title: Validity and reproducibility of electrical impedance tomography for measurement of calf blood flow in healthy subjects.
abstract: The Sheffield electrical impedance tomography; (EIT) system produces images of changes in the distribution of resistivity within tissue. The paper reports on the application of electrical impedance tomography in monitoring volume changes in the limb during venous occlusion. The aim of the study is to assess the feasibility, reproducibility and validity of calf blood flow measurements by EIT. In 14 healthy volunteers calf blood flow is compared, as determined in a calf segment by strain-gauge plethysmography (SGP), with the impedance changes measured by EIT during rest and post-ischaemic hyperaemia. The measurements are repeated to assess reproducibility. The reproducibility for the EIT, assessed from the repeated measurements and expressed as a reproducibility coefficient, is 0.88 during rest and 0.89 during hyperaemia. The reproducibility coefficient for SGP data is 0.83 at rest and 0.67 during hyperaemia. Flow measurements, assessed by means of two methods, correlate well at rest (r = 0.89), but only moderately during hyperaemia (r = 0.51). The correlation coefficient for the pooled flow measurements is 0.98. It is concluded that EIT is a valid and reliable method for assessing blood flow in the limb. Possible applications of EIT in localising fluid changes are discussed.
authors.affiliation: Department of Pulmonary Medicine, University Hospital Vrije Universitait, Amsterdam, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Vonk Noordegraaf
authors.forename: P W
authors.initials: PW
authors.lastname: Kunst
authors.forename: A
authors.initials: A
authors.lastname: Janse
authors.forename: R A
authors.initials: RA
authors.lastname: Smulders
authors.forename: R M
authors.initials: RM
authors.lastname: Heethaar
authors.forename: P E
authors.initials: PE
authors.lastname: Postmus
authors.forename: T J
authors.initials: TJ
authors.lastname: Faes
authors.forename: P M
authors.initials: PM
authors.lastname: de Vries
mesh_terms: D000328:Adult; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D010991:Plethysmography; D012039:Regional Blood Flow / Q000502:physiology; D015203:Reproducibility of Results; D014054:Tomography / Q000379:methods*