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Cardiac Output

VV-ECMO for Residents: Physiology, Evidence, Troubleshooting

July 22 · 19 min · Episode 1 · 27.4 MB
0:00-19:01

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It's three in the morning. Your patient is proned, paralysed, on 100% oxygen, and his P/F ratio is 70. Do you keep cranking the ventilator — or do you pick up the phone?

In this episode Mike and Calum work through veno-venous ECMO the way it actually gets used on an ICU: what it does, who it's for, and the things that catch people out at the bedside.

We cover the single most important idea in ECMO — that it doesn't treat anything, it's a bridge — and why that reframes every decision you make. We get into the physiology consultants love to quiz you on (sweep gas for CO2, blood flow for oxygen, and why a septic, hyperdynamic patient can desaturate with a perfectly functioning circuit). We walk through who actually qualifies, using the EOLIA and CESAR thresholds, the Murray score, and the harder question of whether the lungs have a plausible route back.

Then we take an honest look at the evidence. CESAR randomised to referral, not to ECMO. EOLIA was stopped for futility with an 11% mortality gap — and we unpick why the 28% crossover in the control arm makes "negative trial" the wrong conclusion, and what the individual-patient-data meta-analysis and the COVID-era NHS England data added.

Finally, the practical half: the nationally commissioned UK centres (now including Barts, Bristol and Newcastle) and how to make a referral that gets your patient assessed fast; cannulation configurations; lung-rest ventilation and the bleeding-versus-clotting balancing act; and a rapid-fire troubleshooting round — recirculation, the suddenly desaturating patient, line chatter, and the failing oxygenator. Plus why Harlequin syndrome is a VA problem, not a VV one.

Chapters

  • (00:00) Cold open — 3am, and a P/F of 70
  • (01:16) What ECMO actually is (and isn't)
  • (03:22) Sweep vs flow — the physiology you'll be quizzed on
  • (05:22) Who actually gets cannulated: EOLIA, CESAR, Murray, RESP
  • (07:02) Optimise first — and prone them
  • (07:40) The evidence, honestly: CESAR and EOLIA
  • (10:15) The UK service: 8 commissioned centres
  • (11:11) Cannulation and configurations
  • (12:31) Day-to-day: lung rest and anticoagulation
  • (13:54) Troubleshooting at 2am
  • (16:07) Harlequin — why it's a VA problem
  • (16:49) Weaning and the sweep-off trial
  • (17:49) Wrap-up

Key takeaways

  • ECMO is a bridge, not a treatment — no bridgeable destination, no bridge
  • Sweep gas controls CO2; blood flow controls oxygenation
  • VV-ECMO provides no haemodynamic support — preserved cardiac function is a prerequisite
  • Optimise and prone before you refer
  • Recirculation is the VV gremlin; Harlequin is a VA phenomenon

References

  • Peek GJ et al. CESAR trial. Lancet 2009
  • Combes A et al. EOLIA trial. NEJM 2018
  • Goligher EC et al. Bayesian re-analysis of EOLIA. JAMA 2018
  • Combes A et al. CESAR/EOLIA individual patient data meta-analysis
  • ELSO Guidelines: Management of Adult Patients Supported with VV-ECMO (2021)
  • NHS England Adult ECMO Service Specification
  • Camporota L et al. Outcomes of the NHS England National ECMO Service. BJA 2021

This podcast is for medical education for healthcare professionals. It is not clinical advice — always follow your local protocols and your regional ECMO centre's guidance.