Figure 1: Baseline and parameters:
Stimulation parameters set are: Current (I) of 500uA; Threshold of 140; Duration of 5 seconds; Pause of 0 seconds; Channel set for data collection. This information is set within the UI Figure of the MATLAB GUI (refer to step 4 in the tutorial). We used a SHR animal model of hypertension. Prior to data collection a 35 minute baseline is taken to ensure that we are getting consolidated values. Our base line was taken for 35 minutes and maintained around 154, as seen in Channel 2.
Figure 2: Beginning of data collection showing initial stimulations:
When our signal is above the pre-set threshold of 140 our code demands a signal be routed from the PlexStim stimulator to the multi-electrode stimulating the Common Peroneal nerve. Each stimulation resolves after 5 seconds and is continuously repeated, with no designated pause between individual stimulations, until the threshold is met. Stimulation signal propagation can be seen in Channels 3 and 4.
Figure 3: First dip below threshold and pause in stimulation:
Our signal begins to dip below our threshold of 140 after ~20 minutes of stimulation. We then see the signal alternating slightly above and below our threshold, and proper stimulation occurring when the signal drives above the threshold, while holding off while the signal is below our threshold.
Figure 4: No stimulation as signal remains below threshold:
Our threshold of 140 acted as a ceiling and we were able to maintain below that with increasingly diminishing stimulation.
Figure 5: Stimulation when signal breaks threshold:
Our code allows for minimal supervision, as we show here after a long term duration without any stimulation due to the signal maintaining below the threshold, when the threshold is broken a stimulation is sent and our signal is retrieved back below our threshold.
Figure 6: Final signal at 132:
Our code acts with such a high level of reliability that the concern of the blood pressure dipping below a safe level, assuming the threshold is set at a safe level, is minimal. We have shown the ability to control the signal below a designated threshold safely and reliability without introducing sudden dips that could be cause of alarm to the health of the subject. We ended the study after 65 minutes, demonstrating an ability to reduce the signal by ~8% within the first 20 minutes to first reach below our threshold of 140. From there were able to maintain a steady signal below our threshold for a further 45 minutes, at which point we ended the study.
