Friday, March 27, 2015

Welch Allyn Published Patent Application: Continuous Patient Monitoring

I decided to review this patent application in light of the New York Times Opinion piece I commented on. Here's the to my commentary:

Also, I've gone back to the origins of this blog ... reviewing patents. The first patent I reviewed was one from Medtronic. Here's the link:

The issue raised of particular interest was the high "false alarm" rate generated reported by the author that would lead medical professionals to disregard warnings generated by their computer systems. I wrote that I wanted to follow-up on the issue of false alarms.

The patent application (the application has been published, but a patent has not yet been granted) describes an invention intended to 1) perform continuous automated monitoring and 2) lower the rate of false alarms.

Here are the details of the patent application so that you can find it yourself if you wish:

The continuous monitoring process from a technical standpoint is not all that interesting or new. What is interesting is the process they propose to lower the false alarm rate and determine whether this process in turn will not lower the false negative rate.

Proposed Process of Lowering False Alarms

As mentioned in my earlier article, it appears that false alarms have been a significant issue for medical devices and technology. Systems that issue too many false alarms issue warnings that are often dismissed or ignored. Or waste the time and attention of caregivers who spend time and energy on responding to a false alarm. This patent application is intended to reduce the number of false alarms. However, as I mentioned earlier, can it do that by not increasing the number of false negatives, that is, failure to detect when there is a real event where an alarm should be going off.

Getting through all the details of the patent application and trying to make sense of what they're trying to convey, the following is what I believe is the essence of the invention:

  • Measurement a sensor indicates an adverse patient conditions and an alarm should be initiated.
  • Before the alarm is initiated, the system cross-checks against other measurements that are: 
              1) from another sensor measuring essentially the same physiological condition as the
                  sensor that detected the adverse condition, the measurement from the second sensor
                  would confirm the alarm condition or indicate that an alarm condition should not exist; or
              2) from another sensor or sensors that take physiological measurements that would confirm
                  the alarm condition from the first sensor or indicate that an alarm condition should not

In this model at least two sensors must provide measurements that point to an alarm state.

Acceptable Model for Suppressing False Alarms and Not Increasing False Negatives?

Whatever you do in this domain of detecting adverse patient conditions, you don't want to lower your accuracy of detecting the adverse condition. That is, increase your false negative rate.

So is this one way of at least maintaining your currently level of detecting adverse events and lowering your false alarm rate? On the face of it, I don't know. But it does appear that it might be possible.

One of the conditions the inventors suggest that initiates false alarms are those times when patients move or turn over in their beds. This could disconnect a sensor or cause it to malfunction. A second sensor taking the identical measurement may not functioning normally and have a measurement from the patient indicating that nothing was wrong. The alarm would be suppressed ... although, if a sensor was disconnected, one would expect that there would be a disconnected sensor indicator would be turned on.

Under the conditions the inventors suggest, it would appear that cross checking measurements might reduce false positives without increasing false negatives. I would suggest that care should be given to insure that a rise in false negative rates do not increase. With array of new sensors and sensor technology becoming available, we're going to need to do a lot of research. Much of it would be computer simulations to identify those conditions were an adverse patient condition goes undetected or suppressed by cross-checking measurements.

Post Script

For those who do not know, I am on numerous patents and patent applications (pending patents). Not only that I have written the description section of a few patent applications. So I have a reasonable sense of what is what is not patentable ... this is in spite of the fact that I'm an experimental, cognitive psychologist and we're not general known for our patents.

So, what is my take on the likelihood that this applications will be issued a patent? My sense is not likely. As far as I can tell there's nothing really new described in this application. The core of the invention, the method for reducing false alarms, is not new. Cross-checking, cross-verifying measurements to determine if the system should be in an alarm state is not new. As someone who has analyzed datasets for decades, one of first things that one does with a new dataset is to check for outliers and anomalies - these are similar alarm conditions. One of the ways to determine whether an outlier is real, is to cross check against other measures to determine if they're consistent with and predictive of the outlier. I do not see anything that is particularly new or passes what known in patent review process as the "obviousness test." For me cross checking measures does not reach the grade of patentability.


  1. Hi buddy, your blog's design is simple and clean and i like it. Your blog posts are superb. Please keep them coming.




  2. This is a very attractive information you have presented in a single page. I really appreciate your content and effort.
    Keep it up.

    ALOKA UST-9118

  3. I really like your blog. I really appreciate the good quality content you are posting here for free. May I ask which blog platform you are using?
    GE 8C