Blood pressure is one of the vital signs because it is such a fundamental and important indicator of health. Other vital signs include temperature, oxygen saturation, heart rate, breathing rate and, at some health institutions, pain. Blood pressure is measured by several different techniques. These include listening for the pulse, feeling the arteries, calculating the blood pressure based on pressure waves, and placing a probe in an artery.
Auscultation
According to "DeGowin's Diagnostic Examination" auscultation means listening. This is one of the most common ways to measure blood pressure. This technique utilizes an inflatable cuff that can be wrapped around the arm or leg with an attached pressure gauge. The cuff is usually wrapped around the upper arm with the stethoscope on the inner aspect of the arm above the elbow, to listen for the pulse. The cuff is inflated until no sounds are heard. It is then deflated slowly. When the first pulsing sounds are heard, this is considered to be the systolic pressure, which indicates contraction of the heart. The pressure in the cuff is lowered until these sounds disappear, which indicates the diastolic pressure, indicating the heart is relaxing.
Palpation
Palpation means to ascertain the blood pressure by touch. According to "Clinical Anesthesiology" it is less accurate than other methods, but also faster, and can be utilized during emergency situations to estimate the systolic pressure. The method involves feeling the pulse. If the pulse can be felt in the neck at the carotid artery, the systolic blood pressure may be 60 mmHg or higher. If it can be felt at the femoral artery in the upper leg, it may be 70 mmHg or higher, and if felt at the radial artery at the wrist it may be 80 mmHg or higher.
Oscillometrics
The oscillometric technique also relies on a blood pressure cuff. However, instead of an operator listening for sounds, a computer measures the pulse and calculates the systolic and diastolic pressures. This makes the technique easier for home monitoring.
Arterial Blood Lines
Arterial blood lines measure the blood pressure directly. A small catheter is inserted into an artery, such as the radial artery at the wrist, although many other arteries can be used. The catheter is connected to a fluid filled tubing that is connected to an electronic device that measures the pressure. A computer can display the blood pressure continuously from every beat of the heart.
References
- "DeGowin's Diagnostic Examination"; Richard LeBlond, Donald Brown, and Richard L. DeGowin; 9th Ed 2008
- "Clinical Anesthesiology"; G. Morgan, Maged S. Mikhail, and Michael J. Murray; 4th Ed 2005
