iBece.org

This is the second in a series of articles on Personal Digital Assistants, directed at senior medical students and junior doctors. In PDAs in Medicine: Do I need one? I discussed some of the many ways in which a PDA can help the junior clinician. The aim of this piece is to unravel some of the jargon and simplify the process of finding the right device for you.

When you begin shopping around for a PDA to help you on the wards, you will be confronted with a mountain of acronyms and buzzwords. I’m going to discuss each one in turn, and explore its relevance (or otherwise) to a young doctor on the wards.

Things that matter

Dimensions

In my opinion, the single most important factor when choosing a PDA to be your bedside companion is size. While some of us may feel cool having a brick clipped to our belts, most of us have fashion sense. Ideally, you will want something as small and light as possible, and preferably able to slip inconspicuously into your pocket. For the ladies, this may be less of an issue if you frequently carry your handbag on rounds. Gentlemen, size does matter - but in this case less is more. Often the most powerful devices, with the longest list of features, will be bulky and heavy. As I will discuss shortly, most of these features you can do without.

When it comes to fitting in trouser pockets, thinness (depth) is perhaps more crucial than front surface area. I recommend aiming for 16 millimetres or less on the specification sheet. Remember too that many devices come with carry cases, and these add considerably to bulk. Depending on how careful you are, you may be able to do without full body armour, as long as the screen is protected in some way.

Screen

One caveat in the pursuit of small and light is that you can go too small. PDA-phone combinations are becoming increasingly popular, and as such some very slim and stylish hybrid devices are coming onto the market (O2 Atom, i-mate Smartflip). These devices make sense, and they certainly save you from carrying two separate devices. Unfortunately, often screen size is the first thing to be sacrificed. Whether this is a problem really depends on how you plan to use your PDA. If all you are after is a quick bedside reference (to look up a drug class or medical dictionary definition), then a tiny screen may suffice. If on the other hand you plan to read text much longer than your average SMS, it would be wise to up-size on the screen real estate. A vast library of text books is available for PDAs (some of them free), and you may just be limiting your new PDA’s uses before you even begin.

After size, screen resolution must be considered. The resolution is expressed in pixels (eg. 320 x 240) and describes how many pixels (dots) can fit on the screen. The more pixels, the sharper and less grainy the image. Until recently, PDAs had notoriously poor resolutions, and users had no choice but to put up with poor image quality. Nowadays, even the lower-end PDAs have resolutions that are very readable indeed. Most will have what is known as QVGA (quarter VGA), or 320 by 240 pixels in landscape mode (on its side). The term VGA (video graphics array) is a legacy acronym from the personal computer world, and represents 640 by 480 pixels. As of late 2005, some high-end PDAs began to ship with full VGA screens (HP iPAQ hx4700, Dell Axim X50v) although these are both large and expensive. Some Palm devices sport a resolution mid-way between these, known as HVGA (half VGA), or 320 by 480.

In my opinion, below 3-3.5 inches is too small for extended periods of reading. QVGA on a 3.5 inch screen is adequate, but only just so. Text will be noticeably pixelated (grainy) and again if you’re planning on spending more than brief periods reading your PDA, you will want at least a HVGA screen. I have found little difference between HVGA and VGA in reading normal print-sized text. Naturally, smaller print will appear better on a full VGA screen.

Things that are nice

Memory

In the bad old days of PDAs (my first was a Palm III with 2 MB of RAM), squeezing programs onto very limited memory stores was a cause of much anguish. These days, most PDAs have bucket-loads of onboard memory, and almost all have expansion slots so you can add 2 GB or more at will. Programs will load from either onboard memory or an expansion card, but remember that if you remove your card you lose access to the programs stored on it. Some programs will only run if at least some is loaded onto onboard memory, and it is for this reason that the more you have the better.

New PDAs are advertised as having a certain amount of RAM (random-access memory) and ROM (read-only memory). These values are often around 64-128 MB. The terminology is a little confusing and the role these two types of memory play has changed drastically since the release of Windows Mobile 5 in 2005. Older PDAs stored the operating system and core applications in ROM (which was truly “read-only”), and everything else (programs, data files, etc) in RAM. If the battery ever ran flat, all user files and programs were lost and the device reverted to its factory state. WM5 devices use ROM much in the way a personal computer uses a hard-disk. Everything is stored there (including all personal files) until it is called up to be used, at which point it is copied to the much-faster RAM. The benefit is that if your batteries run out, you will only lose data that hasn’t been saved (just like on your PC).

Having more memory never hurts, but because it can so easily be expanded these days with add-on memory cards, it isn’t as critical an issue as it once was. Expect a medical reference to be up to 10 MB, although most will be less. With my PDA stocked with almost everything I need, I still have more than half of my Palm TX’s 100 MB onboard memory available, and a third of a meagre 256 MB SD card. Should I need more space, I could throw in a 1 GB SD card for less than $AU80.

Battery Life

Battery life is always nice to have more of, but realistically will rarely impact on real-life use. In our work, we may consult the PDA a couple of times a day, rarely for more than a few minutes. I can’t imagine spending more than 30 minutes a day playing with my Palm - and rarely even that much. The exception might be those lonely nights on-call, where you are catching up on some reading in the tea room. Even then however, you’d be pushed to exceed the 4-6 hours or so typical of a PDA these days. By all means, if it comes down to it, chose a model with more juice. But realise that there are more important things to worry about.

Connectivity

We all like to be connected. We’re social beings after all. A common problem with the small and light (and often cheaper) PDAs on the market are their lack of some connectivity options, usually Bluetooth, WiFi or both. But do you really need all of these fancy tricks? Let’s look at them one at a time.

Bluetooth is a short-range wireless connection, most commonly used between mobile phones and hands-free ear pieces. It removes the hassle of cables when connecting two nearby devices together. On a PDA without a phone built-in, the uses of Bluetooth are limited. You may wish to connect your PDA to your mobile, to allow you to surf the net or check your emails. While this sounds fun, it’s a lot less useful in reality. Not only is GPRS internet expensive, but surfing the web on a PDA is awkward to say the least. Given that we work in an environment surrounded by networked PCs, this won’t be a major use. Another option is to use Bluetooth to connect your PC to your PDA to synchronise contacts, appointments and the like. Again, this sounds cool, but the job is just as easily done with infrared or a docking cradle.

WiFi refers to medium-range wireless networking, and currently relies on the 802.11b/g standard. Connecting your PDA to a wireless network allows you again to get online (if that network is connected to the Internet), to access files on other computers, log on to other computers with Remote Desktop software, and more. There is a trend in the United States to wirelessly access patient records and lab/radiology results from any WiFi-enabled PDA in the hospital (with appropriate security settings of course). As such, WiFi is probably more crucial to have than Bluetooth. In most likelihood, Australia will follow suit with this technology in the not-too-distant future.

Infrared used to be the wireless connection of choice in the 90s, before Bluetooth took over. It’s probably the least useful connection of the three, partially because it’s so slow. Transferring files using IrDA is an exercise in patience. One advantage it has is that many laptop computers have infrared ports, while only the more recent models incorporate Bluetooth. Similarly, older mobile phones may not have Bluetooth but may likely have infrared. If you do decide that connecting to the net through your mobile is the way to go, this may be your only bet. There is a non-work-related use of infrared which may appeal to some. Both Palms and Pocket PCs have software available to transform your PDA into a funky universal remote for you home theatre gig.

Things that don’t matter much

Processor

Just like your desktop computer, PDAs have a central processor that is the brains behind the operation. Because of the simplicity of tasks compared to your average PC, these can afford to be significantly slower without a noticeable impact on performance. It is important to realise though, that much talk about CPUs and their speed is relatively academic. Unless you’re planning on playing graphic-intensive games, or running complex calculations, it doesn’t make much difference whether you have 300 or 600 MHz. Sure, things might appear a little snappier, but in practice we’re talking fractions of seconds. Let the computer geeks size up each others CPUs. We’re doctors and we really shouldn’t care.

Again, there is a caveat. The one application that I have noticed to be frustratingly slow on my Palm TX (312 MHz Intel XScale processor) is viewing PDF documents. This doesn’t bother me as I rarely read PDFs. If you plan to fire up Acrobat more than occasionally, it may be worthwhile getting a faster unit. Here’s a tip: the numbers alone don’t tell the whole story. While on face value, a PDA running at 400 MHz may appear quicker than one at 312 or 200, other factors will contribute to the result. There are many benchmarks published comparing real-world speed. A quick Google is all you need.

Operating System

I will go out on a limb and say that most likely you will buy a Windows Mobile PDA. As I discussed in the previous article in this series, functionally there is not much of a difference between PalmOS and Windows Mobile. There is some doubt about the future of PalmOS currently, as PalmSource, the company that develops it, it has been sold off to Japanese firm Access following a split from Palm Inc. in 2003. PalmSource has been sitting on the next version of PalmOS for more than a year, with no hardware vendors interested in taking it up. Even Palm Inc. has begun incorporating Windows Mobile in some of its latest PDA-phone hybrids. The latest gossip is that Access is developing a Linux-based operating system to replace PalmOS, which will (hopefully) maintain backward compatibility with current Palm software.

All of this uncertainty has been great for Microsoft and Windows Mobile devices are by far the most popular on the market today. In practical terms, Windows Mobile is a little less responsive, and a little less user-friendly in my opinion. For the sake of future-proofing your software purchases, I am leaning towards recommending Windows Mobile, even though I myself own a Palm. That said, I still claim that operating system should not be high on your list of priorities.

Summary

There are many buzzwords and features a salesman will throw at you to get you to spend more money. Often, most of these “features” have little real-world use to a medical student or doctor on the wards. I recommend you choose the smallest and lightest PDA with the most attractive and legible screen. These are two factors which you will notice day in, day out. Strongly consider WiFi to future-proof your purchase, but other options are less vital. Memory can easily be upgraded, battery life is not so critical for average use, and don’t get too hung up on the numbers when it comes to processor power.

In the next article in this series, I will discuss a few PDAs which I consider to be favourites, and will give pros and cons of each. Stay tuned.