Temporal Performance of the T-Line® Tensymeter® (Continuous Non-Invasive Blood Pressure Management Device) versus Conventional Invasive Radial Artery Tonometry in Surgical Patients.

G. M. Janelle, S. Gallant, A. Butler, M. Wilson, N. Gravenstein (University of Florida, Gainesville, FL; Tensys  Medical Inc., San Diego, CA)

Presented at the 78th Clinical & Scientific Congress of the International Anesthesia Research Society. Tampa, FL. Anesthesia & Analgesia. 2004;98(suppl 2):S-91.

Tensys® Medical, Inc. has introduced the T-Line® (TL-100) continuous non-invasive blood pressure monitor which produces a beat-to-beat, high fidelity radial arterial pressure (A-line) waveform on any conventional patient monitor with an invasive blood pressure input. The overall accuracy of this monitor in surgical cases as measured against a contra-lateral A-line has been validated. Accuracy data including Bland-Altman and pooled regression data statistics have shown conformance exceeding the AAMI Standards for non-invasive blood pressure monitors. Since the T-Line® is a continuous monitor which produces a real-time waveform, it is important to know how well the T-Line® performs over time contrasted to an A-line.

Methods:

After IRB approval and informed consent, 25 adult patients were studied with the following criteria: 1) normal bilateral Allen's test and 2) left vs. right arm oscillometric mean BP difference < 10 mm Hg. The T-Line® processing algorithms extract, calibrate, and display arterial pressure waveforms from pulsations sensed non-invasively over the radial artery. A T-Line® sensor was placed over the contralateral radial artery to the A-line. All data were zero referenced to the cranial midline and simultaneously recorded from both the T-Line® and A-line. Data were sampled at 160 hz, imported into a Microsoft Excel database, and separated into 10-beat data sets for comparison with simultaneous A-line values as controls.

The sampled recordings were subsequently post-processed for beat-to-beat comparison over the entire surgical period. Specifically, calculations for mean error of mean, systolic and diastolic pressures were made for each 10-minute period of recording. Each 10-minute epoch was then plotted and analyzed using time series analysis. Conventional descriptive statistical measures were also computed for these data.

Results:

Cumulative recording time was 35.8 hours, with a range of 10 minutes to 181 minutes per patient. The average duration of recording was 86 minutes; therefore, fewer epochs were analyzed for longer durations. Mean difference of the mean pressure begins at 0.2 mm Hg and peaked at 0.5 mm Hg over time (range -0.4 to 0.5 mm Hg, Figure 1). Mean differences of systolic and diastolic pressures peaked at 0.8 and 1.3 mm Hg over time, respectively. There were no significant differences in errors over time compared to baseline measurements in systolic, mean, or diastolic pressures.

Conclusions:

There is no degradation in accuracy or performance over the course of monitoring with the use of the T-Line® system compared to A-line measurements. Furthermore, the T-Line® requires no incremental maintenance such as saline flushing of an indwelling catheter, catheter repositioning, or other interventions to maintain patency or reduce the possibility of infection.

References:

• Anesth and Analg 1991;73:213-20
• J Clin Monit 1991;7:13-22.
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3. This abstract was judged "Best in Section" for Equipment and Monitoring at the 78th Clinical & Scientific Congress of the International Anesthesia Research Society (IARS).