Could invasive blood pressure monitoring improve patient outcomes?

Doctor Asher Lewinsohn

As clinicians in pre-hospital emergency medicine, we make quick decisions in high-pressure situations. These decisions affect outcomes for a patient, their survival, and their recovery.

Decisions are made using the evidence we have in front of us. Evidence like blood pressure readings. It’s not just a number, it’s a window into what’s going on under the surface. It can tell us whether a patient’s heart and circulation are functioning well enough to maintain sufficient blood flow to key organs, like the brain. It’s one of the key metrics we use to decide which interventions would be most effective to help save a life.

But what if the tools we use to measure blood pressure aren’t giving us the full picture?

Our latest research, published in the Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, highlighted a critical issue in pre-hospital care: the inaccuracy of non-invasive blood pressure (NIBP) monitoring in critically ill and injured patients.

What we found:

In our study, we compared over 2,300 measurements from 221 patients using two methods: the common cuff-based method (NIBP) and a more precise method that involves inserting a thin tube, known as an arterial line, directly into a patient’s artery. This approach, known as invasive blood pressure (IBP) monitoring, gives us a more accurate beat-by-beat reading of the blood directly through the patient’s artery.

In our research, we discovered that NIBP devices, commonly used in pre-hospital settings, often fail to provide accurate readings. This was particularly shown in the patients who need it the most, for example, those with haemodynamic instability where the body is unable to get enough blood flow to vital organs.

For patients experiencing shock – those with a systolic blood pressure below 90 mmHg – the accuracy of NIBP dropped dramatically, with readings frequently overestimating low blood pressure and underestimating high values. In simple terms, the sicker our patients become, the less accurate the tools we rely on to monitor them become.

Why this matters:

In pre-hospital care, every second counts. Blood pressure is one of the key indicators we use to make decisions. For example, when a patient is in shock, we may need to give them medications to raise their blood pressure, or blood. Or when someone has extremely high blood pressure, we might need to act to lower it quickly. When time is of the essence, we need to know we’re basing our decision-making on the most accurate readings possible.

While cuff-based blood pressure monitors are simple and convenient, our findings suggest that paramedics and doctors should be careful when using them in emergency situations, especially when a patient’s condition is critical. If the technology and resources allow, direct arterial blood pressure monitoring (IBP) should be initiated as early as possible.

This study reminds us that, whether we’re working in an ambulance or a helicopter, we need the best tools available to monitor patients accurately, even before they arrive at the hospital.

What happens now?

To my colleagues in pre-hospital emergency medicine, thank you for all you to help care for some of the sickest patients in their hour of need. We at Thames Valley Air Ambulance, along with our colleagues across the country, constantly strive to improve, learn, and grow. The desire to go above and beyond for patients can sometimes feel like a never-ending quest to know more, do more, and care more.

Responding to new research is one of the ways we can continue to drive the very highest standards of care for our community. This study is a crucial step towards improving pre-hospital emergency medicine and – most importantly – patient outcomes. Our goal is to continue refining how we monitor and treat critically ill and injured patients outside of the hospital, and this means integrating more robust, reliable systems that can be trusted in the most challenging conditions with some of the most critically unwell patients.

After all, it’s the little details that make up the full picture.