🔍 Massive Transfusion Volume Calculator (Forensic Trauma) Simulator

Estimating Scene Blood Loss from Physical Evidence

Forensic teams estimate total blood loss from pooling, spatter, and substrate absorption at a scene.

• ~5.0 L: Average adult blood volume (roughly 7% of body weight)
• >2.0 L: Class IV hemorrhage threshold (over 40% volume loss)
• +10–25%: Absorbent substrate correction (fabric and flooring uptake)
• ±15%: Photogrammetry pool accuracy (typical scene estimate range)

Sources of scene loss evidence

Pooled volume, spatter pattern density, and stained substrate area combine.

Substrate absorption correction

Carpet, soil, and fabric absorb blood, so raw pool volume undercounts loss.

Limits of scene-based estimation

Estimates carry wide error bands and are stated as ranges, not exact figures.

Scene volume is always a reconstructed estimate, never a measured clinical value.

Converting Estimated Loss into a Circulating Volume Deficit

Estimated loss is expressed as a percentage of total body blood volume for severity grading.

• <15%: Class I loss (minimal hemodynamic effect)
• 15–30%: Class II loss (compensated tachycardia)
• 30–40%: Class III loss (decompensating shock)
• >40%: Class IV loss (immediately life-threatening)

ATLS hemorrhagic shock classes

Deficit percentage maps loss onto standard four-class shock severity bands.

Body-weight based volume assumption

Total blood volume is assumed near 70 mL per kilogram body weight.

Deficit as a reconstruction anchor

Deficit percentage anchors every downstream forensic transfusion estimate.

Deficit above 40% is associated with rapid, often unsurvivable decompensation.

Modeling a 1:1:1 Massive Transfusion Volume

Modern massive transfusion protocols replace red cells, plasma, and platelets in balanced ratio.

• 1:1:1: Standard MTP ratio (RBC : plasma : platelets)
• ~450 mL: RBC unit volume (per packed cell unit)
• ~1.3×: Replacement multiplier (accounts for dilution loss)
• ≥4 units: Typical MTP activation (RBC in first hour)

Why balanced 1:1:1 ratios matter

Balanced ratios avoid dilutional coagulopathy seen with red-cell-only replacement.

Modeling total unit count

Estimated deficit volume is divided by unit size across all three products.

Reconstruction, not prescription

The modeled figure reconstructs need, it does not prescribe live treatment.

This models what transfusion volume would have been required, retrospectively.

Time-to-Intervention and Modeled Survival Probability

Survival probability declines sharply as time between injury and transfusion access lengthens.

• 60 min: Golden hour concept (critical intervention window)
• exponential: Survival decay (modeled) (with delay to intervention)
• ~50%: Prehospital death share (of trauma hemorrhage deaths)
• minutes: Time-critical injuries (for major vascular trauma)

The golden hour framework

Outcomes worsen steeply once intervention is delayed beyond about an hour.

Combining deficit and delay

Model multiplies deficit severity against a time-based survival decay curve.

Use in case timelines

Curve helps test whether a documented response time was survivable.

Longer modeled delay lowers survival probability even at constant blood loss.

Forensic Reconstruction Conclusion for Case Testimony

Combined estimates produce a defensible transfusion-need figure for expert testimony.

• Expert report: Output used in (case reconstruction filings)
• Range, not point: Confidence framing (stated with uncertainty bounds)
• Autopsy findings: Cross-checked against (where available)
• Retrospective: Tool classification (not a bedside instrument)

Assembling the reconstruction

Loss, deficit, modeled units, and survival curve combine into one exhibit.

Presenting uncertainty honestly

Every figure is reported as a range with stated assumptions and limits.

Scope of forensic use

Conclusion supports case reconstruction, never active bedside patient care.

This tool reconstructs what care would have required — it treats no one.