All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
The study was performed in six three-month-old male and female pigs (German Landrace) weighing approximately 40 kg. Animals were brought to the animal care facilities at least 7 days prior to the experiments and were housed in accordance to animal welfare recommendations. Animals were provided food and water ad libitum, and their health status was regularly assessed by the responsible veterinarian. A fasting time of 12 h was maintained prior to the experiments. The entire experimental procedure and handling of the animals was supervised by the responsible veterinarian.
1. Anesthesia induction and maintenance of anesthesia
- For anesthesia induction and maintenance of anesthesia, premedicate the animals and deeply sedate them using an intramuscular injection followed by intravenous injections, if necessary, to perform endotracheal intubation. Thereafter, induce and maintain anesthesia by using a combination of a volatile anesthesia agent with a continuous opioid application complemented with an additional opioid bolus injection.
- Perform intramuscular injections of ketamine 20 mg·kg-1, azaperone 4 mg·kg-1, and midazolam 0.1 mg·kg-1 for premedication and sedation.
2. Probe placement
- Place the animal in the right lateral position and flex the animal's back to widen the space between the vertebrae.
- For percutaneous placement of cerebrospinal fluid drainage for measuring and controlling cerebrospinal pressure, identify the level of L 4/5 or L 5/6, puncture the skin and the subcutaneous space with the introducer needle, and remove the inlay needle.
- Place a saline-filled syringe on the needle, and carefully introduce the needle with constant pressure on the fluid-filled syringe.
- Once a loss of resistance is felt as evidence for epidural position, re-introduce the inlay needle, and introduce the needle 2-3 mm further to puncture the dura mater and remove the inlay needle.
- Verify intrathecal position by fast dripping of clear liquor. Introduce the drainage up to 20 cm depth, attach the Luer-lock adapter, and verify the position by careful aspiration of liquor.
- Carefully fix the drainage with sutures and connect it to the cerebrospinal fluid drainage system.