Chapter 17: Fluids and Electrolytes- Calculations for Maintenance Fluid

Question 1

What is the 4/2/1 rule?

Answer 1

Maintenance IV fluids for hourly rate:

• 4 mL/kg for the first 10 kg
• 2 mL/kg for the next 10 kg
• 1 mL/kg for every kg over 20

Question 2

What is the maintenance rate for a 70-kg man?

Answer 2

Using 4/2/1:

• 4 × 10 kg = 40
• 2 × 10 kg = 20
• 1 × 50 kg = 50

Total = 110 mL/hr maintenance rate

Question 3

What is the common adult maintenance fluid?

Answer 3

D5 1/2 NS with 20 mEq KCl/L

Question 4

What is the common pediatric maintenance fluid?

Answer 4

D5 1/4 NS with 20 mEq KCl/L (use 1/4 NS because of the decreased ability of children to concentrate urine)

Question 5

Why should sugar (dextrose) be added to maintenance fluid?

Answer 5

to inhibit muscle breakdown

Question 6

What is the best way to assess fluid status?

Answer 6

Urine output (unless the patient has cardiac or renal dysfunction, in which case central venous pressure or wedge pressure is often used)

Question 7

What is the minimal urine output for an adult on maintenance IV?

Answer 7

30 mL/hr (0.5 cc/kg/hr)

Question 8

What are the common isotonic fluids?

Answer 8

NS, LR

Question 9

What is a bolus?

Answer 9

Volume of fluid given IV rapidly (e.g., 1 L over 1 hour); used for increasing intravascular volume, and isotonic fluids should be used (i.e., NS or LR)

Question 10

After a laparotomy, when should a patient’s fluid be “mobilized”?

Answer 10

Classically, POD #3; the patient begins to “mobilize” the third-space fluid back into the intravascular space