Evaluation of Safety and Accuracy of the T-Line® Tensymeter (Continuous Non-Invasive Blood Pressure Management Device) versus Conventional Invasive Radial Artery Tonometry in Clinically Obese Surgical Patients

R. L. Marcus, S. Ahmad, R. Glassenberg, P. Fitzgerald; (Northwestern University Feinberg School of Medicine, Chicago, IL)

Presented at the International Anesthesia Research Society 80th Clinical & Scientific Congress. San Francisco, CA March 24-28, 2006.

Introduction:

Automated, non-invasive BP (NIBP) monitoring (via upper arm cuff) perform poorly in obese patients with large, cone-shaped upper arms. Currently, obese patients are subject to intra-arterial cannulation (A-line) as a reliable alternative. Tensys® Medical, Inc., has developed a continuous non-invasive BP management device, the (T-Line®) Tensymeter® enabling physicians to circumvent the need for arterial cannulation when frequent blood sampling is unecessary.

Methods:

Prospective cohort study to validate and compare T-Line® systolic, diastolic and mean values to the pressures measured with an intra-arterial catheter in clinically obese patients (B.M.I. > 30 kg/m2) undergoing surgery requiring intra-arterial catheter placement for blood pressure monitoring. The fidelity of the T-Line® versus the A-Line waveforms were evaluated by plotting segments of data over time and analyzing the tracings and major "fidelity" markers, i.e. dichrotic notch to demonstrate that correlation. Informed consent was obtained. The T-Line® was positioned on the subject’s wrist opposite the radial A-line. Continuous, real-time BP data was recorded simultaneously from both the T-Line® and the A-line using an L-Box signal splitter allowing both signals to be simultaneously recorded without interruption to standard monitoring. Data was stored in a Tensys® laptop computer for analysis.

Results:

Nine (9) female patients have been enrolled to date. Total recorded BP time was 1079 minutes (120 min per patient). The mean error and standard deviation of systolic, diastolic and mean BP is shown in Table 1.

Discussion:

The T-Line® provides an arterial waveform, systolic, diastolic and mean blood pressures that compare favorably to that of an invasive A-line. Its availability may circumvent the need for arterial cannulation in obese patients. Our data confirm excellent correlation between the T-line® and A-line within a challenging patient population.

Table 1.