Comparison of the T-Line® Tensymeter® (Continuous Non-Invasive Blood Pressure Management Device) with Conventional Invasive Radial Artery Tonometry in Surgical Patients

Gregory M. Janelle, M.D.; Anthony Butler; Mark Wilson; Nikolaus Gravenstein, M.D. (Anesthesiology, University of Florida, Gainesville, FL)

Presented at the American Society of Anesthesiologists 2003 Annual Meeting. San Francisco, CA. Anesthesiology. 2003;99:A615.

Introduction:

Continuous systemic beat-to-beat arterial blood pressure (BP) is conventionally monitored invasively via an intra-arterial catheter (A-line) and is desirable intraoperatively in subjects with cardiac or cerebrovascular disease and in any case where hemodynamic instability is anticipated. This study was undertaken to validate a novel non-invasive beat-to-beat BP device, the T-Line® Tensymeter®, by comparison to simultaneous A-line recordings.

Materials and Methods:

After IRB approval and informed consent, 13 adult patients were studied with the following criteria: 1) normal bilateral Allen's test and 2) no 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. 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 epochs for analysis with A-line values as controls. T-Line® data are expressed as mean error ± standard deviation for systolic, diastolic, and mean blood pressure (SBP, DBP, MBP) values for each epoch, then subjected to regression and Bland-Altman analyses.

Time to placement was recorded for both devices, expressed as mean ± standard deviation and compared using Student's t-test. A p < 0.05 was considered significant.

Results:

The mean time to signal acquisition was significantly less for T-Line® vs. A-line (4.5 ± 2.3 vs. 10.1 ± 7.4 minutes, respectively, p < 0.05). Simultaneous data were recorded for an average of 78 10-beat epochs/patient. Range of pressure measurements and error bounds are depicted in Table 1. Mean error of SBP, DBP, and MBP were –1.1 ± 7.7, 1.2 ± 5.5, and 0.2 ± 5.2 mm Hg, respectively. Regression analysis resulted in T-Line® r² values of 0.9961 for SBP, 0.9935 for DBP, and 0.9969 for MBP compared to matched A-line epochs. A representative Bland-Altman plot is included (Figure 1). There were no adverse events.

Conclusions:

The T-Line® Tensymeter® is a novel beat-to-beat non-invasive BP monitoring device that requires less time to signal acquisition than invasive A-lines and yields data comparable to an A-line over a wide range of BPs without any of the complications related to placement and insertion of an indwelling arterial catheter. The availability of the T-Line® provides another meritorious option for patients in whom hemodynamic instability is anticipated, but arterial blood sampling is not warranted.

References:

• Anesth and Analg 1991;73:213-20
• J Clin Monit 1991;7:13-22.

Anesthesiology 2003; 99: A615

Table 1. Range of Measurements and Error Bounds

Figure 1. Mean T-Line® vs. A-Line Pressure, Bland-Altman Plot, Patient 1

2003 ASA Meeting Abstracts. Copyright © 2003 American Society of Anesthesiologists. All rights reserved. Published by Lippincott Williams & Wilkins D14 Equipment and Monitoring: Cardiovascular Measurements