Propofol TCI · Comparative Pharmacokinetics

TCI Model Comparison

Marsh · Schnider · Eleveld — Three-Compartment Models Side by Side

Marsh 1991 Schnider 1998/1999 Eleveld 2018
👤 Patient: 40 yr 70 kg 170 cm
BMI 24.2 · LBM 57.0 kg
Target Cp 3.0 µg/mL
▶ Live Simulation
📊 Model Comparison
Marsh
0.00 mg/min 0.0 mg/kg/hr 0.0 mL/hr
C₁ CENTRAL Blood/Plasma V₁=15.96L (0.228×wt) 0.00 µg/mL Cp (target) 0.00 µg/mL C₂ FAST PERIPH. V₂=18.9L 0.00 µg/mL Muscle/viscera C₃ SLOW PERIPH. V₃=238L 0.00 µg/mL Fat/bone/skin Ce Effect-site 0.00 k₁₀ Elimination TCI 3.0µg/mL
Cp (C₁)0.00
Ce0.00
C₂0.00
C₃0.00
Schnider
0.00 mg/min 0.0 mg/kg/hr 0.0 mL/hr
C₁ CENTRAL Blood/Plasma V₁=4.27L 0.00 µg/mL Cp (target) 0.00 µg/mL C₂ FAST PERIPH. V₂=?L 0.00 µg/mL Muscle/viscera C₃ SLOW PERIPH. V₃=?L 0.00 µg/mL Fat/bone/skin Ce Effect-site 0.00 k₁₀ Elimination TCI 3.0µg/mL
Cp (C₁)0.00
Ce0.00
C₂0.00
C₃0.00
Eleveld
0.00 mg/min 0.0 mg/kg/hr 0.0 mL/hr
C₁ CENTRAL Blood/Plasma V₁=?L 0.00 µg/mL Cp (target) 0.00 µg/mL C₂ FAST PERIPH. V₂=?L 0.00 µg/mL Muscle/viscera C₃ SLOW PERIPH. V₃=?L 0.00 µg/mL Fat/bone/skin Ce Effect-site 0.00 k₁₀ Elimination TCI 3.0µg/mL
Cp (C₁)0.00
Ce0.00
C₂0.00
C₃0.00
📦 Compartment Volumes — Current Patient
V₁ Central
Marsh
4.27 L
Schnider
—
Eleveld
—
V₂ Fast Periph.
Marsh
18.9 L
Schnider
—
Eleveld
—
V₃ Slow Periph.
Marsh
238 L
Schnider
—
Eleveld
—
📈 Live Concentrations — All Models
Cp Central
Marsh
0.00
Schnider
0.00
Eleveld
0.00
Ce Effect-Site
Marsh
0.00
Schnider
0.00
Eleveld
0.00
🔢 Calculated PK Parameters — Current Patient
Parameter Marsh Schnider Eleveld Notes
📝 Model Characteristics

🔵 Marsh (1991)

  • Weight-based scaling only — all volumes scale linearly with total body weight
  • V₁ fixed at 0.228 L/kg → 15.96 L for 70 kg (note: some implementations use 4.27 L)
  • Does not account for age, sex, height or body composition
  • Uses plasma targeting (Cp) — no effect-site targeting in original model
  • Simplest model — easiest to understand clinically
  • May overestimate doses in obese or elderly patients
⚠ Use total body weight Most widely used historically

🟠 Schnider (1998/1999)

  • V₁ is fixed at 4.27 L — does NOT scale with weight
  • Clearances scale with age, weight, height and lean body mass (LBM)
  • LBM calculated by James equation (can give negative LBM in morbid obesity!)
  • ke0 of 0.456 min⁻¹ — faster effect-site equilibration than Marsh
  • Designed for effect-site targeting (Ce) — this is clinically important
  • Can produce very high initial infusion rates in lean patients
⚠ Caution in obesity (LBM issue) ✓ Effect-site targeting

🟣 Eleveld (2018)

  • Population PK model built from 30 studies — broadest validation dataset
  • Allometric scaling with continuous covariates: age, weight, height, sex, opioid co-administration
  • V₁ scales with body weight using a sigmoid function — handles extremes of weight better
  • Separate parameters for arterial vs venous sampling
  • Covers neonates to elderly, normal to obese — widest clinical applicability
  • Included in Fresenius Orchestra and newer TCI pumps
✓ Best population coverage ✓ Validated in obesity, elderly