Lean Body Mass Calculator for Perfusion Planning
Calculate LBM and compare indexed flow requirements using actual BSA versus lean BSA in CPB workflows.
Lean Body Mass LBM
Fat-free body mass calculator
Quick summary
Lean body mass (LBM) estimates fat-free body mass and can help contextualize perfusion targets in obesity or extreme body habitus. This calculator compares actual BSA-based flow with lean BSA-based flow to support CPB flow discussions.
Key info
Compare actual BSA vs lean BSA flow guidance.
Boer and Hume LBM formulas.
Lean BSA is a reference value, not a replacement for bedside perfusion assessment.
Flow comparison table (CI 1.0 – 3.0)
BSA actual vs BSA lean flow comparison
| CI | Flow (Actual BSA) | Flow (Lean BSA) |
|---|
Practical note
Use lean-BSA flow as a comparison reference and interpret it with SvO₂, lactate, perfusion pressure, temperature, and local protocol.
▶ Methodology & limitations
What is lean body mass?
LBM means body mass excluding adipose tissue.
Which LBM formulas are used?
Adult estimation formulas are available using Boer and Hume equations.
How is lean BSA flow calculated?
Actual BSA and lean BSA are both calculated with the selected BSA formula, then flow comparison is calculated as CI × BSA.
How should the result be interpreted?
Lean BSA flow is a comparison reference, not a standalone prescription.
Limitations
Adult estimation formulas only; not a pediatric reference model; not a substitute for bedside perfusion monitoring; local protocol should take precedence.
Extended clinical notes & evidence
Additional interpretation for obesity, lean-BSA flow comparison, and CPB context.
Actual BSA vs lean BSA interpretation
Actual BSA-based flow may trend higher in obesity because total body weight contributes to BSA.
Lean BSA-based flow may provide a comparison reference that is closer to fat-free body size.
Neither value should be used alone; bedside perfusion markers remain essential.
LBM formula notes
Adult LBM estimation formulas (Weight in kg, Height in cm).
Boer
Commonly used adult LBM estimation formula.
Equation
Male: LBM = 0.407 × weight + 0.267 × height − 19.2
Female: LBM = 0.252 × weight + 0.473 × height − 48.3
Hume
Alternative adult LBM estimation formula.
Equation
Male: LBM = 0.32810 × weight + 0.33929 × height − 29.5336
Female: LBM = 0.29569 × weight + 0.41813 × height − 43.2933
Both formulas are estimates and can differ by sex, height, and weight.
Pediatric use: limited interpretation
LBM is meaningful as a body-composition concept in children, but this calculator is intended mainly for adult obesity or extreme body-habitus interpretation. Pediatric body composition changes with growth, and adult equations such as Boer and Hume are not pediatric reference models.
For pediatric CPB, follow institutional pediatric perfusion protocols and interpret flow with temperature, DO₂/SvO₂, lactate, NIRS, pressure, urine output, and overall clinical context. Lean-BSA flow should not be used as a standalone pediatric pump-flow target.
Clinical interpretation in CPB
- Use the flow comparison as a discussion aid, not an automatic target.
- Interpret with SvO₂, lactate, perfusion pressure, temperature, urine output, and local protocol.
- In obesity, actual BSA flow and lean BSA flow may diverge meaningfully.
- Consistency and clinical context are more important than a single calculated number.
Selected references
- Boer P. Estimated lean body mass as an index for normalization of body fluid volumes in humans. Am J Physiol. 1984.
- Hume R. Prediction of lean body mass from height and weight. J Clin Pathol. 1966.