Designing safety-critical devices - using the right methodology | Insight, issue 2
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This document summarizes a medical device development methodology created by Team to safely develop devices that enhance user experience and ensure patient safety. The methodology separates safety-critical and user-focused functions to minimize risks from user error or technical issues. It begins with thorough user analysis to identify necessary versus desired functions and optimal user interfaces. A medical system architecture then implements separated safety-critical and user-focused components with independent power, memory and outputs. The methodology aims to deliver regulatory-approved devices that are desirable, appropriate and most importantly safe for users.
Designing safety-critical devices - using the right methodology | Insight, issue 2
- 1. Team / insight. Safety-critical medical functions User focussed functions Battery Button Keypad Basic User Interface Memory RF Bluetooth Zigbee Wi-Fi Cellular GPS Battery Power Mgt Export Power Mgt Microcontroller Sensor Heart Rate Blood pressure Temperature Glucose meter Output Pump Drug delivery Pacemaker Emergency call Location Processor Advanced user interface Data Management Capacitive Touch Wireless COMS Internal External Flash SD Wired COMS Ethernet Phone Health 2.0 Web portal Data Mining Server Internet PSTN Emergency Designing safety-critical devices – using the right methodology BY SEBAST I EN C UV E L I E R M U S S A L I A N Offering enhanced usability and functionality may run the risk of compromising patient safety, but by using a structured development methodology developers can help ensure that safety-critical devices remain safe. Although good design plays an important role in the market success of electronic devices, users often confuse good design with increased functionality. However, as discussed in the last issue of Insight, it’s well known that increased functionality can increase user error – acceptable perhaps in a mobile phone, but not in a safety-critical device. To address this problem, Team has created a methodology specifically designed to deliver safety-critical products which both enhance the user experience and ensure patient safety. Our methodology encompasses the entire design lifecycle, from requirements definition through to eventual manufacturing support, and begins with a thorough analysis of the end user. The aim is to identify - and then to separate - the functions users desire from those they need, while also determining the user interface design that best fits the eventual application. We then introduce our medical system architecture (above) to the design process. This architecture deliberately separates safety-critical and userfocused functions in order to minimise the risk of failure caused by user error or technical malfunction. For example, users may say they want a touch screen, even though such a screen makes it much easier to ‘press’ the wrong ‘button’; touch screens also require power, and if the screen should fail then users may not be able to access essential controls. Our system architecture makes sure that such controls are not affected by the failure of less important functionality, or compromised if such functionality causes user error, perhaps due to mishandling or stress. In the example of the touch screen, this means providing additional, physical buttons with independent power supply, memory and output.
- 2. www.team-consulting.com The regulatory framework for safetycritical devices is particularly demanding and so must also be acknowledged early in the development process, with a system in place for continuous documentation and reporting. SOUPs, or software of unknown provenance, can be an area of specific concern. These often feature in multifunctional devices, and although not necessarily a problem in isolation, when combined may result in unexpected outcomes which regulators want to see thoroughly researched and tested. This provides just a brief snapshot of the extensive process we use in the development of safety-critical devices, a process we find is becoming increasingly relevant as many such devices move out of the clinically controlled environment and into the home. Greater patient freedom, however, brings greater patient risk; our methodology aims to minimise this risk from the outset in order to deliver devices designed with regulatory approval in mind, and which users will find desirable, functionally appropriate and - above all - safe. 22 — 23 EVENTS DID YOU SEE US? DO YOU WANT TO MEET? Injectable Drug Delivery (March 2012, London) RDD 2012 (13-17 May 2012, Phoenix) Andy Fry presented ‘Are electronically enabled delivery devices (EEDDs) the future? Colin Mathews is moderating a session on human factors and Team will have a stand Strategies for Commercial Success of Biosimilars (April 2012, New York) PDA Universe of Pre-filled Syringes (15-17 October, Las Vegas) Andrew Pocock presented ‘Device development for biosimilars’ European Pre-filled Syringes (January 2012, London) Colin Mathews and Andy Fry ran a workshop on auto-injectors DDL22 (December 2011, Edinburgh) David Harris presented ‘Choosing the right device: the case for DPIs’ PDA Universe of Pre-filled Syringes (November 2011, Basel) — Sebastien is part of the electromechanical engineering team where he works on a range of complex medical systems and products. sebastien.cuvelier-mussalian@teamconsulting.com Andy Fry delivered a keynote on ‘Parenteral drug delivery in the future: a view of developments, implications and opportunities’ You can view our articles and presentations on slideshare: slideshare.net/team_medical Team is hoping to speak at the conference and we will have a stand DID YOU READ? Inhalation, June 2012 – David Harris on the technical challenges of designing a DPI Therapeutic Delivery, July 2012 – Andy Fry on electronically enabled delivery devices (EEDDs) EMDT, July 2012 – Steve Augustyn on DFx and its benefit over DFMA Journal of Diabetes Science and Technology, July 2012 – Andy Fry on future injection technologies EMDT, November 2011 – Philip Canner on the unique challenges of fluid handling GEN, November 2011 – Stuart Kay on reducing the cost of regenerative medicine technology