title: Heartrate variation of umbilical artery Doppler waveforms.
abstract: Umbilical artery Doppler waveforms from 20 patients were used to investigate the dependence of resistance index and pulsatility index on beat to beat pulse length over short time periods for individual patients, and on the usefulness of a common normalisation formula. For individual patients the resistance index and pulsatility index were only partially correlated with pulse length. Changes in both indices occurred independently of pulse length. Use of a common normalisation formula resulted in no significant reduction of the coefficient of variation of the resistance index (p greater than 0.1), and a reduction in the coefficient of variation of the pulsatility index of 10% (p greater than 0.001). It is concluded that short term changes in resistance index and pulsatility index cannot be corrected by a common normalisation formula.
authors.affiliation: Department of Medical Physics, Royal Infirmary, Edinburgh.
authors.forename: P R
authors.initials: PR
authors.lastname: Hoskins
authors.forename: F D
authors.initials: FD
authors.lastname: Johnstone
authors.forename: S E
authors.initials: SE
authors.lastname: Chambers
authors.forename: N G
authors.initials: NG
authors.lastname: Haddad
authors.forename: G
authors.initials: G
authors.lastname: White
authors.forename: W N
authors.initials: WN
authors.lastname: McDicken
mesh_terms: D005260:Female; D006340:Heart Rate, Fetal; D006801:Humans; D011247:Pregnancy; D011674:Pulse; D014463:Ultrasonography / Q000379:methods*; D014469:Umbilical Arteries / Q000502:physiology*