title: Assessment of the feasibility of an ultra-low power, wireless digital patch for the continuous ambulatory monitoring of vital signs.
abstract: OBJECTIVE
  Vital signs are usually recorded at 4-8 h intervals in hospital patients, and deterioration between measurements can have serious consequences. The primary study objective was to assess agreement between a new ultra-low power, wireless and wearable surveillance system for continuous ambulatory monitoring of vital signs and a widely used clinical vital signs monitor. The secondary objective was to examine the system's ability to automatically identify and reject invalid physiological data.
  
  
  METHODS
  Single hospital centre.
  
  
  METHODS
  Heart and respiratory rate were recorded over 2 h in 20 patients undergoing elective surgery and a second group of 41 patients with comorbid conditions, in the general ward.
  
  
  METHODS
  Primary outcome measures were limits of agreement and bias. The secondary outcome measure was proportion of data rejected.
  
  
  RESULTS
  The digital patch provided reliable heart rate values in the majority of patients (about 80%) with normal sinus rhythm, and in the presence of abnormal ECG recordings (excluding aperiodic arrhythmias such as atrial fibrillation). The mean difference between systems was less than ±1 bpm in all patient groups studied. Although respiratory data were more frequently rejected as invalid because of the high sensitivity of impedance pneumography to motion artefacts, valid rates were reported for 50% of recordings with a mean difference of less than ±1 brpm compared with the bedside monitor. Correlation between systems was statistically significant (p<0.0001) for heart and respiratory rate, apart from respiratory rate in patients with atrial fibrillation (p=0.02).
  
  
  CONCLUSIONS
  Overall agreement between digital patch and clinical monitor was satisfactory, as was the efficacy of the system for automatic rejection of invalid data. Wireless monitoring technologies, such as the one tested, may offer clinical value when implemented as part of wider hospital systems that integrate and support existing clinical protocols and workflows.
authors.affiliation: Sensium Healthcare Ltd, Abingdon, UK.
authors.forename: Miguel
authors.initials: M
authors.lastname: Hernandez-Silveira
authors.affiliation: MRC Centre for Transplantation, King's College London, Urology Centre, Guy's Hospital, London, UK.
authors.forename: Kamran
authors.initials: K
authors.lastname: Ahmed
authors.affiliation: Sensium Healthcare Ltd, Abingdon, UK.
authors.forename: Su-Shin
authors.initials: SS
authors.lastname: Ang
authors.affiliation: National Heart and Lung Institute, Imperial College London, St Mary's Campus, London, UK.
authors.forename: Fahriya
authors.initials: F
authors.lastname: Zandari
authors.affiliation: Sensium Healthcare Ltd, Abingdon, UK.
authors.forename: Tinaz
authors.initials: T
authors.lastname: Mehta
authors.affiliation: Sensium Healthcare Ltd, Abingdon, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Weir
authors.affiliation: Sensium Healthcare Ltd, Abingdon, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Burdett
authors.affiliation: Sensium Healthcare Ltd, Abingdon, UK Institute of Biomedical Engineering, Imperial College London, London, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Toumazou
authors.affiliation: Centre for Perioperative Medicine and Critical Care Research, Imperial College Healthcare NHS Trust, London, UK.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Brett
mesh_terms: D000553:Ambulatory Care / Q000379:methods*; D005240:Feasibility Studies; D006339:Heart Rate; D006801:Humans; D008131:London / Q000453:epidemiology; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000639:trends; D056152:Respiratory Rate; D059015:Wireless Technology / Q000295:instrumentation / Q000639:trends
keywords: GENERAL MEDICINE (see Internal Medicine)