Techniques & Measurements

This page lists techniques and measurements employed by
the easyTEL+ system for rodents, and used in the area
of measuring cardiovascular, neurological and respiratory
outcomes.

Implanted telemetry | Biopotentials | Blood Pressure | Breathing rate | Acceleration

Implanted telemetry

Physiological measurements are captured, amplified and digitized by a transmitter
surgically implanted and wirelessly transmitted to a receiver within 3 to 5 meters distance.

When received by the telemetry receiver, physiological signals can directly be sent to the acquisition computer, via Ethernet.

Communication between implants and receivers is bidirectional, allowing data collections, but also implant remote control (implant state (on/off), settings and configuration).

Did you know?

Telemetry technique ensures no cross talk between transmitters, allowing
animals to be group-housed in the same room or cage.

Biopotentials

Electrocardiogram (ECG), electroencephalogram (EEG), electromyogram (EMG) or
electrooculogram (EOG) signals can be retrieved using digital telemetry easyTEL+ through implanted electrodes. Various configurations are available:

Single lead biopotential, using a 2-wire electrode:
To get 1-lead ECG, or 1 EEG, EOG or EMG. For ECG, Lead II placement is usually
chosen (but not necessarily).

Dual biopotential:
To get a 2-lead ECG or a combination of 2 biopotentials amongst 1-lead ECG, EEG,
EOG or EMG.

Unipolar configuration, using 3 wires electrode:
In this configuration, the reference electrode is common to both biopotentials.
Unipolar biopotential is easier for the surgery but both biopotentials must be similar (2 EEG or 2 ECG for instance).

Biop 1 = Electrode 1 – Electrode 2
Biop 2 = Electrode 3 – Electrode 2

Bipolar configuration, using 4 wires electrodes:
In this configuration, the biopotential is measured between the positive (red) and
negative (white) electrode, allowing to get two independent biopotentials (EEG and
EMG for instance).

Biop 1 = Electrode 1- Electrode 2
Biop 2 = Electrode 3- Electrode 4
For ECG, lead III can be deduced by the software from leads I and II.

Outcomes

ECG : wave duration, amplitude, ST elevation, QT correction , arrythmia detection,
HRV analysis.

EMG : Temporal and spectral analysis

EEG :
• Sleep scoring
• Epileptic seizure detection
• Spectral analysis

EOG : Temporal and spectral analysis

Blood pressure

Intra-arterial measurement of Blood Pressure (BP) is the preferred technique for
BP measurement because of the ability to directly measure BP over an extended
period. Implants intended for blood pressure acquisition are equipped with a
catheter that will be inserted in an artery (femoral, carotid for example).

Outcomes

• Systolic • Diastolic • Heart Rate • Mean pressure • Duration of breath

References

Post-injury Inhibition of Endothelin-1 Dependent Renal Vasoregulation Mitigates Rhabdomyolysis-Induced Acute Kidney Injury. Jeremiah M. Afolabi et al. Function, 2023.

Breathing rate

Breathing rate can be retrieved from easyTEL+ implants through:

• Blood pressure low frequency variations
• Pleural pressure frequency
• Diaphragmatic EMG low frequency variations

Acceleration

A 3-axis accelerometer inside the implant measures the acceleration in the x-, y- and z-axis.

Any movement of the subject head translates in variations in the x, y, z coordinates of acceleration.

Using the three individual axis signals, IOX2 acquisition software calculates a global acceleration, making it possible to derive information about the animal’s posture (standing on hind legs, on its side etc).