Internet transceivers could test breathing rates non-invasively

Engineers in the US are developing a way to measure breathing rates non-invasively using wireless internet transceivers. A research project at Utah University aims to monitor the breathing of surgery patients, adults with sleep apnea and babies at risk of…

Engineers in the US are developing a way to measure breathing rates non-invasively using wireless internet transceivers.

A research project at Utah University aims to monitor the breathing of surgery patients, adults with sleep apnea and babies at risk of sudden infant death syndrome (SIDS), without the use of any wires or tubes attached to the patients.

The researchers have been able to reliably estimate breathing rates by placing a network of wireless transceivers around a bed and measuring how the motion of the chest and abdomen impedes the radio signals criss-crossing the patient.

‘We can use this to increase the safety of people who are under sedation after surgery by knowing if they stop breathing,’ said assistant professor of electrical engineering, Neal Patwari.

‘We also envision a product that parents put around their baby’s crib to alert them if the baby stops breathing. It might be useful for babies at risk of SIDS.

‘The patient doesn’t have to be connected to tubes or wired to other sensors, so they can be more comfortable while sleeping.

‘If you’re wired up, you’re going to have more trouble sleeping, which is going to make your recovery in the hospital worse.’

He added that, although it would take five years before it became a commercial product, the system would be cheaper than existing breathing monitors because the technique uses off-the-shelf devices similar to those used in home computer networks.

In a new study, Patwari showed that a network of 20 transceivers or nodes could estimate breathing rate to within two fifths of a breath per minute based on 30 seconds of data.

Each of the 20 nodes can transmit and receive to the other 19 one after the other, meaning that there can be up to 380 measurements (20 x 19) of radio-signal strength within a short period of time.

The American Academy of Pediatrics (AAP) opposes the use of home monitors for preventing SIDS and says there is no evidence that they are effective, but also admits that they may be useful in some infants who have had an apparent life-threatening event.

Patwari has formed a spin-off firm, Xandem Technology, to commercialise his previous research into using wireless transceivers to ’see through’ walls and detect intruders or locate people in buildings trapped by a fire or held hostage.

The new study points out the pros and cons of adding wireless breathing detection to the motion-detecting capability.

‘A search-and-rescue team may arrive at a collapsed building and throw transceivers into the rubble, hoping to detect the breathing of anyone still alive inside,’ it said.

‘Police or SWAT teams may deploy a network around a building to determine if people are inside.

‘On the other hand, the ability to measure breathing from a wireless network has privacy implications. If this system can also detect and monitor a sleeping person’s breathing, it would have additional utility for eavesdroppers or thieves.’

Patwari is planning more research into whether different or multiple radio frequencies might detect breathing better than the one 2.4GHz frequency used in the study.

He also wants to test whether or not the system can detect two people breathing at the same rate but not in sync, which could help detect not only the location of hostages in a building, but the number held together.