Body Fluid Compartments; Movement of Fluid Between the Body Fluid Compartments (Starling Forces) Flashcards
(21 cards)
What are the two main subdivisions of Total Body Water (TBW)?
Intracellular Fluid (ICF, 2/3 of TBW) and Extracellular Fluid (ECF, 1/3 of TBW).
How does age affect body water percentage?
Infants (~75-80%) > Adults (~60%) > Elderly (~45-55%).
Why do females have a lower body water percentage than males
Females have more adipose tissue (10% water) compared to skeletal muscle (70% water).
What is the 60:40:20 rule?
TBW = 60% of body weight, ICF = 40%, ECF = 20%.
or a 70kg male, calculate TBW, ICF, and ECF.
TBW = 42L (70 × 0.6), ICF = 28L, ECF = 14L.
What ions dominate in ICF vs. ECF?
ICF: K⁺, Mg²⁺, proteins, organic phosphates. ECF: Na⁺, Cl⁻, HCO₃⁻.
Plasma volume is what percentage of body weight?
5% (e.g., 3.5L in a 70kg adult).
Formula for blood volume using hematocrit (HCT).
Blood Volume = Plasma Volume / (1 - HCT).
A 50kg male with HCT 40% has a blood volume of?
4.16L (Plasma = 2.5L; Blood = 2.5 / 0.6).
Hourly IVF maintenance for an 85kg adult?
125 mL/hr (4mL/kg for first 10kg, 2mL/kg next 10kg, 1mL/kg remaining 65kg).
Expected urine output in a well-hydrated 70kg adult?
35–70 mL/hr (0.5–1 mL/kg/hr).
Which marker is used to measure TBW?
Heavy water (D₂O) or Tritiated water.
Which marker is used for ECF?
Which marker is used for ECF?
How is ICF volume calculated?
ICF = TBW - ECF.
Daily insensible fluid loss in the tropics?
Up to 1500 mL/24hr (vs. 800 mL normally).
A 70 kg patient loses 600mL of fluid via NG tube. How to replace over 4 hours?
Add 150 mL/hr to maintenance (e.g., 110 + 150 = 260 mL/hr).
Nadler Equation for blood volume (men vs. women).
Men: (0.3669 × H³) + (0.03219 × W) + 0.6041
Women: (0.3561 × H³) + (0.03308 × W) + 0.1833
Normal serum osmolarity formula.
2(Na⁺ + K⁺) + Glucose + Urea (normal: 280–305 mOsm/L).
For a 70kg adult with HCT 40%, estimate plasma volume.
3.5L (5% of body weight or ¼ of ECF).
Calculate blood volume using plasma volume and HCT.
5.8L (3.5L / 0.6).
