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Directions for Use 39
Causes and Corrective Action
Table 5. Inaccurate Blood Pressure Readings
Possible Cause Explanation and Corrective Action
Incorrect blood pressure cuff
size.
Use Welch Allyn approved
blood pressure cuffs only.
Determine correct blood pressure cuff size.
• Use reference markings on blood pressure cuff.
• Measure patient’s arm circumference midway between elbow and shoulder (see
“Chart for Determining Blood Pressure Cuff Size” on page 23 to select correct
blood pressure 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 pressure.
• 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 blood pressure cuff no faster than 3 mmHg per second.
• One of the major sources of error in auscultatory blood pressure measurement is
deflating the blood pressure 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
recognition by observer
Use higher quality stethoscope. Have a different observer check patient’s blood
pressure.
Note: Differences of up to 10 mmHg are considered normal and occur for a number of reasons including intra-patient
blood pressure variability, observer hearing differences, and auscultatory deflation rate.
Table 6. Cuff Inflation and Deflation with No Blood Pressure Reading Displayed (or Error Code in
Display)
Possible Cause Explanation and Corrective Action
Leak in pneumatic system Ensure all blood pressure cuff attachments are tight. Carefully
check for leaks in the blood pressure cuff, tubing, and pressure
hose attached to the device.
Arm movement during cycle Keep arm still during blood pressure cycle. Movement may cause
inaccuracies from artifact.
Blood pressure cuff tubing or pressure hose
movement artifact
Do not contact blood pressure cuff tubing or pressure hose
during blood pressure cycle. Movement may cause inaccuracies
from artifact.