Patient monitoring ideas

Why not wireless?

Wired connections in the surgical setting for a surgical patient are a constant headache due to entanglement of the various patient attachments.  These attachments become snagged, twisted, pulled off with constant patient movement from one bed to another and also during intraoperative changes in patient positioning. Some of these connections include the following items:

vascular access:



oxygen tubing

enteric access:

nasal gastric tubes

other transabdominal access (gastrostomy . . .)


pleural tubes

urinary catheters

pneumatic tubing – anti-thromboembolism prophylaxis pneumatic leg sleeves

monitoring attachments:






pneumatic:   NIBP (non-invasive BP)

I am surprised that we don’t use wireless connections in the surgical setting for the things that could be managed wirelessly. A huge amount of time is spent in untangling, unattaching, reattaching connections when moving or repositioning a patient.
In addition, the patient is monitored, then disconnected and this process is repeated at least 4 times during a hospital day visit to surgery. This involves countless connections and disconnections of BP, temp, EKG, NIPB as well as reapplication of disposable items for such monitoring of the same patient such as blood pressure cuffs and saturation probes for oximetry.

Here, again, there is lost time applying and unapplying these removable items to the patient as he travels to and from: admission area preop area operating room recovery roomI would propose that the attachments for monitoring or at least a subset of them be managed wirelessly. Indeed this is not new technology nor could it be a novel idea. For ex, wireless EKG monitoring in telemetry units has been around as long as I can remember, even in the days of pure analog RF technology before the the current days of pervasive digital networking for every conceivable device enabled by better digital and RF technology.
One way to manage this concept would be for the patient to have a small, battery operated, wearable module that would interface to all his monitors. This would use a common or perhaps more restricted RF bandwidth as well as a buffer for the data and a channel identifier that links such data, both RF and stored to that patient’s current hospital visit.
Savings and improvement in care would be realized in the following ways:

Cost of disposables – the patient would use just one BP cuff and oximetry probe instead of removal and loss of such devices as seems to occur with each patient as they move from spot to spot.

Continuity of monitoring – there would effectively never be any monitoring down time in the process of moving or transporting a patient.

Speed of patient transfer – several minutes is wasted in each encounter of the patient in a new location for application of monitors and registration of the patient at the new location as well as recording of the vital signs.

General hassle factor involving patient transfer – The menial task and frustration of applying, removing, untangling monitor attachements is a time waste and constant frustration that is required but is otherwise noncontributory to patient care.

With initial application of such a wearable monitoring system on admission for a day surgical visit, the following chores are reduced or eliminated: Applying monitors Recording data into a chart Removing monitors Untangling these lines while moving a patient Finding the disposable parts which frequently get disposed of between locations.
Now, here is the big question. The solution above is an obvious one, certainly nothing novel or heretofore impractical or even expensive. So it is puzzling as to why we don’t make wireless, wearable monitoring a common practice.

Here are a few recent photos of the wiring mess.



Minimal or No electrode EKG

Another question I have is whether or not there is the need for the standard EKG configuration on a generally healthy surgical patient. I am referring to the signals commonly referred to as ‘leads’ I, II and III.
I put the word ‘lead’ in quotes since it is a confusion to those learning about the lead system. A lead is really a wire or terminal on the body. I guess it would more properly be referred to a signal as such is always a differential between two leads, either actual or virtual as in aVL, aVR, aVF and the precordial ‘leads’. But I’m digressing.
Years ago (20 or so) I experimented with placing some closely spaced electrodes together to get an EKG signal over a very small area. I was making my own circuit boards at the time and I just soldered the electrode snaps directly to the bottom side of the PC board.

For the electrodes, I just cut away most of the sticky part of the standard electrode and I popped them into the snaps on the back side of the board. I left the gelled area of the electrodes intact and taped the whole assembly onto the patient to keep it in place.

On the front side of the 1.5” x 2” PCB I had my instrumentation amplifiers and some buffering circuitry.  All the noise sensitive circuitry was taken care of directly on the patient, thus the signal was low impedance and large and very clean as it came off the board.
I later created an even smaller device and used some bottom sided, closely spaced PCB pads, about 7mm, as the electrodes themselves, thus eliminating the need for any electrodes at all. And I later reduced the board size even further to about 12×15 mm and used the entire bottom of the board as the electrodes, comprised of two differential electrodes and the standard return or bias current electrode.

I used an ultra high input impedance (pico amp bias current) instrumentation config amplifier and found that I could get a clean signal without much galvanic connection. Capacitive coupling with the ultra high impedance enabled enough current to get a decent signal.
Thus, I had created a sort of skin surface EKG gradient measurement device that gave a reasonable EKG signal, although is certainly had a different morphology with more high frequency components and an overall zero DC voltage value.
So I have thought about this since then and how it could be used as a simple, one element device to get an EKG signal without all the wires. It does not provide all the same info but in many patients may provide reasonable information.
This is an example of something that reduces the wiring even further and in fact requires no electrodes at all apart from the PCB etched pads.