Development and Preliminary Validation of LoAD Calc, a Mobile App for Calculating the Maximum Safe Single Dose of Local Anesthetics

Abstract

Local anesthetics systemic toxicity can lead to life-threatening situations. Correct calculation of the maximum safe dose is therefore paramount in preventing such complications. Different solutions have already emerged to support anesthesiologists but are seldom used in clinical practice as they require either access to a computer or specific documents to be at hand. A mobile app could provide an easy and practical solution; however, the few apps already created for this purpose often lack key elements, allowing invalid data to be entered and suggesting doses that might exceed the maximum safe dose. We describe the development of LoAD Calc, a mobile health (mHealth) app developed using a modified version of the Information Systems Research framework, which adds design thinking modes to the original framework. The app was enhanced through multiple iterations and developed with the aid of contextual observations and interviews, brainswarming sessions, prototyping, and continuous feedback. The design process led to the creation of two prototypes which underwent thorough testing by a sample of eight anesthesiologists. The final version of the app, LoAD Calc, was deployed on Apple and Android mobile test platforms and tested again by the same sample until deemed fit for release.

Impact of a Mobile App (LoAD Calc) on the Calculation of Maximum Safe Doses of Local Anesthetics: Protocol for a Randomized Controlled Trial

“…For each vignette, 3 authors will be required to determine the maximum dose of LA the simulated patient should receive according to the rules used to develop the LoAD Calc app [ 12 ], without using the app. These rules, which are derived from the scientific literature, are summarized in Textbox 1 .…”

“…To facilitate the calculation of safe maximum LA doses, a mobile health (mHealth) app, Local Anesthetics Dose Calculator (LoAD Calc), was developed at the Geneva University Hospitals [ 12 ]. This app takes all relevant parameters (IBW and actual weight, height, age, medications, and comorbidities) into account and allows the use of a mixture of 2 different LAs.…”

Perioperative medical emergencies: The role of clinical pharmacists and a review of pharmacotherapy considerations

“…Doses of local anesthetics should be calculated based on ideal body weight and compared with suggested weight-based and non-weight-based maximums, with consideration of further downward dose adjustment based on the number and severity of LAST risk factors present. 29,31,[47][48][49] Suggested maximum local anesthetic doses range in the published literature owing to the limited quality of available data upon which to base these recommendations, and the true patient-specific maximum dose will vary based on a complex interplay of factors. 29,47 Detailed dosing and safety considerations for the use of intravenous lidocaine infusions are discussed in a separate consensus statement.…”

“…This complex determination involves assessing for patient‐, medication‐, and administration‐related risk factors for LAST (Table 6), calculating the total proposed local anesthetic exposure from all sources, comparing this with best available recommendations for maximum safe drug exposure (Table 7), and working with the interprofessional team to adjust, document, and monitor the plan accordingly. Doses of local anesthetics should be calculated based on ideal body weight and compared with suggested weight‐based and non‐weight‐based maximums, with consideration of further downward dose adjustment based on the number and severity of LAST risk factors present 29,31,47–49 . Suggested maximum local anesthetic doses range in the published literature owing to the limited quality of available data upon which to base these recommendations, and the true patient‐specific maximum dose will vary based on a complex interplay of factors 29,47 .…”

“…Suggested maximum doses of local anesthetics 29,[47][48][49]. The maximum safe dose for a particular patient may vary significantly and many other factors should be considered; weight-based doses should be based upon ideal body weight and adjusted downward by 10%-20% based on number and severity of LAST risk factors (see text and references); use smaller of the two listed doses.T A B L E 8 Medication therapies for pheochromocytoma and paraganglioma 40,[53][54][55].…”