Doc 116-03 Copyright 1998-2004 MIE Medical Research Ltd
Getting Started MIE Medical Research Ltd Unpack your Digital Analyser and check that the following components are present: 1 x Digital Analyser Figure 1 1 x Pinch/Grip Transducer Figure 3 1 x Mains power supply cable 1 x CAS software and license dongle (if applicable) 1 x BNC to 9 pin connector lead to connect your computer to the Digital display unit 1 x CAS instruction manual (Doc124) in addition to this manual Referring to the previous illustrations, assemble the instrument as follows: 1. Connect the Pinch/Grip handle to the input marked TRANSDUCER (h) at the back of the Digital Analyser. Ensure that the plug is seated home fully and rotate the outer locking ring clockwise. 2. If you intend to use the system with a computer, connect the BNC connector of the computer lead, supplied with the instrument, to the BNC connector marked COMPUTER (i). Connect the 9 pin plug to the COM port of your computer. The system can be used with any type of computer with a compatible serial interface. However the supplied software has specific hardware and operating system requirements which must be met (refer to the CAS instruction manual for more information) 3. Check that the voltage shown on the instrument is compatible with your mains supply. If in doubt, consult with your supplier. 4. Connect the mains cable to the IEC mains input socket at the back of the display unit. 5. Switch on the Digital Analyser (g). The display should become active. 6. Set the display to zero by pressing the zero button (f). Even if the display initially reads zero, it is important that the zero button is depressed as the display does not indicate negative values. To install the CAS software, please refer to the CAS manual (Doc124). Doc 116-03 Page 1
000 a N lb kg hold zero b c d e f * PRESS ZERO BUTTON BEFORE EVERY TEST * Digital Analyser g Figure 1: Digital Analyser (Front) TRANSDUCER h COMPUTER Tel : +44 113 279 3710 Made in England by medical research ltd. Fax : +44 113 231 0820 E-Mail : support@mie-uk.com Figure 2: Digital Analyser (Rear) I j T-xx ma k WARNING This apparatus must be earthed CAUTION ISOLATE MAINS POWER BEFORE REMOVING COVER PLATE RATING 230 VOLTS 50-60 HERTZ 1998.06 m l p n q r o Figure 3: Pinch/Grip Transducer s a b c d e f g h i j k l m n o p q r s digital display of force press to display force in newtons press to display force in pounds press to display force in kilogrammes press to store and display peak force value press and hold for 1 second to set display to zero before each test mains power switch input socket for transducer (grip handle or myometer) output socket to computers com port IEC mains input socket 230V: 2 x T-32mA mains fuses (5x20mm) or for 100/110V: 2 x T-63mA mains fuses (5x20mm) serial number - should match those on the transducer class B symbol adjust handle to suit different hand sizes width scale - use same handle width in repeated tests for maximum repeatability comfortable ergonomic handles for grip measurement, even with most hand contractures area for pinch strength measurement forces measured over this part of the transducer will be independent of moment errors connect to the transducer input socket (h) on the analyser/display unit Doc 116-03 Page 2
Digital Analyser - Pinch/Grip Introduction The Digital Pinch/Grip Analyser from MIE Medical Research Ltd. is a unique, precision instrument specifically designed to measure accurately the strength and endurance of the hand and individual fingers. This allows the accurate monitoring and assessment of hand function throughout physiotherapy, drug treatment or surgical management. Furthermore, it may also be used to assist in other diagnoses, in particular the Ewing s battery of tests to measure the effects of the autonomic nervous system on the heart (see later). Although the device may be used on its own, much more information may be obtained by linking it to a computer. Our CAS software demonstrates how powerful a tool the Pinch/Grip Analyser can be in the analysis of finger and hand function. First Principles In the past, the measurement of hand grip strength has been fraught with problems. Many papers have shown that the repeatability of hand grip strength is poor. Unfortunately, much of the work published relied on data produced by measurements on either a sphygmomanometer or a crude mechanical device. First we must appreciate that a sphygmomanometer is designed to measure pressure and not force. Pressure = Force Area When we apply a force to the rubber bulb of the sphygmomanometer, the pressure will depend on the contact area between the bulb and the hand. Therefore, according to the way one holds the sphygmomanometer, the pressure will vary even though the force remains the same. It is this basic difference between force and pressure that has caused problems in hand function measurement to date. Simple mechanical devices do not have the sensitivity to be able to detect the small changes in grip strength measurements normally seen through the progress of disease or treatment. Usually, the gradations on mechanical devices are 2.5kg intervals. There are approximately 10 Newtons to the kilogram. This means that the crude mechanical device only measures at 25 Newton intervals. Although this may be perfectly adequate for testing sports people, many rheumatoid patients would find it very difficult to grip more than a few Newtons. Doc 116-03 Page 3
Special Features The Digital Pinch/Grip Analyser incorporates some unique features that ensure maximum accuracy and resolution. The handle is constructed of a special aerospace alloy that has the strength of steel yet is as light as aluminium. This allows the handle to be used by those with very poor strength as well as by those with athletic ability. The handle s special sensors are designed so that no matter where you hold the handle within the black area below the red indicating line (Figure 3 r ), you will always get the correct reading. In other words, the handle is not sensitive to grip placement. The handle width can be adjusted so as to accommodate different hand sizes so that both adults and children may be tested. A scale is attached to the handle so that a note of the handle width may be taken to ensure that any re-tests are comparable. The digital display indicates the applied force either in Newtons force, kilograms or pounds. There is also a hold facility that locks the highest value on the display for a short while so that you can see the maximum grip value during a test. A reset button sets the display back to zero, (see quick reference guide). An output and connecting cable is also provided so that the instrument can be connected to a computer for detailed strength and endurance analysis. Doc 116-03 Page 4
Instructions for Use The Digital Pinch/Grip Analyser is a precision instrument. It has been carefully designed to minimise any mechanical inaccuracies. However, grip strength and endurance can vary in an individual due to physiological and psychological factors. It is, therefore, important to try to minimise these human factors as much as possible. Some human factors may include the following: Human Factor Limb position Fatigue Circadian Rhythms Grip size Pain Motivation Intra Operator Error Inter Operator Error Reason The orientation of the joints affects the mechanical advantage of muscles, e.g. grip strength varies with elbow angle and rotation. Muscle strength and endurance reduces after several close successive tests. However, in many cases the second test indicates greatest grip strength. Research has shown that there are diurnal variations in grip strength as well as more long-term variations, particularly with women. Grip strength varies according to the size of the grip handle. When testing individuals, it is important to always ensure that the handle width is the same for each test. Grip strength and endurance are greatly influenced by the degree of pain the subject experiences during the test and the pain threshold of that individual. Subjects may not exert maximum effort for numerous psychological reasons. It is important that the tester encourages the subject to ensure optimum results. The problem of intra operator error is increased when a formal test protocol has not been developed. Variations in the test procedure are a major cause of intra operator error. A formal test protocol and simultaneous training of operators minimises this error. However, other factors, such as how each operator encourages motivation, can also influence the results. The above table highlights the fact that although the instrument itself is very accurate, there are a number of outside factors that can affect the repeatability of grip and endurance measurement. Therefore, a very important first step is to develop a test protocol according to your own needs and the type of subject that you are testing. Doc 116-03 Page 5
Initiating the Test WARNING: It is essential that, before each test is made, the zero button on the digital display unit is pressed for at least 2 seconds even if the display indicates zero. Before starting the test, please ensure that the subject is able to hold the grip handle unaided. Some subjects are very weak and find that they cannot support the weight of the handle. In this case, you can hold the handle for them. Hold the handle at the base, without touching the two lever arms, and present the handle to the subject for them to squeeze. Make sure that the grip handle is adjusted to the same width as previous tests for that subject, or according to your protocol. If the subject is able to hold the handle, place the handle on the subject s open hand so that no load is applied to the instrument. Choose the units you would like the force to be displayed as, on the Digital Display Unit, by pressing the appropriate button on the front panel. The preferred scientific unit of force is the Newton. CAS software displays data in Newtons only, irrespective of the units chosen on the digital display unit If you wish to display the maximum applied force, then it is necessary to activate the hold facility by ensuring that the hold button is pressed in. (in = on, out = off) It is now necessary to set the display to zero by pressing the zero button on the digital display unit for a minimum of 2 seconds. The Digital Display Unit cannot indicate negative values and so it is necessary to press the zero button even if the display already reads zero. The handle only provides accurate readings when squeezed in the black area of the handle as indicated in figure 3 (r). The instrument is now correctly set and the subject can grip the handle. To minimise the effects of fatigue, it is best if the subject attempts to grip their maximum as quickly as possible. If the subject is being tested in conjunction with the CAS software, then at the end of the test, the computer will make a short bleep. At this point, the subject should let go of the handle as quickly as possible, preferably without leaving any residual load on the transducer, i.e. minimal or no grip applied to the handle. To measure finger pinch grip strength or endurance, follow the above procedure, but squeeze the flat flanges at the end of the grip handle. Adjust the handle width to suit the subject and make a note of the handle width using the scale on the handle body. Doc 116-03 Page 6
Ewing s Hand Grip Test Ewing s hand grip test is an important aspect of measuring the effect of the autonomic nervous system on the heart. The Digital Pinch/Grip Analyser, when used with the VariaCardio TF5 heart monitor 1, allows this test to be made accurately, thereby greatly improving the quality and repeatability of this method of measuring heart function. For detailed information on Ewing s battery of tests, please refer to the VariaCardio TF5 manual. The hand grip test requires that a constant hand grip of 30% of the maximum voluntary contraction be maintained, up to a maximum of 5 minutes. During this period, the heart rate variability and instantaneous pulse rates are recorded using the VariaCardio TF5 system and the blood pressure values are recorded, as indicated in the VariaCardio TF5 manual. Prior to the Ewing Hand Grip Test, the maximum grip strength of the subject must be ascertained as described previously. If a computer is not available for the hand grip test, the easiest way to achieve this is to calculate the 30% value of the maximum grip strength. Then ask the subject to look at the Digital Display Unit while gripping with sufficient force to maintain this value throughout the test. Alternatively, CAS provides a real time biofeedback bar graph display allowing the 30% maximum grip value to be easily ascertained and maintained. For further details refer to the CAS manual. 1 For information on the VariaCardio TF5 please refer to our website: http://www.mie-uk.com Doc 116-03 Page 7
Technical Specifications Parameter Display Range Maximum Force Resolution Accuracy Supply voltage Fuse Calibration Storage/transportation conditions Transportation Operating temperature range Specification 000 1999 Newtons 1000 Newtons 1 N 0.1kg - 1lb > 1% FSO 230V or 100/110V - see label on Digital Display Unit For 230V: 2 x T-32mA mains fuses (5 x 20mm) For 100/110V: 2 x T63mA mains fuses (5 x 20mm) Factory set recalibrate every 12 months +5º to + 45ºC <85% humidity Use original packing materials +5º to +45º C NOTE: If you have more than one instrument, please ensure that the serial number on the transducer matches that on the Digital Analyser Display Unit, otherwise calibration cannot be guaranteed. Multi-Myometers (instruments that have Pinch/Grip handles as well as Myometer transducers) components should all bare the same serial number. Manufactured by: MIE Medical Research Ltd. 6 Wortley Moor Road, Leeds, LS12 4JF United Kingdom. Tel: +44 (0)113 2793 710 Fax: +44 (0)113 2310 820 E-mail: support@mie-uk.com Web Site: http://www.mie-uk.com Doc 116-03 Page 8
Notes Classification: Class 1 with a measuring function Type B Applied Part Suitable for continuous use Servicing: This instrument has no user serviceable parts. For repairs and calibration (due annually), return to manufacturer or an official MIE distributor. Cleaning: Clean the instrument using a dry cloth only. Transducers may be wiped down using a moist alcohol swipe. Ensure that the instrument is switched off during cleaning. Do not use water or any other electrically conducting materials. Exclusions: This instrument is not suitable for use with flammable gases. Not protected against ingress of water Not suitable for use in a sterile environment. Storage: This instrument should be stored in a dry room preferably in its original packing materials between +5º and + 45ºC <85% humidity. Electromagnetic or other interference: This instrument has been built and tested to comply with EN 60601-1-2. This instrument must be earthed. Do not operate the instrument without a transducer plugged in as this may adversely change its interference characteristics. If interference occurs from an external source, remove the source before using the instrument. Any computer port connected to this instrument must comply to IEC60950. Doc 116-03 Page 9