Why we give adrenaline during CPR

Morning — in this week's newsletter:

• 💉 Why we give adrenaline during CPR — and why it is not to restart the heart
• ⏱️ ALS Scribe Mode, if you haven't found it yet
• 📅 Foundation Emergencies Webinars — twenty-two free webinars, Wednesdays from 9 September
• 💷 Your first payslip — why it should show no student loan and almost no income tax
• 📶 What's new — the app now opens on one bar of signal
• 📈 Most read this month

At every arrest, someone draws up adrenaline. Ask why and you will usually get "to restart the heart". It does not restart the heart. Defibrillation restarts hearts, and very few at best. Adrenaline is doing something less heroic.

During conventional CPR without adrenaline, myocardial blood flow is less than 3% of normal.² Whatever it feels like you are achieving with two hands on a sternum, that is what you are achieving.

The reason is that the coronary arteries fill during the recoil phase rather than the compression, and what drives that filling is the gap between aortic diastolic pressure and right atrial pressure — the coronary perfusion pressure. Compressions generate some. They do not generate much. In the human study that pinned the number down, no patient whose coronary perfusion pressure stayed below about 15 mmHg ever regained a circulation.¹ Not very few.. none.

Adrenaline exists in the ALS algorithm to up that number from its very low floor, and it does it through the alpha receptors — clamping the arterioles in muscle, gut and skin so that the pressure you are generating goes to the heart and brain instead of draining into a leg that is not, at that moment, the biggest priority. In the original work it took myocardial blood flow from under 3% of normal to about 15%.² Which is, you will notice, still 15%. The beta effects — the ones that make a beating heart beat faster and harder — are largely along for the ride, and there is a decent argument they are unhelpful, since a myocardium that's not beating does not need to be asked to do more beating.

Then there is PARAMEDIC-2, which is the part nobody enjoys. Eight thousand patients, five of our own ambulance services, adrenaline against salt water, with neither the paramedic nor the patient knowing which. Adrenaline won on the primary outcome: 3.2% alive at thirty days against 2.4%. But survival with a good neurological outcome was 2.2% against 1.9%, and that confidence interval comfortably crosses one — while among the people who did survive, severe neurological impairment was 31% in the adrenaline group against 17.8% on placebo.³

So it buys perfusion. Whether it buys the thing you actually want is a harder question, and the trial that asked it got an answer nobody was hoping for.

Ultimately, what matters is that nobody stops compressing to give it — every pause drops the coronary perfusion pressure back towards zero, and it takes a run of compressions to build it up again. Step back politely to let the drug go in and you have just lost the pressure the adrenaline was given to protect.

⏱️ ALS Scribe Mode, if you haven't found it

At the top of our Emergencies section in the app there is a stopwatch and event log for running an arrest. It keeps the two-minute cycles, and one tap records a rhythm check, a shock, a drug given or a note — so when somebody asks how long we have been going, somebody knows. Logs stay on your device and never reach us.

📅 Foundation Emergencies Webinar Series

Twenty-two live webinars, Wednesdays at 7pm from 9 September. One emergency each, half an hour, free.

Session 1 is A–E assessment and the arrest call: the structured look at a patient who is deteriorating, when to call for help, and what to do in the first minutes of an arrest. Then hypotension and the shocked patient, low urine output and AKI, the new oxygen requirement, and onwards through the emergencies calls you actually get bleeped about.

Register for Foundation Emergencies

💷 Your first payslip: five checks

1. 🎓 Student loan — there should be no deduction. Repayments start the April after you finish your course, so for 2026 graduates that is April 2027. A student loan line on this payslip is an error, and the usual cause is question 12 on the HMRC starter checklist. Payroll can refund it in-year as a minus line on a later payslip; after 5 April it becomes a claim to the Student Loans Company instead.

2. 🧾 £0 income tax in August is correct — as long as the code is cumulative. You have five months of unused personal allowance banked by August, so a first payslip on a plain 1257L usually carries no income tax at all. It starts once your running total overtakes that allowance: September for most people, October if you are on basic pay with no enhancements, and it settles at roughly £400–£500 a month. Budget for that before you set up any direct debits against an August payslip. If you are paying full income tax now, look at the suffix — W1, M1 or X means the code is being worked out month by month and ignoring everything you have banked. National Insurance is not cumulative and comes out from the start either way, about £191.

3. 📊 Basic pay — £3,435.50 a month. Nodal point 1 for 2026/27 is £41,226. If August is lower, the reformed scales are being implemented from September pay and backdated to 1 April, so arrears should follow.

4. 🌙 Enhancements — know which hours actually count. Working “out of hours” does not automatically mean enhanced pay. The 37% night enhancement applies to hours worked between 21:00 and 07:00 on any day. If you work a proper night shift — starting between 20:00 and 23:59 and lasting at least eight hours — the whole shift up to 10:00 attracts the 37% enhancement. A twilight shift that finishes between 00:00 and 04:00 also attracts the enhancement for the whole shift. So an ordinary evening such as 17:00–23:00 only gets enhanced pay for the hours after 21:00.

5. 🏦 Pension — 9.8% of basic pay only. About £336 a month. Additional hours, the night enhancement and the weekend allowance are all non-pensionable, so a figure near 9.8% of your gross is wrong.

Two more: check your shadowing days were paid (basic ÷ 261, about £158 a day), and that a minus figure in the deductions column is a refund rather than a charge. BMA members can run the pay checker against their actual rota.

📶 This week's update

Hospital buildings are where phone signal goes to die, and we put two updates out this week for exactly that:

• 📱 The app opens on one bar. It used to sit waiting on a network that never quite answered. It now gives the network a few seconds, then opens your saved copy if the network is slow.
• 🎟️ Your invite QR appears straight away — the same update means your magic QR button loads instantly even in low signal environments, so you can share bleep.guide with colleagues.

📚 We are also introducing a regular review of every clinical page, so the handbook is checked against current guidance on a schedule rather than whenever something prompts it. If a page reads slightly differently to how you remember it, that is why.

📈 Most read this month

• Suspected acute coronary syndrome — 571 opens
• Asked to write up fluids — 520
• Post-fall assessment — 511
• Fast atrial fibrillation — 403
• The delirious or agitated patient overnight — 386

— Oliver

Med reg in Cambridge; maker of bleep.guide :)