The Go Direct^® Blood Pressure Sensor (GDX-BP) has a light that indicates if the sensor has reported blood pressure parameters. When the sensor indicator light turns solid green, blood pressure parameters have been reported. If the sensor indicator light turns solid red, blood pressure parameters were not reported. In this case, you should repeat data collection. Review the following notes if your sensor returns parameters that you find unrealistic.

The Blood Pressure Sensor (BPS-BTA) works best when you allow the data-collection software to finish collecting data. Blood pressure parameters are reported at the end of data collection.

If problems persist with either sensor, try the following troubleshooting steps:

1. Verify that the release valve is set properly (–2 to –3 mm Hg/s). This problem can occur when the software does not have enough data to calculate both systolic and diastolic readings. It is most likely to happen when the test subject has either large or very small arms. This causes the data-collection run to either terminate too quickly or when too much pressure remains in the cuff after the collection period has ended. This can lead to inaccurate or misleading results for systole, diastole, heart rate, and mean arterial pressure. In some cases, parameters will be missing if you are using a Blood Pressure Sensor (BPS-BTA) with Logger Pro, LabQuest App, Graphical Analysis, or Graphical Analysis Pro. The Go Direct^® Blood Pressure Sensor (GDX-BP) sensor indicator light should report if parameters are missing.
2. Check the release rate. The liner release valve adjacent to the hand pump needs to have an exhaust rate so a pressure of 50 mm Hg is reached between 50 and 70 seconds into the run. For these conditions to be met, the release rate typically needs to be at –2 to –3 mm Hg/s (it is originally set at 3 mm Hg/s). If the cuff pressure has fallen below 50 mm Hg in the first 50 seconds, the flow rate is too high. If the cuff pressure is above 50 mm after 90 seconds into the run, the release rate is too low. It might be necessary for people with large or small arms to adjust the valve to keep it within this specified range. If the problem persists after the valve adjustment, proceed with the next steps for additional common user related issues.
3. Check for movement artifacts. Movement artifacts will lead to improper measurements. The blood pressure sensors are very sensitive to movement artifacts. The arm and hand of the subject must remain still during measurements. In addition, the subject should not touch or move the release valve.
4. Check the placement of the cuff. 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.
5. Check that you are using the right cuff for the subject. Younger students may need a smaller cuff (18 cm to 27 cm arm circumference). Students with larger arms may need a larger cuff. You can purchase small and large cuffs from Vernier. See Blood Pressure Cuffs (CUFF-SM) and (CUFF-LRG, discontinued)