Ashley Miller
@icmteaching
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#zentensivist #FUSIC Haemodynamics National Lead. Ex ICS council. BSE level 2. BJJ ⬛️⬛️🟥⬛️. No politics, no pets, just #foamed #fluids #pocus #haemodynamics
United Kingdom
Joined December 2015
Want to know how to perform lung ultrasound? @GEHealthcare @ICS_updates @I_C_N have collaborated to bring you this video. For more great content visit To find out how to accredit in #FUSIC lung visit ⭐️️
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I’m going to be looking for hydronephrosis more often after hearing Ross’ talk.
(1/x) We often focus on crazy POCUS cases that are so visually impactful (see this effusion 👇) but I am convinced that most of the benefit of POCUS is in its routine application for select populations. Let's take sepsis and see how POCUS upgrades our traditional assessment 🧵
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Sodium disorders are made really complicated in articles and books. @Turningthe_Tide making it make sense here ⬇️.
🧵Why does low protein intake cause hyponatraemia?. Most people find this confusing. But the underlying physiology is beautifully simple. Let’s walk through it 👇. #Hyponatraemia #FluidBalance #MedTwitter #FOAMed
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RT @TrackYourHeart: Open it. Zoom it. Save it. Share it. This is your go-to guide for standard adult TTE views.
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Yesterday’s thread challenged how we teach Starling’s Law. But there’s a bigger problem hiding underneath it. “Preload” might be the most misleading term in clinical physiology. I’ll post a thread soon. It’s time we talked about what to say instead. #MedTwitter #FOAMed #FOAMcc.
🧵 Starling’s Law: Misunderstood, Misapplied, and Still Misleading.1.🚨 “Starling’s Law explains how the heart increases cardiac output.”. You’ve probably heard this a thousand times. But it’s wrong. Or at least - very incomplete. Let’s fix it. Because this matters - for heart.
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Start here ⬇️.
🧵 Starling’s Law: Misunderstood, Misapplied, and Still Misleading.1.🚨 “Starling’s Law explains how the heart increases cardiac output.”. You’ve probably heard this a thousand times. But it’s wrong. Or at least - very incomplete. Let’s fix it. Because this matters - for heart.
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18. 🧵This thread builds on my earlier breakdown of how the system sets flow — and how cardiac output really works:.👉Follow for more physiology that reflects reality, not just the textbook. #FOAMcc #Physiology #CardioTwitter #Starling #CriticalCare.
1/.Most people think the heart drives circulation. But what if that’s backwards?.Anderson’s model flips the whole idea of cardiac output on its head — and it changes how you think about fluid, flow, and failure. 🧵👇.#physiology #FOAMed #MedTwitter #criticalCare #cardiacOutput
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17. Let’s retire the myth that:.“Starling’s Law increases cardiac output.”. Instead:.“Starling’s Law lets the heart match what the system delivers — until it can’t.”. That’s when pressure rises. That’s when failure begins.
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16. 💡 Summary:.Starling’s Law is passive in health, protective in stress, and critical in failure. It doesn’t increase flow. It helps the heart keep up when the system demands more.
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15. 🛑 That’s why it’s a mistake to “fill the heart to improve function.”.Distending the ventricle in search of better output often worsens failure (increases wall stress, oxygen demand, ventricular interdependency).You're stretching a failing system - not supporting a healthy.
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14. 🧠That’s the paradox:. In health:.• Starling modulates.• The system drives. In failure:.• Starling compensates.• The heart limits. Same mechanism. Different roles depending on context.
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13. 📈 But in failure, everything flips. • The heart becomes the bottleneck.• CO now depends on cardiac function and afterload.• Starling is no longer passive — it's compensating.Now the textbook labels apply.
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12. Here’s the key:.In health, the system shifts the blue VR curve (via ↑Pms) to increase flow. The heart doesn’t need to push harder - it just needs to tolerate the new return.
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11. 📉 You’ve seen this diagram. But it’s often misread. 🔵 Blue curves = venous return, set by the system (Pms) - venous volume and elastance.🔴 Red curves = cardiac output, reflecting heart performance.⚫ Flow happens where they intersect
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10. This makes Starling’s Law a servo system:. • It responds to mismatch.• It adjusts local force generation.• No external control required.• It stabilises output in the face of varying return. A buffer, not a throttle.
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9. 🚫 Misconception:.“Increasing contractility increases CO.”.✅ Reality:.Contractility increases so the heart can keep up with increased return. It doesn’t drive flow — it enables flow when demand increases.
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8. In health:. • Venous return increases (↑Pms, ↓venous resistance).• The heart increases rate and contractility to keep up.• Starling’s effect is minimal. In failure:.• The heart can’t keep up.• Filling pressures rise.• Starling’s mechanism kicks in to buffer the.
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7. 💥 So here’s the real twist:. Starling’s Law is always active - but only becomes functionally important when the system is stressed or the heart starts to fail. It’s a servo control mechanism, not a flow generator.
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6. 🫀 Real hearts beat forcefully even when empty:. • During cardiopulmonary bypass.• In low volume states. They don’t need to be “filled” to contract. Stretch modifies output — it doesn't initiate it.
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5.🧪 Starling’s original work used:. • Isolated muscle strips.• Applied weights to stretch them.• Measured force of contraction. It wasn’t a model of the circulation - it was a mechanics experiment.
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