Palpatory method and Korotkoff sounds

Palpatory method

The systolic pressure may be checked by feeling the radial pulse rather than hearing it with the stethoscope. Place the cuff in the usual position and palpate the radial pulse, noting rate and rhythm. Inflate the cuff until the pulse disappears, then add 30 mm Hg more of inflation to get above the systolic pressure. Do not remove your fingers from the pulse or change the pressure of your fingers. Carefully watch the gauge while slowly releasing the pressure in the cuff, and wait until you feel the first pulse beat. Note the reading on the gauge and document the first pulse felt as the systolic pressure. For example, if you first felt the radial pulse return at 102 mm Hg, the palpated blood pressure is recorded as 102/P, with P indicating that the systolic reading was palpated. The diastolic and Korotkoff phases cannot be determined by this method. This method can be very useful in times of a medical emergency, such as shock, when the patient’s blood pressure cannot be auscultated. The palpatory method can be used to determine how far you need to pump the cuff to hear that first beat. This is useful for a new patient.

Korotkoff sounds

Korotkoff sounds are the sounds heard during auscultation of blood pressure. Vibrations of the arterial wall produce these sounds when the blood surges back into the vessel after being compressed by the blood pressure cuff. The sounds were first discovered and classified into five distinct phases by Russian neurologist Nikolai Korotkoff:

Phase I

Phase I is the first sound heard as the cuff deflates. The blood is resurging into the patient’s artery and can be heard clearly as a sharp, tapping sound. Note the gauge reading when this first sound is heard. Record this as the systolic blood pressure.

Phase II

As the cuff deflates, even more blood flows through the artery. The movement of the blood makes a swishing sound. If you did not follow proper procedure in inflating the cuff, you might not hear these sounds because of their soft quality. Occasionally blood pressure sounds completely disappear during this phase. Loss of the sounds, followed by their reappearance later, is called the auscultatory gap. The silence may continue as the needle falls another 30 mm Hg. Auscultatory gaps occur particularly in hypertension and certain types of heart disease, so if you notice such a gap, make sure to report it to the provider.

Phase III

In phase III, a great deal of blood is moving down into the artery. The distinct, sharp tapping sounds return and continue rhythmically. If you do not inflate the cuff enough, you will miss the first two phases completely, and you will incorrectly interpret the beginning of phase III as the systolic blood pressure (phase I).

Phase IV

At this point, the blood is flowing easily. The sound changes to a soft tapping, which becomes muffled and begins to grow fainter. Occasionally these sounds continue to zero. This may occur in children, in patients of any age after exercise or with a fever, or in a pregnant patient with anemia. The AHA recommends that the beginning of phase IV be recorded as the diastolic reading for a child. Some providers call the change at phase IV the fading sound and want it recorded between systolic and diastolic recordings (e.g., 120/84/70, with 84 representing the gauge reading when the sounds of phase III have ended and those of phase IV are beginning). Other providers consider phase IV the true diastolic pressure.

Phase V

All sounds disappear in this phase. Note the gauge reading when the last sound is heard. Record this as the diastolic pressure.