Non-Invasive, Beat-to-Beat Radial Arterial Pressure Monitor (T-Line® TL-100) Provides Blood Pressure Equivalent to Standard Intra-Arterial Catheter

Leslie C. Jameson, M.D. (Anesthesiology, University of Colorado, School of Medicine, Denver, CO)

Presented at the American Society of Anesthesiologists 2003 Annual Meeting. San Francisco, CA. Anesthesiology. 2003;99:A616.

Intra-arterial BP monitoring (IABP) is the standard method to provide continuous and accurate BP monitoring. Complications, time for placement and patient discomfort make an alternative method to obtain continuous and accurate BP values desirable. This study compares the accuracy of the T-Line®. TL-100 (Tensys® Medical, Inc., San Diego, CA), a continuous noninvasive arterial pressure monitor, with simultaneous IABP.

Methods:

After IRB approval and informed consent, 16 adult patients who required IABP for intraoperative monitoring had a T-Line® placed over the opposite radial artery. A signal splitter allowed the IABP transducer signal to be sent to the standard cardiovascular monitor and the study equipment. IABP transducer signal and the T-Line® system were continuously and simultaneously sampled at 160 Hz; both signals were converted to systolic, diastolic and mean blood pressure values by the same BP algorithm. The T-Line® signal algorithm included a scaling factors based on body mass index and additional proprietary variables that were designed to adjust for signal transfer through soft tissue. T-Line® was self adjusting to maintain the "best" signal during use. Each subject's beat-to-beat data was averaged in 10-beat epochs for both the IABP and the T-Line®. Significant clinical/surgical events (IABP flushing, movement) were excluded from the analysis. To evaluate accuracy, linear regression analysis of Bland-Altman plot (difference [T-Line® - IABP], versus average BP), the IABP versus T-Line® plot (identity plot) was performed as well as a distribution of differences analysis for systolic, diastolic and mean BP on each patient. Pooled line equations were weighted for the number of epochs contributed by each patient.

Results:

There were 16 patients, 12 men and 4 women, who ranged in age from 21 to 83 years and had a BMI between 19.2 and 40.4 kg/m². There were 42.7 hours of recordings with an average of 2.7 hours/patient and a range of 42 min. to 9 hrs. Total number of epochs studied were 3,838. The range of measured BP was systolic 65-210 torr, diastolic 95-35 torr, mean 52-113 torr. The mean difference (T-Line® - IABP) for all epochs was systolic 2.2±7.7 torr, diastolic 1.5±6.2 torr, and mean 1.4±6.3 torr. The pooled linear regression line (y=mx+b) for A-Line (y axis) versus T-Line® (x-axis) was: systole-m=1.019, b=0.034 R²=0.997; diastole-m=1.030, b=0.001, R²=0.994; mean-m=1.016, b=0.076, R²=0.995 with ideal relationship being m=1.0, b=0, R² =1.0 and Bland Altman plot was: systole-m=0.038, b=0.020, R² =0.323; diastole-m=0.032, b=-.001, R² =0.243; mean-m=0.040, b=-.011, R²=0.313 with ideal relationship being m=0, b=0, R²=0.

Anesthesiology 2003; 99: A616

Distribution of difference between IABP and T-Line® values (FDA requirement for NIBP)

2003 ASA Meeting Abstracts.
Copyright © 2003 American Society of Anesthesiologists. All rights reserved Published by Lippincott Williams & Wilkins

D14 Equipment and Monitoring: Cardiovascular Measurements