Resources

Clinical calculators for hand-held computers

Stewart Cameron, MD, CCFP

Hand-held computers provide assistance at the point of care for a variety of common clinical decisions. They could help you save time and reduce errors in determining therapy.1

Clinical calculators are popular applications among those who use hand-held computers or personal digital assistants (PDAs). They can be especially useful for family physicians. Clinical calculators can quickly execute a number of formulas for patient management. At the very least they can check and confirm calculations done the traditional way.

Dozens of medical calculators do single functions, from timing labour contractions to determining IV rates. This article describes several multifunction medical calculators for the Palm operating system (OS) that were available at no cost at the time of writing.

MedCalc is one of the best-known Palm OS calculators for physicians. The program was written by Mathias Tschopp, MD, and is available from his website at medcalc.med-ia.net. MedCalc focuses primarily on internal medicine. The version available at the time of writing had 76 formulas, and the list is growing. Formulas can be grouped by type on the home menu screen (eg, Renal, Electrolytes, Cardiology). References for the formulas and even a few practice tips are included. The program is available in English and French.

MedCalc will also let you specify your preference for units. You can change units on the fly and mix them (eg, calculate body mass index by entering height in inches and weight in kilograms). While few family physicians will want to know the cardiac valve area, there are useful formulas that estimate creatinine clearance, anion gap determination, pregnancy dates, steroid equivalency, Apgar scores, coronary artery disease risk, and the Glasgow coma scale. I recently cared for a hospital patient with hyponatremia and used MedCalc to get a formula that accurately predicted the change in serum sodium based on patient age, weight, and type of infusion administered. MedCalc also offers some evidence-based medicine formulas, such as number needed to treat and pretest and posttest probabilities. It has an infusion manager that can quickly determine required IV rates to provide dosages.

The main program takes only 244 K of memory. It also uses MathLib, a program that does a variety of math functions and can be shared by other applications. MedCalc is very easy to use. Most people will be able to work with it completely without instruction. It even allows you to save values on specific patients for later reference. A user group serves those interested in enhancing functionality.

MedCalc should not be confused with MediCalc, a similar but older program designed by David Monbaron. That program, while still available, has not been maintained since it became freeware in 2000. The source code is made available if you have the time and talent to reconfigure it at http://www.angelfire.com/ms/medicalc/.

MedMath, a similar program from Dr Phillip Cheng, has been around since 1999. It can be downloaded from http://smi-web.stanford.edu/people/pcheng/medmath/index.html. It is a much smaller program than MedCalc, requiring only 40 K of memory and needing no math library files. It runs on virtually all Palm devices, even those with older OS versions. It offers 34 formulas that are essentially a subset of those in MedCalc. It has the handy feature of including a numeric keypad on the screen so you can avoid writing numbers altogether. (MedCalc can summon up the Palm keyboard, but the process needs to be repeated for each field, which is quite clumsy.) You can file your favourite formulas or review the last ones used. MedMath allows for either SI or conventional units. The program does not save patient data and is available in English only.

Archimedes is the newest PDA medical calculator. It is available free from Skyscape, a large publisher of medical software for hand-held computers (www.skyscape.com). This offering has a few features that make it an attractive alternative. For starters, it looks better on colour screens, which are rapidly becoming standard in entry-level PDAs. It, too, remembers the last few calculations you did so the formulas you use most are readily available. It also has a link that can take you to other Skyscape titles on your PDA. To reduce screen clutter with the dozens of formulas, they can be viewed by system. You can get a formula by typing the first few letters of its name and the software will present options to choose from, something MedCalc does as well. If you get totally lost, you can search for formulas you need. There are some imperial and metric converters for length, mass, and temperature. There is a help function that often provides normal ranges for the values you are interested in. Archimedes takes up just over 660 Kb of memory.

Archimedes also has some drawbacks. You cannot file the calculations in your own categories, so you will be always wading through formulas you might never need. It also does not have some formulas that are especially useful to family physicians, such as a coronary risk calculator or a pregnancy calculator. There is no ability to use SI units, so if your laboratory reports in this system (as most Canadian ones do), you are out of luck with Archimedes. It also does not appear to be available in French either.

All the above products run on PDAs using the latest version of the Palm OS, version 5. These products are constantly being updated, so missing features are often added to new versions.

If you want to browse single-function programs, many free PDA calculators perform specialized medical functions. A good place to start browsing would be http://pda.tucows.com/palm/calc_med.html.

It is a little frustrating, but none of the calculators mentioned here check your entries for errors. If you make a mistake and input an impossible value, each will faithfully calculate a ridiculous result. This would be a simple thing to correct, and we hope such a feature could be incorporated into future releases. As they all remind you, clinical judgment must prevail. As useful as hand-held computers are, you should not base patient care decisions solely on what your PDA tells you!

Gatifloxacin: hypoglycemia and hyperglycemia Gatifloxacin (Tequin) is a broad-spectrum antibacterial fluoroquinolone with activity against Gram-negative and Gram-positive aerobic and anaerobic microorganisms. It is also effective against clinically important atypical microorganisms.

Dr Cameron is an Associate Professor in the Department of Family Medicine at Dalhousie University in Halifax, NS.

Reference

1. Rothschild JM, Lee HT, Bae T, Bates DW. Clinician use of a palmtop drug reference guide. J Am Med Informatics Assoc 2002;9(3):223-9.

Adverse drug reactions in Canada

• Hypoglycemia and hyperglycemia have been reported following the use of gatifloxacin, usually but not always in diabetic patients.
• Hypoglycemic reactions frequently occurred within the first day of therapy and usually within 3 days. These reactions were reported in diabetic patients receiving either sulfonylurea or nonsulfonylurea oral hypoglycemic medications.
• Most hyperglycemic reactions occurred 4 to 10 days after start of therapy; very elderly patients (>75 years) who might have unrecognized diabetes, age-related decrease in renal function, or underlying medical problems or who are taking concomitant medications associated with hyperglycemia could be at particular risk.
• Blood glucose levels should be monitored carefully when gatifloxacin is used for diabetic patients.
• Gatifloxacin therapy should be stopped and appropriate treatment started immediately if any signs or symptoms of hypoglycemia or hyperglycemia appear.
• Gatifloxacin is mainly eliminated by the kidneys; therefore, a reduced dose is recommended for patients with a creatinine clearance of <0.67 mL/s (40 mL/min).
• Patients should be educated about these possible adverse reactions with gatifloxacin.

Source: Canadian Adverse Reaction Newsletter 2003;13(3)3:1-2. For the complete text of any of these reports, check the website www.hc-sc.gc.ca/hpfb-dgpsa/tpd-dpt/index_adverse_newsletter_e.html.

Improving competence in maternity care

Women’s Advanced Maternity Fellowship for Rural Practitioners

Susan J. Harris, MD, CCFP  Michael C. Klein, MD, CCFP, FCFP

We are pleased to announce that the Women’s Advanced Maternity Fellowship for Rural Practitioners is now being offered through generous donations from Weyerhaeuser, Bank of Montreal, Bell Canada, Provincial Health Services Authority, Zellers, and Interior Health Authority. These organizations have offered support to further the provincial mandate of BC Women’s Hospital and Health Centre to provide competent maternity care to all women and babies in British Columbia.

What does this initiative mean for the communities of British Columbia? First, it offers additional support for physicians to develop and maintain skills in maternity and newborn care and augments the Enhanced Skills Program offered by the University of British Columbia (UBC) and the Rural Education Action Plan.

Second, the initiative offers educational programs for nurses from communities in need. The program will be tailored to the needs of individual nurses and their communities and will include components from the British Columbia Reproductive Care Program, British Columbia Institute of Technology, and BC Women’s Hospital nursing education programs. The initiative also can fund education for midwives or other health professionals providing maternity care. Sponsors aim to build and sustain the entire maternity care team, as all members are needed to keep maternity care in rural areas viable.

Finally, some funds in this initiative are dedicated to further development of Women’s Telehealth: this means that the program will provide support for existing Telehealth connections and programs, curriculum development, and other Telehealth projects.

Funds will be distributed under the guidance of the Advanced Maternity Fellowship Committee, which includes Peter Newbery (Postgraduate Director, UBC Department of Family Practice), Laurie Seymour (nurse at BC Women’s Hospital), Patty Keith (BC Reproductive Care Program), Gerry Marquette (Head of the Department of Obstetrics at BC Women’s Hospital), Susan Harris, and Michael Klein. We are grateful for the support of our donors and partners in the development of the Women’s Advanced Maternity Fellowship and look forward to improved maternity and newborn care in British Columbia. We hope that this enterprise becomes a model for other provinces and communities.

Further information and application forms can be found at http://www.womensfoundation.ca.

Dr Harris is Head of the Department of Family Practice at the BC Women’s Hospital and Health Centre. Dr Klein is Head of the Division of Maternity and Newborn Care at the University of British Columbia’s Department of Family Practice in Vancouver.

Positional plagiocephaly and sleep positioning

Summary of Canadian Paediatric Society statement

Parents are encouraged to place infants on their backs to reduce the risk of sudden infant death syndrome. This can lead to posterior flattening of the skull. The Canadian Paediatric Society position statement on positional plagiocephaly (flat head) describes strategies to prevent this condition: placing the head in different positions on alternate days and, while the infant is awake, having supervised “tummy time.” An information sheet explaining this policy for parents is included in the statement. Visit the website (www.cps.ca) for the full statement.