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Monitoring Consciousness During Surgery Still More Art than Science

Devices for preventing intraoperative awareness come up short

2 min read
Monitoring Consciousness During Surgery Still More Art than Science

There's a fascinating and disturbing study (sub. req.) in the current issue of the New England Journal of Medicine regarding intraoperative awareness. That's the medical term for waking up during surgery while your body, including the muscles needed to speak, remains under anesthesia. This event is fortunately quite rare, but, needless to say, it can be very traumatic for the unlucky few who experience it.

In the study, researchers compared two methods aimed at averting this medical nightmare. The first method, called end-tidal anesthetic-agent concentration (ETAC), tries to determine patients' consciousness based on the amount of anesthetic in their breath. It's the older and more accepted method, but it works only for inhaled anesthesia (as opposed to infused or injected). The second, newer method, called bispectral analysis, tries to assess patients' consciousness more directly using electroencephalogram (EEG).

Both methods use a numeric range that is supposed to signify when a patient might not be fully under anesthesia. The NEJM study represents the first time the two approaches have been compared on a large scale at multiple clinical centers. The results were unsettling: the ETAC seemed to work slightly better than the EEG-based method, but neither was particularly successful. Out of about 3,000 patients in each group, there were 19 cases of "definite or possible" awareness associated with the EEG method, compared with eight in the groups being monitored with the ETAC method. And, as an accompanying editorial points out, 41 percent of the awareness incidents occurred when the numeric readings were in the devices' target ranges.

Clearly there's room for improvement, but that doesn't mean that trying to develop a device to monitor anesthetized patients is a bad idea. A growing number of neuroscientists are working to quantify consciousness with various types of technologies, including MRI and other neuroimaging systems. Perhaps one or more of these approaches will soon be used to enhance or possibly replace the ETAC and EEG-based methods.

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A photo showing machinery in a lab

Foundries such as the Edinburgh Genome Foundry assemble fragments of synthetic DNA and send them to labs for testing in cells.

Edinburgh Genome Foundry, University of Edinburgh

In the next decade, medical science may finally advance cures for some of the most complex diseases that plague humanity. Many diseases are caused by mutations in the human genome, which can either be inherited from our parents (such as in cystic fibrosis), or acquired during life, such as most types of cancer. For some of these conditions, medical researchers have identified the exact mutations that lead to disease; but in many more, they're still seeking answers. And without understanding the cause of a problem, it's pretty tough to find a cure.

We believe that a key enabling technology in this quest is a computer-aided design (CAD) program for genome editing, which our organization is launching this week at the Genome Project-write (GP-write) conference.

With this CAD program, medical researchers will be able to quickly design hundreds of different genomes with any combination of mutations and send the genetic code to a company that manufactures strings of DNA. Those fragments of synthesized DNA can then be sent to a foundry for assembly, and finally to a lab where the designed genomes can be tested in cells. Based on how the cells grow, researchers can use the CAD program to iterate with a new batch of redesigned genomes, sharing data for collaborative efforts. Enabling fast redesign of thousands of variants can only be achieved through automation; at that scale, researchers just might identify the combinations of mutations that are causing genetic diseases. This is the first critical R&D step toward finding cures.

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