Paediatric Propofol TCI Workbench

Kataria · Paedfusor · Eleveld — three-compartment plasma and effect-site kinetics for the child in front of you
V1 central V2 muscle V3 fat Effect site Speed 6×

Patient

5.0 y
20 kg
110 cm
16.5BMI kg/m²
—FFM (Al-Sallami) kg

Model

0.26 /min
Opioid flag only alters Eleveld (lower clearance and V3). Kataria has no published ke₀ — the default shown is a time-to-peak estimate (Muñoz 2004). Paedfusor's ke₀ is the value in its published parameter set.

Infusion control

3.0 µg/mL
0.00Plasma Cp · µg/mL
0.00Effect site Ce · µg/mL
0.0Rate · mg/kg/h
0.0mL/h of 1 % propofol
0Total mg · 0 mg/kg
00:00Elapsed · mm:ss
—Decrement min → 1.0
—Time to peak effect · min
1.0 µg/mL
window 60 min

Model parameters · Paedfusor

computed for this patient
—V1 L · /kg
—V2 · L
—V3 · L
—Cl L/min · mL/kg/min
—Q2 · L/min
—Q3 · L/min
rate constant/minrate constant/min
k10—ke0—
k12—k21—
k13—k31—

Compartment amounts

0V1 · mg
0V2 · mg
0V3 · mg
Watch where the drug goes. Early in an infusion most of what you give is filling V2 and V3, not being cleared — that is why the pump's rate falls over the first twenty minutes.
Teaching pearls for this state
Model sources and caveats

Kataria 1994 (Anesthesiology 80:104): children 3–11 y; weight-and-age model: V1 = 0.41·wt, V2 = 0.78·wt + 3.1·age − 16, V3 = 6.9·wt L; Cl = 0.035·wt, Q2 = 0.077·wt, Q3 = 0.026·wt L/min. No ke₀ in the original; 0.41 /min is a time-to-peak-effect estimate (Muñoz et al. 2004).

Paedfusor (Absalom & Kenny 2005, BJA 95:110): 1–16 y. V1 = 0.4584·wt L (1–12 y; 13–16 y step down to adult 0.2228), k10 = 0.1527·wt−0.3 (1–12 y), k12 0.114, k21 0.055, k13 0.0419, k31 0.0033, ke₀ 0.26 /min as published.

Eleveld 2018 (BJA 120:942): general-purpose model, neonate to elderly, with allometric scaling (Cl ∝ wt0.75), a post-menstrual-age maturation function for clearance and Q3, Al-Sallami fat-free mass for V3, and ke₀ = 0.146·(wt/70)−0.25 /min (arterial). Opioid flag lowers Cl and V3.

The TCI controllers here are educational: plasma targeting refills V1 to target and then replaces what leaves it; effect-site targeting finds the bolus whose peak Ce just reaches target (no overshoot) and then holds plasma at target. Real pumps differ in limits and in ke₀ choices. Decrement times are model predictions, not measurements.