Sometimes the Blood Pressure Sensor does not report Blood Pressure parameters in LabQuest App. This can happen when data-collection is stopped before sufficient data have been collected. If you press Stop before the run ends, there will not be enough data points to calculate systolic and diastolic values. Let the LabQuest continue collecting data until it stops on its own.
The pressure from the cuff can be released once the cuff pressure falls below 50 mmHg, but do not stop data collection. The LabQuest will not report blood pressure parameters until it has run a full 100 seconds and stops on its own.
If problems persist, the pressure release valve is likely set too low. Determine if the cuff pressure was above or below 50 mm Hg at the end of the trial. If the cuff pressure is above 50 mm Hg by the end of the trial, no blood pressure parameters will be calculated.
You can calculate the slope in mm/Hg from the release valve during a trial BP run using LabQuest App. The slope should be calculated during the last half of the trial. The release rate should be within neg 2-4 mm Hg/s (it is originally set at neg 3 mm Hg/s). Release rates less than -1 mm Hg/s typically fail. Turning the release valve ½ a turn clockwise will open the valve and this should fix the problem.
Be aware that the problem will persist if the release valve is set correctly and the cuff is pumped too high. The user should verify that the cuff is pumped to the appropriate pressure during the run.
This is a problem that is common if you are located at an altitude above 6,000 ft (1,800 m). The Blood Pressure Sensor will fail on the LabQuest App or in Logger Pro when used at factory settings if you are at or above this altitude.
To record proper measurements at altitudes above 6,000 ft (0.8 ATM or 609 mm/Hg) the pressure release valve will need to be readjusted. The pressure release valve is set to release at a rate of 3.0 mm Hg/s at sea level, where atmospheric pressure is 1 ATM or 760 mm/Hg. At higher altitudes, the pressure release valve will exhaust at a slower rate. To use the Blood Pressure Sensor at altitudes above 6,000 ft (1,800 m), open the pressure exhaust valve by turning it ½ a turn clockwise. The user should calculate the slope in mm/Hg from the release valve during a trial. The slope should be calculated during the last half of the trial. The release rate should be within 2-4 mm Hg/s (it is originally set at 3 mm Hg/s).
Release rates less than -1 mm Hg/s typically fail.
1) Movement artifacts will leads to improper measurements. The BPS is very sensitive to movement artifacts. The subject’s arm and hand must remain still during measurements. In addition, the subject should not touch or move the release valve. Movement artifacts will be decreased if the person holding the pressure bulb lifts their index finger during the recording.
2) The cuff is not properly placed. Proper placement of the pressure cuff will increase the accuracy of the blood pressure measurements. The rubber hoses from the cuff should exit over the brachial artery and be 2 cm above the crease in the elbow.
3) The cuff is not appropriate for the subject. Younger students may need a smaller cuff (18 cm to 27 cm arm circumference). This small blood pressure cuff can be ordered separately: order code CUFF-SM. The large cuff is also available for students with arm circumferences greater than 39 cm: order code CUFF-LG
These instructions above (1-3) are located in the BPS Sensor Booklet.