"Smart pen" could monitor patients' anesthetic levels during surgery
Everyone responds to general anesthetics differently, which can make administering the correct dose tricky. A new device is designed to help, by continuously monitoring anesthetic levels in patients' bloodstreams during surgical procedures.
Ordinarily, anesthesiologists base initial dosages on factors such as age, weight and gender.
One thing that they don't know ahead of time, however, is how much of the drug will end up actually circulating within an individual patient's bloodstream. For this reason, they may end up administering supplemental doses of the anesthetic during the operation, in order to keep the patient asleep and unaware. For safety reasons, though, they should still be using as little of the drug as possible.
With this situation in mind, scientists from Switzerland's EPFL research institute, the Lausanne University Hospital and the Polytechnic University of Turin have developed an experimental "smart pen" device that continuously measures anesthetic levels within a patient's bloodstream. More specifically, sensors in the tool's needle – which is inserted into a vein – detect concentrations of the commonly used anesthetic propofol, in the blood serum.
Because propofol tends to stick to the tips of needles instead of being completely drawn in, the drug has previously proven difficult to precisely measure within the blood. The new device addresses this issue utilizing artificial intelligence-based algorithms, which compensate for the sticking problem when calculating bloodstream propofol levels. It then transmits that data via Bluetooth, allowing the dosage of any supplemental propofol – if needed – to be adjusted automatically.
In lab tests conducted so far, the device has been shown to accurately measure anesthetic concentrations in human blood samples. Tests on animals and people are now being planned.
"Propofol is one of the best anesthetics out there, but getting the dosage just right can be complicated," says Lausanne University Hospital's Prof. Thierry Buclin. "So an easy-to-use system that can monitor propofol concentrations in the operating room would be a major step forward in surgery and intensive care."
The research is described in a paper that was recently published in the journal IEEE Transactions on Biomedical Circuits and Systems.