14.10 : Assessment of blood pressure in brachial artery(two-step method)

Measuring blood pressure is a fundamental skill in healthcare that aids in diagnosing and monitoring hypertension and other cardiovascular conditions. An aneroid sphygmomanometer, commonly used in clinical settings, offers a manual and precise method for blood pressure measurement. The technique for using this instrument involves specific steps that must be carefully executed to ensure accuracy. The following detailed description outlines a two-step technique for assessing blood pressure using an aneroid sphygmomanometer, including the rationale for each step.

Initial Preparation:

• Begin with hand hygiene to minimize the risk of microbial transmission and cross-infection, a standard precaution for infection control.
• Next, inform the patient about the procedure, which is essential for alleviating anxiety and ensuring their cooperation, both of which can influence blood pressure readings.

Cuff Placement:

• Properly position the cuff about one inch above where the brachial artery was palpated. Correct placement is vital as it ensures the accuracy of the readings.
• Ensure that the cuff is not too loose or tight. A tight cuff could falsely produce high blood pressure readings by excessively compressing the artery, and a loose cuff shows a falsely low blood pressure reading.

Finding the Baseline:

• Palpate the brachial artery again to confirm the best location for the cuff. Begin inflating the cuff while noting when the pulse under the cuff is no longer detectable. This point helps determine how much further to inflate the cuff to ensure complete arterial occlusion.

Determining the Maximum Inflation Level:

• Continue inflating the cuff to about 30 mmHg above the point where the pulse disappeared. Ensuring the artery is fully occluded allows for accurate systolic pressure measurement upon cuff deflation.

Estimating Systolic Pressure:

• Start deflating the cuff and observe the gauge for the pressure reading at which the pulse reappears.
• It provides an initial estimate of the systolic pressure, guiding the inflation level in subsequent steps for a more precise measurement.

Rest Period:

• Fully deflate the cuff and allow the arm to rest for about one minute. This pause is necessary to let the blood flow return to normal in the arm, preventing any residual effects of the previous inflation from influencing the next set of readings.

Precise Measurement:

• Position the stethoscope's diaphragm over the brachial artery and re-inflate the cuff to 30 mmHg above the previously estimated systolic pressure. This pre-inflation ensures that the artery is adequately occluded before listening for Korotkoff sounds, crucial for determining systolic and diastolic pressures.

Identifying Systolic and Diastolic Pressures:

• Slowly release the cuff's valve and listen for the first Korotkoff sound, which signifies the systolic pressure.
• Gradually deflate the cuff until the Korotkoff sounds completely disappear, indicating the diastolic pressure. These sounds are critical indicators of the changing blood flow dynamics as the pressure is released.

Post-procedure:

• After the measurement, remove the cuff and ensure patient comfort.
• Perform hand hygiene again to ensure safety.
• Promptly record the measured blood pressure values accurately, as these values are essential for patient monitoring and management.