title: Effect of Applying Force to Self-Adhesive Electrodes on Transthoracic Impedance: Implications for Electrical Cardioversion.
abstract: BACKGROUND
  Current guidelines disagree on the role for applying force to electrodes during electrical cardioversion (ECV) for atrial fibrillation, particularly when using self-adhesive pads. We evaluated the impact of this practice on transthoracic impedance (TTI) with varying force and in individuals with differing body mass indices (BMI). We additionally assessed whether specific prompts could improve physicians' ECV technique.
  
  
  METHODS
  The study comprised three parts: (1) TTI was measured in 11 participants throughout the respiratory cycle and with variable force applied to self-adhesive electrodes in anteroposterior (AP) and anterolateral (AL) configurations. (2) Three participants in different BMI classes then had TTI measured with prespecified incremental force applied. (3) Ten blinded cardiology trainees simulated ECV on one participant with and without prompting (guideline reminders and force analogies) while force applied and TTI were measured.
  
  
  RESULTS
  The AP approach was associated with 13% lower TTI than AL (P < 0.001). Strongly negative correlations were observed between force applied and TTI in the AL position, irrespective of BMI (P ≤ 0.003). In all cases, 80% of the total reduction in TTI observed was achieved with 8 kg-force (∼80 N). All prompts resulted in significantly greater force applied and modest reductions in TTI.
  
  
  CONCLUSIONS
  Applying force to self-adhesive electrodes reduces TTI and should be considered as a means of improving ECV success. Numerically greater mean force applied with a "push-up" force analogy suggests that "concrete" cues may be useful in improving ECV technique.
authors.affiliation: Arrhythmia Service, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: F Daniel
authors.initials: FD
authors.lastname: Ramirez
authors.affiliation: Biomedical Engineering, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Fiset
authors.affiliation: Biomedical Engineering, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Cleland
authors.affiliation: Biomedical Engineering, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Zakutney
authors.affiliation: Arrhythmia Service, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Pablo B
authors.initials: PB
authors.lastname: Nery
authors.affiliation: Arrhythmia Service, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Girish M
authors.initials: GM
authors.lastname: Nair
authors.affiliation: Arrhythmia Service, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Calum J
authors.initials: CJ
authors.lastname: Redpath
authors.affiliation: Arrhythmia Service, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Mouhannad M
authors.initials: MM
authors.lastname: Sadek
authors.affiliation: Arrhythmia Service, University of Ottawa Heart Institute, Ottawa, Ontario, Canada. dbirnie@ottawaheart.ca.
authors.forename: David H
authors.initials: DH
authors.lastname: Birnie
mesh_terms: D000269:Adhesives; D000328:Adult; D001281:Atrial Fibrillation / Q000628:therapy; D002307:Cardiography, Impedance / Q000379:methods; D004554:Electric Countershock / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D000269:Adhesives
keywords: atrial fibrillation; body mass index; cardioversion; electrodes; impedance; transthoracic