Common complaints on CRADLE VSA (and how to combat)
The accuracy of the device has been extensively proven in pregnancy. Therefore, most problems with the device are due to the way it is used rather than the device itself. The most common reasons complaints and their explanations are shown below:
It is normal physiology for a woman’s BP to vary up to 15mmHg every minute. Therefore, if you do consecutive readings with the VSA or indeed any BP machine you will see slight variation in results with each reading. This also means that the accuracy of the device cannot be assessed by testing it on only one woman in clinic/comparing to other devices.
The CRADLE VSA measures BP by detecting blood flow through the artery. It is therefore sensitive to talking and movement in the arm as it may incorrectly detect this movement and show an inaccurate reading. This is why we recommend that women sit still and quiet during blood pressure measurement and that all abnormal readings are checked again to confirm accuracy.
Blood pressure can also be elevated if women are anxious on their first blood pressure reading or have not had adequate time to rest. This is not a FALSE reading but a higher, inaccurate reading because the woman has caused a natural temporary rise in her blood pressure. This is why we recommend that the woman rests for 5 minutes prior to blood pressure measurement.
The CRADLE VSA cannot give false readings, even if the battery is low. If it has been able to detect the blood pressure then this will displayed, otherwise an error message may be displayed. Please see the CRADLE User Manual for reference of these.
Most digital blood pressure devices have never been formally validated as accurate pregnant women especially those with elevated blood pressure. Some can underestimate BP by as much as 30mmHg. As such, new readings from the CRADLE VSA may seem higher or lower than usual to users who are unfamiliar with the device, but they need to consider that this is because this may be the first time that they have been able to measure BP accurately. In addition, the CRADLE VSA is able to pick up VERY low readings and VERY high readings that other devices may not be able to measure.
If comparing to mercury sphygnomometer it is helpful to consider the problems associated with measuring BP using auscultation. Auscultation requires skill and training. It is easy to get inaccurate readings from deflating the cuff too fast or not hearing the sounds clearly. If this is the preferred method of blood pressure measurement then it can also be used on the CRADLE VSA. You can auscultate and watch the digital numbers decrease on the screen as the cuff deflates instead of the column of mercury. Therefore, you can test that what you hear is the same as the VSA shows you. This can be a helpful technique to prove the accuracy of the device to yourself and others, rather than comparing to other, non-validated, devices.
When first switching on the CRADLE VSA, it will show a small battery sign like this one on the bottom right of the screen. This is part of the start up screen and does not reflect the battery status.
When this sign persists on the screen it indicates that the battery is starting to become low but around 100 readings can be taken prior to the battery completely draining. These measurements will be as accurate as when the battery is full. You should therefore not charge the device every time you see this otherwise you will damage the battery life. Instead only charge when the battery is nearly/completely drained and the VSA does not turn on. This will preserve the battery life. You will be provided with sufficient VSA to ensure you have spare devices fully charged at all times to avoid interruptions to care.