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Wireless monitoring

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Patrick Schoettker
added 7 research items
Routine monitoring of blood pressure during general anaesthesia relies on intermittent measurements with a non-invasive brachial cuff every five minutes. This manuscript provides first experimental evidence that a physiology-based pulse wave analysis algorithm applied to optical data (as provided by a standard fingertip pulse oximeter) is capable of accurately estimating blood pressure changes in-between cuff readings. Combined with the routine use of oscillometric cuffs, the presented novel approach is a candidate technology to increase patient safety by providing beat-to-beat hemodynamic measurements without the need of invasive monitoring procedures.
Obtaining accurate continuous blood pressure monitoring is mandatory in critically-ill, anesthetized patients or during long and challenging surgical procedures. The gold standard for continuous BP measurement (invasive arterial catheter) is complex and associated with morbidity. This study presents a simple way to measure non-invasive BP continuously without additional equipment in the operating room. To allow non-invasive beat-to-beat BP measurement, we used a commercially available pulse oximeter probe and we analysed its signals via the OBPM library of algorithms in order to assess performances of this new technology. Our results demonstrate feasibility of continuously estimating BP changes in the operating room via the analysis of pulse oximeter optical signals by the OBPM library of algorithms. Further studies are needed but this research validates a promising track towards non-invasive continuous monitoring of BP in the perioperative setting.
The performance of estimating Systolic Blood Pressure (SBP) in anesthetized patients via Pulse Arrival Time (PAT) techniques was studied with respect to the minimum required time in between two recalibration procedures. Materials: a clinical trial [NCT02651558] involving 14 patients was conducted measuring PAT from an ECG and an arterial line inserted into the radial artery. Methods: comparison of BP estimates from PAT measurements against invasive BP values was performed in terms of mean error and standard deviation of the error (AAMI/ANSI/ISO 81060-2), cumulative percentage of readings falling within 5, 10 and 15 mmHg (BHS criteria), and MAD-Mean Absolute Difference (IEEE Std 1708). Two calibration strategies were explored, involving time between recalibration periods ranging from 10 seconds to 8 minutes. Results: assuming an affine calibration function between PAT and SBP, different slope (Mean Slope:-1.45, CI:-1.64 to-1.27 mmHg/ms) and offset values (Mean Offset: 575, CI: 517 to 633 mmHg) were found in between patients. In addition, given a patient, affine calibration functions at different anesthesia phases also showed to be variable. When assessing agreement in terms of existing international standards it was found that PAT-based SBP estimates complied with requirements when time between two calibrations was smaller than 60 seconds. Conclusions: the use of anesthetic agents compromises the implementation of PAT-based techniques to estimate SBP.