Is a smart blood pressure watch suitable for people with high blood pressure

Smart Blood Pressure Watch Definition

A smart blood pressure watch is a watch that is comparable in size to an ordinary watch and can be worn on the wrist for several hours or even days to monitor human blood pressure at any time. A smart blood pressure watch is a true wearable medical device, completely different from a wrist-type electronic blood pressure monitor, which can be worn on the wrist for more than a few minutes before it becomes unbearable for the wearer, so a wrist-type blood pressure monitor cannot be called a smart blood pressure watch.

Types of smart blood pressure watches

Smart blood pressure watches can be divided into the following categories in terms of principle.

1. Photoelectric method (PPG)

The bracelet emits a kind of photoelectric signal to the skin, and the pulse wave at the wrist area is collected by the sensor, and then the blood pressure value is estimated by a specific calculation formula. When used, the bracelet is simply worn on the wrist to directly measure blood pressure.

2, photoelectric + ECG method (PPG + ECG)

Is based on the photoelectric signal, and adds a few pieces of metal, used to collect the ECG signal, integrated two signals, to estimate the blood pressure value. When using it, you need to use your finger to press the metal button on the surface to measure properly.

3、Oscillometric method

There is a micro airbag on the back of the bracelet, through the process of inflation, pressurization, and then deflation, automatic measurement of blood pressure, which is the same principle as the electronic sphygmomanometer, except that it is used on the wrist, rather than the arm.

Smart blood pressure watch advantages and disadvantages

1. Photoelectric method (PPG)

The pulse waveform at the wrist area is captured by a photoelectric sensor, and the analysis of characteristic parameters such as the rising slope of the pulse wave and the duration of the wave can lead to a specific calculation formula to estimate the blood pressure value. For example, the slope of the rising waveform of the ejection phase increases when the blood pressure is high.

Advantages.

1. Simple acquisition method, only need photoelectric sensor and algorithm, good user experience.

2. Can continuously monitor blood pressure.

Disadvantages: 

Accuracy to be verified, there is no monitoring device and algorithm recognized by the medical community that can meet medical standards.

2. Photoelectric + ECG method (PPG + ECG)

The time difference between the ppg and ECG waveforms is analyzed by combining the pulse wave ppg and ECG signals collected at the wrist area by photoelectric sensors.

This time difference is called PTT and represents the time difference between the blood flow to the test site (e.g. wrist) from the start of the heartbeat.

because the ECG signal propagation acquisition principle is the speed of light, the propagation time can be neglected as 0, while the blood flow to the wrist takes a certain amount of time.

This PTT is mainly influenced by the blood flow velocity, which is mainly influenced by the blood pressure.

The invention of this technology is based on the premise that blood is an ideal fluid, and the corresponding blood pressure reference values are derived by processing the optical signals of different individuals.

So the stability of the light source, the individual variability (fatness and thinness degree and vascular distribution differences), and the advanced signal processing technology all affect the accuracy and stability of the blood pressure measurement.

Advantages.

Accuracy is higher than simply analyzing the ppg waveform, but no mass-produced product has yet passed US FDA certification.

Disadvantages.

1. Manufacturing costs and user costs are higher than single photoelectric blood pressure measurement.

2. The acquisition method is relatively complex, which requires a photoelectric sensor and ECG module, and the user needs to monitor both ppg and ECG signals when measuring. Usually, the ECG watch is tested by a single lead duplex to test the difference of heart voltage of both hands, which requires one hand to press on the watch that is worn on the other hand.

3. Oscillometric method watch-type blood pressure monitor

Indirect measurement of blood pressure is divided into Auscultatorymethod and Oscillometricmethod. The Oscillometric method is used in electronic sphygmomanometers.

The process of measuring blood pressure by the oscillometric method is the same as that of the Koch sound method. The cuff is pressurized to block the flow in the brachial artery and then slowly decompressed, during which sounds and small pulses of pressure are emitted from the arm.

The Koch method relies on manual recognition of the sound coming from the arm and interpretation of systolic and diastolic pressures.

The oscillometric method, on the other hand, relies on an instrument that recognizes the small pulses coming from the arm to the cuff and differentiates them to derive a blood pressure value.

Advantages.

The accuracy is relatively high.

Disadvantages.

1. high cost.

2. The product is larger and uncomfortable as it affects the user's life when inflated and pressurized.

We see that the history of blood pressure measurement has gone through 3 stages.

The first stage is the so-called invasive stage, that is to say, the need to cut open the blood vessels of the measurement program, of course, this program is certainly not accepted by the general public, but the current use of implantable sensors to measure is still an invasive program. 

The second stage is to enter the non-invasive measurement, using mercury sphygmomanometer measurement, which is what we specify today by the standard.

The third stage of automation, the electronic sphygmomanometer we commonly use at home, is gradually becoming less ready from the direction of development, but gradually increasing in portability, thus reflecting the need to lower the threshold of blood pressure management itself. 

Artificial use of optical measurement of the program can further make blood pressure measurement of the user cost reduction, even the ordinary people can pay attention to their blood pressure at any time.This technology, the smart blood pressure watch, is not a substitute for a medical blood pressure monitor. It is also not used for medical purposes, but daily health management. Reducing the cost for everyone to know their body status is what it is all about.