Welch Allyn 420 Series - SYMPTOM: Inaccurate Blood Pressure Readings

42 Welch Allyn
SYMPTOM: Inaccurate Blood Pressure Readings
Note: Differences of up to 10mmHg are considered normal and occur for a number of reasons including
intra-patient BP variability, observer hearing differences, and auscultatory deflation rate.
Possible Cause Explanation and Corrective Action
Incorrect cuff size.
Use Welch Allyn approved cuffs
only.
Determine correct cuff size.
• Use reference markings on cuff.
• Measure patient’s arm circumference midway between elbow
and
shoulder (see “Chart for Determining Cuff Size” on page 29
to select correct cuff size).
Patient’s arm position Ensure patient’s arm is at heart level.
Arm movement during blood
pressure cycle
Keep arm still during blood pressure cycle.
• Movement may cause inaccuracies from artifact.
Blood pressure taken over
clothing
Take blood pressure on a bare arm.
Arrhythmia Check for regularity of heart rate (palpate pulse or check device).
• Moderate to severe heart rate irregularities may make blood
pressure difficult to measure.
Incorrect reference Use the correct Korotkoff sound to determine diastolic blood pres-
sure.
• Many listeners incorrectly equate diastolic blood pressure with
the disappearance of sound only (phase 5). The Welch Allyn Spot
Vital Signs was developed using the American Heart Association
recommendations, which state that phase 5 be used unless
sound continues to 0 mmHg, in which case the change in the
quality of sound (phase 4) is to be used.
Deflate cuff no faster than 3 mmHg per second.
• One of the major sources of error in auscultatory blood pressure
measurement is deflating the cuff too quickly. The American
Heart Association recommends deflation no faster than 3 mmHg
per second.
Only use a sphygmomanometer that is calibrated.
• An uncalibrated sphygmomanometer may take inaccurate blood
pressure measurements.
Change in blood pressure
between auscultatory reading
and Welch Allyn Spot Vital Signs
reading
Check blood pressure immediately prior to Welch Allyn Spot Vital
Signs reading.
Poor auscultatory sound recog-
nition by observer
Use higher quality stethoscope. Have a different observer check
patient’s blood pressure.