Oct 06, 2023
Protocol for vagus nerve stimulation in anesthetized pigs (subject-2)
- Oliver Armitage1
- 1BIOS Health
Protocol Citation: Oliver Armitage 2023. Protocol for vagus nerve stimulation in anesthetized pigs (subject-2). protocols.io https://dx.doi.org/10.17504/protocols.io.n92ldzdx7v5b/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: July 22, 2022
Last Modified: October 06, 2023
Protocol Integer ID: 67283
Keywords: Pig, Vagus nerve stimulation, Heart, Stimulation Parameters, Evoked compound action potential, Cardiac, vagus nerve stimulation, protocol for vagus nerve stimulation, vagus nerve, pigs under anaesthesia, organ response, anesthetized pig, anaesthesia, exogenous nervous signal, mapping vns parameter, relationship between vns parameter, visceral organ, vns parameter, stimulation, cardiac effect, function for therapeutic purpose, heart failure space
Funders Acknowledgements:
SPARC
Grant ID: OTA-20-004
Abstract
The Vagus nerve innervates a number of thoracic and visceral organs. Exogenous nervous signal, for example, Vagus nerve stimulation (VNS) provides a route to modulating their function for therapeutic purposes. However, the relationship between VNS parameters and organ responses is poorly understood as evidenced by a number of failed human trials, for example, in the heart failure space.
This study will contributes to our understanding of the relationship between VNS parameters and the organ responses. It does so by mapping VNS parameters (at a fine resolution) to their immediate neural and cardiac effects in 2 pigs under anaesthesia.
Equipment Setup
We do the setup of the BIOS A1 System (electrophysiology).
Load BIOS Neurotool software for neural recording acquisition and stimulation.
Place cuff electrodes in saline. Take impedance measurement to confirm system is functional.
Animal Preparation
We prepare the animal before the surgery.
Animal under anesthesia breathing naturally.
Intubate the animal and start mechanical ventilation.
Place the pig in supine position and mark incision.
Surgery
We do the nerve preparation and device implantation.
Installation of the vitals monitoring (respiratory pressure, ECG, blood pressure).
Make incision on the neck and expose 8cm of the left vagus nerve.
Cuff installation:
- Installation of cuff A most rostrally (record1)
- Installation of cuff C most caudally
- Installation of cuff B closer to cuff A (record2)
Distance from the center of cuff A to center of cuff C is 5.4mm. Distance from the center of cuff A to center of cuff B is 1.7mm.
Data Acquisition Validation
We validate the quality of the physiological and neural signals.
Visually validate the quality of the vitals. For the ECG, the r-peaks should be clearly visible to ensure a good extraction of the heart rate.
Neural signals validated using BIOS neural analytics pipeline. Analyses looks for presence of underlying endogenous signals (e.g. respiration), afferent<>efferent velocity spectrum decomposition, among others.
Stimulation Protocol
Once we validated the quality of the data acquisition systems, we start the stimulation protocol.
Set the the following stimulation parameters in BIOS Neurotool software:
- Pulse width: 500us
- Train duration: 5s
- Stimulation shape: monophasic
- Polarity: anodic
Conduct a grid search by doing the cartesian product of the frequency and current parameters.
- Frequency: {2Hz, 10Hz, 20Hz, 30Hz}
- Current: {0.05mA, 0.5mA, 1mA, 1.5mA, 2.5mA}
After each stimulation, wait for the physiological signals to return to baseline.
Termination
Once testing is complete, the animal is terminated.