How to Repair Broken Shielding on ECG Cables

The work done by engineers in a developing country includes a range of smart repairs that help hospitals save significant expenses.

Equipment cables are common examples of broken parts found in developing countries. Just a week ago I described how our group found seven vital signs monitors out of use at Roosevelt National Hospital in Guatemala. This last week, our group found the cables for the monitors, however the shielding on them was broken. The picture on the left shows the cable with broken shielding, while the picture on the right depicts the noisy — and clinically useless — ECG signal.

Buying one new ECG   cable for a patient monitor would cost $51 if purchased on eBay.  However, it is feasible to fix the ECG cables and avoid the cost of purchasing new parts.  In order to do this, we performed three simple steps:

1) Wrap foil carefully around the ECG cables.

2)  Ensure that the foil is electrically connected to the ends of the original ECG cable shielding.

3)  Wrap the foil tightly in electrical tape

The photo on the right shows the resulting ECG signal. The ‘p-q-r-s-t” sequence of a normal ECG signal can be seen on the screen.

The result is still not optimal, as there is residual noise interfering with the signal. Our group is currently investigating ways to make the shielding more effective so that the foil is optimally electrically connected along the entire length of the cables.

The EWH Guatemala Winter Institute 2014/15 Roosevelt Group considering the resulting signal and if it can be further improved.
The EWH Guatemala Winter Institute 2014/15 Roosevelt Group considering the resulting signal and if it can be further improved. Left: Caty Lin – George Mason University, Middle behind: Shanyce Stewart, Rochester Institute of Technology, Middle in front: Becca Avena – Marquette University and Co-op at GE Healthcare, Right: Mohammad Ali – George Mason University.

 

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