title: A modified device for continuous non-invasive blood pressure measurements in humans under hyperbaric and/or oxygen-enriched conditions.
abstract: BACKGROUND
  It would be desirable to safely and continuously measure blood pressure noninvasively under hyperbaric and/or hyperoxic conditions, in order to explore haemodynamic responses in humans under these conditions.
  
  
  METHODS
  A systematic analysis according to 'failure mode and effects analysis' principles of a commercially available beat-by-beat non-invasive blood pressure monitoring device was performed using specifications provided by the manufacturer. Possible failure modes related to pressure resistance and fire hazard in hyperbaric and oxygen-enriched environments were identified and the device modified accordingly to mitigate these risks. The modified device was compared to an unaltered device in five healthy volunteers under normobaric conditions. Measurements were then performed under hyperbaric conditions (243 kPa) in five healthy subjects.
  
  
  RESULTS
  Modifications required included: 1) replacement of the carbon brush motorized pump by pressurized air connected through a balanced pressure valve; 2) modification of the 12V power supply connection in the multiplace hyperbaric chamber, and 3) replacement of gas-filled electrolytic capacitors by solid equivalents. There was concurrence between measurements under normobaric conditions, with no significant differences in blood pressure. Measurements under pressure were achieved without problems and matched intermittent measurement of brachial arterial pressure.
  
  
  CONCLUSIONS
  The modified system provides safe, stable, continuous non-invasive blood pressure trends under both normobaric and hyperbaric conditions.
authors.affiliation: Department of Internal Medicine, Academic Medical Center, University of Amsterdam, The Netherlands.
authors.forename: René
authors.initials: R
authors.lastname: van der Bel
authors.affiliation: Department of Medical Technology, Academic Medical Center, University of Amsterdam, The Netherlands.
authors.forename: Bart C
authors.initials: BC
authors.lastname: Sliggers
authors.affiliation: Finapres Medical Systems, Amsterdam, The Netherlands.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: van Houwelingen
authors.affiliation: Department of Internal Medicine, Academic Medical Center, University of Amsterdam, The Netherlands, MRC/ARUK Centre of Musculoskeletal Ageing Research, School of Life Sciences, The Medical School, University of Nottingham, Queen's Medical Centre, Nottingham, UK.
authors.forename: Johannes J
authors.initials: JJ
authors.lastname: van Lieshout
authors.affiliation: Department of Human Physiology, University of Oregon, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Halliwill
authors.affiliation: Hyperbaric Medicine, Academic Medical Center, University of Amsterdam, The Netherlands.
authors.forename: Robert A
authors.initials: RA
authors.lastname: van Hulst
authors.affiliation: Department of Internal Medicine Academic Medical Center at the University of Amsterdam Meibergdreef 9, 1105AZ, Amsterdam The Netherlands Phone: +31-(0)20-566-5808, E-mail: C.T.Krediet@amc.uva.nl.
authors.forename: C T Paul
authors.initials: CT
authors.lastname: Krediet
mesh_terms: D001274:Atmospheric Pressure; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000295:instrumentation*; D015924:Blood Pressure Monitors; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006931:Hyperbaric Oxygenation; D010991:Plethysmography / Q000295:instrumentation; D015203:Reproducibility of Results
keywords: Patient monitoring; cardiovascular; hyperbaric facilities; physiology