Pharmacy to Dose: BP Control in Neurologic Emergencies

 

 

 I had the distinct honor of being invited on to the one and only Pharmacy to Dose podcast last week talking about a topic which is so important to our day to day life in the NeuroICU – acute blood pressure control. Take a listen to the episode whenever you get a chance – we split it up into two parts, the first on the pathophysiology of blood pressure control in neurologic emergencies, and the second on the specific agents we use in this setting, how to dose them, and how to choose between them. It was a blast talking with Nick and I figured I would provide a snapshot of some of the things we talked about on the podcast. Nick nicely outlines the papers I mention in the podcast here, and I’ll give some additional thoughts below.



So why do we care about this? Why is it that nearly every patient admitted to the NeuroICU, at least those with a vascular problem, get some strict SBP goal on admission rather than the universal MAP > 65 we usually see in the MICUs and SICUs? The core concept at play here is cerebral autoregulation, a concept familiar to most of us. Jack Rose and Stephan Mayer have a wonderful review article in Neurocritical Care which discusses why optimizing blood pressure in neurocritical illness is so important they go in-depth into the underlying physiology of blood pressure control that I would highly recommend if you’d like a more in-depth view of why this matters.1

We talk about lots of great stuff in the episode, and here are some highlights from the first episode:

  • The extreme hypertension following an ICH and other related neurologic events is often a response to, rather than the direct cause, of the event. Hypertension is the leading cause of ICH, but this refers to the chronic vascular changes (lipohyalinosis and Charcot-Bouchard aneurysm development) rather than the extreme hypertension seen in the ED.
  • Blood pressure just a surrogate for blood flow. Flow is proportional to pressure, but this is only true in laminar flow. In turbulent flow (like in a ratty, atherosclerotic vessel), the relationship is more complex, but blood pressure is still our best guess as to how well oxygen is getting to the brain (in the absence of invasive brain tissue oxygenation monitoring or blood flow monitoring).
  • In ischemic stroke, higher blood pressures are generally better. In some patients, particularly those with poor collaterals, artificially increasing blood pressure may be an effective way of increasing perfusion. Guy Rordorf’s classic case series is a great example of how the neuro exam can improve when blood pressure is driven up.2
  • In hemorrhagic stroke, lower blood pressure are generally better, to a floor of 130 mmHg. INTERACT33 was not picky in who they selected to get a goal of 140 mmHg which I think clarifies some of the concern about being picky in who gets that goal. While some data have demonstrated that dropping pressures too much too fast (lowering by >90 mmHg associated with AKI in one study4) and individual cases of extreme hypertension should be evaluated on a case by case basis, getting patients’ pressures down is the best intervention we have to improve outcomes.
  • The best blood pressure after a thrombectomy is still an open question. The one answer we now definitively have is not to drive patients pressures too low after excellent (>TICI2B) reperfusion.

The second episode comes out soon - make sure to subscribe to Pharmacy to Dose to stay up to date on the meds we use and how to use them.

Thanks for the invite, Nick!

 Andrew Webb, PharmD, BCCCP

Clinical Pharmacist, Neurocritical Care

Massachusetts General Hospital

Ajwebb@mgh.harvard.edu

@AJWPharm



References

1.            Rose JC, Mayer SA. Optimizing blood pressure in neurological emergencies. Neurocrit Care 2004;1(3):287–99.

2.            Rordorf G, Cramer SC, Efird JT, Schwamm LH, Buonanno F, Koroshetz WJ. Pharmacological Elevation of Blood Pressure in Acute Stroke. Stroke 1997;28(11):2133–8.

3.            Ma L, Hu X, Song L, et al. The third Intensive Care Bundle with Blood Pressure Reduction in Acute Cerebral Haemorrhage Trial (INTERACT3): an international, stepped wedge cluster randomised controlled trial. Lancet 2023; Epub.

4.            Burgess LG, Goyal N, Jones GM, et al. Evaluation of Acute Kidney Injury and Mortality After Intensive Blood Pressure Control in Patients With Intracerebral Hemorrhage. J Am Heart Assoc 7(8):e008439.

 

Location: Boston, MA, USA

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