During factory calibration, we attempt to ensure the environment is as similar as possible to what the Kaha Pressure telemeter (TRM54P, TRM54PP, TRM54PB, TRM56SP) will experience when implanted in an animal. You may check the offset either pre- or post-implantation. You need to precisely set the environment for the offset test as detailed below.
For pre-implantation testing:
Telemeters with pressure catheters are shipped sterile and dry, when implanted there will be an equilibration period and the pressure values recorded in the first 48 hours after surgery may have an offset of up to 20 mmHg. Before making any recordings from the implanted telemeter it is important to control certain factors.
Key factors that need to be controlled are:
1. Hydration: Telemeters should be soaked for a minimum of 48 hours prior to offset check. It is important to ensure that, when checking the offset, the sensor tip is no more than 5 mm under the water so as to avoid a head of pressure effect.
Please Note: If your telemeter has biopotential (TRM54PB) or SNA lead wires (TRM56SP) these also need to be submerged during the testing procedure to prevent ambient noise affecting the pressure signals.
2. Turn on time: On the bench, all telemeters have a signal settling period when first switched on. In order to correctly account for this “turn-on effect”, telemeters should be in Active Mode on a SmartPad for a minimum of FOUR (4) hours prior to checking the offset pressure.
3. Telemeter Temperature: Telemeters should be at 38°C for a minimum of 30 min prior to recording values.
4. Light: Light will affect the sensor and so the telemeters need to be in the dark.
For post-implantation testing:
1. The telemeter can be removed from the animal whilst still in Active Mode, put immediately in a Tergazyme solution and placed on the SmartPad.
2. Once cleaned, it can be placed in warm water at 38°C for 30 minutes in the dark. The output voltage obtained from the SmartPad at this zero-pressure level should be close to 1.0 V.
For further technical assistance with this or any other issue, please contact ADInstruments Technical Support by clicking HERE.