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Modern anesthesia monitors that are commonly used in operating rooms such as GE Datex S/5 (System 5) series monitor (GE Datex Ohmeda, Helsinki, Finland) allows external data logging through its RS 232 (Recommended standard 232) serial communications port on the monitor. A large set of physiological data can be captured in real time such as invasive or non-invasive arterial blood pressure, ECG, ST segment data, oxygen saturation, end-tidal carbon dioxide, anesthetic agent identification and concentration, temperature, entropy, BIS, EEG. Logging of this data is important for documentation and research purposes.[1] Capturing these vital signs can allow for statistical analysis, development of models of anesthetic maintenance and recovery, hemodynamic-respiratory interactions.[2] Automated data capture and record-keeping accurately stores events that maybe otherwise omitted in manual data logging.[3] These data capture components maybe used to develop anaesthesia information management systems that help in quality assurance.[4]
The RS 232 communication port maybe identified through its standard male 9 pin D-shaped connector on the backend of the GE Datex S/5 monitor. The user may refer to the user manual for confirmation. Physiological data is sent from the monitor on request through this port, at a time interval of 5 seconds or greater, by a valid binary data-frame request constructed by client software with checksum verification of both sent and received bytes. These frames are transmitted in 8-bit binary format using hardware handshaking.
We describe an open source tool VSCapture developed in C# programming language on the .NET/Mono platform that allows the tool to run on Windows, Macintosh OS X, Linux Ubuntu operating systems. Unlike commercial solutions that cost several thousands of dollars and maybe available only for limited operating systems, this tool can be freely downloaded and installed from its project page https://sourceforge.net/projects/vscapture/. The program requires the .NET 4 runtime that maybe downloaded and installed on Windows operating system from the Microsoft download page http://www.microsoft.com/en-us/download/details.aspx?id = 17718. Running the program on Linux or Macintosh OS X requires a Mono version of VSCapture that can be installed from the project website, also required is a Mono runtime from http://www.go-mono.com/mono-downloads/download.html (Xamarin Inc, USA). The capture of data is based on an event-triggering programming paradigm at the serial port.
Hardware requirements for interfacing a PC with the anaesthesia monitor, includes a serial port and a standard null modem serial cable. Most modern laptop computers do not have this RS 232 serial port. However, inexpensive converter cables that plug into the Universal Serial Bus (USB) port of the laptop and provide a serial port conversion are commercially available, such as Future Technology Devices International (FTDI limited, UK) or PL2303 (Prolific Technology Inc., Taiwan) chip-based USB-serial cables. In addition, an inexpensive standard null modem serial 9 pin D-shaped female-female cable is required to connect the serial port of the PC to the serial port of the monitor. After the software is opened, the cables can be connected, the user is then prompted to select the port to which the cable has been assigned. In Windows operating system, looking up the hardware Device Manager can reveal the COM port number. In Linux and Macintosh OS X operating systems, the name can be obtained from the list of available ports shown by the software such as/dev/ttyUSB0 or driver specific names. The next step involves entering a 5 second or greater data transmission interval in the software. Subsequently, data is captured to the console screen in real-time and in a larger subset to a CSV (comma separated value) file called “AS3ExportData.csv”. This is captured to the same folder as the program [Figure 1]. This file maybe directly opened in spreadsheet software such as Microsoft Excel for statistical analysis or archiving, after the program has terminated (using the Escape key on the keyboard).
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Figure 1: VSCapture software capturing physiological data in real time on the Windows operating system
The software presented above maybe used by anesthesiologists involved in research, to capture anaesthetic data from the GE Datex S/5 series monitor with minimal initial expense and hardware requirements. Future efforts from open source developers could involve the development of a graphical user interface, adding graphical data analysis tools in the software.
1. Liu D, Görges M, Jenkins SA. University of Queensland vital signs dataset: Development of an accessible repository of anesthesia patient monitoring data for research Anesth Analg. 2012;114:584–9
2. Kennedy RR, French RA. The development of a system to guide volatile anaesthetic administration Anaesth Intensive Care. 2011;39:182–90
3. van Schalkwyk JM, Lowes D, Frampton C, Merry AF. Does manual anaesthetic record capture remove clinically important data? Br J Anaesth. 2011;107:546–52
4. Peterfreund RA, Driscoll WD, Walsh JL, Subramanian A, Anupama S, Weaver M, et al Evaluation of a mandatory quality assurance data capture in anesthesia: A secure electronic system to capture quality assurance information linked to an automated anesthesia record Anesth Analg. 2011;112:1218–25
