Development of prototype bandage lapper for constant tension bandaging required for effective...

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Basic research

Development of prototype bandage lapper forconstant tension bandaging required for effectivemedical-clinical treatments

Someshwar Bhattacharya, Tasnim Shaikh*, Roshan Purushottam Solao

Textile Engg. Department, The Maharaja Sayajirao University of Baroda, Kalabhavan, Vadodara,Gujarat 390 001, India

KEYWORDSBandage lapper;Pressure mapper;Unwinding tension;Crepe bandage

Abstract Application of the bandaging materials is a skilled task and requiredconsiderable practice to perform it correctly. The variation in bandaging pressureis introduced due to different tensions applied by different persons during lapping.So, a handy mechanical bandage lapper is developed. This helps in keeping lappingtension uniform and adjustable irrespective of the bandager. Its proficiency ischecked by bandaging two persons with different fore-arm circumferentialmeasures. Bandaging is done at three different limb positions with and withoutthe use of bandage lapper up to three layers by the same bandager. Three differentlapping tensions viz; 0.40 kgf, 0.45 kgf and 0.50 kgf are set up for bandage lapper tostudy their impact on bandage pressure. Pneumatic bandage pressure mapper isdeveloped for the measurement of bandage pressure. Seven trials separated bydifferent time intervals are conducted for each variable. This has prevented recordof consistency of bandage pressure measure by chance.Crepe bandage, normally employed for the management of Oedema in clinical

treatment is used throughout the study. Higher coefficient of variations up to 15%in pressure values are found when bandaging done without the lapper. However,identical pressure, coefficient of variation less than 0.3% for all except 0.8% forbandaging done at 0.45 kgf for second person at position 1, is mapped whenbandaging done with the lapper by the same bandager.ª 2012 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Introduction

Bandages are designed to perform a whole varietyof special functions depending upon the type ofwound and medical requirements. They can bewoven, knitted, or nonwoven or either elastic or

* Corresponding author. Tel.: þ91 9725014289.E-mail addresses: [email protected] (S. Bhattacharya),

[email protected] (T. Shaikh).

0965-206X/$36 ª 2012 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.doi:10.1016/j.jtv.2012.04.001

Journal of Tissue Viability (2012) 21, 54e63

www.elsevier.com/locate/jtv


non-elastic. The most common application ofbandage is to hold dressings in place over wounds.The ability of a bandage to perform this function islargely determined by accuracy of its lapping [1,7].

The degree of compression produced by anybandage system over a period of time is deter-mined by complex interactions between fourprinciple factors:

➢ The physical structure and elastomeric proper-ties of the bandage,

➢ The size and shape of the limb to which it isapplied,

➢ The skill and technique of the bandager and➢ The nature of any physical activity undertaken

by the patient [3,4].

Thus for identical bandage and patient,compression therapy bymeans of bandage becomesextremely effective only by the consistency oflapping of bandager. It becomes ineffective ifapplied too loosely whereas cause pain, could beintolerable and even harmful if applied too tightly[5]. Thereby development of portable mechanicallapping device is thought off. Variations caused dueto person employed can be eliminated by the use ofthis device during lapping. Thus helps in achievingdesirable uniform compression. Pneumatic pres-sure mapper is also fabricated for the measure ofsub-bandage pressure during the study. This paperdescribes design features of both the devices andsignificance of practical implementation of thelapper.

Experimental

The first phase of experimental work is relatedwith the fabrication of bandage lapper and

pressure mapping device for the study. The prac-tical proficiency of the lapper is evaluated exper-imentally in the second phase.

Materials

Crepe bandage of 6 cm width is used for this study.It is tested for its physical structural properties,type of weave, constituent yarn count, threaddensity, GSM, thickness. Mechanical properties,viz; tenacity and percent extension are measuredon Lloyd tensile strength machine working on CRLmethod. They are liable to affect its performanceduring lapping [5,10]. Test specifications used fortensile testing are as follows:

➢ Cross head speed ¼ 50 mm/min➢ Gauge length ¼ 20 mm➢ Strip width ¼ 25 mm

Comfort associated air permeability value ismeasured at 10 mm water level pressure onMetefem air permeability tester.

Methods

Bandage lapperThe main principle of bandage lapping instrumentis to maintain uniform bandage tension duringlapping over a body.

Design features of bandage lapperThe design features of the bandage lapper areillustrated in Fig. 1. Rectangular aluminium body(12 cm � 6 cm) is used for bandage lappinginstrument. This shape and light weight ofaluminium has provided ease of gripping of lapperby hands during lapping. Dimensions of the

Figure 1 Bandage lapping instrument.

Development of prototype bandage lapper 55


rectangle are chosen in accordance to the sizes ofsupport bandage normally used for the manage-ment of oedema in clinical treatment.

Instrument is composed off totally three rollers,two rubber coated top rollers (each of 15 mm Ø)and one aluminium bottom roll (5 mm Ø). They allare fitted on the bearing for their free rotationaround their axis. Bushes of the first top roller arefixed with side wall but bushes of the second rollare fitted in the slotted bracket. Thus secondroller is capable of making lateral displacementwith respect to first one. This helps in setting thenip pressure as per the unwinding tension in thebandage required during lapping. The setting isdone with the help of two spiral spring loaded setscrews, [Fig. 1]. Half of the spring is passedthrough the groove of aluminium slot. Thisprevents deflection of spring when tension isincreased with the help of screw. Bottom roller isremovable and used as spindle for windingbandage on it. It is secured into the slot of adapterby the holding screw during lapping.

Arrangement for setting unwinding tension forbandage lappingFixed measuring scales, one on each side, cali-brated in millimetre are used initially [Fig. 1].They define linear displacement in screw positionwith reference to the nip pressure appliedto bandage unwinding. The interrelationshipbetween linear displacement of screws andbandage unwinding tension is established by con-ducting pilot trials. For each unit displacement ofscrews the unwinding bandage tension is measuredon Lloyd tensile tester [Fig. 2]. Average of fiveconsecutive test readings is used for the finalcalibration of measuring scale in terms of bandageunwinding tension in kgf.

Bandage passage through lapperBandage is wound on the bottom roller. Top rollersare set to desired unwinding tension with the helpof set screws. Then bandage is passed through thenip of the top rollers for lapping as per shown inFig. 3.

Bandage pressure mapping devicePhotograph of bandage pressure mapper devel-oped and used for the present study is shown inFig. 4(aeb). It works on the same working principleof blood pressure measuring device. Bandagepressure is related to the pressure changes in thefluid on the application of an external pressure.Thus bandage pressure measured by this device isreported in terms of mmHg as Mercury is used asfluid in manometer. Its selection is based on itsfavourable properties like non stickiness on glasssurface and faster reversal to the original positionon the release of pressure due to its higher densityas compared to other fluids used during pilot trialexperimentations, viz; water, kerosene. This haspermitted the measure of wide range of bandagepressure within small size manometer more accu-rately. The accuracy level of pressure measure-ment recorded for selected crepe bandage duringpilot trials was 0.0125% based on 50 readings at99% confidence level.

Experimental set up is composed off manom-eter, compressor, air valves, silicon tubes andsensor. A small rubber balloon in flatten at fixedpressure is used as rubber diaphragm. It serves asa sensor during bandage pressure measurement.Compressor is having air inlet valve connected tothe manometer with the help of silicon tube.Second end of manometer is connected with thesensor (rubber diaphragm) via two way controlvalve.

Figure 2 Lloyd tensile strength tester set up used forthe unwinding tension measurement of bandage duringlapping.

Figure 3 Passage of bandage through lappinginstrument.

56 S. Bhattacharya et al.


CalibrationThe rubber balloon is in flatten with fixedcompressed air and attached with silicon tube.Both the valves are kept closed. End of the balloonis wrapped well by the adhesive tape over thesilicone tube to prevent leakage of air. Balloon airis then allowed to pass through manometer byopening the two way valve. The change inmanometer pressure is calibrated with the help ofair inlet valve of the compressor.

Balloon size is optimized for attaining accuracyof measure without uncomforting to the patientduring lapping in pilot trials. The fixed in flatteningair pressure of the balloon decided experimentallyis 0.1758 kg/cm2. It is used throughout the

experimentation to calibrate the instrumentagainst this preferable size of in flat balloon.

Bandage pressure measurementAfter calibration of pressure mapper, sensor end ofsilicon tube is fixed with adhesive tape on thedesired limb position [Fig. 5(a)]. Both the valvesare kept open during measurement. Bandage iswrapped with bandage lapper at constantunwinding tension [Fig. 5(b)]. This exerts externalpressure on the sensor kept underneath thebandage and changes manometer pressure.Change is read off directly from the fixed scale asa pressure in respected unit of fluid used in themanometer, viz; mmHg. The same way bandage

Figure 4 (a) Photograph of bandage pressure mapper. (b) Schematic diagram of bandage pressure mapper.



pressure is mapped for bandaging done withoutlapper.

Two persons with different circumferentialmeasure of fore-arm (Table 1) are considered forthe study.

Bandaging is done with and without the lappingapparatus by the same bandager. Three lappingtensions normally practiced in bandaging, viz;0.40 kgf (67 g/cm), 0.45 kgf (75 g/cm) and 0.50 kgf(83 g/cm) are set for each person on lapper [4];(Steve et al, 2003). However such accurate lappingtension setting is not possible for the classicalmode of bandaging. So, it is done as per normalmanual bandaging process without consciouslychanging unwinding tension. Lapping is done atthree different limb positions just below the wristand elbow (Fig. 6) up to three layers. Bandagepressure in each case is measured with newlydesigned pressure mapper. Seven readings spreadover different time intervals, viz; 0 min, 15 min,1 h, 4 h, 12 h, 1 day and one week. Time factorconsidered to check significance of consistency oflapping arises is not due to the chance in eachcase.

Results and discussion

Specifications of crepe bandage fabric used for thestudy are reported in Table 2. Bandage pressuremapped for three layers laid with and withoutlapper for two persons at three limb positions

Table 1 Circumferences of fore-arm.

Person Circumference of fore-arm (mm)

Position 1 Position 2 Position 3

1 185 210 2502 160 190 215

Figure 6 Fore-arm (Anterior side).

Figure 5 Bandage pressure measurement.

Table 2 Specifications of crepe bandage sample.

Bandageproperties

Width(mm)

Weave Fabric sett Count (tex) Thickness(mm)

Mechanical properties

WarpEPCM

WeftPPCM

Warp Weft Tenacity (g/tex) Extension (%)

Warp Weft Warp Weft

1. 60 Plain 19 25 24.6/2 66.7 0.93 1640.4 818.3 406.1 69.7



Figure 7 (a) Bandage pressure measurement for person 1 at limb position 1. (b) Bandage pressure measurement forperson 2 at limb position 1.



are reported graphically in Figs. 7e9(aeb)respectively.

Bandage pressure measured for IInd person ishigher as compared to the Ist Person at all thelapping tensions and layers under consideration[Figs. 7e9(aeb)]. This is mainly attributed to thepresence of stiffer bonny structure than flexiblemuscular species at the limb with lower circum-ferential measure (Table 1). This has notpermitted compression under applied lappingforce. This has also gone in agreement with Lap-lace law [4,6e10]. As per this law the pressureexerted by the bandage depends on the fabric, theelastomeric characteristics of the bandage, on thetension applied, the number of overlapped layersand the anatomical characteristics (size andshape) of the limb being bandaged. The quantityof the interaction of these events is expressed bythe Laplace law (Equation (1)). The applied pres-sure (P) will be directly proportional to the tension(T ) of the elastic material and the number (n) ofspires applied, while it will be inversely propor-tional to the radius (r) of the compressed surfaceand the width (h) of the bandage. Thus going inaccordance to the Laplace law, the decreased inpressure is found with the increase in radius of thelimb for IInd person to Ist person for identicalconditions of bandaging.

Laplace law P ¼ Tn=rh ð1Þwhere P ¼ pressure exerted on the skin,T ¼ tension applied to the bandage, n ¼ number ofspires applied, r ¼ radius of compressed area,h ¼ bandage width.

Similarly the drop in the bandage pressure,while shifting mapping point from 1st limb positionto the 3rd limb position (Fig. 6), has also attributedto increase in limb size (r) for both the persons(Table 1).

Going in agreement with [9], at identicalbandage tension (T ), radius of limb (r) andbandage width (h), bandage interface pressure (P)recorded is higher with the increase in spirals/layers (n), in all the cases [Figs. 7e9(aeb)].

The inclination in the bandage pressure mappedwith the increase in lapping tension (T ) used forlapper unit for both the persons at all three limbpositions. It has also proven agreement to Laplacelaw. This feature of mechanical lapper can facili-tate in bandaging at high compression level or lowcompression level [2] as per the need of medicinaltreatment.

Almost identical quantum of pressure (% Coef-ficient of variation less than 0.3% for all except0.8% for IInd person at 45 kgf tension) is mapped at

different time intervals in each case for bandagingdone with lapper by the same bandager. But themarked fluctuation in bandage pressure startingfrom 9% up to 15% is found in classical mode ofbandaging in each case, although done by thesame bandager [Figs. 7e9(aeb)]. This is mainlyattributed to the subjective mode of controllinglapping tension in classical mode, viz; manualjudgement. Thereby variations caused in lappingtension (T ) have made bandage interface pressure(P) to vary. Whereas, instrumental bandaging hasa provision to set and control uniform lappingtension. Thereby it has helped in nullified humanerror irrespective of time and operator duringbandaging. Thus it is not exaggerating to mentionthat instrumental lapping permits uniformity ofbandaging at different pressure level as per theneed of medicinal treatment over a period of time.

Conclusion

A pressure bandage can hold the cotton close tothe wound and apply pressure, to stop thebleeding and allow blood to begin clotting. Theeffectiveness of compression bandaging dependsupon the degree of pressure provided and, this inturn, is determined by a number of factorsincluding the physical and elastomeric propertiesof the fabric, the size and shape of the limb, theskill or technique of the operator and, mostimportantly, the tension produced in the bandagefabric during the application process. The tensiondeveloped in most flat bandages during applicationis determined entirely by the operator. Studieshave shown that the tension with which bandagesare applied by different nurses varies significantlyfrom person to person. So, a portable bandagelapper is developed with the provision of settinglapping tension. Experiments done with twopersons with different circumferential measurehave proven the proficiency of this device inattaining constant pressure bandaging with crepebandage. The coefficient of variation recorded forbandage pressure at different tension level withlapper is less than 0.3% for all cases except 0.8%for 45 kgf tension level for IInd person. However itis less than 1% for all. The coefficient of variationrecorded is ranging between 9 and 15% for classicalmode. Thus the pressure achieved by same band-ager on the repeated application of a bandagewith lapping apparatus is much more consistentthan the classical mode.

The effectiveness of instrumental application ofcompression bandage is checked successfully fordifferent size and shape of limbs, number of spirals



and bandage tension. The pneumatic bandagepressure mapper is developed and used for thestudy. The results obtained for each variable haveshown good agreement with Laplace law.

Conflict of interest statement

There is no conflict of interest among us as well asany organization or employer. This is solely basedon our own basic research work done in thedirection of product development in the field ofmedical textiles.

References

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