If any medical device were ever a game-changer, this is it.
I come from the first generation of emergency physicians trained in ultrasound during residency, being part of a class that paid its own way to complete the SAEM course in 1996 after it became apparent that our own faculty lacked the skills to teach us this new technology.
SonoSite had just developed the first portable ultrasound machine targeted at emergency physicians, the 180, and it bet everything that its new device would capture the market. After a rough beginning and several years in deep debt, SonoSite won its bet and became the top manufacturer of the ultraportable machines used by forward medical units in Iraq and by stateside emergency departments. I owe a debt of gratitude to Kevin Goodwin, SonoSite's chief, who donated a 180 during the company's startup years to a nonprofit medical organization I helped found. For the next decade, we used it all over Africa while volunteering medical services in remote impoverished areas. It saved many lives, and we still use it today.
Fast forward to 2009 with an introduction to Signostics, a startup bioengineering firm based in Palo Alto, CA. After several years of research and development, Signostics received FDA approval in May to begin selling a device called the Signos. Like the 180, the Signos is the company's gamble that a new ultrasound technology could take the emergency medicine market by storm.
Here's the game change: the Signos is truly a pocket-sized machine. The photo says it all. Even better, it costs $4,000 well-equipped, a figure that many emergency physicians have available for their annual continuing educational reimbursement.
The Signos is the brainchild of Neil Bartlett, MD, an Australian physician and engineer who moved his family (including a 15-year-old) to Silicon Valley a few years ago after sinking a small fortune into developing it. It's already been sold to veterinarians, among whom it is known as the Speq. Nevertheless, the main push has always been to get the device into the hands of physicians.
The Signos is similar to a traditional ultrasound, but Signostics broke through the $20,000 portable ultrasound price barrier by removing all but a single crystal from the scanning head. In all other ultrasounds (including the new handheld P10 by Siemens), this head is composed of multiple crystals that are pulse-sequenced by control software to obtain the screen images with which we are familiar.
Not so with the Signos. To obtain an image, the user must perform the physical motion that normally is generated virtually by the control software. This requires a new set of skills that make the manual and video tutorials mandatory viewing. I'm certain it also will spawn a new crop of CME courses, ultrasound fellowships, and a research party wagon that everyone who is someone in academic circles will want to ride.
The process begins by anchoring the probe over a gelled anatomic area of interest. While carefully ensuring that the probe tip does not slip, the device is activated by pushing a button on the left side of the screen, which is held in the nonscanning hand. The image is obtained by slowly rocking the probe back and forth. By directing the static ultrasound beam through space, two dimensions are created on the screen, and traditional triangular images are formed. The process is similar to moving a flashlight over a large painting in the dark to see the whole canvas or watering a garden with a hose. With practice and care, with emphasis placed on practice, I can complete a FAST scan in the same time it takes me to do it with our department's SonoSite MicroMaxx.
The Signos's images are not pristine, but part of the reason is that they are confined to an area the size of an iPhone screen. For what we do as emergency physicians - searching for free fluid, abscesses, aneurysms, and even hydronephrosis - I've found the Signos images more than adequate. For the old-timers reading this piece, the difference in resolution between the latest SonoSite and the Signos is about the same as the difference between a 35 mm photo taken with 800 versus 100 ASA film. It's noticeable, but it doesn't matter unless you're in the business of making posters out of your prints. And that is certainly made up for many times over by being able to carry it in your pocket because it's that small and because it's cheap enough to own.
After using the device for the past few months, it's difficult not to imagine the Signos or similar technology replacing my stethoscope someday. If Signostics succeeds in marketing this device to physicians (rather than emergency departments), all of us might find that the standard in bedside diagnosis changes from auscultation to direct imaging in the-not-so-distant future. (Remember when we did skull films instead of CT scans for head trauma?)
As the photo shows, the Signos has two parts: the touch screen and the probe. A flip-up cover on the screen hides a mini-USB port, headphone jack, AC adaptor connection, and microSD slot. A stylus is hidden on the top right corner of the screen and an LED light on the left, ostensibly for checking a patient's throat or pupils between scans. The software is robust, well thought out, amply beta-tested, and better, in my opinion, than the software on SonoSite's machines. Much of the software's appeal comes from being able to use a touch screen. After being shown how to scan, I was able to maneuver through caliper measurements, review images, and edit patient data before reading the manual that was originally missing from my review unit. After obtaining the manual, I was impressed to find the Signos had a built-in microphone for attaching voice notes to my scans, something I found easier to use than typing my notes in real-time during a patient scan. The software also allows users to add patient demographic data after scanning, a feature not offered by several other vendors of portable ultrasound machines.
I also appreciated the manual's explanation of M-mode scanning, something that I had used little in emergency practice except for pneumothorax screening. In addition to providing an integrated tool for calculating fetal heart rates using M-mode, Signostics has invented a method to map out panoramic anatomy in a rectangular format that provides better images than the triangular-shaped B-mode format. This takes advantage of the single-crystal design, allowing the user to create images by moving the probe linearly over areas of interest while in M-mode. In practice, I was able to obtain a two-dimensional MRI-like image of a deep long calf abscess that I subsequently drained in the ED.
Signostics deliberately modeled the Signos on the personal digital assistant. Future iterations of the device software, which theoretically could be updated via web downloads, could make use of its card memory, CPU, microphone, speaker, and touch screen. As a systems analyst in a prior career, I can attest that it would be a simple task to update the Signos software to run ePocrates, UpToDate, and POISINDEX or even play MP3 recordings, making it both a full-featured medical PDA for the emergency physician as well as the go-to bedside ultrasound, simply because its form allows it to be pocketed.
The Signos comes with a 2GB microSD card, AC adapter, and USB cable. A pleasant surprise is that images are saved on the memory card accessible by software included for uploading images to a computer, unlike other ultrasound vendors who require a separate software purchase for external image viewing and manipulation. Attaching the Signos to an Internet-connected computer via the USB cable also allows device updates to be downloaded and installed automatically.
Figure. A scan taken...Image Tools
Battery life is excellent. The Signos puts itself into a low-power mode when inactive, and lasts several ED shifts at a time without needing to be charged.
The probe comes standard with both 3.5 MHz and 7.5 MHz transducers, which are interchangeable simply by screwing one off and replacing it with the other. I found the probe tips, both under an inch in diameter, to be much more useful than the larger corresponding SonoSite probes for finding targets for intravenous placement or ultrasound-guided procedures.
My one major beef is that the Signos does not come with a belt clip. While it fits in the pocket of my white coat, I belong to the generation of emergency physicians that prefers to go coatless and my most-used instruments are the ones that fit in my pants pockets. Right now it's a stethoscope, which I wear on a leather belt clip, a set of trauma shears, a small Leatherman, and an iPhone loaded with ePocrates. If I had a clip for the Signos, I'd put it on at the beginning of a shift, and use it on nearly every patient simply because I had it instantly at hand. Instead, it sits in a case on a desk in the ED, leading to a toss up between it and SonoSite for patients that I'm serious about scanning.
This device instantly impressed me with its size, price, user-friendliness, and design. For residents learning ultrasound for the first time, mastering the eye-hand coordination needed to do Signos scans will probably become a matter of competitive pride. For those of us who were raised on traditional multi-crystal probes, the learning curve will be steeper. All in all, if the Signos succeeds in emergency medicine, it will do so because it will bring ultrasound to the masses, finally allowing individuals rather than institutions to meet the first and most important rule in gun fighting: bring a gun.
© 2009 Lippincott Williams & Wilkins, Inc.