Fully automated post-op flap monitoring

  • It goes without saying that the company's imaging technology itself is superb!

    Gourav Banerjee
    Leeds Beckett University

  • I expect to be using Moor Instrument’s technology for many years to come!

    Faisel Khan, PhD
    Ninewells Hospital & Medical School

  • We can't recommend Moor instruments highly enough. The technology is at the cutting edge and the support second to none.

    Paul Sumners, PhD
    London South Bank University

  • In a nutshell, moorFLPI-2 is the most user-friendly system for studying cerebral blood flow regulation in rodents.

    Chia-Yi (Alex) Kuan, MD, PhD
    Emory University School of Medicine

  • Laser Doppler Imager is a standard accurate method we now use in our cerebral blood flow and brain perfusion in our laboratory.

    Momoh A. Yakubu, PhD
    Texas Southern University

  • Moor Instruments have consistently provided excellent help and support for my research.

    Kim Gooding, PhD
    University of Exeter Medical School

  • I cannot rate the company or the staff highly enough.

    Jim House, PhD
    University of Portsmouth

  • We have found Moor equipment to be extremely dependable and innovative.

    Dean L. Kellogg, Jr., MD, Ph.D
    University of Texas Health Science Center

This system has now been superseded by the moorVMS-TREND, for full details please click here.

New and unique features are offered by TREND flap monitoring to simplify the task of assessing flap progress post surgery. The monitor uses laser Doppler technology and provides measures of micro-vascular blood flow and temperature at two sites. Optic probes are available for surface, buried and oral flaps. The large graphical display shows smoother traces – due to use of a noise rejection protocol. Baseline levels and alarm levels are monitored and set automatically by the monitor.

This system has now been superseded by the moorVMS-TREND, for full details please click here.

The following products are AVAILABLE TO BUY ONLINE and work with the TREND

This system has now been superseded by the moorVMS-TREND, for full details please click here.

This section lists the more common questions our customers have with regards to the TREND. If you have a question you would like answered that does not appear below then please email us. We are happy to help!

Q. Can data be sent between the DRT4/TREND and a PC for storage, further analysis etc?
A. Yes, this is easily done via the Serial or USB ports of the PC, using our dedicated Windows software package (moorSOFT). Data transfer can be 'live' - i.e. at the time of measurement or after the measurement by downloading from the DRT4/TREND memory. Where conditions and space allow we recommend live monitoring as the safest form of data capture.

Q. How long is the stored data safe in the DRT4/TREND without connecting it to the electrical supply?
A. We would always recommend downloading data as soon as practically possible to safeguard your measurement. However your data is safe for at least eighteen months (new DRT4/TREND) - as the data is saved by an internal battery. As the DRT4 gets older, or the battery weaker this 'safe' time is reduced.

Q. What is the longest period of time the DRT4/TREND can record data for?
A. In stand alone mode the DRT4/TREND system can store 3 days of continuous data.

Q. How are the alarm levels set?
A. Alarm levels are set automatically by the monitor after 30 minutes of baseline assessment. A visual alarm shows whenever blood flow drops below the alarm level and an audible alarm sounds if low flow is sustained for a pre-defined period. The alarm level is set as a percentage of the measured baseline level. Manual override is available.

Q. Can the trace be analysed?
A. Yes. On board automated analysis divides the time span into around 10 equal time segments, and the mean flow is displayed for each time segment at the touch of a single key. This is usually sufficient for routine use, but further analysis and export to Spreadsheet format is possible with the Moorsoft for Windows/TREND package.

Q. How does the trace differ from a normal laser Doppler trace?
A. The trace is much smoother than a normal laser Doppler trace due to the use of a novel noise rejection protocol. This makes the traces far easier to interpret and the alarm setting more reliable. Temporary live monitoring is also available to allow confirmation of pulsatility in the signal - an important factor in deciding the health of a flap.

Q. What tissues can be sampled with DRT4/TREND?
A. Probes are available for exposed surface flaps (use DP1T-V2 or similar), flaps covered by dressings (use DP11sc), buried flaps (use side or end viewing endoscopic designs, DP6b or DP6ds) or oral flaps (use DP8c suturable titanium disc probe). Other probes can be used in other situations should the TREND protocol prove useful in other critical monitoring situations.

This system has now been superseded by the moorVMS-TREND, for full details please click here.

There are numerous references where our laser Doppler monitors are cited. The list below is a small selection. Please contact us for reference lists on your chosen subject.

Hales J R S, 1985.
Skin arteriovenous anastomoses: their control and role in thermoregulation.
In Cardiovascular shunts: Ed Johansen K and Burrgren W W, pp 433-451.

Hellner D, Schmelzle R, 1993.
Laser Doppler monitoring of free microvascular flaps in maxillofacial surgery.
Journal of Cranio-Maxillo-Facial Surgery, 21, 25-29.

Jones B M and Mayou B J, 1982.
The Laser Doppler flowmeter for microvascular monitoring: a preliminary report.
British Journal of Plastic Surgery, 35, 147-149.

Nilsson G E, Tenland T and Oberg P A, 1980.
Evaluation of a Laser Doppler Flowmeter for Measurement of Tissue Blood Flow.
IEEE Trans Biomed Eng, BME-27 (10), 597.

Oberg P A.
Chapter 6. Innovations and Precautions.
Laser-Doppler Blood Flowmetry edited by A P Shepherd and P A Oberg, published by Kluwer Academic Publishers.

Sacks A H, Ksander G, O'Neill H and Perkash I.
Difficulties in laser Doppler measurement of skin blood flow under applied external pressure.
Journal of Rehabilitation Research and Development, 25 (3), 19-24.

Svensson H, Holmberg J and Svedman P, 1992.
Interpreting laser Doppler recordings from free flaps.
Scand J Plast Reconstr Hand Surg, 27, 81-87.

Tenland T, Salerud E G, Nilsson G E and Oberg P A, 1983.
Spatial and temporal variations in human skin blood flow.
Int J Microcirc: Clin Exp 2, 81-90.

This system has now been superseded by the moorVMS-TREND, for full details please click here.

Moor Instruments are committed to product development. We reserve the right to change the specifications below without notice.


Laser Safety Classification Class 1M per IEC 60825-1:2001 and
Class 1 per 21 CFR 1040.10 and 1040.11
Output power 1.6mW max.
Wavelength 785nm ± 10nm
Angular spread of laser light from probe tip 28° ± 5°
All specifications include cumulative measurement uncertainties and expected increases in values after manufacture.


Range 5-50°C
Resolution 0.1°C, accuracy ± 0.3°C
Patient isolation (per IEC 601-1 Class 1 type BF)


Bandwidth: high pass 20Hz
Low pass selectable 3KHz, 15KHz, 22KHz
Output time constants: 0.02s, 0.1s, 0.5s, 1.0s, 3.0s
Automatic gain control and zeroing


Graphical/digital LCD screen display
40Hz maximum data display rate to 1/min minimum display rate
0-1000 arbitrary perfusion units, percentage change
2 serial interface RS232 (1 optically isolated)
Analogue outputs 0-10V D/A 12 bit 4 channel (external bus)
Analogue inputs 0-2.5V A/D 10 bit 4 channel (external bus) Serial Numbers up to and including 3124
Analogue inputs 0-10V A/D 12 bit 4 channel Serial Number 3125 and above


Flash memory programmable from PC
Alarm levels and event markers
Trends – data review and time scale compression
500Kbyte battery backed memory
Percentage change and areas
Mean, maximum, minimum values.
Calibration – storage of probe scaling constants


Universal voltage switch-mode power supply
range 100 to 230V at 55VA, 50 to 60Hz
Dimensions W H D mm 280 x 160 x 360
Weight 7kgs


Temperature 0-45°C
Humidity 0-80% RH
Atmospheric pressure 500 – 1060hPa
Operating temperature 15-30°C
Electrical safety standards IEC 601-1:
Type of protection against electric shock: Class 1
Degree of protection against electric shock: Type BF
Degree of protection against ingress of liquid: IPXO (not protected)
Degree of protection against flammable anaesthetics – Equipment not suitable for use in the presence of a flammable anaesthetic mixture with air or with oxygen or with nitrous oxide.
Mode of operation – continuous.


Accuracy: ± 10%, relative to Moor Instruments ‘standard’ DRT4
Precision: ± 3% of measured value
Range: 0-1000 AU

Accuracy: ± 10%
Precision: ± 5%
Range: 0-1000AU

Accuracy: ± 10%
Precision: ± 3%
Range: 0-255AU