Unit 31

Sphygmomanometer Gauges

Basic Principles of Reading Sphygmomanometer Gauges

• A sphygmomanometer is an instrument calibrated for measuring blood pressure (BP) in millimeters (mm) of mercury (Hg).

• There are two main types of sphygmomanometer gauges, mercury and aneroid.

Basic Principles of Reading Sphygmomanometer Gauges

• The mercury sphygmomanometer as shown on the next slide has a long column of mercury. – Each line on the gauge represents two millimeters of

mercury (mm Hg). If it is calibrated correctly, the level of mercury should be at zero when viewed at eye level.

– Because blood pressure is recorded as the pressure drops in the gauge, it is best to learn to read the gauge in a backward direction.

Basic Principles of Reading Sphygmomanometer Gauges

• Mercury sphygmomanometer gauge.

Basic Principles of Reading Sphygmomanometer Gauges

• The aneroid sphygmomanometer gauge as shown on the next slide does not have a column of mercury. It is calibrated equivalent to mm Hg, and each line represents 2 mm Hg. – Note that long lines represent a multiple of 10.

• Because readings are recorded as the pressure drops, it is best to learn to read the gauge in a backward direction.

Basic Principles of Reading Sphygmomanometer Gauges

• Aneroid sphygmomanometer gauge.

Basic Principles of Recording Blood Pressure

• Blood pressure (BP) is a measurement of the pressure that the blood exerts on the walls of the arteries during the various stages of heart activity.

• There are two types of BP measurements: systolic and diastolic.

Basic Principles of Recording Blood Pressure

• Systolic pressure occurs in the walls of the arteries when the left ventricle of the heart is contracting and pushing blood into the arteries. – A normal range for systolic pressure is 100 to 120 mm

Hg.

• Diastolic pressure is the constant pressure in the walls of the arteries when the left ventricle of the heart is at rest, or between contractions. – A normal range for diastolic pressure is 60 to 80 mm Hg.

Sphygmomanometer Gauges

• Example: On the aneroid sphygmomanometer gauge shown on the next slide (calibrated equivalent to mm Hg; each line represents 2 mm Hg), a reading 4 lines below 160 would be what?

Sphygmomanometer Gauges

– A reading 4 lines below the 160 mark equals:

160 – 2 – 2 – 2 – 2

= 152 mm Hg

- The correct reading would be 152 mm Hg.

Practical Problem

• When using an aneroid sphygmomanometer as shown on the next slide, what is the correct reading 2 lines below the 120 mark?

Practical Problem

Practical Problem