I Thought I Knew How to Take BP—Until the Data Proved Me Wrong

December 8, 2025

The Hidden Risk in Routine Readings

Accurate blood pressure (BP) measurement is not just a routine task; it’s a clinical decision point with direct implications for diagnosis and management. Nearly half of US adults have hypertension, yet only one in four achieves adequate control, according to the Centers for Disease Control and Prevention (CDC). With statistics like these, every BP measurement represents a critical opportunity to detect, classify and manage a patient’s cardiovascular risk status.

The 2025 American Heart Association (AHA) guidelines leave no room for debate: accuracy is non-negotiable. Every BP reading feeds into real clinical decisions—from team-based workflows and home monitoring to risk-based treatments. These aren’t academic exercises; they’re the realities of daily care. That’s why “close enough” can never be good enough for BP.

This blog will review the foundational practices that improve BP validity, starting with one of the most overlooked factors: patient positioning. Back support, arm alignment and foot placement may seem minor, but research shows they can shift readings by 5–10 mmHg—enough to change a clinical decision. However, positioning is only the starting point. Other controllable factors—such as cuff size, bladder fullness, recent caffeine or nicotine use and environmental stressors—can compound inaccuracies, leading to potential misclassification and inappropriate management.

The Real-World Problem: Positioning Errors Are Everywhere

Recent evidence shows just how widespread these errors are:

• Primary care offices: In an observational study of 25 primary care offices, improper patient positioning during BP measurement was common and led to meaningful errors. Readings taken on the exam table averaged more than 2 mmHg higher than those in the correct seated position, causing 13% of patients to be misclassified as prehypertensive or hypertensive when they were actually normotensive.

• Home BP Self-Measurement Errors: A study of hypertensive patients self-using their own BP monitors found that only 3% measured without error, while 60% made three or more errors.

• World Health Organization (WHO): The WHO identifies that inaccurate BP measurement is a global barrier to hypertension diagnosis and control, especially in low- and middle-income countries.

• Lancet Commission on Hypertension: Inaccurate BP measurements are identified as the leading cause of misdiagnosis and treatment of hypertension worldwide.

From clinics to homes and across healthcare systems worldwide, patient positioning remains a critical variable influencing the reliability of BP measurement.

Clinical Impact of Poor Positioning

Multiple peer-reviewed studies have quantified how common posture errors can alter blood pressure readings, even in controlled clinical settings. The following table summarizes findings from published research studies on the individual impact of common arm, back and leg positioning errors:

A ±5–10 mmHg shift in BP measurement can push a patient across a diagnostic threshold, reclassifying an “elevated” reading as overt hypertension or, conversely, masking true hypertension. In high-volume practices, the results of positioning errors can cascade into broader system problems—unnecessary prescriptions, missed interventions and distorted population health data.

The CORRECT BP Study: Real-World Missteps Matter

While there are many studies on the effects of individual errors related to patient positioning, the CORRECT BP study—previously discussed in our August blog, "It's Time to Get the CORRECT BP at Every Visit: Why Positioning Matters and What the Research Is Telling Us"—quantified the combined impact of unsupported back, unsupported arm, legs crossed/feet dangling positioning errors, demonstrating how routine missteps produce measurable shifts in systolic and diastolic BP readings.

In the CORRECT BP study, the data showed that when these three positioning factors were not properly controlled, systolic readings averaged 7 mmHg higher and diastolic readings 4.5 mmHg higher compared to AHA recommended technique. These findings were statistically significant (p < 0.001) and clearly demonstrate that even small deviations in posture can lead to clinically meaningful shifts in blood pressure, underscoring the importance of proper patient positioning at the point of care.

To ensure consistency, clinicians should confirm these three key positioning factors with every BP measurement:

• The patient’s back is fully supported.

• The arm is supported with the cuff positioned at heart level.

• The feet are flat on the floor, with no leg crossing or feet dangling.

What’s New: Designing for Consistency in Positioning

Achieving proper patient positioning can be challenging in busy clinical environments, where time constraints and workflow demands increase the risk of error. Equipment designed to standardize support and posture can help reduce variability and align practices with the 2025 AHA guidelines. The Midmark 626 Barrier-Free^® Examination Chair with Patient Support Rails+ provide stable support for the back, arms and feet. Its low seat height of 15.5 inches exceeds new accessibility standards, supporting both accuracy and inclusive care. The result is more than just convenience. Consistent positioning removes ambiguity and helps safeguard against time-pressure shortcuts that compromise BP measurement accuracy.

Positioning Is Just the Starting Line

Attention to the described positioning details can help eliminate variability and prevent downstream diagnostic errors. Other considerations for improved BP measurements include the following:

• Empty bladder

• No caffeine, exertion, smoking at least 30 minutes to 1 hour prior

• Use of correct cuff size, correct placement

• A period of rest, 3-5 minutes, prior to measurement

• No talking or active listening during measurement

Even when positioning is flawless, these other conditions can alter BP readings. According to the AHA and multiple peer-reviewed studies, the following factors also can affect BP measurement:

Each of these factors has been shown to raise systolic BP in independent studies. While their effects have not been evaluated cumulatively, even one variable can be enough to alter a diagnosis or treatment.

Raising the Bar for Every Reading

BP measurement is often viewed as routine, but its clinical importance cannot be overstated. Even a shift of 5-10 mmHg can significantly alter the clinical picture.

Think about it:

As mentioned, nearly half of US adults have hypertension—and many others have BP in the “elevated” range (systolic 120–129 mmHg, diastolic <80 mmHg), just below the diagnostic threshold. For patients with BP just below or just above the diagnostic threshold, even a small measurement error can change the course of care and lead to an added diagnosis, unnecessary laboratory testing or prescription medication or conversely, mask emerging risk and delay appropriate intervention.

The 2025 AHA guidelines emphasize that every BP reading represents a clinical decision point. Achieving precision depends on controlling the environment, positioning the patient correctly and standardizing the BP measurement process. In hypertension, a few millimeters should not be “close enough”—but they can be the difference between timely prevention and a missed opportunity.

Additional Resources:

• White Paper: Validating the Clinical Impact of Proper Positioning on BP Measurement

• eBook: Ensuring Accurate BP Measurement for Improved Patient Outcomes

• Webinar: Enhancing BP Measurement Accuracy to Improve Hypertension Control + Chronic Disease Outcomes

• Webinar: Enhancing the Patient Clinical Experience

• CORRECT BP Study

About the Author

With a background in critical care and trauma nursing, combined with an MBA focused on the medical device industry, I bring a unique combination of clinical expertise and business insight to my work. My experience in the ICU and as a flight nurse has given me a deep firsthand understanding of urgency, precision and reliability in patient care and the critical role medical equipment plays in that environment.

In my current role at Midmark, I support the Veterinary division, but my clinical background has also led me to collaborate with the Medical division on authoring a clinical blog aimed at improving healthcare practices. I'm passionate about the intersection of clinical accuracy and technology. I believe that how equipment is used is just as important as the tools themselves in achieving optimal clinical outcomes. This drives my work—ensuring healthcare professionals have both the tools and knowledge to improve patient care and deliver the highest standards of treatment.