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Utilizing a unique and proprietary combination of sophisticated signal-processing algorithms and proprietary pressure-sensing technology, the T-Line® System, via its adhesive radial artery sensor, optimizes the signal from the patient’s radial artery and produces an accurate, physiologic, beat-to-beat arterial pressure waveform, without the need for cuff calibration.
Intermittent or continuous blood pressure during surgical procedures is monitored to provide valuable information about cardiac output, cardiac pressures and hemodynamic stability. Interpretation of perioperative BP is useful in that it enables physicians to intervene with proper therapy as necessary. Perioperative BP is specifically monitored to evaluate the effects of anesthetic medications on the cardiovascular system, the adequacy of noxious reflex suppression, fluid overload or deficit, need for blood replacement, as well as the need for vasopressor or vasodilator therapy. Continuous beat-to-beat arterial BP monitoring is highly desirable in subjects with cardiac or cerebrovascular disease, in surgical procedures where periods of rapid blood loss are likely, and in any case where hemodynamic instability is anticipated.
The Tensys® T-Line® Blood Pressure Monitoring System is a continuous, non-invasive alternative for perioperative blood pressure management. The T-Line® System comprises a non-invasive, single-patient-use adhesive sensor in combination with hardware that houses sophisticated electronics and signal processing algorithms that extract and process the radial arterial pressure waveform. The T-Line® System displays the beat-to-beat radial arterial pressure waveform with accompanying blood pressure values either on its own stand-alone display or via the standard invasive blood pressure channel on compatible patient monitors.
A significant technical breakthrough is embodied in the T-Line® System’s ability to intelligently locate and track the radial artery while continuously displaying a self-calibrated, arterial pressure waveform. The product architecture and signal-processing capabilities of the T-Line® System have been designed to mimic those of the standard radial arterial line. With this configuration, the T-Line® blood pressure waveform can be presented to the clinician in exactly the same location and with an equivalent fidelity to that of an invasive A-Line transducer. In addition, the T-Line® System can gracefully tolerate significant amounts of motion and same-arm NIBP cuff inflations.
The T-Line® has been validated against a contralaterally placed invasive A-Line reference and has been found to meet the standards as specified in the AAMI SP-10:2002 Accuracy Specification 188.8.131.52.B. More specifically, this validation testing confirmed a mean difference between T-Line® and A-Line values not exceeding 5 mm Hg with one standard deviation not exceeding 8 mm Hg for systolic, mean and diastolic values.
In general, the T-Line® System compares as favorably to a NIBP cuff as does an invasive A-Line. When making this comparison it is important to note that an A-Line and a traditional NIBP device measure blood pressure quite differently. Specifically, a standard cuff-based NIBP monitor only directly measures the mean arterial blood pressure and extrapolates the systolic and diastolic values via a number of different algorithms (most of which are distinct and proprietary to each monitoring equipment manufacturer). Alternatively, the A-Line waveform is a direct representation of the pressure waveform within the artery itself. The A-Line waveform is, however, substantially smoothed and processed by the “host” patient monitor and is subject to the well-documented effects of hydraulic coupling artifact. Therefore, a comparison of the T-Line® System or an A-Line to a traditional NIBP device can only reasonably be made with respect to mean arterial pressure and, to a lesser extent, systolic and diastolic values.
The T-Line technology has been in hospital Operating Room use since 2003 and has been used in well over 20,000 hospital surgical cases.
To date, Tensys® has six (6) independent institutions in various stages of clinical evaluations with additional clinical collaborations actively under consideration.
The fundamental technology of Tensymetry® has been developed using special single-use, comfortable elastomers and polymeric materials, which enhance extraction of the radial artery pulse under a variety of anatomic conditions. The technology for elastomeric sensors of this type is extremely well understood, and has an excellent clinical track record. Alternatively, a fully reusable non-elastomeric pressure sensor would be quite expensive and potentially uncomfortable for the patient, and would require frequent and potentially costly recalibration.
The T-Line® has been used on numerous OR, PACU and ICU patients and has not interfered with intravenous (I.V.) line placement, access or flow provided that the two devices do not occupy the same space. Additionally, there has been no interruption in pulse oximetry performance when used on the same extremity. The use of an NIBP cuff on the same arm as the T-Line® will only result in the interruption of T-Line® monitoring when the cuff is inflated (i.e., occluding flow).
The patient is fitted with a snug-fitting wrist restraint that flexes the patient’s wrist in a comfortable position, stabilizing the area of interest and facilitating access to the location of the patient’s radial artery. The T-Line® System gently positions the sensor directly over the radial artery and extracts a calibrated waveform via partial compression of the radial artery supported by the head of the radius. Extensive trials on both current and earlier system prototypes indicated that subjects did NOT experience pain, even after numerous hours of continuous monitoring. Upon cessation of monitoring, patients will typically have a red indentation on their wrist indicating the precise location of the sensor. Testing showed no evidence of a single incidence of a pressure “mark” or skin effect not substantially resolving within 20-30 minutes post-removal. It is important to note that the steady-state compressive force applied by the T-Line® does not occlude blood flow.
Much like an invasive A-Line, the T-Line® System may be temporarily disrupted by extreme or vigorous patient motion. With the cessation of motion, the T-Line® System will independently reacquire the pressure signal and maintain monitoring continuity within a clinically reasonable period of time. The “time to recovery” is dependent on the severity of the motion episode. Should the T-Line® need to re-acquire its lateral position, an obvious non-physiologic square wave will be displayed at the last known valid blood pressure. A typical time to re-acquire optimal lateral position is one to three (1-3) minutes.
Throughout our clinical evaluation, the T-Line® has been very effective at monitoring both very high (systolic pressures above 200 mm Hg) and very low (diastolic pressures below 30 mm Hg) pressures. A significant number of both morbidly obese patients and patients with advanced peripheral vascular disease were studied in the early clinical work. It is further noted that the T-Line® technology is also quite robust in patients with compromised cardiac output and/or abnormal heart rhythms. The T-Line® is indicated for adult patients who weigh between 90 and 400 lb.
Extensive time and effort have been invested in designing a quick, intuitive and simplistic setup and T-Line® initialization sequence. Typically, experienced users can complete the T-Line® setup in 1-3 minutes, with experienced users routinely applying the system in approximately 30 seconds. Once the T-Line® has been set up and the patient’s height and weight have been confirmed, an additional 2-3 minutes is required for completion of the initialization sequence.
The T-Line® System utilizes body mass index (BMI, computed using height and weight) in its signal-processing and pressure measurement algorithms. The precise utilization of BMI is the subject of multiple patent applications on file with the U.S. Patent and Trademark Office.
No. The T-Line® System is limited to adult patients only who weigh between 90 and 400 lb. and are between 4’6″ and 6’6″ tall.
No. There is currently no shelf-life restriction on the T-Line® Radial Artery Sensors.
The T-Line® System is currently limited to 18 hours of continuous monitoring on a single patient at a single monitoring site. Attaching a new sensor to the opposite extremity (wrist) will accommodate longer monitoring.
Given that the T-Line® transducer is physically located on the patient’s wrist, and not in a “bank” of transducers mounted on an I.V. pole, the user will not be adjusting for head-height differences via common A-Line practice (i.e., sliding the transducer bank up or down the I.V. pole depending on the organ of interest). Rather, the T-Line® user will be able to adjust for physical head-height differences (physical height of the wrist, where the transducer is located, to the organ of interest) electronically using key presses on the Tensys® Interface Module at any time during a surgical case. This physical adjustment is presented to the user on the main screen on the Tensys® Interface Module display and is automatically applied to the running real-time waveform. Essentially, the T-Line® software electronically corrects for head-height differences in a manner analogous to raising or lowering the A-Line transducer bank on an I.V. pole.
No. Currently the T-Line® is indicated for use on monitoring the radial arterial pulse only.
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