# Train of Four > Smartphone app for measuring train-of-four ratio during anesthesia. (iPhone/iPad app by ObjectGraph LLC.) - Source: https://appshunter.io/ios/app/train-of-four/id975809647 (this page in markdown: same URL + `.md`) - Developer: [ObjectGraph LLC](https://appshunter.io/developer/284700705) - Category: Education, Medical - Price: Free - Rating: 4.80/5 from 4 App Store ratings · 1 written reviews indexed - Age rating: 4+ - Requires: iOS 7.0 · 2 MB - Languages: American English - Released: 2015-08-20 - Data updated: 2026-08-20 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/train-of-four/id975809647/reviews.md ## What is Train of Four? During administration of general anesthesia, neuromuscular blockade is best measured with a train-of-four (TOF) ratio technique, which utilizes a nerve stimulator and a measurement device, such as mechanomyography. During TOF stimulation, the nerve stimulator causes a short burst for four muscle twitches. The force of each twitch is related to the degree of neuromuscular blockade. By dividing 4th to the 1st twitch height, one can assess TOF ratio. The ratio >0.9 is considered as safe for extubation of endotracheal tube and complete reversal from the neuromuscular blockade. Although nerve stimulators are widely accessible to anesthesiologists, the measuring devices are not. Therefore, instead of measuring TOF ratio, anesthesiologist generally rely on count of twitches and pharmacological reversal for everyone. This practice has been shown to be problematic. Data suggest that even mild degrees of residual paralysis (TOF 0.7-0.9) may be associated with significant impairment of respiratory and pharyngeal muscle function. Several studies have demonstrated that many patients continue to arrive in the postanesthesia care unit with TOF ratios <0.9. By combining the built in accelerometer in the iPhone along with the app, we have developed an alternative way of measuring the TOF ration. Our app development team included an anesthesia resident (RB) and an attending (MP) who, provided the medically relevant content, and a computer programmer (KT) to translate the vision into the computer's language. The next step will be a validation study of the predictive value of TOF ratio measured by iphone as compared with conventional mechanomyography devices and visual assessment. ## Key features - TOF ratio measurement - Uses iPhone accelerometer - Assesses neuromuscular blockade - Aids in extubation safety - Developed by medical professionals ## Recent user reviews (1 of 1) All indexed reviews: https://appshunter.io/ios/app/train-of-four/id975809647/reviews.md ### 4/5 — The intention is amazing *2021-11-23* I’m an anesthesiologist, and the accelerometer and the sensor for mechanomyography does not always work quite well in our institution. Would you mind if we study the efficacy of this app on our patients? ## Frequently asked questions about Train of Four ### What is the primary function of Train of Four? Train of Four is designed to measure the train-of-four (TOF) ratio, a key indicator for neuromuscular blockade during general anesthesia. It helps anesthesiologists assess when it is safe to extubate a patient. ### How does Train of Four measure the TOF ratio? The app utilizes the built-in accelerometer of an iPhone or iPod to measure the force of muscle twitches during TOF stimulation, providing an alternative to traditional mechanomyography devices. ### Is Train of Four suitable for all devices? Train of Four is currently supported on iPhone and iPod devices. It is rated for ages 4 and up, making it accessible for a wide range of users. ### What is the TOF ratio considered safe for extubation? A TOF ratio greater than 0.9 is generally considered safe for extubation of an endotracheal tube and indicates complete reversal from neuromuscular blockade. ### What is the update frequency for Train of Four? Train of Four was last updated on August 20, 2015, with version 1.0. Further updates would depend on the developer's ongoing development plans. ### What are the user reviews like for Train of Four? Train of Four has received excellent user feedback, boasting a rating of 4.8 stars from 4 ratings, indicating high user satisfaction with its functionality. ### Does Train of Four have ads? No, Train of Four does not contain advertisements. It is a completely ad-free application for users. ### What is the price of Train of Four? Train of Four is available for free. There are no costs associated with downloading or using the application. ## Version history (last 1 release) ### 1.0 — 2015-08-20 This app has been updated by Apple to display the Apple Watch app icon. ## Apps similar to Train of Four | App | Rating | Price | Category | | --- | --- | --- | --- | | [NYSORA360](https://appshunter.io/ios/app/nysora360/id1598340698) | 3.1 (7) | Free | Education | | [ASA My Learning](https://appshunter.io/ios/app/asa-my-learning/id1016602670) | 1.9 (7) | Free | Education | | [Learn ICU](https://appshunter.io/ios/app/learn-icu/id1580836868) | 4.6 (168) | Free | Education | | [Thalamus](https://appshunter.io/ios/app/thalamus/id918406174) | 3.8 (477) | Free | Education | | [MAC Check by NBCRNA](https://appshunter.io/ios/app/mac-check-by-nbcrna/id6475875391) | 1.6 (7) | Free | Education | | [Anesthesia MCQ](https://appshunter.io/ios/app/anesthesia-mcq/id1591819311) | — | Free | Education | ## More apps by ObjectGraph LLC - [iRetroPhone - Rotary Dialer](https://appshunter.io/ios/app/iretrophone-rotary-dialer/id284700702) - [iSeismometer](https://appshunter.io/ios/app/iseismometer/id304190739) - [Fart Piano Free - Make Everyone Laugh](https://appshunter.io/ios/app/fart-piano-free-make-everyone-laugh/id332117986) - [Cat Piano Free HD](https://appshunter.io/ios/app/cat-piano-free-hd/id376752605) - [Halloween Sound Shelf](https://appshunter.io/ios/app/halloween-sound-shelf/id398908619) - [Geo Measure: Area & Distance](https://appshunter.io/ios/app/geo-measure-area-and-distance/id451326903) All apps by ObjectGraph LLC: https://appshunter.io/developer/284700705 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-20.*