29 Jun, 14 | by scarley
A couple of years ago I was very (very, very) peripherally involved in an RCT investigating the management of ruptured abdominal aortic aneurysm. The IMPROVE trial was well designed and reported it’s results in 2014. The abstract is shown below, and I must admit that to my surprise there did not appear to be a definable advantage to endovascular repair.
Anyway, this post is not about the trials results per se, rather we received a comment from Prof. Janet Powell on behalf of the trial investigators that may have relevance for those of us in emergency and critical care medicine. One of the great advantages of large trials is the ability to look through data to see whether other themes and associations become apparent and this is what the trial team have done. Such data analysis has risks, but it can be an excellent way of generating hypotheses for future research, and observational data can also help us stop and think about current practice.
I digress. Read the letter from Janet below and then share your thoughts. As an emergency physician this observation raises a myriad of questions about data, analysis, resuscitation targets, association vs causality etc. and whenever I start thinking I know I’m getting better. So please, read, think, learn and please debate. Janet asks how we can work together to resolve and explore these results and surely that’s an offer that the EM and surgical communities should grasp.
Blood pressure targets for the elderly with bleeding and vascular emergencies
The IMPROVE trial is the largest randomised trial of a strategy of endovascular repair versus open repair for ruptured abdominal aortic aneurysm, with over 600 patients . Nearly all these patients started their care pathway in the emergency department and detailed evaluation of this large cohort of patients has raised some discussion points relevant for those in emergency care.
When we started this trial, we recommended that patients were managed with fluid restriction and hypotensive haemostasis, with systolic blood pressure targets of 70-80 mm Hg, to prevent further bleeding and optimise outcomes. These recommendations were based on emergency care guidelines for patients with abdominal trauma and the opinions of some leading vascular surgeons [2,3]. Hindsight is a wonderful thing. The patients we enrolled had an average age of 76.7 years: were these blood pressure targets far too low for this age group who were likely to have other cardiovascular disease and high cardiovascular resistance?
Cohort analysis has shown that there was a linear relationship between lowest systolic blood pressure and mortality (Table 1) and suggests that in these patients a blood pressure target of 100 mm Hg might save more lives. Lowest systolic blood pressure was directly related to outcome in a linear fashion, with each 10 mm Hg increase translating into a 13% relative improvement in the odds of survival to 30-days . 30-day mortality rates of <30% were only achieved in those in whom the lowest blood pressure was 100 mm Hg or more.
Management of other aortic conditions, particularly aortic dissection, may similarly be disadvantaged by unrealistic blood pressure targets. For aortic dissection the rapid blood pressure lowering to <100mm Hg, which is recommended , comes mainly from evidence in turkeys.
How can we work together to get the evidence for appropriate blood pressure targets for the elderly population with bleeding and other vascular emergencies? The current observational evidence is not sufficient and the question needs to be addressed in one or more randomised trials.
Janet Powell for the IMPROVE trial investigators
1 Endovascular or open repair strategy for ruptured abdominal aortic aneurysm: 30 day outcomes from IMPROVE randomised trial IMPROVE trial investigators BMJ 2014;348:f6771
2 Joint Royal colleges Ambulance Liaison Committee. Ambulance Service Clinical Practice Guidelines; 2006. www.jrcalc.org.uk/guidelines.html [accessed 1 September 2013].
3 Mayer D, Pfammatter T, Rancic Z, Hechelhammer L, Wilhelm M, Veith FJ et al. 10 years of emergency endovascular aneurysm repair for ruptured abdominal aortoiliac aneurysms: lessons learned. Ann Surg 2009; 249: 510–515
4 Observations from the IMPROVE trial concerning the clinical care of patients with ruptured abdominal aortic aneurysm. IMPROVE trial investigators Br J Surg 2014
5 The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. Accessed March, 2014 at www.nhlbi.nih.gov/guidelines/hypertension/jnc7full.pdf
So you have your invitation. Get in touch with the IMPROVE team to discuss, share and explore this observation.