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ECMO DOβ‚‚/VOβ‚‚ Calculator

ECMO DOβ‚‚/VOβ‚‚ Calculator

Comprehensive oxygen delivery assessment with Impella integration, native CO estimation from echo, and clinical decision support

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ECMO Configuration

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Impella / Percutaneous VAD

LV Unloading
β–Ά How does Impella contribute to total flow & LV unloading?

Impella + VA-ECMO ("ECPella") β€” Physiology

VA-ECMO increases LV afterload by returning blood retrograde into the aorta. This can cause LV distension, increased LVEDP/PCWP, pulmonary edema, and LV thrombus. Impella directly unloads the LV by aspirating blood from the LV cavity and ejecting it into the ascending aorta.

Flow Contribution to DOβ‚‚

Impella flow does NOT simply add to ECMO flow for total cardiac output the way native CO does. The Impella takes blood from the LV and ejects it antegrade β€” this blood is already being returned to the aorta by ECMO (in a circuit), so it represents recirculated volume between the Impella and ECMO return cannula.

However, the Impella creates forward flow through the aortic valve, which:

β€’ Maintains pulsatility and coronary perfusion
β€’ Prevents aortic root stasis and valve thrombus
β€’ Decompresses the LV, reducing wall stress and Oβ‚‚ demand
β€’ May improve end-organ perfusion via maintained pulse pressure

How This Calculator Handles Impella

For left-sided Impella (CP, 5.0, 5.5), the flow is not added to total systemic flow because it recirculates with ECMO. The primary benefit is LV unloading, not additional DOβ‚‚.

For Impella RP (right-sided), the device pumps from IVC/RA β†’ PA, which can augment pulmonary blood flow and improve LV preload.

Max Flows by Device

Impella CPup to 3.5 L/min (14 Fr)
Impella CP Smartup to 4.3 L/min (14 Fr)
Impella 5.0up to 5.0 L/min (21 Fr, surgical)
Impella 5.5up to 5.5 L/min (21 Fr, surgical)
Impella RP / RP Flexup to 4.0 L/min (right-sided)
Clinical Pearl: In ECPella, run Impella at maximal support (P8–P9) and titrate ECMO flows down. Monitor LVEDP, PCWP, and aortic valve opening on echo.
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Patient

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Hemodynamics & Native CO

β–Ά Estimate Native CO from LVOT VTI on Echo

LVOT VTI Method β€” Step by Step

Native cardiac output can be estimated from TTE or TEE using the LVOT velocity-time integral (VTI).

SV = LVOT CSA Γ— LVOT VTI CO = SV Γ— HR Where: LVOT CSA = Ο€ Γ— (LVOT diameter / 2)Β² = LVOT diameterΒ² Γ— 0.785

Step 1: Measure LVOT Diameter

Parasternal long-axis (PLAX) view, mid-systole, inner edge to inner edge. Typical: 1.8–2.3 cm.

Step 2: Measure LVOT VTI

PW Doppler at LVOT (apical 5-chamber or deep transgastric on TEE). Trace the velocity envelope. Normal: 18–22 cm. On VA-ECMO with severe LV failure, VTI may be <5–10 cm.

Step 3: Calculate

LVOT CSAβ€”
Stroke Volumeβ€”
Native CO (SV Γ— HR)β€”
Native CIβ€”
Estimated Native CO: β€”

Interpreting VTI on VA-ECMO

VTI < 5 cmMinimal native ejection
VTI 5–10 cmSome recovery, partial support
VTI 10–15 cmModerate recovery
VTI > 15 cmGood native function, consider weaning
Limitations on ECMO: LVOT VTI may underestimate native CO if the aortic valve doesn't open every beat. A non-opening AV means VTI β‰ˆ 0. Always check for AV opening on M-mode or 2D. PA catheter thermodilution is unreliable on VA-ECMO.
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Laboratory Values

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Vasopressors / Organ Function

Optional
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DOβ‚‚ / VOβ‚‚ Ratio
Enter Data
ECMO β€” Native β€” Impella β€”
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Oxygen Delivery Breakdown

DOβ‚‚
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Critical DOβ‚‚
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Est. VOβ‚‚
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Oβ‚‚ Extraction
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Oxygen Content & Delivery

CaOβ‚‚ (Arterial Oβ‚‚ content)β€”
CvOβ‚‚ (Venous Oβ‚‚ content)β€”
Total Effective Flowβ€”
  ↳ ECMOβ€”
  ↳ Native COβ€”
  ↳ Impellaβ€”
DOβ‚‚ (Oβ‚‚ Delivery)β€”
DOβ‚‚ Index (per kg)β€”
DOβ‚‚ Index (per mΒ²)β€”

Oxygen Consumption & Ratio

Estimated VOβ‚‚β€”
VOβ‚‚ via Fick (from SvOβ‚‚)β€”
DOβ‚‚ / VOβ‚‚ Ratioβ€”
Oβ‚‚ Extraction Ratioβ€”
Critical DOβ‚‚ Thresholdβ€”
BSA (DuBois)β€”

ECMO Flow Adequacy

Target (50 mL/kg/min)β€”
Target (60 mL/kg/min)β€”
Target (70 mL/kg/min)β€”
Current % of Optimalβ€”
VIS Scoreβ€”

Native CO from LVOT VTI

LVOT Diameterβ€”
LVOT CSAβ€”
Stroke Volumeβ€”
Native CO (VTI)β€”

Enter patient data and calculate to see recommendations.

Calculate first to generate scenarios.

Required DOβ‚‚ to Reach Target
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Enter patient data and calculate first.

Hgb Γ— Flow Nomogram β€” DOβ‚‚/VOβ‚‚ Ratio at Each Combination

Calculate patient data first to generate the nomogram.
< 2.0 Critical 2.0–2.4 Borderline 2.4–3.0 Compensated 3.0–4.5 Adequate > 4.5 Optimal Current Target

Recommended Pathways to Target

Pathways will appear after calculation.

Impella & LV Unloading

DeviceNone
Flowβ€”
Max Device Flowβ€”
% of Maxβ€”
Primary Roleβ€”
Added to Total Flow?β€”

ECPella Strategy

Select an Impella device to see strategy recommendations.

CaOβ‚‚ = (Hb Γ— 1.34 Γ— SaOβ‚‚) + (PaOβ‚‚ Γ— 0.003) CvOβ‚‚ = (Hb Γ— 1.34 Γ— SvOβ‚‚) DOβ‚‚ = Total Flow Γ— CaOβ‚‚ Γ— 10 VOβ‚‚ = Total Flow Γ— (CaOβ‚‚ βˆ’ CvOβ‚‚) Γ— 10 [Fick] Oβ‚‚ER = (CaOβ‚‚ βˆ’ CvOβ‚‚) / CaOβ‚‚ BSA = 0.007184 Γ— H⁰·⁷²⁡ Γ— W⁰·⁴²⁡ [DuBois] ── Native CO from Echo ── LVOT CSA = Ο€ Γ— (d/2)Β² = dΒ² Γ— 0.785 SV = CSA Γ— VTI | CO = SV Γ— HR ── Impella in ECPella ── Left (CP/5.0/5.5): NOT additive to DOβ‚‚ Right (RP): Augments pulm. flow β†’ ↑ LV preload

Reference Thresholds

Critical DOβ‚‚/VOβ‚‚β‰₯ 2.0–2.4
Normal DOβ‚‚/VOβ‚‚4–5 : 1
Critical DOβ‚‚3.8–4.5 mL/kg/min
VA-ECMO Flow Target50–70 mL/kg/min
Normal LVOT VTI18–22 cm
HΓΌfner's constant1.34 mL Oβ‚‚/g Hb

Key References

Guglin et al. VA-ECMO for Adults. JACC Expert Panel, 2019
Lorusso et al. EACTS/ELSO/STS/AATS Consensus, 2021
Spinelli & Bartlett. Hb–Flow model. ASAIO J 2014
Ronco et al. Critical DOβ‚‚. JAMA 1993
Pappalardo et al. ECPella. EuroIntervention 2017
Schrage et al. Impella + VA-ECMO. Eur Heart J 2020
⚠ Clinical Decision Support Tool β€” Not a Substitute for Clinical Judgment. All calculations are estimates. Always correlate with clinical picture, trends, and multidisciplinary team assessment.