title: Variability--the drama of the circulation.
abstract: The two most common vital signs, ie, pulse and blood pressure (BP), are obtained to seek guidance in clinical management of patients in virtually all primary care practices. Even a cursory glance at their values, whether it is within a person over time or between patients on a particular day, reflects an amazing degree of variability. In this brief editorial we provide a focused review of the assessment and the importance of variability in within-patient heart rate and BP and conclude with a few thoughts about the discordance in significance attached to these ubiquitous clinical measures.
authors.affiliation: Department of Medicine, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Mario F
authors.initials: MF
authors.lastname: Rubin
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Brunelli
authors.forename: Raymond R
authors.initials: RR
authors.lastname: Townsend
mesh_terms: D001775:Blood Circulation / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D002940:Circadian Rhythm / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans