Acoustic Respiratory Monitoring: What Is It?

4/17/2007 by Clark Venable
An intriguing press release last week from Masimo (known for their motion artifact-resistant pulse oximeters) begins as follows:

"Masimo, the inventor of Pulse CO-Oximetry and Read-Through Motion and Low Perfusion pulse oximetry, reported that three new independent studies, including one presented the recent International Anesthesiology Research Society (IARS) Clinical & Scientific Congress in Orlando, concluded that Masimo Acoustic Respiratory Monitoring technology (ARM) is "at least as accurate as capnometry" and "significantly more reliable" for monitoring respiration in spontaneously breathing patients."


The release then refers to "an adhesive bioacoustic sensor applied to the patient's neck and connected to a breathing frequency monitor prototype" which in turn accurately monitors respiratory rate.

If this device does what I think it does, it will become the standard of care for post-surgical patients very rapidly.  We've been looking for a way to reliably monitor respiratory rate on the floors, once patients are discharge from the recovery room.  For example, a patient may receive pain medications from multiple sources, with unpredictable onsets.  How do we know their maximum respiratory depression won't happen after they've been delivered to their hospital room?

A patient can receive oxycontin and celebrex orally from a surgeon before their knee replacement surgery, then more fentanyl, morphine, and versed from us (anesthesia).  The surgeon may then inject bupivicaine and morphine into the joint at the conclusion of surgery (without necessarily telling the anesthesiologist). I might also do a femoral nerve block to further reduce post-op pain.  All of us are trying to do right by the patient but, given the right set of circumstances, are setting them up for significant respiratory depression post-op.  The ability to reliably monitor respiratory rate with this new Masimo monitor would be a huge patient safety advance.

The Society for Technology in Anesthesia abstract is here.