3700 SYS Instruction and Service Manual Rev B

© 2007 Wescor, Inc. All rights reserved. Printed in the United States of America. The information contained in this document is subject to change without notice. Wescor, Macroduct, Webster Sweat inducer, Sweat Chek and Pilogel are trademarks of Wescor, Inc. Other trade names used in this document may be trademarks of their respective owners, used here for information only. US Patent Numbers 4,266,556; 4,542,751. UK Patent Number 2116850.

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TABLE OF CONTENTS

section

1INTRODUCTION 1.1 1.2 1.3 1.4 1.5 1.6 1.7

User's Manual Overview ... 3 To Our Valued Customers ... 4 Important User Information ... 5 System Components... 6 Webster Sweat Inducer ... 8 Pilogel® Iontophoretic discs ... 12 Macroduct Sweat Collector ... 16

section

2

SWEAT INDUCTION AND COLLECTION 2.1 2.2 2.3 2.4

Inducing Sweat... 21 Collecting Sweat ... 27 Abbreviated Instructions... 33 Information for Parents... 34

section

3

SWEAT ANALYSIS 3.1

An overview to Sweat Analysis ... 37

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TABLE OF CONTENTS

section

4

TROUBLESHOOTING AND MAINTENANCE 4.1 4.2 4.3 4.4

Troubleshooting ... 41 Cleaning the Electrodes ... 44 Cleaning the Macroduct Straps... 45 Replacing Inducer Batteries ... 46

APPENDIX A Specifications ... 49

APPENDIX B Supplies and Replacement Parts ... 53

APPENDIX C A Perspective on the Sweat Test ... 57 References ... 61

APPENDIX D Procedure for High Skin Resistance ... 65

Index Index ... 67

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1.1 User's Manual Overview This manual covers the complete laboratory procedure for the laboratory diagnosis of cystic fibrosis through examination of sweat electrolyte concentration. The steps preliminary to sweat analysis–sweat stimulation and collection, are accomplished using the Macroduct® Sweat Collection System.

CAUTION! Never attempt sweat collection until you are thoroughly familiar with the procedures and cautionary information detailed in this manual. Abbreviated instructions printed elsewhere are provided for reference only and should not be used as a substitute for the complete information contained in this manual.

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1.2 To Our Valued Customer Thank you for purchasing the Macroduct Sweat Collection System. We are confident that this is the finest sweat testing system in the world. As the acknowledged world leader in sweat testing products for the laboratory diagnosis of cystic fibrosis, Wescor is dedicated to providing customer support in all aspects of the use of this product and sweat testing theory and practice. From the beginning, our goal has been to identify problems in sweat testing, delineate the precise cause of false diagnosis, and then to devise innovative solutions. We have accomplished this with the added benefit of vastly simplifying procedures while remaining within the strict boundaries of acceptable accuracy. Wescor is ready to help you resolve any difficulty with the operation or performance of the Macroduct system. If you cannot resolve a problem using the information in this manual, please contact us. Wescor Inc. 459 South Main Street Logan, Utah 84321-5294 USA TELEPHONE: 435 752 6011 TOLL FREE:

800 453 2725

FAX:

435 752 4127

E-MAIL:

[email protected]

WEBSITE:

www.wescor.com

PLEASE NOTE: Wescor’s Authorized European Representative for matters relating to the Medical Device Directive is: MT Promedt Consulting GmbH Altenhofstraße 80 D-66386 St. Ingbert, Germany Tel. +49 6894 581020 Fax +49 6894 581021 email [email protected]

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1.3 Important User Information APPLICATION: The Macroduct System is intended for laboratory use by qualified personnel for stimulation and collection of sweat for analysis in the diagnosis of cystic fibrosis. Anyone operating the Macroduct System must be thoroughly familiar with the procedures and cautionary information detailed in this manual before attempting to use this equipment. SPECIFICATION OF SAFE USE: Using this device in a manner not specified by Wescor, Inc may impair the safety protection designed into the equipment and may lead to injury. Do not use where flammable anesthetic is present or in any oxygen-enriched environment. STATEMENT OF ENVIRONMENTAL LIMITS: This equipment is designed to be safely operated at 5° to 35 °C, maximum relative humidity 80%. EXPLANATION OF SYMBOLS FOUND ON EQUIPMENT: I

Run

O

Stop International Attention Symbol. Calls attention to important information and instructions in the user’s manual. Type BF equipment complying with Medical Equipment Safety Standard EN60601-1.

Current Flow Indicator

Low Battery Indicator

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1.4 System Components

Supply Kit for 6 sweat tests 12-Pilogel® Discs, 6 - Macroduct Sweat Collectors

6-Small Sealable containers

Webster Sweat Inducer

Sweat Dispenser

Velcro Electrode Attachment Strap (red)

Velcro Electrode Attachment Strap (black)

Macroduct Strap, Extra Large (39 cm)

Electrode Set Macroduct Strap, Large (25 cm)

Macroduct Strap, Medium (18cm)

Nippers Macroduct Strap Small (14 cm)

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1.4 System Components CATALOG NUMBER 3700-SYS DESCRIPTION

UNIT

CATALOG NO.

Webster Sweat Inducer

1 each

Model 3700

Electrode Set

1 each

320566

Electrode Attachment Strap (red)

1 each

320585 Red

Electrode Attachment Strap (black)

1 each

320585 Black

Supplies kit for 6 sweat tests (12-Pilogel® Discs, 6-Macroduct Sweat Collectors, 6-Small Sealable containers)

1 each

SS-032

Sweat Dispenser

1 each

RP-065

Nippers

1 each

RP-066

Macroduct Strap, Small (14 cm)

1 each

SS-128

Macroduct Strap, Medium (18 cm)

1 each

SS-129

Macroduct Strap, Large (25 cm)

1 each

SS-130

Macroduct Strap, Extra Large (39 cm)

1 each

SS-131

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1.5 Webster Sweat Inducer The Webster Sweat Inducer is an integral part of the Macroduct Sweat Collection System. Its design is based on years of clinical experience, research, and product development, with patient safety and comfort given paramount importance. It is a fully automatic unit featuring advanced electronic circuitry and many fail-safe and operator convenience features. How It Works

3700

WEBST

ER SW

DUCER EAT IN

When the RUN/STOP switch is moved to the “I” position, a brief tone signals that external electrode circuit resistance is acceptable and that the instrument has begun to deliver iontophoretic current. Current delivery is confirmed by a green CURRENT FLOW INDICATOR. The tone sounds again briefly at the completion of iontophoresis. Iontophoretic current rises to 1.5 mA during a 1730 second interval, remains at 1.5 mA for 5 minutes, then decreases in the final 6 seconds to zero, at which time the instrument switches off. This "profiling" of iontophoretic current prevents the sensation of electrical shock that results when current changes abruptly. The CURRENT FLOW indicator is wired in series with the electrodes.

3700

WEBST

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ER SWEAT

ER INDUC

During the complete iontophoretic sequence, the total electrical charge delivered to the positive electrode is approximately 450 millicoulombs or 78 millicoulombs/cm2. Due to impurities in the agar, Pilogel discs contain sodium and other cations in total molar concentrations approximately equal to that of the pilocarpinium ion. These therefore compete with each other for transport of electrical charge which produces an approximately 50% reduction in the amount of pilocarpine that would have been delivered to the glands in the absence of such salts. However, sufficient drug is transported to produce maximal sweat stimulation.

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1.5 Webster Sweat Inducer FAULT CONDITIONS To maximize safety, the inducer continuously monitors the current. If an unexpected condition is detected the current turns off and an alarm sounds. This alarm continues until you move the switch to STOP (0). A fault condition can occur if one of the electrodes becomes detached. An alarm may also be due to low batteries, (see next page). See Section 4 for more details about fault conditions and alarms.

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1.5 Webster Sweat Inducer

SWE WEBSTER

3700

LOW BATTERIES The alarm sounds if the batteries are low when the switch is moved to RUN (I). In this case, the amber LOW BATTERY indicator will also be illuminated, and the inducer will not start. The alarm continues until the control switch is moved to the STOP (0) position.

CER AT INDU

3700 3700 WEBSTER SWEAT INDUCER

WEBSTER SWEAT INDUCER

!

LOW BATTERY RUN

STOP

CURRENT FLOW

If batteries get low during iontophoresis, the instrument completes the cycle using remaining power in the batteries, but at the end of the cycle, the tone sounds and the LOW BATTERY indicator flashes. To disable the LOW BATTERY alert, push the switch to the STOP (0) position. Replace batteries before attempting another iontophoresis cycle. See Section 4.4.

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1.5 Webster Sweat Inducer ELECTRODES

Wipe Stainless Steel Electrodes Check for cracks in lead wires

3700

WEBSTER

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The high-grade stainless steel electrodes require only minimal maintenance. This consists of cleaning them with purified water after each use so they will be ready for the next procedure (See Section 4.2). Lead wires should be periodically inspected for breaks or cracks in the insulation. If electrode wires, insulation, or the plastic electrode housing exhibit cracks or breaks the electrode set should be replaced.

NOTE: If you activate the run switch while the electrodes are not attached to the patient’s limb, an “open circuit” alarm will sound. To disable the open circuit alarm, push the switch to the STOP position.

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1.6 Pilogel® Iontophoretic Discs The traditional reagent solutions for pilocarpine iontophoresis are pilocarpine nitrate and sodium nitrate. These have been applied either to absorbent fabric (such as gauze) or to discs of thick paper that are then interposed between the electrode surfaces and the skin. Such reagent reservoirs have always presented problems to both operators and patients. Pilogel iontophoretic discs were developed specifically to overcome these and other problems. They consist of a solid agar gel that is 96% water, into which is dissolved 0.5% pilocarpine nitrate and a trace of antifungal compounds. The discs are approximately 6 mm thick and sized to fit snugly into the standard Wescor recessed electrodes. Pilogel is supplied in a resealable vial containing 12 discs intended for one-time use (sufficient for 6 iontophoretic sweat stimulations). Discs are used in both positive and negative electrodes. Sweat stimulation occurs under the positive electrode, while the disc under the negative electrode completes the electrical circuit. The Pilogel system provides monumental improvements in patient safety, efficiency of sweat stimulation, and convenience to the operator.

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1.6 Pilogel® Iontophoretic Discs EFFICIENT SWEAT PRODUCTION Reliable, uniform, gel-to-skin contact ensures delivery of pilocarpine over the whole skin area, thus providing total gland stimulation and maximal sweat yield. Despite being mostly water and presenting a "wet" surface to the skin, Pilogel discs do not exude fluid even under the pressure applied during limb attachment. This eliminates any possibility of "bridging". Gel-fitted electrodes may be placed in close proximity without risking a short circuit, a great advantage when dealing with neonates. Pilogel eliminates the need to apply gauze or paper pads. The discs are immediately ready for use. There is no need to prepare or store reagent solutions. With Pilogel, the electrodes, once fitted, require no further attention during iontophoresis.

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1.6 Pilogel® Iontophoretic Discs ENSURING PATIENT SAFETY The Macroduct system represents a dramatic improvement in patient safety over previous sweat induction and collection methods. Pilogel discs provide an air-free continuous conduction medium and even distribution of current over the stimulated skin area, reducing the possibility of electrical burns to the skin. The Pilogel disc fits snugly into the recess of the electrode, preventing disc separation from the electrode. This virtually eliminates any possibility of a burn from direct metal-to-skin contact. BURNS DURING IONTOPHORESIS The Macroduct Sweat Collection System has become perhaps the most frequently used system in hospitals and clinics worldwide. While the Macroduct system is clearly superior to previous methods, burns during iontophoresis have not been totally eliminated. Based on reports from practitioners, we estimate a frequency of 1 burn in 50,000 iontophoretic procedures. Burn descriptions vary from “tiny black pinholes in the skin” to “crater-like, third degree burns two to three millimeters in diameter.” In most of the reported cases the children have exhibited no sign of pain or discomfort during iontophoresis, and the burn was not discovered until the electrodes were removed Parents must be informed and allowed to read the “Information for Parents” included with the Macroduct supply kit (see also Section 2.4). You should also have them sign an appropriate release form before performing this procedure. If the procedures outlined in the manual are followed correctly, burns should be extremely rare.

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1.6 Pilogel® Iontophoretic Discs We strongly recommend the following burn prevention procedures:

1

Do not use Pilogel discs that have an unusual appearance (fractures etc.)..

2

Electrode strap pressure should promote firm contact between the skin and the gel disc. Straps should not be tight enough to crush the disc between skin and electrode.

3

Leave skin slightly wet after washing the area where the electrode will be attached (OR) Add a drop of water to either the skin or the pilogel surface (after installation in the electrode).

NOTE: Although these recommendations are designed to prevent burns during iontophoresis, there is no guarantee they will not occur. Any institution providing sweat tests should thoroughly explain this possibility to parents and obtain a written waiver from them prior to iontophoresis. Besides limiting liability from an unfortunate incident, parents thus warned can make an informed decision about testing their child and are less likely to be upset if a burn occurs.

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1.7 Macroduct Sweat Collector The Macroduct Sweat Collector is a disposable plastic device with a shallow concave undersurface that covers the skin area previously stimulated by pilocarpine iontophoresis. The collection surface is contoured such that when firmly applied to the stimulated area, the skin bulges into the concavity, leaving no air space. At the apex of the conical surface, a tiny orifice leads to a small-bore plastic tube or duct, having an inside diameter of approximately 0.64 mm, and coiled into a spiral. The base of the sweat gland is 2 to 3 mm beneath the surface of the skin. Fluid secreted by the gland creates hydraulic pressure that moves the fluid upward through the sweat duct to emerge from the skin as sweat. When sweat surfaces beneath a Macroduct collector, this same hydraulic pressure forces it into the air-free interface between the skin and the concave surface of the collector. Since the pressure of the skin against the collector surface is greatest at the rim and decreases inwardly toward the center, the secreted sweat is directed to the orifice and into the plastic "macroduct.” After attachment, sweat becomes visible in the spiral tube of Macroduct within one to four minutes, depending upon the relative elasticity of the skin and the subject's sweating rate.

NOTE: For best results, the stimulated skin area should cover deep flesh such as reasonably thick musculature. Thin skin sections overlaying palpable tendons or bony structures are not suitable as collection sites.

The emergent sweat is turned blue by contact with a small amount (≤ 10 nanomoles) of blue water-soluble dye (FDC certified food color) applied to the Macroduct collection surface. This allows easy assessment of the volume produced at any time during collection.

BLUE COLORED SWEAT

This dye does not interfere with sweat chloride assay by colorimetry. The dye contributes slightly to the osmolality and sodium content of the sweat sample. Even with a low sweat yield of only 20 µL, this contribution will not exceed 1.5 mmol/kg or 1.0 mmol/L, respectively, and is negligible. The spiral collection tube capacity is approximately 85 microliters. This is adequate for average sweat production levels (50 to 60 microliters) in thirty minutes of collection. This volume is sufficient for all current methods of sweat analysis (see Notes Regarding Sweat Yield p.17). At the end of the collection period, the collector must remain on the limb until the pristine sweat specimen is removed by severing the plastic tube at its attachment point. See complete instructions in Section 2 before attempting this procedure.

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1.7 Macroduct Sweat Collector

Advantages of Macroduct (a) By preventing any exposure to an air space the collected sweat is not subject to condensate error. (b) Evaporation of sweat can only occur at the advancing meniscus in the plastic collecting duct. This has been found by measurement to produce a negligible loss of 0.1 microliters per hour. (c) The operator can gauge the amount of sweat produced at any time, a unique and unprecedented feature that eliminates guesswork in deciding the duration of the collection period. (d) The patient has complete mobility during the collection period. (The collector can be over-wrapped with an elastic bandage to keep curious young fingers from causing mischief.) (e) Macroduct collects sweat passively and automatically, driven by the same hydraulic pressure that causes sweat to move from the base of the sweat gland to the skin surface. There is no “harvesting” procedure during which the integrity of the sweat specimen is liable to be compromised by human error or other factors.

Notes Regarding Sweat Yield Technologists experienced with the Gibson and Cooke pad absorption method of sweat collection often raise the question of the “100 mg Rule,” or some variation, which requires a minimum sweat volume for the analytical result to be valid. To the extent that such requirements were imposed to mitigate the error possibilities of the pad absorption method, they may be disregarded, since Macroduct collection is free of such errors. On the other hand, some authorities have suggested that the minimum yield rules were promulgated because low sweating rates are associated with anomalous electrolyte concentrations, and therefore may give rise to a misleading diagnostic result. In order to establish an equivalent minimum yield threshold for Macroduct, one must take into account the differences in electrode size (area) and the recommended collection times for the two methods. Applying these ratios shows that an average collection of 50 µL in 15 minutes using Macroduct is equivalent to a yield, in terms of sweating rate, of approximately 350 mg by the pad absorption method. Conversely, the sweat yield with Macroduct corresponding to the “100 mg Rule” is approximately 15 µL.

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