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Table of Contents
Year : 2022  |  Volume : 6  |  Issue : 3  |  Page : 182-186

AnesthCalc™ is associated with superior accuracy and faster accomplishment in simulation-based anesthesia drugs dosage calculation

1 Department of Anesthesiology and Intensive Care, Faculty of Medicine, Sriwijaya University—Mohammad Hoesin Hospital, Palembang, Indonesia
2 Department of Anesthesiology and Intensive Care, Kayu Agung Regional Hospital, Indonesia

Date of Submission25-Nov-2021
Date of Decision24-May-2022
Date of Acceptance31-May-2022
Date of Web Publication27-Jul-2022

Correspondence Address:
Mayang Indah Lestari
Department of Anesthesiology and Intensive Care, Faculty of Medicine, Universitas Sriwijaya—Mohammad Hoesin Hospital, Palembang
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/bjoa.bjoa_157_21

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Background: Medication error is one of the barriers to achieving sustainable patient safety. We aim to determine the efficacy and reliability of a smartphone dosage calculator application (AnesthCalc™) when compared with the manual calculation of various anesthetic drugs to prevent medication error. Materials and Methods: This is a pre-test–post-test intervention study. There are 52 participants who included residents in anesthesiology, which is divided into two groups. Each group performed two simulation cases in which they had to calculate drugs dosage in anesthesia settings. One set of cases was performed with the app and the other set was performed manually. The order of drugs and simulation patients was randomized. The accuracy and the deviation of administered drug doses were recorded. Accuracy of dosage was categorized as either accurate (80–100% of target dose) or inaccurate (less than 80%), whereas the deviation of dosage was categorized as either deviant (<50% or >200% of target dose) or safe (between the range). Results: There is a significant increase in the accuracy of calculation between the manual group and that using the app group (from 46% to 92%, a mean increase of 18.29%, P < 0.005). There is a significant decrease in the duration of calculation between without using the app group and with using the app group (from 32.92 to 18.79 s, a mean decrease of 30.55 s, P = 0.001). Conclusion: AnesthCalc™ is a valid and reliable instrument as it increases users’ accuracy and shortens calculating time. AnesthCalc™ may be the potential to reduce calculation errors and may increase patients’ safety.

Keywords: Anesthesia, medication errors, mobile application, patient safety

How to cite this article:
Lestari MI, Zulkifli, Zainal R, Mulia MI. AnesthCalc™ is associated with superior accuracy and faster accomplishment in simulation-based anesthesia drugs dosage calculation. Bali J Anaesthesiol 2022;6:182-6

How to cite this URL:
Lestari MI, Zulkifli, Zainal R, Mulia MI. AnesthCalc™ is associated with superior accuracy and faster accomplishment in simulation-based anesthesia drugs dosage calculation. Bali J Anaesthesiol [serial online] 2022 [cited 2022 Aug 10];6:182-6. Available from: https://www.bjoaonline.com/text.asp?2022/6/3/182/352403

  Introduction Top

One of the barriers to achieving sustainable patient safety is medication error. Medication errors include mistakes in indication, patient identification, timing, drug selection, and more frequently, dose calculation. When medication errors occur, they can produce an impact, not only for patients but also for hospitals. Medication errors can potentially prolong the length of stay in the hospital, increase the cost of treatment, and increase the risk of morbidity and mortality. A review in the USA claimed that medication errors occurred in 8 of 1,000 patients, often as wrong doses and wrong drugs, and accounted for a loss of $8,439 medical expenses.[1]

Anesthesiologists are particularly known for their association with high-alert drugs. High-alert drugs are particular drugs that produce a higher risk of causing significant harm in patients if incorrectly given. Anesthesiologists also have a reasonably unforgiving workload, such as a time-critical work condition and demanding long working hours, so medication error events are likely to ensue. A study in the USA revealed that the administration of anesthetic drugs contributed to 19% of all medication error events. However, the figures were expected to be more eminent due to low reporting.[2] Similarly, a study in Japan reported that about 27% of all medication error incidents in all hospitals involved anesthesia drugs.[3]

Advances in technology make it easier to access information in all fields, including public health services. Anesthetic drug dose calculation technology can provide benefits in anesthesia practice. Programming experts have developed applications, both in a smartphone or computer program,[4],[5],[6] that aim to simplify the calculation of doses for health workers, especially anesthesiologists and nurse anesthetists who are very reliable on the accuracy of drug doses. National surveys in the USA[4],[6],[7] and the UK[8] found that all healthcare providers working in the anesthesiology field, including nurse anesthetists, resident anesthetists, and consultant anesthesiologists, relished using a dose calculator installed in their smartphones and found it helpful in their work when administering anesthetic drugs, whether inhalation, local, or general.

We have been trying to develop an application called AnesthCalc™ to facilitate anesthesiologists and prevent medication errors. This study aims to determine the discrepancy between AnesthCalc™ and manual calculation on accuracy and calculating time of various anesthetics drugs.

  Materials and Methods Top

The study is an analytic observational study with a pre-test–post-test interventional approach. Ethical clearance was from the Institutional Review Board (registry number 13/KEPKRSMH/2020 dated on January 24, 2020). The research subjects were all anesthesia residents at the Faculty of Medicine, Sriwijaya University, Indonesia, who were willing to be included in the study. Research subjects obtained a briefing for consent to their willingness to participate in the study as well as how to operate the application.

Characteristics of research subjects include age, sex, and level of residency. We divide anesthesia residents into three categories: level I (first and second year); level II (third year), and level III (fourth year and up). Research subjects would work on case scenarios manually and then with the help of the AnesthCalc™ application. The fundamental objective of this application is to consolidate the references to find dose information and calculation assistance. This calculator consists of a database containing drugs and their dosage information according to valid pieces of literature. Each subject enters their patient’s age and body weight, after that they select a drug and then calculate the appropriate dose. The app will then present all the comprehensive information for drug administration in a summary. Stepwise, the methods are as described below.

In two simulated scenarios, two groups of the subjects had to calculate and administer the drug administered at the target dose to the examiner. Each subject completed two sets of scenarios: one set without the application and one set using the application. The order of application usage is randomized (either for the first scenario or the last) using computer-generated randomization. Simulation cases are presented to participants on a tablet or paper computer. Case information includes the patient’s weight and age, the vignette, the drug to be administered, and the target dose. The correct dose should be given in milligrams. Subjects then count and administer medication within 120 s, displayed as a countdown on the tablet computer. The two sets of scenarios contain 12 different cases each. As the primary endpoint, the variables to describe the accuracy of a given dose were calculated as follows:

[Accuracy of administered dose = no. of cases with correct dose/total cases × 100%].

A given dose may be incorrect, but may still be safe, underdose, or overdose. As the secondary endpoint, the variables to describe the deviation or the safety of a given dose were calculated as follows:

[Safety of the administered dose = administered dose/target dose × 100%].

We divided the dosing accuracy into two groups. We classified doses within the range of 80–100% of the target dose as “accurate,” and “inaccurate” if otherwise. Meanwhile, we divide the dosing deviation into two groups. We rate doses within the range of 50–200% of the target dose as “safe,” whereas outside the range as “deviated.” Literatures stated that the drug limit deems unsafe to use if given less than 50% or more than 200% of the target dose.[9],[10] After participation in the study, participants were asked to fill out a short questionnaire to provide perceptions, motivations, and interests in using the application. In other words, they were asked to rate applications with “yes” and “no” answers [Table 1].
Table 1: Questionnaire

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We used SPSS 25.0 for data analysis. We analyzed the difference of means between paired groups (pre-test and post-test) using the Wilcoxon test if the data are non-parametric or paired t-test otherwise. We also analyze the difference of proportion between interventions using χ2. A P-value less than 0.05 was considered statistically significant.

  Results Top

A total of 52 anesthesia residents were recruited as subjects [Table 2] with a mean age of 32.35 ± 3.34 years. Based on the accuracy of the quiz, there were 39 subjects (75%) who used the application in the “accurate” category. Meanwhile, when asked to complete the scenario without the app, only 19 subjects (36.5%) landed in the “accurate” category. There was a significant difference in the dosage calculating accuracy proportion between the groups using the application and those not using the application (P < 0.001). Based on the deviation of the dose administered, 38 subjects were using the app (73.1%) and landed within the “deviated” category. Meanwhile, in the group that did not use the application, there were 14 subjects (26.9%) who deviated from the dose. However, statistically, there was no significant difference in the proportion of dose deviations between the groups using the application and those not using the application (P = 0.08).
Table 2: Subjects’ characteristics

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The median accuracy was higher in the group using AnesthCalc™ than the group not using it (92% vs. 46%) [Table 3]. The median dose-processing time was faster in the group using AnesthCalc™ (18.79 vs. 32.92 s). In the analysis of mean difference [Table 4] using Wilcoxon’s test, a significant difference in average accuracy was found in the group using AnesthCalc™ (P < 0.001), with a tendency to increase the final score by 18.29% when using the application. Meanwhile, there was a significantly shorter difference in the mean duration of the calculating dosage in the group using AnesthCalc™ (P = 0.001), with a tendency to decrease the processing time by an average of 30.55 s.
Table 3: Comparison of dose accuracy and dose safety proportion between groups

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Table 4: Comparison of anesthesia dose calculation with AnesthCalc™ and without the app

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According to the feedback questionnaire handed 2 weeks after the simulation, 42 respondents (80.8%) claimed the app to be a helpful tool for safe drug administration and for preventing medication errors. Forty-eight (92.3%) respondents testified that AnesthCalc™ should be implemented into the anesthesia standard procedure so anesthesiologists can use this application in the clinical setting and be part of the curriculum. All 52 respondents said that the app could decrease their stress levels in the workplace. Forty-seven respondents (90.4%) will recommend the app to other anesthesiologists outside their institution if they are given the chance. However, 46 (88.5%) respondents rejected the idea if users need to buy AnesthCalc™ before using it and demand the app to be free.

  Discussion Top

A prudent treatment process, primarily in pharmacology, is crucial to guarantee patient safety. There are several reasons for medication errors during the treatment process. First, errors occur during the prescription of drugs. It can be an incorrect choice of a drug that is contraindicated or intolerable to the patient. Another related reason is that the dosage of the drug might also be miscalculated. Drugs may be prescribed correctly, but an incorrect dosage or poor handling may follow. Dosage calculation errors are the most prevalent etiology of medication errors in the anesthesia field[2],[11] and are accountable for swollen costs in the healthcare economy.[1] This quasi-experimental study suggests that a mobile app offering a dosage calculator may efficiently reduce medication errors in emergency medicine. In the simulated scenarios, the app is proven to potentially decrease the number of calculation errors or mitigate severe medication errors like underdose or overdose, which are a high risk to patient safety. Behest to our apprehension, this study is the first attempt at validating a mobile app in Indonesia, and it demonstrates that the app increases the probability of safe drug usage and vice versa reduces the likelihood of drug dosage deviation.

Medication errors, such as dosage errors or wrong drugs administered, are often underreported in hospitals and purposely not documented in the hospital, mainly because hospitals tend to protect their credibility and reputation by not disclosing such fallacies.[12],[13] To tackle this issue, we choose to hold a prospective simulation to describe the medication errors incidences among our anesthesiology residents. We feel that a supervised prospective simulation in the same place can examine the ability of anesthesiology residents and predict their tendency of errors while working. In this study, we formulate an ideal quiz that consists of at least one commonly used drug in anesthesia settings and validate the quiz first in a pilot test. In our study, we found that 33 out of 52 (63%) residents wrongly calculated their given set of dose quizzes. Our finding is in line with a study in Brazil which found that 91.8% of anesthesiologists experienced an average of 5–7 medication errors per respondent. The most frequent errors were wrong drugs (68.4%), followed by dosage errors (49.1%).[14] Another study in Japan also found that the most frequent medication error experienced by anesthesiologists in Japan between 1999 and 2007 was overdosing (25%), followed by wrong medication administration (23%).[3]

The dosages in the “accurate” dosage range are interpreted as very safe drug usage, as they precisely define the key answers of the quiz. We confidently claim that the frequency of this “safe” drug usage could significantly increase among the users. We still tolerate a dose within 20% of the actual dosage (80–100%) to be accurate because several previous studies revealed that a drug dosage was considered harmful if given <20% of the target dosage.[13],[15],[16] In contrast, deviations of >200% or <50% were labeled “deviated” as they might be considered to cause harm to the patient. We found that the frequency of deviated dosages in groups without the app (14 of 52, 26.9%) was quite similar to the previous studies. Ashcroft et al.[10] found that the prevalence of underdose and overdose among inpatients was 2,174 out of 11,235 visits (19.35%). Larose et al.[16] found that the dosage error happened in 7 of the 80 subjects (9%), this time among pediatricians, and one pediatrician did an average of 7.5 medication errors per 100 prescriptions. By using the AnesthCalc™ app, the large majority of respondents calculated the drugs accurately (75%) and, more importantly, they were in the “safe” dosage range (88.5%) even if they were not accurate. In 2003, Kirk et al.[17] revealed that hospitals that utilized a computerized dose calculator found a decreased medication error rate from 28.2% of cases to 12.6% among 4281 prescriptions. A study on 100 pediatricians in TX, USA found that an electronic dosing calculator created by Murray et al.[18] may reduce the number of medication errors per patient visit. Before the implementation of the app, there were 10 errors in 28,400 visits, compared with after implementation, there was only a single error in 17,900 visits. A study in Germany found that a dose calculation application was valid and well applied in an emergency department setting, with a dosage accuracy of 98% among 74 attending anesthesiologists.[19] The recent finding was a quasi-experiment in Brazil by Jara et al.[20] It found that the implementation of a dosage calculator smartphone app can greatly diminish anesthetic-related deaths upon using doses of ketamine and xylazine (an analog of clonidine) among mice, with astonishing total mortality of 8 in 773 subjects (1.03%) compared with not using the app, which accounted to 17 deaths in 166 (10.3%).

The app had a significant influence on the time the participants needed to calculate the drug dosage. By using the app, respondents exhibit a quicker calculation with a median of 18 s per case. Calculating with the app statistically can save at least 30 s when compared with manual calculation. However, we cannot determine whether the recorded time needed to calculate the dosage was also influenced by the users’ ability to operate the app. Otherwise, the app seems feasible enough to calculate the dose with or without urgent time factors. Furthermore, it increases the self-confidence of the user, as shown by the questionnaire survey. One research supports our finding, which found that nurse anesthetists in MS, USA, who used a dose calculation application E-Calutron™, found a benefit to the accuracy of administering drugs according to the dose.[6] A survey held at a teaching hospital in Philadelphia, PA, USA found that 60% of residency anesthetists, consultants, and nurse anesthetists enjoyed using a mobile application Epocrates™ to calculate anesthetic drug doses every week while on duty.[7] Another survey in Chicago, IL, USA found that anesthetic dose calculators QxMD™ were used more frequently for regional anesthetics and anti-thrombotic drugs among anesthetic consultants because they feel a significant boost in their confidence.[4]

We encounter several limitations. We admit that simulated scenarios will never resemble actual emergencies, as a simulation will discard any external disturbances and physiological stressors that are lacking in the exam setting. These might abbreviate the enthusiasm of using the app or implement the correct approach of the app when applied in a significantly stressful work environment. Secondly, we admit that our respondents’ level of knowledge on anesthetic drugs could not be homogeneous. One because there was an uneven distribution of residents’ education level, and two because we also did not pre-screen the prior default knowledge of each respondent. Thus, there may be a respondent bias occurring in our population. A group of freshmen may not have previous experience in dosage calculation, whereas the senior ones already have a broader knowledge of dosages and can use it in their agenda. That is why we suggest doing a further study on a wider scale of the anesthesiology population (emergency/outpatient settings, residents/attending consultants, and more) to abolish the blurred lines between the two and generalize the use of the dosage calculator application. Furthermore, future studies need to consider and analyze those contributing factors which might be related to the ability to use a dosage calculator application as, like many other clinical instruments, there is a strong possibility that a dosage calculator is an operator-dependent modality.

  Conclusion Top

The AnesthCalc™ mobile app can be a valid, reliable, and feasible tool to reduce calculation errors in drug administration among anesthesiologists. With a simple mobile app, the utilization of a standard smartphone may contribute a positive impact on perioperative or critical patient safety. A more comprehensive mobile app that combines medical literature database, calculator (both clinical and drug dosage), formulary, or a time organizer for drug administration should be further developed and tested in clinical studies to increase healthcare providers’ productivity.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Table 1], [Table 2], [Table 3], [Table 4]


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