Monitoring Blood Pressure: Hospitals' Continuous Watch

Hospitals use a variety of methods to constantly monitor blood pressure. One common method is 24-hour ambulatory blood pressure monitoring, where a soft inflatable cuff is wrapped around the patient's upper arm and connected to a small monitoring device worn on the waist or belt. The cuff automatically inflates and deflates at regular intervals, taking measurements every 30 minutes during the day and every hour at night. This method allows patients to continue their normal daily activities while providing a more accurate assessment of their blood pressure throughout the day. Additionally, hospitals may employ continuous noninvasive arterial pressure (CNAP) devices, which can provide real-time data and continuous monitoring during emergency transfers and in prehospital settings. These devices are safe and feasible for monitoring blood pressure in patients en route to the hospital. Other modern sensor technologies, such as cuffless wrist-worn devices, are also being used for remote patient monitoring and in hospitals to automatically capture critical cardio-pulmonary health data.

Inflatable cuff monitors

When used in combination with a stethoscope, inflatable cuff monitors can also help to measure diastolic pressure, which is the pressure exerted between beats. Both numbers are used to determine a patient’s reading.

There are two main types of inflatable cuff monitors: manual and digital. Manual devices, including aneroid sphygmomanometers, require a trained provider to use a stethoscope to listen for blood flow sounds while inflating and deflating the cuff. This type of monitor is commonly used in hospitals, urgent care facilities, and primary care offices.

Digital blood pressure monitors, on the other hand, are commonly used at home and in medical settings. They automatically inflate the cuff and provide a digital reading of systolic and diastolic pressure. Some advanced models also include features like irregular heartbeat detection and wireless connectivity for tracking blood pressure trends over time.

Continuous non-invasive arterial pressure (CNAP) devices

CNAP devices provide continuous, non-invasive blood pressure monitoring. They are safe to use in pre-hospital settings and during patient transfers, as demonstrated in several studies. CNAP technology can be used as an alternative to invasive intra-arterial catheter systems (IBP) and offers several advantages. It is non-invasive, provides continuous real-time blood pressure measurements, and is safe and easy to use. CNAP devices can also measure advanced hemodynamics and provide quick feedback to support therapeutic decision-making.

The CNAP finger sensor provides a full set of non-invasively measured, continuous patient signals and hemodynamic parameters. These include blood pressure waveform, cardiac output, stroke volume, systemic vascular resistance, pulse pressure variation, and stroke volume variation. The device is easy to set up, with measurements ready in 1.5 minutes. CNAP technology has been validated in numerous studies and is widely used, with over 5,500 customers worldwide.

CNAP devices have been shown to be highly accurate in measuring blood pressure. They can detect rapid blood pressure changes that may be missed by intermittent upper-arm measurements. This continuous monitoring can improve patient safety, especially during complex procedures. CNAP technology has been compared to the "gold standard" of invasive blood pressure monitoring, with studies showing a high level of accuracy.

Intermittent oscillometric measurements

The oscillometric method is advantageous as it requires less skill than the auscultatory technique and can be operated by untrained staff or even automated for patient home monitoring. It is also suitable for long-term measurements and general practice. Additionally, it does not carry the risks associated with invasive arterial pressure monitoring, such as bleeding, haematoma, infection, and nerve damage.

However, it is important to note that oscillometric monitors may produce inaccurate readings for patients with heart and circulation problems, including arteriosclerosis, arrhythmia, preeclampsia, and certain other conditions. The accuracy and precision of oscillometric measurements, particularly in critically ill patients, are constantly debated.

24-hour ambulatory blood pressure monitoring

The monitor can be programmed to take readings every 10 to 30 minutes during the day and at longer intervals of up to an hour at night. The frequency of readings ensures that fluctuations in blood pressure throughout the day and night are captured. This is important because blood pressure can be influenced by various factors such as anxiety, diet, exercise, sleep, and medication.

The data collected by the device is then downloaded and analysed by a doctor, who can provide a summary report of the patient's blood pressure control. This includes information such as the 24-hour average blood pressure, average daytime and nighttime blood pressure, and the percentage drop in blood pressure at night. Ambulatory blood pressure monitoring provides a more comprehensive understanding of a patient's blood pressure than single, in-clinic measurements, which may be influenced by stress or anxiety.

Ambulatory blood pressure monitoring is particularly useful for diagnosing and managing hypertension, as it can identify patterns such as "white coat hypertension" and "masked hypertension". "White coat hypertension" refers to patients with normal blood pressure at home but high readings during office visits, while "masked hypertension" is when patients exhibit normal blood pressure in the clinic but have high readings outside of it.

Wireless, non-invasive, medical-grade wrist-worn devices

While hospitals typically use upper-arm cuff monitors to constantly monitor blood pressure, there are now wireless, non-invasive, medical-grade wrist-worn devices available for this purpose. These devices are usually in the form of smartwatches and are capable of tracking blood pressure continuously throughout the day.

The YHE BP Doctor Fit, for example, is a smartwatch that features a patented inflatable air cuff to detect blood pressure fluctuations. It promises medical-grade accuracy and has been validated by experts. The watch also has a vibrant AMOLED display, long battery life, and a functional smartphone application.

Another example of a wireless wrist-worn device for blood pressure monitoring is the Omron Evolv, which is compatible with the Apple Watch. While the Apple Watch alone cannot measure blood pressure, it can be linked to a compatible monitor like the Omron Evolv to synchronize blood pressure data.

It is important to note that wrist-worn monitors may not be suitable for everyone, and healthcare providers generally recommend upper-arm monitors as the gold standard for accuracy. Wrist monitors can provide accurate readings when used according to instructions and when obtained from a reliable source, such as the American Medical Association's list of validated monitors.

Before using a wrist-worn device for blood pressure monitoring, it is advisable to consult a healthcare provider to determine the most suitable option for your individual needs.

Frequently asked questions