In-house development of automatic iontophoresis current source for sweat chloride test
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Abstract
Background: The standard method for cystic fibrosis screening is pilocarpine iontophoresis sweat chloride test. The iontophoresis device must supply reliable and accurate electrical current within the safety range. The researchers determined that an in-house development of reliable automatic iontophoresis current source for sweat chloride test would have an impact to cost and popularity of the test in Thailand. Furthermore, it will promote the development of a technological self-reliance in the future.
Objectives: Automatic iontophoresis current source was designed and fabricated to conform to IEC 479-1 electrical safety standard and CLSI C34-A3 Sweat Chloride Testing Standard. Performance of the device was tested by performing sweat chloride test in healthy volunteers.
Materials and methods: Design and develop automatic iontophoresis current source for sweat chloride test with electrical safety standards IEC 479-1 and conform to CLSI C34-A3 standard. The developed device will be tested by performing classic sweat chloride test (CST) in healthy adult volunteers.
Results: Seventy healthy volunteers (age between 18 to 40 years old) were recruited. No history or signs of illness or being treated for diseases including the lungs, liver, pancreas, and intestines were found. 27 males and 43 females are compared between control and test with pilocarpine iontophoresis using stimulated direct current of 1.0 mA for 4 minute (0.07 mA/cm2) and 30 minutes for sweat collection. The electrical current used was far lower than recommendation by CLSI C34-A3 standard and other known studies, but still can give out weight of sweat (more than 0.077 gram) as recommended by CLSI C34-A3 standard. Mean weight of collected sweat in male volunteers are 0.35±0.10 gram and 0.17±0.08 gram in female volunteers. And there are significant differences in chloride concentration obtained from male and female volunteers that correlated with previous studies.
Conclusion: The in-house development of automatic iontophoresis current source device for sweat chloride test was successful and successfully used in the sweat chloride test in normal healthy adult volunteers. Sweat can be stimulated effectively with low iontophoresis current in normal subject. Moreover, compare with CLSI-C34-A3 recommendation, the device can stimulate sweat production far more than minimum sample weight of 0.077 gram with lower electric current and shorter duration of stimulated time.
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Personal views expressed by the contributors in their articles are not necessarily those of the Journal of Associated Medical Sciences, Faculty of Associated Medical Sciences, Chiang Mai University.
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