Philippe L. Bedard, MD, and Feisal A. Adatia, MD, MSc, First Year Ophthalmology Resident; University of Toronto, Toronto, ON.

Many health care professionals use handheld computers to access medical reference information and drug databases at the point of care.¹ There are many specific infectious disease software applications for handheld computers, which combine information regarding specific microbial pathogens and sites of infections with antimicrobial databases and treatment guidelines. Infectious disease software may minimize medication prescription errors and promote more rational use of antimicrobials. This article briefly reviews the salient features of five popular infectious disease applications.

ePocrates ID
ePocrates ID is available with ePocrates Rx Pro, the purchase-based suite which includes the popular handheld drug database, ePocrates Rx. Users can search by location, bug or drug. ePocrates ID provides a numbered list of recommended antimicrobial regimens for both empiric and specific pathogen-based therapy. For each antimicrobial, users can tap on a hyperlink to be connected with ePocrates Rx for more detailed drug monographs. ePocrates ID offers the simplest and most intuitive interface of any available infectious disease handheld application. Busy clinicians can quickly find treatment recommendations and a wide range of well-organized antimicrobial information at the point of care. However, users should be aware that the manufacturer of ePocrates has the ability to track how information is accessed on ePocrates ID.² Another drawback is that ePocrates cannot be run from an expansion memory card. ePocrates Rx Pro is expensive and users must renew their subscription annually. Unlike the core drug database in ePocrates Rx, ePocrates ID is not automatically updated with each hotsync operation, although users can download quarterly updates.

The Sanford 2003 Guide to Antimicrobial Therapy
The Sanford Guide is the handheld version of the popular paper-based infectious disease handbook. The opening screen of the handheld version is split into a "rapid reference" section of 17 commonly used tables and a searchable alphabetical index. The Sanford Guide provides the most detailed coverage of antimicrobial spectra, adverse medication effects and drug interactions and the most extensive literature references. However, unlike other applications, the information in the Sanford Guide is not organized by individual drug monographs, making it difficult to find information about a particular antimicrobial or clinical infection quickly. The search feature in the Sanford Guide is also cumbersome, as scroll bars must be used extensively to find information.

Johns Hopkins Division of Infectious Diseases Antibiotic Guide
Information in this guide may be searched through three side tabs entitled diagnosis, pathogen or antibiotic. Of the reviewed programs, this is the only one which is free and that automatically updates when a handheld syncs with a desktop computer. While being quite comprehensive and having undergone vigorous review for accuracy, this program does not provide any pediatric dosing. As well, drug monographs cannot be accessed through diagnosis or pathogen tabs, adding time required to search for drug details.

The 5-Minute Infectious Diseases Consult
This program is one of the extensive catalogues of medical reference books available from Skyscape. For users of other Skyscape references, the link feature allowing cross-referencing of databases is an attractive benefit. There are four indices that can be searched: Main Index, Microorganisms, Medication Index and Table of Contents. The Main Index is organized into basics, clinical manifestations, diagnosis, treatment, follow-up and selected readings. Perhaps the best feature of this program is its speed and ease of navigation. It is the most expensive of the reviewed databases and provides less drug monograph information than the other alternatives.

Infectious Diseases and Antimicrobials Notes
This program is formatted to run in iSilo, an e-book reader. It has the following sections: antimicrobial spectra index, prophylactic therapy, normal flora, organisms and treatment, infectious disease and treatment and antimicrobial treatment. This program has several attractive features. Its prophylactic therapy section provides details on prevention of infection with chemotherapy and provides surgical antibiotic prophylaxis notes. Its inclusion of a normal flora section is also quite educational. However, it requires extensive scrolling and lacks sidebar tabs seen in other applications. Furthermore, it does not disclose author information or provide references for its citations.

Conclusion
There is a variety of alternatives for users in search of an infectious disease reference for their handheld computers. ePocrates ID and Johns Hopkins Division of Infectious Diseases Antibiotic Guide provide the most concise and easily navigable treatment guidelines for particular clinical scenarios. The Sanford 2003 Guide to Antimicrobial Therapy may be most appropriate for specialists well acquainted with the paper-based version of the guide. The 5-Minute Infectious Diseases Consult offers the most extensive diagnostic information and can be linked with other Skyscape applications. Finally, the Infectious Diseases and Antimicrobials Notes may appeal to those in search of information regarding microbial flora and antimicrobial prophylaxis.

References

1. Adatia FA and Bedard PL. "Palm reading": 1. Handheld hardware and operating systems. CMAJ 2002;167:775-80.
2. Adatia FA and Bedard PL. "Palm reading": 2. Handheld software for physicians. CMAJ 2003;168:727-34.
3. Miller SM, Beattie MM, Butt AA. Personal digital assistant infectious diseases applications for health care professionals. Clin Infect Dis 2003;36:1018-29.

Philippe L. Bedard, B.Arts, Sc, Fourth Year Medical Student.
Feisal A. Adatia, MSc, Fourth Year Medical Student.

Increasingly, physicians are turning to handheld computers for a variety of applications in their medical practices. For physicians interested in purchasing their first handheld computer or upgrading their existing model, this brief article introduces some important considerations.

Operating System
Although there are many different manufacturers of handheld computers, most handheld devices run on two operating systems (OS): Palm OS or Microsoft Pocket PC (formerly Windows CE). To determine which OS is most suitable, you should take into account which platform your colleagues are using to facilitate information exchange. The Palm OS is the current industry leader. Recently, Pocket PC has made significant market inroads with the release of more inexpensive models. In the medical arena, there are far more medical software titles designed for the Palm OS; however, many new medical programs are compatible with the Pocket PC as well.

The Pocket PC interfaces with MS Word and Excel out of the box. Files created in Microsoft applications on a desktop computer can easily be transferred back and forth with a Pocket PC. Most Palm OS devices come bundled with Documents to Go, a software program that allows you to work with Word and Excel files without the loss of fonts. Both platforms synchronise with Outlook for the popular functions of scheduling, contacts and to-do-lists.

Processor Speed, Memory and Expansion Support
The speed of the processor determines how quickly a handheld is able to retrieve information. Only recently have Palm OS handhelds started to use the faster processors that power Pocket PC devices. The fastest Palm OS devices run OS version 5.0. A handheld computer's internal RAM memory is akin to the hard drive of a personal computer. Palm OS handhelds offer either 8 or 16MB of internal RAM memory. Generally, this amount of memory is sufficient to support all of the personal information management programs on Palm OS devices, including calendar, to-do-list and datebook, along with one or two more space-intensive medical reference tools, such as pharmacopoeias and electronic textbooks. Newer models of Pocket PCs feature 32 or 64 MB of internal RAM. It is difficult to compare processor speeds and memory across these two platforms because the Pocket PC platform is more resource-hungry.

Many newer handheld models allow users to increase the storage capacity through expansion memory cards. Expandable Palm OS devices offer expansion slots that allow users to add an additional 8-256MB of expansion memory to their devices. However, of the current Palm OS devices, only select high-end Sony CLIE devices have dual expansion slots. There are several Pocket PC models that offer dual expandability, such as the inexpensive Dell Axim and various Toshiba models. Both Palm OS and Pocket PC handhelds are compatible with many peripheral add-on devices through their expansion slots, including digital cameras and full-size keyboards.

Size and Weight
Generally, Palm OS handhelds tend to be thinner and lighter than Pocket PCs. Some of the new and more popular Palm OS devices, such as the Sony T series and the Palm's Tungsten T, are small and light enough to fit comfortably into a shirt pocket. However, some multimedia Palm OS devices which also house built-in digital cameras, are larger. The new HP iPac H1910 is the smallest of the Pocket PC family.

Screen
Palm handhelds feature either a monochrome or colour screen. However, not all monochrome screens are identical; some offer much sharper resolution that makes for easier reading of text. Similarly, like digital cameras, colour handhelds differ in the number of colours that are supported and the screen resolution. Currently, Palm OS handheld screens range from 160X160 pixels to 320x480 pixels. All Pocket PC devices feature a colour screen with resolution of 320x240 pixels. If you plan to use your handheld to read a lot of text or to view graphics, it may be worthwhile to invest in a higher-end resolution model.

Input Methods and Convergence Features
Handspring's Treo and the Sony CLIE TG50 and N series are Palm OS devices with built-in thumb-boards which are an alternative to stylus-driven data input. High-end Palm handhelds offer MP3 playback and voice recording features that are standard on all Pocket PCs. Phone-hybrids, Internet and e-mail functions and digital cameras also are available on some models of Palm OS and Pocket PC devices.

In summary, a clear understanding of your handheld needs should guide your decision-making. If all that you require is quick and simple calendaring, reminders and contact management, then an inexpensive Palm OS handheld should suffice. If you foresee your handheld as a medical information resource at the point of care, look to an expandable Palm OS device or a low-end Pocket PC. Finally, if you have greater multimedia demands, desire a colour screen, and would like to play MP3s, watch video clips or edit digital pictures, then consider Palm OS 5 devices or a new Pocket PC.