title: Pulsed direct and constant direct currents in the pilocarpine iontophoresis sweat chloride test.
abstract: BACKGROUND
  The classic sweat test (CST) is the golden standard for cystic fibrosis (CF) diagnosis. Then, our aim was compare the production and volume of sweat, and side effects caused by pulsed direct current (PDC) and constant direct current (CDC). To determine the optimal stimulation time (ST) for the sweat collection. To verify the PDC as CF diagnosis option.
  
  
  METHODS
  Prospective study with cross-sectional experimental intervention. Experiment 1 (right arm): PDC and CDC. ST at 10 min and sweat collected at 30 min. Currents of 0.5; 0.75; 1.0 and 1.5 mA and frequencies of 0, 200, 1,000 and 5,000 Hz applied. Experiment 2 (left arm): current of 1.0 mA, ST at 5 and 10 min and sweat collected at 15 and 30 min with frequencies of 0; 200; 1,000 and 5,000 Hz applied Experiments 1 and 2 were performed with current density (CD) from 0.07 to 0.21 mA/cm2. Experiment 3: PDC was used in typical CF patients with two CFTR mutations screened and or with CF diagnosis by rectal biopsy and patients with atypical CF.
  
  
  RESULTS
  48 subjects (79.16% female) with average of 29.54 ± 8.87 years old were enrolled. There was no statistical difference between the interaction of frequency and current in the sweat weight (p = 0.7488). Individually, positive association was achieved between weight sweat and stimulation frequency (p = 0.0088); and current (p = 0.0025). The sweat production was higher for 10 min of stimulation (p = 0.0023). The sweat collection was better for 30 min (p = 0.0019). The skin impedance was not influenced by ST and sweat collection (p > 0.05). The current frequency was inversely associated with the skin impedance (p < 0.0001). The skin temperature measured before stimulation was higher than after (p < 0.0001). In Experiment 3 (29 subjects) the PDC showed better kappa index compared to CDC (0.9218 versus 0.5205, respectively).
  
  
  CONCLUSIONS
  The performance of the CST with CDC and PDC with CD of 0.14 to 0.21 mA/cm2 showed efficacy in steps of stimulation and collection of sweat, without side effects. The optimal stimulation time and sweat collection were, respectively, 10 and 30 min.
authors.affiliation: Departament of Pediatrics, Faculty of Medical Sciences, State University of Campinas, 13083-887 Campinas, SP, Brazil. carlacg.gomez@gmail.com.
authors.forename: Carla Cristina Souza
authors.initials: CC
authors.lastname: Gomez
authors.forename: Maria de Fatima
authors.initials: Mde F
authors.lastname: Servidoni
authors.forename: Fernando Augusto de Lima
authors.initials: FA
authors.lastname: Marson
authors.forename: Paulo Jose Coelho
authors.initials: PJ
authors.lastname: Canavezi
authors.forename: Adriana Mendes
authors.initials: AM
authors.lastname: Vinagre
authors.forename: Eduardo Tavares
authors.initials: ET
authors.lastname: Costa
authors.forename: Antonio Fernando
authors.initials: AF
authors.lastname: Ribeiro
authors.forename: Maria Angela Gonçalves de Oliveira
authors.initials: MA
authors.lastname: Ribeiro
authors.forename: Adyleia Aparecida Dalbo Contrera
authors.initials: AA
authors.lastname: Toro
authors.forename: Celia Regina
authors.initials: CR
authors.lastname: Pavan
authors.forename: Michelle Vivine Sá Dos Santos
authors.initials: MV
authors.lastname: Rondon
authors.forename: Sonia Leticia Silva
authors.initials: SL
authors.lastname: Lorena
authors.forename: Francisco Ubaldi
authors.initials: FU
authors.lastname: Vieria
authors.forename: Jose Dirceu
authors.initials: JD
authors.lastname: Ribeiro
mesh_terms: D000328:Adult; D001706:Biopsy; D002712:Chlorides / Q000032:analysis; D003550:Cystic Fibrosis / Q000175:diagnosis*; D017097:Electric Impedance; D004568:Electrodiagnosis / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D007478:Iontophoresis / Q000009:adverse effects / Q000379:methods*; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D010862:Pilocarpine / Q000494:pharmacology; D011446:Prospective Studies; D012007:Rectum / Q000473:pathology; D013542:Sweat / Q000737:chemistry / Q000378:metabolism*; D013545:Sweat Glands / Q000187:drug effects / Q000503:physiopathology; D013997:Time Factors; D055815:Young Adult
chemical_list: D002712:Chlorides; D018721:Muscarinic Agonists; D010862:Pilocarpine