Implant monitors patients after surgery

A tiny wireless sensor could reduce the number of deaths and complications following transplants or high-risk surgery, its US developers claim.

The sensor, which can be implanted into patients, will inform doctors if organs are not getting adequate bloodflow following surgery.

It monitors blood circulation to the organ, by detecting the absorption of wavelengths of light by the tissue. This data is then transmitted to a nearby receiver.

Detecting circulation problems could quickly reduce complications, said Nance Ericson, a researcher in the engineering, science and technology division of Oak Ridge National Laboratory in the US.

Existing methods involve invasive procedures or extensive laboratory testing, and by the time doctors realise there is a problem it is often too late and the organ or tissue is already irreversibly damaged, said Ericson. ‘The problem arises when the patient is closed up [after surgery], as there is not a very good non-invasive method of monitoring the tissue. This sensor gives physicians real-time information on blood circulation. It is basically a watchdog.’

The research team, which also includes Mark Wilson, a surgeon at Pittsburgh University, and Gerard Coté, an optical biosensing engineer at Texas A&M University, is being funded by the US Department of Energy’s Office of Science.

Ericson will spend the next year miniaturising the technology, allowing surgeons to implant the device precisely, either below the skin or in the deep tissue. The sensor could possibly remain in the body, to avoid further surgery.

The research could also lead to photonics-based microsensors for monitoring other substances, such as arterial blood gases, an indicator of respiratory problems, or serum lactate, which can reveal the severity of tissue injury. ‘We are developing the electronics and communication systems necessary to make this device very small. Once we have that platform we could put other sensors on it to measure things in different parts of the body,’ said Ericson.