14.5 : 用于测量血压的设备

There are two methods for determining blood pressure.

The direct method is invasive and requires peripheral artery cannulation. 

The indirect method is non-invasive and requires a specific device such as a mercury sphygmomanometer, an aneroid sphygmomanometer, an electronic BP monitor, or a Doppler ultrasound device.

The mercury sphygmomanometer has a manually inflatable cuff attached to the mercury-infused column. Many nations have banned this device because mercury is a toxic substance.

A manual aneroid sphygmomanometer has a bulb, valve, manometer, cloth, or disposable vinyl compression cuff and has an inflatable bladder.

Two tubes are attached to the bladder within the cuff. One connects to a manometer, and the other is to a bladder inflation bulb.

The manometer has a glass-enclosed circular gauge containing a needle. It indicates the air pressure applied to the cuff in millimeters of mercury or mmHg.

Electronic or automated BP monitors sense blood flow pressure within the artery, record the pressure readings, and display them in digital numbers.

The Doppler ultrasound device contains an ultrasound probe and is used in conjunction with a BP cuff. It amplifies faint pulse sounds to measure blood pressure.