title: Diagnosis of PLMD from increased pulse rate variability on overnight oximetry.
abstract: OBJECTIVE
  This study was undertaken in a group of patients with periodic limb movement disorder (PLMD) to assess whether the presence of increased pulse rate variability (PRV) without desaturation on overnight oximetry was suggestive of the occurrence of periodic limb movements (PLMs).
  
  
  METHODS
  Seventy sleepy patients with a polysomnographic diagnosis of PLMD and 25 controls with obstructive sleep apnea were included in this retrospective study. All patients had undergone initial domiciliary oximetry and subsequent polysomnography (PSG). The oximetry tracings were independently interpreted by five sleep unit personnel for the presence of increased PRV. Further, the association between increased PRV and PLMs was evaluated in the summary graph of the PSG.
  
  
  RESULTS
  Fifty seven (81.4%) patients had definite evidence of increased PRV without episodes of desaturation on initial oximetry, which was later confirmed to be due to PLMs on PSG. 13 (18.6%) patients had no PRV on oximetry and PSG but had PLMD. The inter-interpreter concurrence in suspecting a diagnosis of PLMD based on oximetry alone was more than 80% in 64 (91%) patients.
  
  
  CONCLUSIONS
  The presence of isolated increased PRV on overnight oximetry is a valuable tool in suspecting nonsleep apnea disorders like PLMD.
authors.affiliation: Sleep Disorders Unit, guys' and St. Thomas' NHS Trust, London, England, UK.
authors.forename: Uma M
authors.initials: UM
authors.lastname: Krishnaswamy
authors.forename: Sean E
authors.initials: SE
authors.lastname: Higgins
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Kosky
authors.forename: Simone
authors.initials: S
authors.lastname: Delacy
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Williams
keywords: oximetry; periodic limb movements; pulse rate variability