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Time & Time Again

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This blog post is dedicated to the updates made in SimTIVA since start of the year 2024 up to April. In my last blog post, I mentioned that SimTIVA simulations are based on 2 hour infusions by default. However, receiving multiple feedback from users (thank you!), this seems to be a major constraint clinically as anaesthetists may use SimTIVA to guide infusions lasting over 2 hours. I have changed the default infusion scheme data generation to cover 6 hours so as to maximize the convenience to the user. So, for every change in the infusion rate, or starting/changing of a target in CPT/CET scheme, the infusion data will cover 6 hours starting from the time of change. To clarify, this doesn't mean that SimTIVA program ends in 6 hours time, it merely means that starting from the last time you have started/changed the infusion rate or CPT/CET target, the data will last for 6 hours. To continue using SimTIVA before that time limit expires, simply enter another infusion rate or CPT/CET ta
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Time

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 One characteristic of SimTIVA is that it is meant to run in real time at the bed side. That means, you may run SimTIVA in parallel with what you are infusing in real time when doing an actual clinical case. However, time management in a browser, or specifically when using JavaScript to code, is not so simple. Erratic behavior can occur. For example, the mobile device running SimTIVA can go to "sleep" mode, or the tab running SimTIVA may not be active, and all these myriad of scenarios may cause the clock to stop ticking if programming is done poorly and this needs to be taken into account to match the SimTIVA time with "real time".  SimTIVA manages time like this. When the user "delivers" an infusion scheme, data are generated for every second for CP, CE, and infusion rate, among other things, for the next 7,200 seconds (or 2 hours). There are series of 7,200 data points for each of CP, CE, and infusion rate. When simulation is running, the current time i
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Journey

STANPUMP and Open Source SimTIVA's mathetical calculations to PKPD are based on STANPUMP, a computer program created by Dr. Steven Shafer, written in C programming language and runs on MS-DOS. As its core, STANPUMP gives SimTIVA the ability to solve the equations to CP and CE targeting. It is very generous and visionary of Dr. Shafer to share the source code to STANPUMP on the public domain (available on OpenTCI ) so that many other PK and TCI simulators could be built upon STANPUMP's pharmacokinetic engine, not to mention many more pump manufacturers who build TCI pumps based on Dr. Shafer's work. My programming skills are limited. SimTIVA started off as a small personal project, and my initial task was to transcribe STANPUMP (written in C) to JavaScript, which I am more familiar with. Today, SimTIVA has grown into a somewhat mature product and has attracted some international recognition. This is a stage which I had not imagined. To take this project forward, as encourage
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Minor Update & Twitter/X

 Hi! SimTIVA has been updated, to introduce the following improvements iPhone functionality has been dramatically improved Fullscreen mode: on the main chart, you can click the "expand" icon to show the chart in fullscreen. This is an improvement after feedback that the chart is small and cannot display much information. Whereas on the fullscreen chart, the infusion regimen, with bolus and rate changes, are visualized on the graph over time - to help understand the relationship between dosing regimen and its effect on CP/CE. Added Alfentanil https://twitter.com/simtiva_app Also, I have been active on Twitter / X as well. You may contact me on Twitter / X for comments, ideas, and suggestions. Twitter and social media are more suitable for discussions. I also offer occasional video tutorials and insights on the Twitter feed. Thanks!
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Major Update

 Today marks the major update of Simtiva to V4. A long hiatus occurred between V3 and V4, the development of this change was in progress for one year. The main reason for the time spent in development was the introduction of a "complex mode", or a dual mode, which propofol and opioid (remifentanil or fentanyl) simulations can be run simultaneously. The unique advantage of having a "complex mode" is to explore the pharmacodynamic (PD) interaction between these the hypnotic-analgesic combination. A preset endpoint, the probability of tolerance to laryngoscopy (PTOL) was chosen as the measure to quantify the combined effect of these two drugs. A isobologram chart allows the user to explore different combinations of propofol-remifentanil to achieve the exact same PD effect along the same isobole curve. Moreover, the isobologram chart is sensitive to time, as time progresses, the current time point, as marked by a bright red dot, will move on the screen, with the past an
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Progressive Web App: Why?

SimTIVA is a progressive web app (PWA). For those unfamiliar with this term, PWA's are are web apps built and enhanced with modern APIs to deliver enhanced capabilities, reliability, and installability while reaching anyone, anywhere, on any device, all with a single codebase (from web.dev). Why progressive web app and not just an ordinary app? Users are often confused by this question, why isn't SimTIVA put on App Stores (Google Play, Apple App Store) like many other apps? In fact, modern web browser technology has become so mature in recent years that a "web app" can function within the browser window very much like an app you install from App Store on your smartphones. The trend is quite remarkable. If you have experienced using some of these progressive web app products, such as Google News, or Spotify Web Player, the web app looks and works like an app you install from the App Store. The major advantages of having SimTIVA as a web app are: No restrictions imposed
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Origin

Welcome to SimTIVA blog.  SimTIVA is a program which simulates the behaviour of a target-controlled infusion pump. It is similar to other existing programs, such as TIVA trainer on PC's, and iTIVA on smartphones. But the major differences are: SimTIVA is completely free; and also it can be run on any browser, on computers and smartphones. Origin of the project The idea started in October 2020, almost one year ago. At that time, I have already developed a paediatric calculator app, which has branched off into anaesthetist's and paediatric intensivist's versions (you can read more about the paediatric calculator project here ). I wanted to use the experience for something else, something more.  The clinical question is like this. If you give propofol, after a bolus, it enters the bloodstream and will eventually reach the brain (the effect site) and exert its anaesthetic effect. The plasma concentration and the effect site concentration are expressed as CP and CE respectively
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