Cardiac Output is a podcast on cardiothoracic anaesthesia and intensive care medicine. Dr Mike Charlesworth and Dr Calum Downes discuss the evidence, the controversies and the practicalities of modern practice.
Episodes
Minimally Invasive Cardiac Surgery, Part 1: Setting Up the Case
The patient's on femoral bypass for a mini mitral. You've stopped ventilating so the surgeon can get the right lung down. The pump flow looks fine, but the right-sided cerebral oximetry is drifting down, and there's still a little pulse on the arterial line. The heart is still ejecting blood that has just been through lungs nobody is ventilating.
This is the first of four episodes on minimally inv
Thoracic Regional Anaesthesia: Getting the Paravertebral Right
Ask anyone in an exam what shape the paravertebral space is and they'll say a wedge. Look at a CT scan, or a cadaver with dye in it, and it's something else: a continuous channel beside the vertebral bodies, with pouches sticking out between the ribs. Put your local anaesthetic in the channel and it spreads over several levels. Put it in a pouch and you've done an intercostal block.
In this episod
The Aortic Valve, Part 2: Stenosis, Regurgitation and LVOT
"Severe aortic stenosis means a mean gradient over forty." Yet in one study of patients with true severe stenosis examined on TOE after induction, 54 per cent had a mean gradient under forty. General anaesthesia lowers the flow, and the gradient falls with it.
This is part two of two on the aortic valve on transoesophageal echo, following the aortic valve chapter of the fourth edition of Practical
The Aortic Valve, Part 1: Anatomy, Measurement and Bicuspid
Two numbers for the same aortic annulus: 23 mm on the 2D long-axis view, 27 mm on the 3D reconstruction — and the surgeon is sizing a valve. Neither number is wrong.
This is part one of two on the aortic valve and left ventricular outflow tract on transoesophageal echo, built around the aortic valve chapter of the fourth edition of Practical Perioperative Transoesophageal Echocardiography. We star
Cheap Knowledge, Scarce Experience: Training Generation Alpha
If you're listening to this in the car or at the gym, you're part of the argument in this episode.
Mike talks through his new editorial in Anaesthesia, "Cheap knowledge, scarce experience: training Generation Alpha" — and Calum points out the irony of discussing it on a podcast, along with the paper's own warning that a poorly produced podcast can be less useful than a dry lecture.
We cover how ea
The Right Ventricle, Part 2: Function and Congestion
After a straightforward valve operation, TAPSE is twelve millimetres — well under the transthoracic normal. But the fractional area change is 40 per cent, the 3D ejection fraction is 48 per cent, and the lactate is falling. Which number is lying?
This is part two of two on the right ventricle on transoesophageal echo, following the right ventricle chapter of the fourth edition of Practical Periope
The Right Ventricle, Part 1: Anatomy, Physiology and Views
In the 1940s, researchers burned away most of the right ventricular free wall in dogs, and the venous pressure barely moved. For decades, the right ventricle was treated as a passive conduit. Nobody who has watched one fail coming off bypass believes that now.
This is part one of two on the right ventricle on transoesophageal echo, built around the right ventricle chapter of the fourth edition of
The Mitral Valve, Part 2: Grading Regurgitation and Stenosis
A patient comes for coronary bypass. Last month's echo called the mitral regurgitation severe. After induction, it looks moderate. The surgeon asks: "Do I need to touch the valve?"
This is part two of two on the mitral valve on transoesophageal echo, following the mitral valve chapter of the fourth edition of Practical Perioperative Transoesophageal Echocardiography. It's all about severity — and
The Mitral Valve, Part 1: Anatomy, Views and Mechanism
The cross-clamp is on, the atrium is open, and the surgeon looks up over the drapes: "Is it P2 or P3 — and is the anterior leaflet involved?" Everyone turns to the person with the TOE probe.
This is part one of two on the mitral valve on transoesophageal echo, built around the mitral valve chapter of the fourth edition of Practical Perioperative Transoesophageal Echocardiography. We start with why
The Cath Lab Call: Anaesthesia for Primary PCI
"Anaesthetist to the cath lab. Primary PCI, five minutes." Then the pause, while everyone waits to hear whether the patient is self-ventilating or intubated.
This episode is about anaesthesia for primary PCI — one of the few places where you're surrounded by people and still somehow on your own. We cover the range of patients the call can mean, from mid-arrest on a mechanical compression device to
Carcinoid Heart Disease: Ready for the Ventricle
In carcinoid syndrome, you must never give adrenaline. Most of us were taught that — but it comes from decades-old experiments in end-stage patients who had never been near octreotide. So does the rule still stand?
This episode is carcinoid heart disease, from the tumour to intensive care. We start with neuroendocrine tumours and carcinoid syndrome, why the syndrome usually needs liver metastases,
How Much Heparin on ECMO? (RATE)
Sixty-five per cent of patients on standard-dose heparin on ECMO had a severe bleed. Eleven per cent had a severe clot. And the heparin is there to prevent the eleven.
This is a journal club on RATE, published in The Lancet in July 2026: the first adequately powered randomised trial of anticoagulation intensity on ECMO. Three hundred and thirty adults on veno-venous or veno-arterial ECMO across se
Cardiomyopathy: Look Before You Squeeze
A thirty-four-year-old for a hernia repair. After induction the pressure falls to fifty systolic, and the trainee reaches for adrenaline. The echo shows a thick septum, a tiny cavity and the mitral leaflet slapping into the outflow tract — and the pressure gets much worse.
This episode is the cardiomyopathies: the main types, how they present, what they look like on echo, and why getting the label
Cardiac Output Monitoring: Believe the Patient
Day one after mitral valve surgery. The monitor says the cardiac index is a healthy three point two. The lactate is six, the feet are cold and the urine has stopped. One of those numbers is lying — and it isn't the lactate.
This episode is cardiac output monitoring, for the exam and for the bedside: how each device works, the physiology underneath, when we actually use them, and where each one mis
Cardioplegia: Stopping the Heart Safely
Forty minutes into an aortic valve replacement, the cross-clamp is on and the heart is arrested. Then a little electrical activity starts creeping back on the ECG. What do you do? Tell the surgeon — out loud, straight away — because that heart is waking up while it's still ischaemic. The anaesthetist is part of myocardial protection, even though the solution runs through the perfusionist's pump.
T
AF on the Unit: Fix the Physiology First
Eight o'clock ward round, day two after a coronary artery bypass, and the monitor shows atrial fibrillation at a hundred and fifty. Calum's answer is amiodarone — and that is the single most common wrong answer on the unit. Not because amiodarone is wrong, but because of where it sits in the order.
This is atrial fibrillation on the cardiothoracic intensive care unit, top to bottom. And it matters
TOE in Theatre: The Probe Earns Its Keep
Last episode we put a probe on the chest. This one goes down the oesophagus — and it starts somewhere uncomfortable.
Inserting a transoesophageal probe is something we do to a patient that can cause them significant harm. Maybe once a year, sometimes more, a patient comes to harm because an anaesthetist put a probe down. We do a great many of these, so it is not unreasonable to think we sometimes
Transthoracic Echo on the Unit: Five Views and Six Patterns
Three in the morning. A patient on the unit is hypotensive, the noradrenaline is going up, and somebody has already given a litre. What is the fastest way to actually know what's wrong?
Put a probe on them.
This is the first of two foundation episodes on echocardiography — the thing that turns a guess into a diagnosis, at the bedside, in about ninety seconds. Today it's transthoracic echo on the i
Journal Club: GLP-1 Agonists and Aspiration (GLIMPSE)
Recorded minutes after the live launch at Annual Congress 2026, and published the same day the paper appears in Anaesthesia.
GLIMPSE — the GLP-1 receptor agonist Management in the Peri-operative Setting project — is a national, prospective, multicentre cohort study delivered through the UK resident research networks across all four nations, and it is the largest thing anyone has done on this quest
TOE for Mechanical Support 2: VADs and the Impella
Before we touch a single image, we sort out the vocabulary — because almost everyone muddles these devices, and once you have muddled them you cannot reason about them. People say "VAD" and mean five different machines, sitting in different places, for different lengths of time.
So: three questions, and every device answers all three. Which ventricle? How long is it meant to stay in? Surgical or p
TOE for Mechanical Support 1: Balloon Pumps and ECMO
We've spent a lot of this series on machines — balloon pumps, ECMO circuits, ventricular assist devices. This episode is about the tool that makes all three of them safe.
The argument is that in mechanical circulatory support, transoesophageal echo is not an investigation you order. It is part of the device. It confirms the indication, guides the cannulas in, optimises the support once it is runni
Cardiopulmonary Bypass: What It Does to the Patient
"Draw me a cardiopulmonary bypass circuit." Venous cannula, reservoir, pump, oxygenator, back to the aorta, cross-clamp, cardioplegia, vents, suckers. Good — that's a pass. The mark comes when you can say what each component does to the patient rather than what it does to the blood, and that is the difference between a trainee who has memorised a diagram and a senior who understands a machine.
Thi
Intra-Aortic Balloon Pumps: Timing, Traces and Trials
Two in the morning, day one after a long CABG. The patient has a balloon pump in, the augmented pressure has dropped, and the urine output has fallen away over the last three hours. The easiest thing in the world at that hour is to re-zero the transducer, decide the trace looks a bit better, and go back to what you were doing. By the end of this episode you'll know exactly why that's the wrong ans
Journal Club: Iron Before Cardiac Surgery (ITACS)
Something different this episode. No 3am emergency — instead, a pre-assessment clinic on a Tuesday afternoon, a woman booked for an aortic valve replacement in six weeks, and a haemoglobin of 118. Do you give her intravenous iron?
ITACS, published in The BMJ in August 2026, is the best answer we have ever had to that question. It is also a trial with a great deal to teach about how to read a paper
Protamine: The Most Dangerous Drug We Give Every Day
You will have noticed that consultants tend to give the protamine themselves, and if you're an ST3 who hasn't done much cardiac, nobody asks you to do it. Most people assume that's habit. It isn't.
This is the theatre half of the bleeding week — the drugs, the traps in the tests, and a salvage case at the far end of what's possible. Last episode was the unit.
Please note: the doses and drug choice
Bleeding After Cardiac Surgery: Products, TEGs and HIT
Two in the morning, day zero after cardiac surgery. The chest drains have been filling steadily for an hour, the nurse is looking at you, and the surgical registrar is on the phone. Your instinct is to send a TEG and wait for it to tell you what to do — and that instinct, the one we are all taught, may be exactly what harms this patient.
This is the intensive care half of the bleeding week: rester
Endocarditis Surgery: Timing, Bleeding and Vasoplegia
Last episode we diagnosed endocarditis. This one operates — and it opens on the number that reframes the whole disease: more than half of patients with endocarditis will meet the criteria for cardiac surgery.
Half of them go through one of the biggest operations a human being can have, while septic, followed by a long intensive care stay and very often a tracheostomy. And the outcomes remain poor
Endocarditis for Residents: Cultures, Criteria and Echo
Cast your mind back to medical school. You were taught to examine a patient starting at the hands, looking for splinter haemorrhages, Osler's nodes and Janeway lesions. When did you last actually see any of them?
Not because we've stopped looking — because the disease has changed underneath us. In this episode Mike and Calum work through infective endocarditis: why it presents so differently now,
What Would You Do? Cognitive Bias in ECMO Decisions
Important note: every case in this episode is completely fictitious. The scenarios are teaching constructs, invented to illustrate patterns of clinical reasoning. No case describes a real patient, and any resemblance to any individual is entirely coincidental.
In ECMO, the hard part is almost never the cannulation. Putting cannulas in and troubleshooting hypoxia are learnable. What's hard is the d
Check the Tube. Then Check It Again.
Something a bit different this episode. We've spent this series on pumps and valves and circuits — today it's the airway, and the lung you're deliberately collapsing.
Mike and Calum work through thoracic and cardiac airway management: one-lung ventilation, the difficult double-lumen tube, the shared airway, and a couple of scenarios that will catch you out badly if you haven't thought about them f
TAVI for Residents: Evidence, Rapid Pacing and Sedation
Everybody asks how you anaesthetise a patient for a TAVI. The answer takes about four seconds: it's lidocaine into the groin. For more than 95% of our patients that is very nearly it — transfemoral, local anaesthetic, a little procedural sedation from a nurse, and they never meet an anaesthetist at all.
Which raises the obvious question: why do a whole episode on it? Because the fact that the anae
Empty, Not Vasoplegic: Aortic Stenosis After Surgery
It's two in the morning. Your patient had an aortic valve replacement this afternoon — good ventricle, off bypass without a fuss — and the noradrenaline has crept up again. Your general intensive care instinct says work out why they're vasoplegic and turn the pressors up. In this specific patient, that instinct is wrong. Nine times out of ten they aren't vasoplegic. They're empty.
In this episode
VV-ECMO for Residents: Candidacy, Runs and Oxygenators
Our first episode covered veno-venous ECMO the way it gets examined: sweep for CO₂, flow for oxygen, who qualifies, and how to read CESAR and EOLIA honestly. This episode is everything we didn't say — not the physiology, but the service. How ECMO got here, who actually says yes to a referral, and the things that genuinely shorten a run.
Please note: this reflects local Wythenshawe practice. Take t
You Can't Clamp a Torn Aorta: DHCA Explained
Here's the puzzle. Your patient has an acute type A dissection, so the ascending aorta is torn. To do cardiac surgery you need to cannulate the aorta and cross-clamp it — but the ascending aorta is both dissected and the thing you're about to operate on. So you can't cannulate it, and you can't clamp it. What do you do?
The answer is that you cool the patient right down and stop the circulation al
Think Aorta: Hypertensive Emergencies and Dissection
A thirty-five-year-old with chest pain, a bit sweaty, a bit anxious, and a blood pressure that's frankly high. In a lot of departments that patient gets a troponin, a D-dimer, possibly a label of anxiety — and goes home. If that pain was an acute type A dissection, they are not going to get better.
In this episode Mike and Calum work through hypertension and the acute aortic syndromes as they actu
Heart and Lung Transplants: The First 48 Hours in ICU
The operation is over. The new heart and lungs are in, and the patient has just arrived on the unit. This is where you actually earn your keep.
In this episode Mike and Calum work through the first forty-eight hours after a heart or lung transplant — and almost everything comes back to one structure: the right ventricle. This is the postoperative ICU half; the theatre half is the previous episode.
Heart and Lung Transplants: The Twelve Hours in Theatre
The phone goes at eleven at night. There's a donor heart, and it's coming here. In a few hours that organ is going into a patient who is, right now, sitting on a ward waiting for you.
In this episode Mike and Calum work through heart and lung transplantation from the listing call to the handover on the unit — the twelve hours in the middle. This is the theatre half; the postoperative ICU episode i
Cardiac Theatre for Residents: Vasoplegia, SAM and Pacing
Your noradrenaline is climbing, and climbing, and the pressure still won't hold. The tank's the right size and the pump is working — so what do you reach for next?
In this episode Mike and Calum get scrubbed for the theatre half of the cardiac topic: the problems that show up on the table rather than on the unit, and the ones that catch people out. This is the companion to the ICU episode on heart
Mechanical Circulatory Support in ICU: Cardiac Output, VA-ECMO and VADs
It's the middle of the night (again). Your post-op cardiac patient looks awful, and the nurse says the cardiac output's low. Do you reach for a number — or do you look at the patient?
In this episode Mike and Calum work through heart failure and mechanical circulatory support the way it actually plays out on a cardiothoracic ICU: how you know the output is low, what the devices really do, and how
VV-ECMO for Residents: Physiology, Evidence, Troubleshooting
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
