Refinements in the dimensional analysis method of dose calculation problem-solving

The use of ratio and proportion, dimensional analysis, and equations to solve pharmacy calculations problems

INTRODUCTION

To evaluate the effects of using different problem-solving approaches on the success rates of student pharmacists in solving problems throughout a pharmacy calculations course.

METHODS

A survey was administered to first-year students (N = 96, response rate 100%) near the completion of a pharmacy calculations course. The survey assessed whether students used the approaches of ratio and proportion (RP) or equations vs. dimensional analysis (DA) to solve calculation problems involving conversions, weight-based doses, flow rates, electrolyte solutions, and expressions of concentration. Questions used on course exams were tagged according to topics. Mean success rates in solving tagged questions were correlated with the problem-solving approaches that students used.

RESULTS

Approximately 60% of students used RP/equations, 30% used DA, and 10% used both approaches equally. The success rate of students solving conversions was 74% ± 24% for RP, 84% ± 14% for DA (P < .05 vs. RP), and 91% ± 12% for the use of both approaches equally (P < .05 vs. RP). Success rates in solving calculation problems of weight-based doses, flow rates, electrolyte solutions, and expressions of concentration were similar across all approaches.

CONCLUSIONS

The use of DA, or the combination of RP and DA equally, may be advantageous for solving conversions but not for the other types of calculation problems studied. Therefore, for most topics, pharmacy calculations instructors can demonstrate the method of their choice. Since a considerable number of students use each of the approaches, the demonstration of both approaches in class may be advantageous.

How do nurses solve drug calculation problems?

This article reports on a pilot study that examined the cognitive processes and strategies used by senior nurses to solve written drug calculation problems.

METHODOLOGY

Verbal protocol methodology was used to gain and analyse data from eight senior nurses now working in the education setting. The data was analysed using verbal protocol analysis.

RESULTS

Nurses used a range of strategies to solve the problems, not just the nursing formula. The cognitive processes of the nurses showed a larger number of steps devoted to problem representation and only a few steps devoted to actually solving the problem.

CONCLUSION

Nurse educators need to consider the importance of problem representation in solving drug calculations and in particular ensure that written questions are representative of clinical practice.

Safety in numbers 7: Veni, vidi, duci: a grounded theory evaluation of nursing students' medication dosage calculation problem-solving schemata construction

This paper evaluates nursing students' transition through schemata construction and competence development in medication dosage calculation problem-solving (MDC-PS). We advance a grounded theory from interview data that reflects the experiences and perceptions of two groups of undergraduate pre-registration nursing students: eight students exposed to a prototype authentic MDC-PS environment and didactic transmission methods of education and 15 final year students exposed to the safeMedicate authentic MDC-PS environment. We advance a theory of how classroom-based 'chalk and talk' didactic transmission environments offered multiple barriers to accurate MDC-PS schemata construction among novice students. While conversely it was universally perceived by all students that authentic learning and assessment environments enabled MDC-PS schemata construction through facilitating: 'seeing' the authentic features of medication dosage problems; context-based and situational learning; learning within a scaffolded environment that supported construction of cognitive links between the concrete world of clinical MDC-PS and the abstract world of mathematics; and confidence-building in their cognitive and functional competence ability. Drawing on the principle of veni, vidi, duci (I came, I saw, I calculated), we combined the two sets of evaluations to offer a grounded theoretical basis for schemata construction and competence development within this critical domain of professional practice.

Can effective teaching and learning strategies help student nurses to retain drug calculation skills?

Student nurses need to develop and retain drug calculation skills in order accurately to calculate drug dosages in clinical practice. If student nurses are to qualify and be fit to practise accurate drug calculation skills, then educational strategies need to not only show that the skills of student nurses have improved but that these skills have been retained over a period of time. A quasi-experimental approach was used to test the effectiveness of a range of strategies in improving retention of drug calculation skills. The results from an IV additive drug calculation test were used to compare the drug calculation skills of student nurses between two groups of students who had received different approaches to teaching drug calculation skills. The sample group received specific teaching and learning strategies in relation to drug calculation skills and the second group received only lectures on drug calculation skills. All test results for students were anonymous. The results from the test for both groups were statistically analysed using the Mann Whitney test to ascertain whether the range of strategies improved the results for the IV additive test. The results were further analysed and compared to ascertain the types and numbers of errors made in each of the sample groups. The results showed that there is a highly significant difference between the two samples using a two-tailed test (U=39.5, p<0.001). The strategies implemented therefore did make a difference to the retention of drug calculation skills in the students in the intervention group. Further research is required into the retention of drug calculation skills by students and nurses, but there does appears to be evidence to suggest that sound teaching and learning strategies do result in better retention of drug calculation skills.

Student nurses need more than maths to improve their drug calculating skills

Nurses need to be able to calculate accurate drug calculations in order to safely administer drugs to their patients (NMC, 2002). Studies have shown however that nurses do not always have the necessary skills to calculate accurate drug dosages and are potentially administering incorrect dosages of drugs to their patients (Hutton, M. 1998. Nursing Mathematics: the importance of application. Nursing Standard 13(11), 35-38; Kapborg, I. 1994. Calculation and administration of drug dosage by Swedish nurses, Student Nurses and Physicians. International Journal for Quality in Health Care 6(4), 389-395; O'Shea, E. 1999. Factors contributing to medication errors: a literature review. Journal of Advanced Nursing 8, 496-504; Wilson, A. 2003. Nurses maths: researching a practical approach. Nursing Standard 17(47), 33-36). The literature indicates that in order to improve drug calculations strategies need to focus on both the mathematical skills and conceptual skills of student nurses so they can interpret clinical data into drug calculations to be solved. A study was undertaken to investigate the effectiveness of implementing several strategies which focussed on developing the mathematical and conceptual skills of student nurses to improve their drug calculation skills. The study found that implementing a range of strategies which addressed these two developmental areas significantly improved the drug calculation skills of nurses. The study also indicates that a range of strategies has the potential ensuring that the skills taught are retained by the student nurses. Although the strategies significantly improved the drug calculation skills of student nurses, the fact that only 2 students were able to achieve 100% in their drug calculation test indicates a need for further research into this area.

Use of dimensional analysis to reduce medication errors

The purpose of this pilot study was to determine whether using dimensional analysis as the method of mathematical computation could reduce nursing medication calculation errors. The sample for this study consisted of second-year baccalaureate nursing students in a required clinical skills course. Students in the control group were taught medication calculations using the traditional math method during one semester, whereas students in the experimental group were taught the same material using dimensional analysis during the next semester. Analysis of the collected data from a medication dosage calculation examination revealed the dimensional analysis group scored with greater accuracy than the traditional math group.

An investigation to find strategies to improve student nurses' maths skills

Being able to perform drug calculations accurately is an essential skill for nurses. Many studies, however, have demonstrated that nurses need to improve this area of their practice and in particular their mathematical skills. Several strategies have been implemented to develop the drug calculation skills of nurses, with mixed success. This article reports on a study that was carried out to investigate whether strategies implemented within a second-year pre-registration course were perceived by students to be helpful in improving their mathematical skills for drug calculations. The results demonstrated that students felt their mathematics and confidence improved as a result of these strategies. The students' evaluation of the learning strategy that they found most helpful in learning drug calculation gave a mixed result, indicating that students have differing learning styles and needs. The study also indicates that student nurses were able to integrate the mathematical skills into their nursing practice by having different strategies that allowed them to develop conceptual, mathematical and practical skills concurrently. The study recommends the implementation of integrated strategies to address drug calculation skills in student nurses, although further research is still required.

Clinical skills: a practical guide to working out drug calculations

With the publication "Building a Safer NHS for Patients" (Department of Health (DoH), 2004), the importance of ensuring safe medication administration has returned to the NHS agenda. Over the last 10 years, nurses' deficiency in accurate drug calculations has been highlighted. A number of proactive strategies have been employed, including increased focus on the topic during undergraduate training programmes, drug calculation tests and, more recently, providing information via hospital intranet sites. This article attempts to describe the basic drug calculation formulae required to calculate medication doses safely and accurately and administration rates, giving working examples to apply theory to clinical practice.

The 4 Cs: a model for teaching dosage calculation

Performing dosage calculation can be viewed as the ability to perform the 4 Cs: compute, convert, conceptualize, and critically evaluate. Ability to perform the 4 Cs is dependent on a variety of student and program factors. A model for teaching dosage calculation, grounded in research on mathematical success, is presented. Strategies for teaching dosage calculation based on this model are discussed.