1 - Wescor Inc.

NANODUCT ®Neonatal Sweat AnalysisSystemInstruction/Service Manual57-0003-01ACOPYRIGHT 2006 WESCOR INC

© 2006 Wescor, Inc. All rights reserved.Printed in the United States of America.Wescor, Nanoduct and Pilogel are trademarks ofWescor, Inc.Other trade names used in this manual may betrademarks of their respective owners, usedhere for information only.U.S. Patent Number 6,198,953.All information in this document is subject tochange without prior notice.

TABLE OF CONTENTSsection1INTRODUCTION1.1 Customer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31.2 Important User Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41.3 System Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5section2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13section3INTERPRETING THE SWEAT TEST3.1 Units of Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .253.2 Automatic Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .273.3 Diagnostic Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .283.4 Initial Sweating Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29i

TABLE OF CONTENTSsection4TROUBLESHOOTING ANDMAINTENANCE4.1 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .334.2 Cleaning the Instrument . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .344.3 Battery Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .374.4 Calibration and Checking Control Values . . . . . . . . . . . . . . . . . . . . .38APPENDIX AInstrument Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43APPENDIX BAccessories, Supplies, and Replacement Parts . . . . . . . . . . . . . . . . . . .47APPENDIX CSupplemental InformationCystic Fibrosis: A Brief Description of the Disease . . . . . . . . . . . . . . . .51Evolution of Sweat Test Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52Development of the Nanoduct Neonatal SweatAnalysis System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54APPENDIX DInstrument Setup Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59APPENDIX EPilocarpine Iontophoresis: Requirements and Risks . . . . . . . . . . . . . . .65APPENDIX FSerial Data Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73ii

S E C T I O N 1INTRODUCTION

S E C T I O N 1INTRODUCTION1.1 Customer ServiceThank you for purchasing the Nanoduct Neonatal Sweat Analysis System. We believeit is the best diagnostic sweat testing system for newborns available. We are confidentthat you will be satisfied with our product.Wescor is dedicated to assisting in every aspect of sweat testing theory and practice.Wescor is the acknowledged world leader in the development of innovative systemsfor cystic fibrosis diagnosis by sweat testing.This manual contains basic maintenance, troubleshooting, and service information.Wescor is prepared to help you resolve any difficulty with the operation or performanceof your Nanoduct Neonatal Sweat Analysis System. If you are unable to solve aproblem using the procedures described in this manual, please contact us.Customers should contact Wescor by telephone, fax, or e-mail. Outside the U.S.,many of our authorized dealers offer customer service and support.TELEPHONE435 752 6011 Extension 0 - Operator171 - Orders172 - Service173 - Product Information & PricingTOLL FREE (US and Canada)800 453 2725 Extension 0 - Operator171 - Orders172 - Service173 - Product Information & PricingFAX435 752 4127E-MAILservice@wescor.comWEBSITE:www.wescor.com/biomedicalMAILING ADDRESS:Wescor, IncBiomedical Products Division459 South Main Street3

S E C T I O N 1INTRODUCTION1.2 Important User InformationThis manual describes the complete procedure for the laboratory diagnosis of cysticfibrosis, particularly in the early neonatal period, through examination of sweat electrolyteconcentration using measurement of electrical conductivity. Section 1 gives a briefdescription of the system and its components. Section 2 describes the procedure forstimulating and analyzing sweat. Section 3 gives needed information on the analysis ofsweat. In addition, instructions for troubleshooting and maintenance of the system areprovided in Section 4. A detailed description of the development of the Nanoduct Systemis presented in Appendix C.INTENDED APPLICATION AND CLASSIFICATIONAPPLICATIONThe Nanoduct System is intended for laboratory use by qualified personnel to providelaboratory diagnosis of cystic fibrosis.Anyone operating Nanoduct must be thoroughly familiar with the procedures and cautionary informationdetailed in this manual before attempting a sweat test. Abbreviated instructions printed elsewhereare provided for reference only. Do not use them as a substitute for the complete information containedin this manual.CLASSIFICATIONThis equipment is classified as Type BF Medical Equipment, Internally Powered.SPECIFICATION OF SAFE USE:Using this equipment in a manner not specified by Wescor may impair safety protectionand may lead to injury. Do not use where flammable anesthetic is present or in anyoxygen-enriched environment. Do not connect the serial port to external sources whilethe Nanoduct is connected to a patient.STATEMENT OF ENVIRONMENTAL LIMITSThis equipment is designed to be safely operated at 15 to 30 °C, maximum relativehumidity 80%.EXPLANATION OF SYMBOLS FOUND ON EQUIPMENTType BF equipment complying with Medical Equipment Safety StandardEN60601-1.4

S E C T I O N 1INTRODUCTION1.3 System Description5

S E C T I O N 1INTRODUCTION1.3 System DescriptionNanoduct is a complete, integrated system forinducing and analyzing sweat for cystic fibrosis(CF) diagnosis—all while attached to thepatient. This reduces the possibility of intrinsicerror and enables pristine samples to beobtained from neonates and analyzed in situ.Nanoduct incorporates the classic method ofinducing sweat by pilocarpine iontophoresis.The pilocarpine is introduced into the skin ofthe patient using controlled DC electrical currentfrom the Nanoduct induction/analysismodule. This is followed by continuous-flowanalysis using the unique sensor.StorageContainerResults appear quickly on the display. Duringthe process the operator installs and thenremoves the various components that fit in theholders described later.A description of the various components ofthe Nanoduct system follows.Sensor Cell ConnectorIontophoreticElectrodesHolders Holders6

S E C T I O N 1INTRODUCTION1.3 System DescriptionHoldersTwo plastic holders are attached to the patientwith comfortable but secure non-latex elasticstraps. These holders accept the electrodes andlater the sensor, holding them securely against thepatient’s skin. Holders are color-coded, one red toaccept the (positive) anode and subsequently thered sensor; the other black to accept the (negative)cathode. Strap retainers are pushed throughthe holes in the strap to maintain the correct tension.Iontophoretic ElectrodesTwo color-coded electrodes, one red for the anode(positive) and the other black for the cathode(negative), are otherwise identical, both having asmall stainless-steel disc as the electrode plate.These electrodes are part of the electrode cableassembly (see below) that also includes the sensorcell connector to attach the separate sensorcell. Both electrodes have projecting flanges, forsecuring the electrodes in the holder rings.Electrodes provide current from the modulethrough Pilogel discs during iontophoresis. Theblack cathode electrode also serves as an electricalreference to detect sweat flow to the sensorcell during the analysis phase.Electrode Cable AssemblyThis dual purpose cable assembly includes thered anode and black cathode iontophoretic electrodesand also the red sensor cell connector. Thecable connects to the Induction/Analysis Moduleat the electrode connection socket.7

S E C T I O N 1INTRODUCTION1.3 System DescriptionPilogel ® Iontophoretic DiscsPilogel discs are small (surface area 2.5 cm 2 ) iontophoreticdiscs that are inserted into the electrodeassemblies prior to iontophoresis. Thesediscs are designed especially for neonates, andhave a pilocarpine concentration of 1.5 %, for optimumstimulation of the sweat gland and to reduceiontophoresis time to approximately 2.5 minutes.PilogelIontophoreticDiscsPilogel discs contain sufficient glycerol to providesubstantial protection of gels against damage fromaccidental freezing. Cracked discs due to freezingcan contribute to burns. See Appendix E for moreinformation.Pilogels contain trisodium citrate, an excellentbuffer in the acid range of pH. This reduces anodicacidification of the gel during iontophoresis by90%. At the cathode, the increased pilocarpine, agood buffer at moderately alkaline pH, alsoreduces iontophoretic accumulation of alkali. Thisbuffering prevents skin burns due to pH change inthe gel. Each of these features contribute to thesafety of the procedure. See Appendix E forimportant information about pilocarpine iontophoresis.Sensor CellColor-coded red, the sensor has two externalflanges (as with the electrodes) for latching to thered holder. The base of the sensor is a shallowconcavity leading at its center to an entry port,and from there to an internal fine channel passingby two analyzer micro-electrodes, forming amicroconductivity cell.The sensors pass through stringent quality controlsbefore shipment to the customer. To beaccepted, sensors must be highly consistentthroughout each batch.8

S E C T I O N 1INTRODUCTION1.3 System DescriptionINDUCTION/ANALYSIS MODULEThe battery operated electronic induction/analysismodule controls the Nanoduct system. The moduleperforms 6 separate functions:• Provides a timed and controlled current foriontophoretic sweat stimulation.• Measures electrical conductivity of theexcreted sweat during the analysis phase.• Automatically averages the conductivityreading over a defined 5 minute period.• Automatically computes the initial sweatingrate.• Displays the above information on the LCDreadout and reports sweat test and calibrationresults to the serial port.• Provides a time and date display for calibrationand test results.CONTROL AND CONNECTIONSElectrode SocketThe electrode socket on the front panel of theinduction/analysis module connects the electrode/sensorcable assembly to provide electricalcurrent for sweat stimulation and to receive sensorsignals to the induction/analysis module during theanalysis phase.Electrode SocketFront Panel KeypadsKeypadsON keypad controls power to the module. Thismust be on during iontophoresis and analysis.OFF keypad terminates all operations and turnspower to the module off.Note:To preserve battery power, leave power off except while performing atest. In addition, during idle periods the instrument shuts down automaticallyafter 10 minutes and must be turned on again to complete testingor retrieve a result.SELECT/ENTERUsed to select options and start the iontophoresisand analysis phases of the sweat test. A warningtone sounds if a fault condition occurs–such as anopen electrode or circuit fault. The fault conditionis displayed and reset by pressing ENTER.9

S E C T I O N 1INTRODUCTION1.3 System DescriptionDisplayDISPLAYThe LCD alphanumeric read-out displays all functionsand results as they occur, including iontophoresisstatus and analysis results, plus thetime and date of the last procedure. The userresponds to prompts on the display to activatevarious functions. The instrument emits a shortbeep tone at the start and end of each operation.WESCORNANODUCTVERSION X.XThe instrument displays conductivity measurementsin mmol/L (equivalent NaCl) during analysis.If desired, display readings can be suppressedso readings are not visible, but can be recalled ata later time.LOW BATTERYCheck ControlsIontophoresisSweat AnalysisRecall ReadingNOTE:Date and time indications are in theformat yyyy-mm-dd; hh:mm. Dates,times and other data shown in thismanual are for example only, Actualdata during use will vary.LOW BATTERY IndicatorIf the battery voltage drops below a preset level asthe instrument is turned on, “Low Battery” appearson the display. When this indicator first appearsyou can usually complete 1 to 2 tests before adead battery. If battery power is too low to completea test, the module will automatically shut offand iontophoresis cannot be started. You mustreplace the battery to continue. See Section 4.3for information.Note:The inducer/analyzer is powered by one 9 Volt cell,which should provide a minimum of 100 tests with astandard alkaline battery, or 200 tests with a lithium battery.SERIAL PORT ConnectorThe RS232 compatible connector can be used toprint out results of sweat tests (with a time anddate stamp). Do not connect a line poweredprinter or computer when the instrument isattached to a patient. See Appendix F for details.Serial Port10

S E C T I O N 2SWEAT INDUCTIONAND ANALYSIS

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat TestIMPORTANT NOTE:Check calibration before each session of use by usingthe instructions in Section 4.4.Sensor Cell andSensor Cell ConnectorPilogel IontophoreticDiscsSensor CellConnectorElectrode CableAssemblyIontophoreticElectrodesCalibrationPlateInduction/AnalysisModuleHolders & StrapsStrap RetainerPostsWARNING!Due to the remote possibility of ignition, neverattempt iontophoresis on a patient receiving oxygen-enrichedrespiratory therapy in an enclosedspace. With medical approval, remove the patientfrom that environment during iontophoresis.1 Assemble Equipment and SuppliesMake certain you have everything on handfor the complete procedure:• Sweat induction/analysis module.• Two holders.• Two holder straps with strap retainer posts.• Two Pilogel discs.• One sensor.• Electrode cable for connecting the iontophoreticelectrodes or the sensor to theinduction/analysis module.You will also need a supply of deionizedwater, alcohol, cotton balls or gauze pads,and cotton swabs, and a roll of 1-inch wideplastic surgical tape (3M Transpore recommended).Make sure that the battery forthe sweat inducer/analysis module is notdead, and that the gel discs are rubbery,translucent and not cracked or otherwisedamaged.2 Inspect Electrodes, Leads, and Cablesa. Clean the electrodes if necessary (seeSection 4.2). Check the lead wires and insulationfor damage.b. Connect the electrode cable assembly tothe electrode socket.13

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat Test3 Calibrate and Check Control ValuesTurn the power on. Check for low batterycondition on the display. The arrow on thedisplay should indicate Check Controls onthe menu.We recommend checking control values(using the built in calibration plate) beforeeach session. See Section 4.4 for details.NOTE:Selecting the FORCE CAL. option will bring upthe Check Controls operation whenever theinstrument is turned on. See Appendix D.4 Clean Selected Skin AreasSelect the anodic (positive) skin site for thegreatest density of sweat glands. The sitemust be well-removed from the wrist wheremovement of tendons or ligaments couldpossibly affect the stability of the attachedunits. In neonates, the optimum site is theflexor aspect of the forearm, approximatelyhalf way between wrist and elbow. Thecathodic (negative) electrode site is not ascritical, place it an inch or two from theanode in the direction of the elbow.WARNING!Never place electrodes across the chest or onopposite limbs. Even though the DC iontophoreticcurrent is extremely low, there is a very remote riskof interference with cardiac rhythms.Inspect the selected sites. The skin shouldbe free of fissures and any structural abnormality.There should be no inflammation orsigns of eczema. Apart from exacerbatingthe complaint, there is always the possibilityof contamination of the sweat by serousexudates.14

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat TestTo minimize the electrical impedance (resistance)of the skin, remove as much deadepithelial material, dirt and fatty substancesas possible by swabbing the area vigorouslywith surgical alcohol, followed by plenty ofdistilled or deionized water. Then totallyremove the excess water.5 Attach the HoldersNOTE:Wescor provides perforated non-latex elasticstraps of different lengths to fit infants, older childrenand adults.To save time, pre-arrange strap holderassemblies to fit varying sizes of patients.Select the red holder and attach a rubberstrap of appropriate size as follows:a. Attach the strap to one side of the holder byinserting it, from below, through the holderslit, and down to form a small loop. Align twoperforations in this loop and push a strapretainer post through the aligned holes suchthat the post points away from the patient’sarm. (In use, the flat retainer base shouldrest against the skin of the patient.)b. Run the free end of the strap through theopposite slit from below. Hold this loopopen as you run the arm of the patient upthrough the loop.c. Place the holder precisely over the cleanedskin site selected for sweat stimulation andhold it down while drawing the free end ofthe strap down and around the arm. Pull thestrap to tighten, stretching slightly and affix itto the retainer post.15

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat Testd. Grip the holder and lift it briefly above theskin to equalize strap tension on each sideof the holder, then replace it on the skin surface.Adjust strap tension as needed toensure correct contact.NOTE Attach the strap firmly, but avoid excessivetightness. Correctly applied, the holdershould grip the skin firmly enough to resistmoderately forceful attempts to change itsposition. The surrounding skin areas shouldmove with the holder when it is moved.e. Draw the skin back around the holder toremove any underlying wrinkles.f. Position the negative (black) holder (on thesame limb) in the same manner.6 Insert Pilogels Into the Iontophoretic ElectrodesInsert a gel into each electrode assembly.Press lightly and rotate to ensure an air-freeand moist interface between electrode plateand gel.7 Insert Each Electrode Into Its HolderFit the red (positive) anode into the holderwith the red locking ring and fit theblack (negative) cathode into the holderwith the black locking ring as follows:16

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat TestLocking Ring32 a. Rotate the holder locking ring to align cutoutswith those of the underlying holder thearrow indicator should be at Position 1(shown at left). Match the latching flanges of1the electrode with the cut-outs and insert thegel-fitted electrode into the holder.ElectrodeLatching Flangeb. Lightly press the electrode down against theskin and maintain pressure while rotating thelocking ring counter-clockwise until thearrow indicator is in line with the holder strapholes (Position 2 at left). Release pressureon the electrode and continue to slowlyrotate the locking ring counter-clockwiseuntil the electrode clicks into the detent(Position 3 at left).NOTE:Electrode wires must be securely taped to the patient’sarm to prevent disturbing the gel-to-skin contact duringiontophoresis. Use 1-inch surgical tape to secure wiresfirmly to the skin about 2 inches from each strain relief.Leave slack between taped area and electrodes to preventstrain to the electrode assembly.Tape17

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat TestNANODUCT(Date) (Time)Check ControlsIontophoresisSweat AnalysisRecall ReadingIontophoresis8 Activate Iontophoresisa. After completing Check Controls the arrowon the display should indicate Iontophoresison the menu.IncreasingCurrentIontophoresisFullCurrentENTER to ContinueIontophoresisCompleteb. Press ENTER to start iontophoresis. The displaywill show: INCREASING CURRENT. Oncecurrent has reached the full 0.5mA, the displaywill show FULL CURRENT and that level ismaintained for 2 minutes. Once full currentis achieved the Time Bar shows the remainingtime. Current will then decrease to zero(indicated by a short beep). The display willshow: IONTOPHORESIS COMPLETE.c. Press ENTER to return to the main menu.c9 Remove the Red ElectrodeWhile applying pressure to the red electrodewith the index finger, rotate the upper ringapproximately 90° clockwise until the cutoutsalign with the electrode flanges. Thenremove the electrode.CAUTION:Do not disturb or remove the red holder. It mustremain in place during analysis. In addition, leavethe negative (black) electrode, gel, holder andtape-downs in position to provide a ground contactfor initial sweat rate determination.18

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat Test10 Clean and Dry the Skin in the Collecting AreaUse a cotton swab to absorb any surfacemoisture from the entire skin area insidethe holder, followed by clean dry swabs tocompletely dry the area. Without delay,proceed to the next step.NOTE:If the sensor is not inserted immediately, repeatthe cleaning and drying procedure just beforeattaching the sensor.11 Insert Sensor Into Positive HolderInsert the sensor (without being attachedto the wiring harness) into the holder (redlocking ring) as described in steps 7a and7b, taking care not to disturb the holder ortouch the bottom of the sensor.Confirm that the Induction/Analysis moduleis ON.19

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat Test12 Connect Sensor to the Red Sensor ConnectorWith the sensor in the holder, press the sensorconnector fully onto the red sensor, sothat the two electrode pins seat in the matingreceptacles (orientation is not important).NANODUCT(Date) (Time)Check ControlsIontophoresisSweat AnalysisRecall ReadingNOTE: The sensor cable must be securely tapedto the patient’s arm approximately 2 inches fromthe strain relief. Be sure to leave enough slack inthe cable on the sensor side of the tape-down toprotect it from inadvertent tugging. Make sure thetape-down doesn’t disturb the sensor’s even contactwith the skin surface. Make sure the blackelectrode cable is still securely taped down.S w e a t A n a l y s i sSuppress ReadingsDisplay ReadingsS w e a t A n a l y s i sP l e a s e w a i t . . .13 Activate Sweat Conductivity AnalysisImmediately after the sensor is placed in theholder, Press ENTER.The instrument will then prompt you tochoose to display readings during testing orto suppress the reading for recall at a latertime. Press SELECT to make your selectionand then press ENTER.NOTE: A patient should produce sufficient sweat within 30minutes after iontophoresis. If the Nanoduct doesnot detect sufficient sweat to report “Sweat at FirstElectrode” within 30 minutes, or 30 minutes haselapsed between seeing “Sweat at First Electrode”on the display and seeing sweat testing dataappear on the display, the test should be aborteddue to insufficient sweat production.20

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat TestS w e a t A n a l y s i sSweat atFirst ElectrodeDisplay with readings suppressedS w e a t A n a l y s i sAveragingConcentration43 mmol/L eq NacLInitial Sweat rate4.1 g/m 2 /minDisplay with readings shown14 Record the ResultWith the sensor in place, the display usuallyindicates sweat contact with the firstelectrode within a few minutes. Afteranother 2 to 6 minutes (all timing isapproximate) the conductivity displayshould begin to show continuous data (ifDISPLAY READINGS has been selected).Simultaneously the initial sweating rate ing/m 2 /min is displayed. If the black electrodeis removed and the Initial SweatRate is reported as invalid, the resultfrom the sweat test remains valid.The continuous data remains on display,and after 3 minutes, the display showsthat averaging has commenced. The timebar at the bottom of the display indicatesremaining time once sweat reaches thesecond electrode. The mean sweat conductivityis displayed after another 5 minutes.ENTER to Continue(Date) (Time)Mean ElectrolyteConcentration45 mmol/L eq NaClInitial Sweat Rate:4.1 g/m 2 /minCompleteThis value is compared with the establishedconductivity ranges for childrenunder 16 years (normal = 0 to 60mmol/L; equivocal = 61 to 80 mmol/Land CF = above 80 mmol/L) for a diagnosticappraisal, and becomes the reportedtest result. A typical final display isshown at left. See Section 3 for completeinformation.Once the test is completed the displayflashes COMPLETE and the control moduleemits a short beep. The date and timethe test was completed is displayed.Press ENTER to return to the main menu.21

S E C T I O N 2SWEAT INDUCTION AND ANALYSIS2.1 Performing the Sweat Test15 Remove Holders and Sensor, and CleanElectrodesDisconnect the cable from the sensor,remove the sensor from the holder and discardthe used sensor. Disconnect the cableplug from the socket of the SweatInduction/Analysis module and turn OFFthe power.Remove the holders from the patient andgently wash and dry the entire skin areasinvolved in the test.Wash and dry the electrode plates.wash & dry metal platesNANODUCT(Date) (Time)Check ControlsIontophoresisSweat AnalysisRecall Reading16 Recall the Display ReadingIf you selected SUPPRESS READINGS, or ifthe control unit powers off, the last readingcan be recalled by selecting RECALL READ-ING on the display menu and pressingENTER.Recall Reading also outputs the last readingto the serial port where it can be printedif a serial printer is connected to the port.22

S E C T I O N 3INTERPRETING THESWEAT TEST

S E C T I O N 3INTERPRETING THE SWEAT TEST3.1 Units of ConductivityElectrical conductivity, essentially an electricalmeasurement, should properly be measured insiemens/cm. However, we use conductivity to indirectlymeasure electrolyte concentration. Sincemedical professionals are more familiar with standardchemical units (such as mmol/L) for concentration,the siemens/cm units have not been usedfor conductivity values in the practice of clinicalchemistry, to prevent confusion. Wescor hasretained the mmol/L (equivalent NaCl) unit usedby other sweat conductivity instruments in thepast. Unfortunately, this unit has also producedconfusion in some quarters.It is therefore important to define and explain themeaning of this expression. The readout, both asdisplayed continuously and as the electronicallyaveragedvalue is expressed in mmol/L (equivalentNaCl).This means that the sweat sample has an electricalconductivity that is equivalent to that of anNaCl solution of the displayed mmol/L concentration(at the same temperature). THE READINGS INSUCH UNITS DO NOT REPRESENT THE ACTUAL CON-CENTRATION OF EITHER SODIUM OR CHLORIDE IN THESWEAT.The level of electrical conductivity is a function ofthe molar concentration of ionized molecules in asolution. Sweat samples are made up of sodium,potassium, and a small contribution by ammonium,as the cation contribution. The anions balancingthese are mainly chloride, with lactate andbicarbonate. Thus, the conductivity can be seenas a measure of the total electrolyte in mmol/L.Clinical trials have amply demonstrated that sweattotal electrolyte and sweat chloride are equallyeffective analyses in the diagnosis of CF. As thereare other ions contributing to the conductivity other25

S E C T I O N 3INTERPRETING THE SWEAT TEST3.1. Units of Conductivitythan sodium and chloride, the mmol/L (equiv.NaCl) value of a sweat sample will always exceedthe actual molar sodium or chloride concentrationas analyzed specifically. The diagnostic range istherefore different from that established for chloride.The electrolyte selected for calibration referencehappens to be sodium chloride but it could havebeen any other salt. The chemical nature of thecalibration solution is immaterial, because the referenceranges for sweat conductivity will be basedupon comparison with the calibration value, andwill be valid whatever electrolyte is used as a reference.For example, if lithium nitrate had beenselected as the reference salt, it may have produceda possibly different but equally reliable andeffective reference range. Conductivity valueswould then have been expressed as mmol/L(equivalent LiNO 3 ). Though such an alternativecalibration option is not recommended, it wouldhave had the advantage that since no mention ofsodium or chloride is made, the results would notbe mistakenly seen as representing actual sweatsodium or chloride levels.26

S E C T I O N 3INTERPRETING THE SWEAT TEST3.2 Automatic AveragingRate of Sweating (g/m 2 /min)Fig. 1890768070605504A403B302C20100 5 10 15 20 25 3010035Time (minutes)Conductivity v TimeRate of Sweating v TimeConductivity (mmol/L)Automatic AveragingExamination of the data showing the relationshipbetween sweat conductivity and time after attachingthe sensor, obtained on all the subjects in theoriginal test of the system, and typically shown inFig.1, allowed the selection of optimal settings forthe averaging circuitry. After a variable lapse oftime (Period A, Fig.1) during which the sweat isgradually filling the channel in the sensor, it reachesthe second electrode, thereby completing theconductivity cell circuit and producing a displayedconductivity reading. During the next 3 minutes(Period B, Fig.1), this reading usually falls sharply,and then assumes a steady rate of decrease thatis maintained thereafter.This initial rapid change has been termed the “firstsample phenomenon” and the reason for it is notyet clear. In the steady phase of decrease of conductivity,the average rate of decrease is about15% per 10 minutes (during the period 10 to 20minutes after the first reading). The best time periodfor averaging commences after the initial rapidfall stabilizes, that is at 3 minutes from the firstreading, thus avoiding the “first sample phenomenon”.It then continues for the next five minutes(Period C, Fig 1) during which the sweating rate isstill near-maximal.The induction/analysis module is therefore programmedto make an average conductivityassessment by noting the time at which the firstconductivity result is displayed, allowing a timelapse of 3 minutes and then commencing a 5minute averaging period, after which the meanvalue is displayed.27

S E C T I O N 3INTERPRETING THE SWEAT TEST3.3 Diagnostic RangesNormal = 0 to 60 mmol/L*Equivocal = 61 to 80 mmol/L*CF = above 80 mmol/L**equivalent NaClUsing the data displayed in Fig 1, which showboth sweat rate and conductivity variation withtime after stimulation, the Nanoduct averagedvalue (over period C) was obtained (46 mmol/L).This can be compared with the value (47 mmol/L)that would theoretically have been obtained usinga Macroduct-obtained mixed sweat yield over 30minutes, the standard collection time used in theclinical trial that provided the basic results for theselection of the currently-established normal,equivocal, and CF diagnostic ranges. It is clearthat the Nanoduct results may confidently be evaluatedwith reference to these ranges, for childrenunder 16 years of age, normal 0 to 60 mmol/L,equivocal 61 to 80 mmol/L, and CF above 80mmol/L. (equivalent NaCl).In non-CF adults, the normal range is frequentlyextended into the equivocal levels, but never sufficientlyto provide false positive diagnosis.28

S E C T I O N 3INTERPRETING THE SWEAT TEST3.4 Initial Sweating RateOne advantage of the unique continuous-flowsensing device of the Nanoduct System is that itallows computation of the initial sweating rate. Thevolume of the sensor channel from the first electrodeto the second electrode contact is preciselyknown, as is the collecting surface area. After thesensor is attached to the arm, the time taken forthis volume to be filled with sweat is measured bythe Induction/Analysis module.Applying an algorithm with the fill time as the solevariable allows a display of the initial sweating ratein the conventionally accepted units of grams persquare meter of skin surface per minute. Thisdatum is available when the first reading is displayedon the continuous record of conductivity.29

S E C T I O N 4TROUBLESHOOTING AND PREVENTIVEMAINTENANCE

S E C T I O N 4TROUBLESHOOTING AND PREVENTIVE MAINTENANCE4.1 TroubleshootingSYMPTOMHigh resistance fault during iontophoresis.CAUSE/SOLUTIONHigh skin or electrode-to-skin resistance.Inspect the electrodes and clean if necessary.Place a drop of deionized waterdirectly on the clean skin beneath thepilogel disk.Make sure the electrodes are securedwith adequate tightness to the patientslimb.Open loop fault during Iontophoresis.Loose electrode or broken cable.Be sure both electrodes are insertedinto the holders and that the cable isconnected to the control unit.Over current fault during iontophoresis.Control unit immediately shuts off.Control unit may be damaged.Do not continue to run or use the controlunit. Contact Wescor for furtherinstructions.Battery voltage too low. Replace battery.Control unit failure. ContactWescor for further information.Low battery display.Low battery voltage. Replace battery.Display remains blank when turned on.Display does not change from “Waiting For Sweat.”Dead battery. Replace battery.No sweat detected.Check expiration date on Pilogel. Checkthat straps are secure and cable is connectedto control unit. Inspect cable forany damage.The patient’s sweat rate may be verylow. Wait sufficient time to allow sweatto flow. (Not to exceed 30 minutes.)Orifice on sensor cell blocked.Set Clock menu is displayed when instrument is turned onBattery for clock is dead.Replace clock battery.NOTE: This instrument is designed and tested to meet EN61326 standards for electromagnetic compatibilityfor laboratory equipment. However, if you suspect electromagnetic susceptibility or interference, reorient orrelocate the equipment to correct the problem.33

S E C T I O N 4TROUBLESHOOTING AND PREVENTIVE MAINTENANCE4.2 Cleaning the InstrumentWhen needed, the induction/analysis modulesurfaces and accessories should bewiped down using a soft cloth dampenedwith mild detergent or 10% householdbleach solution.Electrodes must be cleaned following eachiontophoresis procedure as follows:1 Remove any remaining gel from electrodes.2 Use a cotton ball or swab moistened withpurified water to clean each electrode thoroughly.3 If the electrode appears dirty after anextended idle period, or will not clean withsteps 1 and 2, use a small round piece oflight duty cleaning pad (such as 3M ScotchBrite TM #7445) to buff the electrode surface.CAUTION!Never use harsh abrasives such as steelwool, sandpaper, or emery cloth to cleanelectrodes. Never scrape electrodes withmetal tools. If the electrode surface isscratched or pitted it will not perform asspecified and must be replaced.34

S E C T I O N 4TROUBLESHOOTING AND PREVENTIVE MAINTENANCE4.2 Cleaning the InstrumentUse the following options to clean Nanoductstraps, holders and attachment strap retainersor any other parts that come into contactwith a patient:Option A:1 Soak the straps for 30 minutes in a freshlyprepared 10% dilution of household bleach.2 Rinse soaked straps thoroughly in tap water.3 Allow to air dry.Option B.1 Autoclave the straps for 30 minutes at 121ºC.CAUTION:Do not autoclave the Nanoduct holders (red or black) orthe attachment strap retainer post. Autoclaving willdestroy these parts.35

S E C T I O N 4TROUBLESHOOTING AND PREVENTIVE MAINTENANCE4.2 Cleaning the InstrumentOption C: Treat straps as disposables1 Discard straps after each use.2 Purchase new straps from Wescor (SeeAppendix B for complete information.Contact Wescor for current prices and orderinginformation.36

S E C T I O N 4TROUBLESHOOTING AND PREVENTIVE MAINTENANCE4.3 Battery Replacement1 The battery compartment is on the bottom ofthe induction/analysis module. Turn the uniton its side to access the battery compartment.Use a flat bladed screwdriver or similartool to lift the battery pack out of itsreceptacle.2 Remove the spent battery from the holder.3 Replace with a 9 volt lithium or alkaline battery(ANSI/NEDA 1604).4 Push the battery pack back into the instrumentuntil the retaining latch engages.5 Dispose of the spent battery according tobattery manufacturer’s instructions and localregulations.NOTE:If the instrument will be unused for anextended time, remove the battery.Batteries can leak and damage terminals ifleft unused for extended periods.37

S E C T I O N 4TROUBLESHOOTING AND PREVENTIVE MAINTENANCE4.4 Calibration and Checking Control ValuesPatient SimulatorWescor offers the Patient Simulator forthose who wish to measure unknown samplesas part of a proficiency study or to verifyor validate the function and accuracy ofthe Nanoduct instrument. Contact Wescorfor more information.NANODUCT(Date) (Time)Check ControlsIontophoresisSweat AnalysisRecall ReadingNOTE:This instrument uses an extremely stablesingle set point calibration. The calibrationplate is provided to verify that the instrumentis functioning properly and to allow for recalibrationwhen necessary.The calibration plate has one calibrationvalue, 80 mmol/L (equivalent NaCl) andthree control values: 40, 60, and 120 mmol/L(equivalent NaCl).Instructions:1 Select “Check Controls” on the menu andpress ENTER.2 Connect the electrode cable assembly to theelectrode socket and connect the sensor cellconnector to the 80 CAL connection on thecalibration plate. Select “Calibrate” andpress ENTER. The instrument will now calibrateto 80 mmol/L and display “80 mmol/Leq NaCl” when completed. Optionally forchecking control values, connect the sensorcell connector to any of the 3 control values.The selected value will show correspondingmmol/L eq NaCl ±1.Refer to the following page to see howthis procedure is followed using the displayscreen prompts.38

S E C T I O N 4TROUBLESHOOTING AND PREVENTIVE MAINTENANCE4.4 Calibration and Checking Control ValuesNANODUCT2007-07-21* 9:22 *1 Check Controls2IontophoresisSweat AnalysisRecall Reading*Date and time indications are inthe format yyyy-mm-dd; hh:mm.Dates, times and other data shownare for example only, Actual dataduring use will vary.CHECK CONTROLS3 Electrolyte4Concentration:80 mmol/L eq NaClExitCalibrateCheck ControlsCalibration Date2007-07-21* 09:27*Shows date and time of last calibrationfor a few seconds. Sendsdata to serial port.CHECK CONTROLSElectrolyteConcentration:80 mmol/L eq NaClExitCalibrateConnect the sensor cell connectorto the 80 mmol/L connector on thecalibration plate.C a l i b r a t i n gP L E A S E W A I T. . .5 6C a l i b r a t i o nC o m p l e t e2 0 0 7 - 0 7 - 2 1 9 : 3 3Sends data to serial port.7CHECK CONTROLSElectrolyte Concentration80 mmol/L eq NaClExitCalibrate39

A P P E N D I XSPECIFICATIONSA

A P P E N D I XASPECIFICATIONSReadout. . . . . . . . . . . . . . . . . . . . . . . . . . 128 x 64 dot graphic. Supports up to 8 lines of 18 charactersor numerals, with multi-lingual support.Sound. . . . . . . . . . . . . . . . . . . . . . . . . . . . Alert and Alarm signals.Keyboard . . . . . . . . . . . . . . . . . . . . . . . . . . ON, OFF, SELECT and ENTER keys.Electrode Connection. . . . . . . . . . . . . . . . 6 pin locking medical connector to mate with induction/conductivitycell, cable.Serial Connection. . . . . . . . . . . . . . . . . . . 9 pin connector compatible with RS232.Electrical. . . . . . . . . . . . . . . . . . . . . . . . . . One 9.0 Volt Lithium battery (Alkaline battery may be used)100 milliwatt power use during operation. Typical solidstate,over-current circuit protection. 3.0 Volt lithium coincell for real time clock.Sweat Induction Control. . . . . . . . . . . . . . Current profile controlled for use with Pilogel®Iontophoretic disks with multiple fail-safe circuits to limitcurrent. Nominal current is 0.5 (±.02) mA for 2.5 minutes(± 02 Sec.) Maximum fail-safe current limited to 5 mA.Sweat AnalysisReal Time Clock. . . . . . . . . . . . . . . . . . . . . Conductivity with readout in mmol/L (equivalent NaCl).Range 3 to 200 mmol/L (equivalent NaCl). Error 1% or lessfrom 25 to 150 mmol/L (equivalent NaCl). Initial sweatingrate reading 0 to 50 g/m 2 /min. Single point automatic calibration80 mmol/L (equivalent NaCl).. . . . . . . . . . . . . . . . . . . . ± 2 minutes per year.Operating Temperature . . . . . . . . . . . . . . . 15 to 30 degrees C.Storage and Transport Temperature . . . . . 0 to 60 degrees C.Regulatory . . . . . . . . . . . . . . . . . . . . . . . . . Meets EN 61326 Standards for EMC compatibility. MeetsIEC 60601 standards for safety. Manufactured underWescor’s quality system (ISO 13485: 2003). Bears the CEmark as a Class IIa medical device. Certificate issued byBSI 0086.Physical . . . . . . . . . . . . . . . . . . . . . . . . . . . Housed in portable carrying case. Storage compartment forsupplies. Handle for ease of carrying.Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 cm.Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 cm.Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 cm.Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . Less than 2.25 kg.43

A P P E N D I X BACCESSORIES, SUPPLIES,& REPLACEMENTPARTS

A P P E N D I XACCESSORIES, SUPPLIES & REPLACEMENT PARTSBACCESSORIESCalibration Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AC-081Nanoduct Patient Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AC-111SUPPLIESNanoduct Supply Kit for 6 sweat tests . . . . . . . . . . . . . . . . . . . . . SS-043Nanoduct User’s Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RP-360REPLACEMENT PARTSNanoduct Control PCB Assembly . . . . . . . . . . . . . . . . . . . . . . . . Factory Service OnlyElectrode Cable Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RP-359Strap Retainer Post . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RP-353Positive Red Electrode and Sensor Cell Holder . . . . . . . . . . . . . RP-357Negative Black Electrode Holder . . . . . . . . . . . . . . . . . . . . . . . . RP-358Holder Attachment Strap, Small, 1 each . . . . . . . . . . . . . . . . . . . RP-354Holder Attachment Strap, Medium, 1 each . . . . . . . . . . . . . . . . . RP-355Holder Attachment Strap, Large, 1 each . . . . . . . . . . . . . . . . . . RP-356Case Latch, 1 each . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RP-347Clock Battery, 1 each . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RP-23847

A P P E N D I XSUPPLEMENTAL INFORMATIONC

A P P E N D I X CSUPPLEMENTAL INFORMATIONCystic Fibrosis: A Brief Description of the DiseaseCystic fibrosis of the pancreas (or mucoviscidosis)is due to one of the manyknown ‘inborn errors of metabolism’ thatare fundamentally the result of aberrationsin the structure of the genetic material. It isclassed as lethal because of the very poorprognosis afforded to sufferers. The inheritanceis autosomal recessive, so that anaffected child must inherit one defectivegene from each of the parents to behomozygotic. Such parents must then atthe least be carriers (heterozygotes). Thedistribution of the genetic anomaly varieswith racial types. It is predominantly associatedwith Caucasians in whom it occursin about 1 in every 1500 to 2000 livebirths.The symptoms of the disease are manifold,however they are not strictly specificand hence physicians often have difficultyin distinguishing CF from other childhooddiseases on the basis of medical diagnosisalone. The most serious clinical featuresare the pulmonary problems stemmingfrom abnormally viscous exudates inthe lungs, requiring urgent physiotherapyand antibiotic treatment to offset the everpresentrisk of pneumonia. The pancreasis also affected by over-viscous secretionsthat reduce its output of digestiveenzymes, thus the child tends to fail tothrive because the food ingested passesthrough the alimentary canal without thenormal enzymic breakdown necessary forabsorption of nutrients. Fortunately, thelatter problem is relatively easily correctedby the addition of animal pancreaticextracts to the diet. The use of “pancreas”in the disease name arose because of theidentification (in 1938) of pancreatic abnormalitiesduring post-mortem examinationof children that had died with a set ofsymptoms that were not as yet associatedwith a specific illness. It should be notedhere that CF sufferers may differ quitewidely in the degree to which they exhibitthe various symptoms. Some may be relativelyless affected in the respiratory airways,others may show more serious pancreaticproblems. A feature of the inheritanceis that carriers do not exhibit thesymptoms of CF.In 1953, it was found that children afflictedby the disease are prone to acute hyponatremiaduring hot weather. Investigationson the cause of the loss of sodiumshowed that the eccrine sweat of childrenwith CF contains 3 to 4 times as much saltas that of unaffected subjects. Subsequentwork showed that this salt increase is notobserved in presumed carriers. This wasthe first intimation that a laboratory test forthe disease was conceivable. The sweattest was born, and remains to this day theprincipal laboratory diagnostic test for thisdisease. In recent years the discovery of“the CF gene” promised a new laboratorydiagnostic approach. Intensive studies ofthis gene have revealed hundreds of variantsthat may, or may not, produce thetypical CF symptoms.There is no doubt that this research will inthe future illuminate the effects of differentgenetic abnormalities on the biochemicalpatterns of the individual. However, thesweat test will remain the definitive laboratorydiagnostic test for some time yet.51

A P P E N D I X CSUPPLEMENTAL INFORMATIONEvolution of Sweat Test MethodsThe sweat test has traditionally involvedthree separate, sequential procedures —stimulation of the sweat glands, collectionof their secretion, and sweat analysis.Early stimulation procedures involved totalbody heating followed by placing thepatient in a bag, or, later by heating followedby collection from a limited area ofskin covered by a hermetically-sealedabsorptive pad. Both of these methodsendangered the infants and proved unsatisfactory.The heating was eventuallyavoided by using pilocarpine iontophoresisto induce the glands to sweat maximally.Following this, the sweat was collected ina pre-weighed pad and re-weighed, elutedand analyzed.The method is usually known as theGibson and Cooke 1 pad absorption sweattest or the QPIT (quantitative pilocarpineiontophoresis test). This procedure haspersisted over the years and is still beingperformed, particularly by CF centers. It istime-consuming and tedious, requiringmany manipulations where human errormay intervene, and in one particular stepoffers technical difficulties that virtuallyensure some degree of error, particularlywhen the sweat sample size is very small.Laboratorians in CF centers who specializein this method develop the requisiteskill to maintain reasonably accurateresults, but this is generally not the case inoutlying clinics and hospitals, where thetest is only occasionally requested, leadingto unacceptably high risk of false results.While the iontophoretic transport of pilocarpineinto the glands has remained theuniversally preferred method of sweatstimulation to this day, the need for a simplermethod of collection and analysisspawned the development of alternativeprocedures during the late 60’s and early70’s. Principally among these were thecup-collection systems, which used electricalconductivity for analysis, and the directskin chloride electrode system.These methods were highly innovative,procedurally simpler than the Gibson andCooke method, and were initially commerciallysuccessful. They nevertheless failedin their objective to eliminate false diagnosticresults. The adoption of these newprocedures on a wide scale exacerbatedthe problem, evoking a storm of criticismin the professional literature, with calls fora return to the original pad-absorptionwhich was now regarded as the “referencemethod” 2, 3, 4 . In fact, CF referral centersin the United States, operating underaccreditation of the Cystic FibrosisFoundation were forbidden to use anysweat test method other than the QPIT.These early attempts to simplify the sweattest failed for two principal reasons: (1)error intrinsic to the method of collectionand beyond the control of the operator, or(2) extreme susceptibility to variations inoperator technique. The direct skin chlorideelectrode, though offering unrivaledsimplicity, was very prone to operator variabilityin manual skill, and gave poorresults due mainly to great difficultiesexperienced in the control of evaporationerror.52

A P P E N D I X CSUPPLEMENTAL INFORMATIONEvolution of Sweat Test MethodsThe cup collection method was examinedfor potential intrinsic error by Webster 5who found that the phenomenon of condensateformation on the walls of the plasticcups was the principal cause of thetrouble. His quantitative measurements ofthe degree to which this occurred inunheated plastic cups showed that theerror was always significant and very oftenreached proportions sufficient to producefalse positive results. The error was avoidedby using a metal collector cup that wasmaintained at above skin temperaturethroughout sweat collection, condensationwas prevented and the error disappeared.In 1978, Wescor introduced the Model3500 Webster Sweat Collection Systemthat employed an electrically-heatedmetallic collector cup. 6 It was the first“simplified” sweat collection system worthyof comparison with the Gibson and Cookemethod, it enjoyed considerable success,and was free from any criticism by usersand related professionals. It was howeverburdened by a problem common to allcup-collection systems, that is, the need to“harvest” the sweat accumulated beneaththe cup during collection.Wescor’s determined commitment toresolve this problem eventually led to theinvention of the MACRODUCT ® SweatCollector. 7 This innovation completely supplantedthe heated cup, while retaining itsadvantages by the use of a collector thatanaerobically collected sweat by using thehydraulic pressure of the sweat glands topump the secretion directly from the ductsinto a fine-bore capillary tube. This systemhas been very successfully employed bothin the US and internationally since 1983.Vested in Wescor’s scientific and engineeringstaff is a combination of manyyears experience in laboratory sweat testingand in the development of modernelectronic instrumentation. The Wescoraim in the field of sweat testing hasalways been to provide quality instrumentationto meet a number of criteria.1. Elimination of all intrinsic sourcesof error concomitant to previouscollection methods.2. Ensuring impeccable accuracy inthe diagnostic result by reducinghuman error potential to the lowestpossible level.3. Maximization of patient safety andcomfort.4. Maximization of operator conveniencewithin the stricturesimposed by objectives 1, 2 and 3.These objectives have led to considerableinnovative improvements in all aspects ofsweat testing, iontophoretic safety measures,collection methods and also in theanalytical phase of the test. With the introductionof the Model 3600 MACRODUCTSweat Collection System in 1983, all ofthe comprehensive objectives had beenaccomplished. Paramount among the system’sseveral unique features was theinnovative MACRODUCT disposablesweat collector.53

A P P E N D I X CSUPPLEMENTAL INFORMATIONDevelopment of the Nanoduct Neonatal Sweat Analysis SystemDuring almost twenty years of successfuldeployment of the Macroduct Sweat-ChekSystem it began to be realized that a trulyneonatal sweat test was needed, one thatpreserved the error-free anaerobic handlingof the sweat sample employed inMacroduct, yet at the same time was particularlydesigned to meet the specialrequirements of the newborn infant duringthe first two weeks of life.In the interests of effective early managementof newborn CF patients it is highlydesirable that a definitive laboratory diagnosisbe made as early as possible, allowingprompt initiation of appropriate medicalprocedures, especially those correctingmalnutrition due to pancreatic deficiencyand those protecting the infant from airwayproblems. The frequency of “insufficientsweat,” or “no sweat” reports from laboratorieshas been unsatisfactorily highthroughout the history of sweat testing onvery young infants. Recent years has seenincreasing emphasis on “screening tests”to newborns, particularly the combinationof immuno-reactive trypsin assays andgenotype analysis. Both of these havebeen very useful, but have not reachedthe status of a definitively diagnostic procedureas has the sweat electrolyte test.The reason for sweat test failures is wellunderstood by those professionallycharged with sweat test performance. Thesize of iontophoretic electrodes and collectionparaphernalia is usually inappropriatelylarge for effective use on the extremelysmall and frail limbs of the newborn. Manytechnologists are wary of attempting thisdaunting task due to the distinct possibilityof causing a burn, and also because of therisk of producing a false result in the padabsorptiontest by inability to control evaporationand condensation errors, particularlywhen handling tiny infants and dealingwith low sweat yields. The MacroductSystem, which employs the smallest electrodesand collector of all methods usedup to 1998, is nevertheless frequentlyfound to be inappropriately-sized for testswith neonates. It is obvious that anyattempt to devise a sweat test for newbornbabies must involve, as a fundamentalrequirement, equipment for iontophoresisand collection that is scaled down to minimaldimensions, enabling their effectiveapplication to extremely small limbs.It is also evident that this approach, takenalone, would merely aggravate the problemby limiting even further the number ofsweat glands involved and thereby reducethe sweat yield to as little as 3-6 microlitersin 15 minutes collection. In suchcases the traditional methods for gatheringthe sample, storing it in a sealed container,and taking aliquots for presentation toan instrument for analysis would clearlynot be feasible, because the potential forserious error would be very difficult, if notimpossible, to control.Such limitations could be avoided if noattempt was made to collect the minutesweat yield. Instead, the sweat is channeledfrom the sweat duct openings insuch a way that it passes directly andanaerobically into a conical collectinginterface, just as it does in the Macroductdevice, and thence to a microbore tubewithin the collector that is equipped with54

A P P E N D I X CSUPPLEMENTAL INFORMATIONDevelopment of the Nanoduct Neonatal Sweat Analysis Systemelectrodes and becomes a conductivitycell for analysis of electrolyte concentration.Research and development atWescor provided evidence that thisapproach was feasible, and sweat testsusing the prototype equipment illustratedthe simplicity and ease of operation of themethod and the speed at which definitiveresults could be obtained.In effect, the apparatus, called theNanoduct Neonatal Sweat AnalysisSystem, 8 incorporates a flow-through conductivitycell that provides, in situ, continuousreadings as the sweat enters it fromthe sweat ducts. This type of data has notbeen available in any test method to date,making the Nanoduct unique. All othermethods involve analysis of a mixed sampleobtained over the whole collectionperiod. The sweat is not seen, nor is it collectedas a visible sample.With the development of this neonatal procedure,the opportunity presented itself tomake desirable modifications with the aimof improving the safety and shortening thetime of iontophoresis, and to provide theelectrode gels with protection against accidentalfreezing.This method was first published in theAnnals of Clinical Biochemistry in 2000. 855

A P P E N D I X CSUPPLEMENTAL INFORMATIONReferences1. Gibson, L. E., Cooke, R. E., A test for concentration of electrolytes in sweat in cystic fibrosisof the pancreas utilizing pilocarpine iontophoresis. Pediatrics 1959; 23: 545-9.2. Gibson, L. E., The Decline of the Sweat Test. Comments on Pitfalls and Reliability. ClinPediatr. 1973; 12: 450-3.3. Rosenstein, B. J., Langbaum, T. S., Gordes, E., and Brusilow, S. W., Cystic fibrosis: problemsencountered with sweat testing, JAMA, 240, 1987, 1978.4. Gibson, L. E., Cooperative study comparing three methods of performing sweat tests to diagnosecystic fibrosis.5. Webster, H. L., and Lochlin, H., Cystic fibrosis screening by sweat analysis. A critical reviewof techniques, Med J. Aust., 1, 923, 1977.6. Webster, H. L., and Barlow, W. K., New approach to cystic fibrosis diagnosis by use of animproved sweat-induction/collection system and osmometry, Clin. Chem., 27, 385, 1981.7. Barlow W. K., and Webster H. L., A simplified method of sweat collection for diagnosis ofcystic fibrosis. Proceedings of the 9th International Cystic Fibrosis Congress. Brighton,England, June 9th-15th 1984. Lawson D. (ed), John Wiley & Sons, New York; 1984; 204.8. Webster H. L., Quirante C. G., Micro-flowcell conductometric sweat analysis for cystic fibrosisdiagnosis. Ann Clin Biochem, 2000 Vol. 37, 399-407.56

A P P E N D I XUSING THE SETUPMENUD

A P P E N D I XUSING THE SETUP MENUDThe Setup Menu allows you to configure theinstrument for your use, to run an instrument selftest, or to operate the instrument in a demonstrationmode.Press SimultaneouslySETUP MENU2007-07-21 9.25ExitConfigureSelf TestDemo ModeAccessing the Setup Menu:1 While pressing and holding down the SELECTand ENTER keypads, press the ON keypad.After a few seconds, the display will show:“SETUP MENU.”Make selections by pressing ENTER when thepointer is next to your choice.Select “Exit” to return to the main operationmenu.Using the Configure OptionSETUP MENU2007-07-21 9.26ExitConfigureSelf TestDemo ModeThe Configure Option allows you to set the clock,change the display language, set options such asdefault status for suppressing or displaying testresults, and forcing a Calibration Check when theinstrument is turned on.1 Select “Configure” from the Setup Menu andpress ENTER.59

A P P E N D I X DUSING THE SETUP MENUCONFIGURE MENUExitSet ClockSet OptionsChange LanguageSet TimeSet DateExitSet Clock(Date) (Time)Set 24 Hour Clock(Hour: Minutes)SELECT to adjustENTER to setSetting or Adjusting Time and Date DisplaySetting Time1 To set or adjust the time on the clock, select“Set Clock” in the CONFIGURE MENU and pressENTER . Then select “Set Time” and pressENTER.2 The display shows the “Set 24 Hour Clock”menu with either the hours or minutes flashing.Select hours first and enter the correct hourand press ENTER. Then select “Minutes” andenter the correct minute. Then press ENTER.Set Clock(Date) (Time)Set TimeSet DateExitSetting Year, Month and Day1 Select “Set Date” and press ENTER.Set Year2006-02-15SELECT to adjustENTER to setSet Month2006-02-15SELECT to adjustENTER to set2 While the year position is flashing, pressSELECT to adjust the year. Then press ENTER.3 While the month position is flashing, pressSELECT to adjust the month. Then press ENTER.4 While the day position is flashing, press SELECTto adjust the day. Then press ENTER.Set Day2006-02-15Press EXIT to return to the previous MENU.60SELECT to adjustENTER to set

A P P E N D I X DUSING THE SETUP MENUCONFIGURE MENUExitSet ClockSet OptionsChange LanguageSetting or Adjusting Options1 While in the Configure Menu select “SetOptions” and press ENTER.Set Display Optionfor Sweat AnalysisSuppress ReadingsDisplay ReadingsCalibration Optionon Start UpCal. OptionalForce Cal.2 To either display or suppress the results ofthe sweat test, select either “SuppressReadings” or “Display Readings” and pressENTER.3 The Calibration Option menu allows you toautomatically go to the Check Controls menuon power-up of the instrument. Choose“Force Cal.” for this option or “Cal. Optional”to calibrate only when you need to. PressENTER when you have made your selection.Setting Language OptionsExitSet CheckSet OptionsChange Language1 You can set the display language in the configuremenu. Select “Change Language” andthen press ENTER.CONFIGURE MENUSet languageEnglishFrenchGermanSpanish2 Select the desired language and then pressENTER.Select and press ENTER to return to theSETUP MENU.61

A P P E N D I X DUSING THE SETUP MENUSelf Test displaysSETUP MENUDate TimeExitConfigure MenuSelf TestDemo ModeSelf Test ModeENTER to ContinueUsing the Self TestThe Self Test allows testing of current output, conductivity,and battery voltage.To use the Self Test, select “Self Test” in theSetup Menu (see the far left column of displays).CAUTION:Do not run Self Test while the module is connected toa patient.#, ## Battery VoltSelf Test ModeENTER to continueConnect Electrodesto check current#.### m. A.Self Test ModeENTER to ContinueConnect toCalibration Plateto check operation## mmol/L eq NaClSelf Test ModeENTER to ContinueConnect to PrinterSELECT KeyTo test SerialCommunicationDemo Mode displaysDEMO MODEDate TimeExitCheck ControlsIontophoresisSweat AnalysisIontophoresisDEMO MODEFull CurrentSweat AnalysisDEMO MODEElectrolyteConcentration## mmol/Leg NaClInitial Sweat Rate#.# g/m 2 /minUsing the Demo ModeThe Demo Mode is used to simulate typical displaysthat are seen during normal operation. Thiscan be useful for demonstrating instrument functionor to familiarize the user with the instrumentNo actual iontophoresis or sweat analysis occursin this mode and only simulated results areshown. In this mode the instrument functionsmuch like it would when running on an actualpatient. The display screen and menu appears asit would during an actual test with the exceptionthat “Demo Mode” appears at the top of the displayand the Check Controls option is not availablewhile in this mode. The instrument must beoperated in Normal Mode in order to check controlsor calibrate. While running in this mode, theENTER key acts as a shortcut key and advancesthe instrument through the phases of the operationallowing yo to see the next display without waitingfor the full instrument countdown.62

A P P E N D I XPILOCARPINEIONTOPHORESIS:REQUIREMENTS AND RISKSE

A P P E N D I X EPILOCARPINE IONTOPHORESIS: REQUIREMENTS AND RISKSIn common with all sweat test proceduresfor the diagnosis of cystic fibrosis sincethe inception of the sweat test, sweat mustbe induced in order to be analyzed.In modern medical practice the sweatglands in a limited area of the skin arestimulated by local application of cholinergicdrugs, particularly pilocarpine. Thesesubstances are introduced to the glandsby iontophoresis (in the case of pilocarpine).These drugs act by mimickingthe action of the natural physiologicalgland stimulator, acetylcholine, which isliberated at the gland by signals from theautonomic nervous system. The iontophoreticprocedure depends upon theapplication of a small and brief direct currentto the skin via electrodes, the anodeof which, being positive, drives the positively-chargedpilocarpine from the reservoirof drug sufficiently to reach theglands.The requirements for Pilocarpine, asdefined in the Wescor Quality Procedures,are primarily that the form and source ofthe drug be pilocarpine nitrate and thepurity being that specified by the UnitedStates Pharmacopeia (USP Grade). Theconcentration of aqueous pilocarpinenitrate solution should be sufficient to initiatea maximal sweat-yielding responsefrom the glands. The Wescor concentrationfor Nanoduct meets this requirementat a minimal level of 1.5%. Where positively-chargedsalt ions (acting as iontophoretictransport competitors) are absent fromthe drug solution, the requirement may bemet by 1.0% pilocarpine. The literature onpilocarpine shows no evidence of allergicsensitivity to the drug.Wescor gel drug reservoirs are qualitycontrolled to meet these requirements inPilogels manufactured in-house, usingspectrophotometric procedures to checkthe pilocarpine content of the gels in eachbatch.Burns Under IontophoresisMinor skin burns have been an unwelcome,adverse side-effect of pilocarpineiontophoresis from the beginning. Unusualsensitivity to pilocarpine has sometimesbeen assumed to be the cause of “burns”but there is no firm evidence for this contention.Majority opinion seems to supportthe proposition that some types of stimulatingapparatus are prone to cause burns,particularly when associated with proceduralerror.Such burns are extremely rare withWescor sweat stimulating systems. Theyuse a sophisticated microprocessor controllerand a very low total delivery current(0.5 milliamperes in the NanoductSystem). Pilocarpine is contained inunique gel reservoirs. The gels alsoinclude compounds that further protect thepatient from skin damage by preventingacid accumulation, by minimizing the riskof gel breakage, and by substantiallyreducing the time of electrical drug transport.These features markedly reduce, butdo not entirely eliminate, the possibility ofskin burns.65

A P P E N D I X EPILOCARPINE IONTOPHORESIS: REQUIREMENTS AND RISKSMost individuals exhibit a mild erythema(redness) at the skin stimulation site. Insome cases one or more blister-like weltsmay also form. These are often mistakenfor burns, but are more likely to be a temporaryreaction to the passage of electricalcurrent. Such “blisters” invariably disappearwithin 2 or 3 hours, leaving no aftereffects.Based on current data and reportedevents, the apparent burn rate usingWescor instruments is less than 1 in50,000. The low rate is due to Wescor’sinsistence on proper test procedurestogether with built-in equipment safety provisionsthat minimize the risk of even mildskin injury. It is highly unlikely that patientswill suffer a burn during the stimulationphase of the sweat test.We realize these statistics will be of scantcomfort to the parents of a child who hasthe misfortune of suffering the “1 burn in50,000.” However, experience has shownthat when burns do occur, the injury isminor with little or no scarring.66

A P P E N D I XSERIAL DATA OUTPUTF

A P P E N D I X FSERIAL DATA OUTPUTData is automatically sent out on the serial port whenever“Recall Reading” or “Check Controls” is selected from themain menu. If a printer is correctly connected to the serialport, the data can be printed or the data can be capturedwith the use of a computer. The output from the RecallReading selection will be the date, time and result from thelast sweat test completed. The output from the CheckControls selection will be the date, time, and calibrationvalue from the last calibration. In addition, if a new calibrationis completed, the new date, time, and calibration valuewill be transmitted to the printer or computer.The Nanoduct serial port uses a DB9 connector on theinstrument front panel. This port is for asynchronous serialcommunication with a printer or computer. It uses standardnon-return-to-zero (NRZ) format at RS-232 voltage levels.SERIAL OUTPUT TECHNICAL DATAOutput voltage level:Nominal ± 9 voltsMaximum ± 15 voltsMinimum ± 5 voltsData protocol:9600 bps1 Start bit8 Data bitsNo parity1 Stop bitBy entering Self Test Mode the following serial output canbe sent”DATE TIME PRINT TEST.” This can be used fortesting the printer and cable.69

A P P E N D I X DSERIAL DATA OUTPUTPin Diagram:Pin 1 2 3 4 56 7 8 9Pin # Mnemonic Description1 N/C No Connection2 RXD Receive Data (output)3 TXD Transmit Data (input)4 N/C No Connection5 GND Signal Ground (passive)6 N/C No Connection7 N/C No Connection8 N/C No Connection9 N/C No ConnectionThe serial port is configured as Data Communications Equipment(DCE). This enables the Nanoduct to be connected directly to mostcomputers which are usually configured as Data TerminalEquipment (DTE). Most printers are configured as DCE, in whichcase a null modem cable is required.Data output is in ASCII characters.Reading format of output:_ _ _ DATE TIME READINGmmol/L eq NaCl.Calibration format of output:CAL DATE TIME 80mmol/L eq NaCl.70

INDEX

INDEXAccessories 47Alkali Accumulation (during iontophoresis)8Anodic Acidification 8Automatic Averaging 21, 25, 27Batterylow 10, 18, 33replacement 10, 37Buffer (see Trisodium Citrate)Burns Under Iontophoresis 65-66Cable Assembly 9, 13, 18Cable Connector Socket 9Calibration 38-39Citrate Buffer (see Trisodium Citrate)Conductivityautomatic average 9, 21, 25cell 10measurement 9, 10, 21, 25, 26,27Units of 10, 21 25, 26Configure Option 59-60CurrentDC 6flow indicator 18Customer Service 3Cystic Fibrosis (CF) 6, 54Diagnostic Ranges 28Display 9, 10, 21language settings 61suppressed readings 10, 60Environmental limits 4Electrode(s)anodic (positive) 7, 14, 18cable assembly 7, 13cathode (negative) 7, 14cleaning 34color coding 8flanges 7inspection 13installing 16, 17iontophoresis 7reference 7First Sample Phenomenon 27Fault Condition 9low battery 9, 10, 33open electrode 9, 33circuit 9, 33Flanges 17Glycerol 8High Resistance 14, 33Holder(s) 7, 13, 14, 22straps 13, 14, 15rings 16, 17Induction/Analysis Module 6, 7,9, 10, 13, 20, 22Iontophoresis 6, 9, 13, 16, 18,61, 62current 6, 18, 61, 62time 18Initial Sweating Rate 9, 21, 29KeypadsON 9, 18OFF 9, 22ENTER 9, 18, 21SELECT, 9, 21Latching Flanges 17LCD Readout (See Display)Low Battery Indicator 10, 18, 33Microconductivity cell (see conductivitycellON Switch (see Keypads)Open Loop Fault 33Patient Simulator 38, 47Pilogel ® Iontophoretic Discs 8,13, 16, 33, 65Pilocarpine Iontophoresis (Seeiontophoresis)Pilocarpine 8, 65-66Power Supply 43Quality Control 8Recall Reading 22Replacement Parts 47Self Test Option 62Sensor 8, 13, 18, 20, 21, 27cable 20connector 7, 13, 20flanges 8socket 9Setup Menu 59Skincondition 14, 65-66electrical impedance of 14Specifications 43Supplies 47Suppress Reading 22Sweatanalysis 6, 9, 10analysis results 10chloride in 26contamination of 14flow 7glands 14, 61sodium levels 26stimulation 9, 61rate 7, 21, 33test 21Trisodium Citrate in Pilogels 8Troubleshooting 33Units of Conductivity Measurement10, 21, 25, 2673