Madias Formula. Which is what?

2. The required volume, and thus rate, is determined by what?

Answer 25

1. estimates the change in serum sodium caused by 1 liter of any infusate
2. • dividing the change in serum sodium desired for a given period of time by the value obtained from Madias formula

Question 26

How do we gather the expected losses for maintenance therapy? 2

Insensible losses: look for? 3
(whats healthy for insensible losses)

Answer 26

1. urine (measure hourly if necessary)
2. GI (stool, stoma, drains, tubes, fistula, N/V/D)
3. Insensible (500ml a day in health)
   - Sweat
   - Exhaled
   - Fever (increase by 100ml/day/degree centigrade)

Question 27

Who needs maintenance therapy? 3

What is the goal?

What should be enough to prevent catabolism?

After 1-2 weeks of being unable to eat we should order what?

Answer 27

1. Unable to eat or drink normally for a prolonged period of time
2. Perioperative period
3. Ventilated patients
4. Goal: To maintain fluid and electrolyte balance and provide “nutrition”
5. Dextrose should be enough to prevent catabolism
6. After 1-2 weeks of being unable to eat should have TPN or enteral nutrition

Question 28

Monitoring parameters
for maintenance therapy?
2

Answer 28

1. Need baseline serum sodium
2. Need baseline weight
   Estimate net gain or loss of fluid daily

Question 29

Maintenance therapy
1. What kind of patient?

2. Actual requirement is less than ___ per day
3. Can begin with ___ of IV fluid per day
   -of what?
4. -Provides ___ g of sodium chloride (3.4 g of Na)
   - ____ calories from dextrose
   and ___ mEq of K+
5. Giving 2L or 2000mL over
   24 hours, how much per hour?
6. Round up or down but be specific ___ mL/h or____ mL/h

Answer 29

1.

• Not eating,
• physically inactive,
• afebrile (adult)

2. 1 L
3. 2L
   - 0.45% NS D5 +20 mEq K+
4. 9,
   - 400, 20
5. 2000/24 = 83.33
6. 80, 100