November 2023

Authors: Rob Hirst, Andy Neill, Dave McCreary, Becky Maxwell, Chris Connolly, Nikki Abela / Codes: / Published: 06/11/2023

Clinical Question

How should we measure BP and physiology following an intracranial bleed?


Ma et al, Lancet, 2023


  • when you have a bleed in the brain it’s often due to chronically raised BP. it makes sense if there’s some bleeding that lowering the pressure might reduced further bleeding and improve outcomes. We have however struggled to prove that. Indeed given what we know about cerebral perfusion pressure and auto regulation in the brain there could be an argument that lowering the pressure may even be a bad idea. Enter the INTERACT investigators who have made a Peter Jackson style trilogy out of this story and this is INTERACT-3 return of the low systolic…


  • this is a typical NEJM type mega study, lots of centres, however all based in LMIC across the world. the only implication is that uncontrolled hypertension is likely more common in these countries due to lack of primary care and maybe that might affect applicability.
  • they enrolled sites that had what looks like pretty poor pre existing protocols and approaches to ICH.
  • excluded aneurysms or tumours etc and strokes
  • sites were randomised to usual care followed by a bundle that included targeting a BP<140. It also included controlling the sugar and treating temperature. They also reversed coagulation issues.
  • these targets were maintained for 7 days
  • outcome was the now familiar mRS at 6 months
  • powered for a 5.6% absolute improvement in this outcome


  • 122 hospitals – 7000 pts included (which is shy of their 8000 target) – as expected 95% of the bleeds were related to high BP.
  • there was slightly more IV BP medicine given in the intervention arm but it wasn’t hugely different (80 vs 70%). This was similar with all the targets of the bundle which were all better but only slightly. –
  • they showed a better mRS with the outcome and met their statistical significance it seems. I say it seems because i honestly don’t have the stats chops to be able to critique it effectively.


  • I suspect this will be used as a stick to say that a BP of 140 is the target which i think remains unproven.
  • I think they’ve proved that this bundle of care introduced to health care systems that didn’t already do what seem like fairly basic things made a difference. The usual secondary benefits apply with these bundles in that all of a sudden everyone simply pays more attention and makes a little more effort.
  • So this is great and should be embraced but as with all bundles it doesn’t tell us which bit of the bundle is making most of the difference.

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