The stethoscope typically is placed over which artery when the bp is auscultated?

Blood pressure assessment is an integral part of clinical practice. Routinely, a patient’s blood pressure is obtained at every physical examination, including outpatient visits, at least daily when patients are hospitalized, and before most medical procedures. Blood pressure measurements are obtained for a wide variety of reasons, including screening for hypertension, assessing a person’s suitability for a sport (see the Medscape Reference topic Sports Physicals) or certain occupations, estimating cardiovascular risk (see the Medscape Reference topic Risk Factors for Coronary Artery Disease), and determining risk for various medical procedures.

Blood pressure measurements are also obtained routinely when following a hypertensive patient to assist with tailoring of medications and treatment of hypertension. Finally, blood pressure measurements are crucial for identifying if a patient is in potential or actual clinical deterioration.

Two methods for measuring a blood pressure exist, the direct and indirect method. The direct method is the criterion standard and consists of using an intra-arterial catheter to obtain a measurement. It is used more commonly in the intensive care or operative settings. This method, however, is not practical due to its invasiveness and its inability to be applied to large groups of asymptomatic individuals for hypertension screening. [1]

Therefore, the indirect (noninvasive) method is typically used. The indirect method involves collapsing the artery with an external cuff, providing an inexpensive and easily reproducible way to measure blood pressure. The indirect method can be performed using a manual cuff and sphygmomanometer, a manual cuff and doppler ultrasound, or with an automated oscillometric device. The manual method requires auscultation of the blood pressure, whereas the automated system depends on oscillometric devices.

With manual blood pressure measurements, both observer and methodological errors can occur. Observer errors include digit preferences, inattention, overly rapid cuff deflation, and hearing deficits, while methodological errors include not accounting for beat-to-beat variations in the pulses and sequential rather than simultaneous comparisons. [2] Automated oscillometric devices remove the observer errors that can occur with manual measurements but are not without faults. The inaccuracy of the oscillometric devices has been criticized, and some concern exists that using these devices in certain populations, such as hypotensive, hypertensive, trauma, or cardiac arrhythmia patients, can lead to inappropriate management. [3]

For example, in one study, mean systolic and diastolic blood pressures were significantly greater using a mercury manometer than automated oscillometric techniques. [4] These findings have important clinical implications, as the oscillometric techniques may falsely indicate that a patient treated for hypertension is now normotensive and requires no further medication adjustment. Regardless of these inaccuracies, automated oscillometric devices are used more frequently and appear to be sufficiently accurate for most clinical uses. [3] Furthermore, automated devices may give more accurate readings in the setting of patients with the syndrome of white-coat hypertension. [5]

Another key component of measuring a manual blood pressure is an understanding of the Korotkoff phases. The Korotkoff phases have been classified as 5 phases with phases I, IV, and V integral to obtaining an accurate blood pressure measurement. Descriptions of the 5 Korotkoff phases are outlined in the table below.

Table 1. Korotkoff Phases (Open Table in a new window)

The Korotkoff sounds are believed to originate from a combination of turbulent blood flow and oscillations of the arterial wall. Of note, some believe that using the Korotkoff sounds instead of direct intra-arterial pressure typically gives lower systolic pressures, with one study finding a 25 mmHg difference between the 2 methods in some individuals. [6, 7] Furthermore, some disagreement exists as to whether Korotkoff phase IV or V correlates more accurately with the diastolic blood pressure. Typically, phase V is accepted as the diastolic pressure due to both the ease of identifying phase V and the lower discrepancy between intra-arterial pressure measurements and pressures obtained using phase V. [8] Phase IV, alternatively, is used to measure the diastolic pressure if a 10 mmHg or greater difference exists between the initiation of phase IV and phase V. This may occur in cases of high cardiac output or peripheral vasodilatation, children under 13 years old, or pregnant women.

Regardless of whether a manual or automated method is used, the blood pressure measurement is a key part of clinical medicine. The following is a description of the indications, contraindications, and techniques for obtaining a blood pressure using both manual and automated devices.

Guidelines

Recommendations from the Canadian Hypertension Education Program include measurement of blood pressure using electronic (oscillometric) upper arm devices rather than auscultation for accurate office blood pressure measurement, and, in patients with increased mean blood pressure (but < 180/110 mm Hg) on visit 1, use of ambulatory or home blood pressure monitoring before visit 2 to rule out white coat hypertension. [9]

The U.S. Preventive Services Task Force recommends ambulatory blood pressure monitoring over office-based monitoring as a better predictor of long-term cardiovascular outcomes. [10]

When assessing a blood pressure which artery is the stethoscope placed over?

Which artery is Auscultated in blood pressure?

Which of the following pulses is Auscultated with a stethoscope?