title: An evaluation of a new continuous blood pressure monitoring system in critically ill patients.
abstract: OBJECTIVE
  To determine if the DxTek monitor, which is a device that measures blood pressure (BP) noninvasively and continuously by means of pulse velocity and wave shapes derived from the pulse oximeter optical plethysmograph and electrocardiogram is as accurate as an oscillometric cuff device when compared with intraarterial BP measurement.
  
  
  METHODS
  Prospective, comparative study.
  
  
  METHODS
  University Medical Center.
  
  
  METHODS
  28 intensive care unit patients.
  
  
  METHODS
  Blood pressures were reported every minute by intraarterial catheters and DxTek and every 10 minutes by an oscillometric monitor for 2 to 5 hours. DxTek calibration was performed initially and when specified patient manipulations by caretakers were performed (on average, every 100 minutes). Comparisons with intraarterial pressure included: 1) DxTek calibrated with arterial catheter pressure, 2) DxTek calibrated with oscillometric pressure, and 3) oscillometric pressure.
  
  
  RESULTS
  When comparing oscillometric pressure to intraarterial pressure, the averages of the mean differences (bias) were -4.0 mmHg for systolic (SBP) and < 1.5 mmHg for diastolic (DBP) and mean (MAP) pressures. The averages of the standard deviation of the differences (precisions) were 9.6, 6.4, and 6.3 mmHg, respectively. With the DxTek device calibrated to intraarterial pressure, comparison of the DxTek pressure to intraarterial pressure resulted in a bias < OR = 0.5 mmHg for all three pressures and an average precision of 10.1 mmHg for SBP, 6.0 mmHg for DBP, and 6.7 mmHg for MAP. With the DxTek device calibrated to the oscillometric pressure, the DxTek pressure compared to the intraarterial pressure resulted in average biases of -5.1, -0.8, and -2.2 mmHg and average precisions of 11.1, 7.7, and 8.1 mmHg for SBP, DBP, and MAP, respectively.
  
  
  CONCLUSIONS
  The DxTek monitor provides continuous, noninvasive BP measurements with an accuracy comparable to oscillometric devices.
authors.affiliation: Department of Anesthesiology, UMass Memorial Medical Center, Worcester, MA 01655, USA. Stephen.Heard@umass.med.edu
authors.forename: S O
authors.initials: SO
authors.lastname: Heard
authors.forename: A
authors.initials: A
authors.lastname: Lisbon
authors.forename: I
authors.initials: I
authors.lastname: Toth
authors.forename: R
authors.initials: R
authors.lastname: Ramasubramanian
mesh_terms: D001795:Blood Pressure Determination / Q000295:instrumentation*; D002138:Calibration; D016638:Critical Illness; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D011446:Prospective Studies