All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. Surgical extraction of the cardiopulmonary block.
- Anesthesia:
- Use a combination of a sedative (xylazine) and a barbiturate (pentobarbital).
NOTE: Different anesthetic cocktails can be used with no effect on experimental outcomes.
- First, sedate the healthy New Zealand rabbits with a single intramuscular injection of xylazine hydrochloride (3-5 mg/kg). Ensure that the rabbits remain calm and relaxed to allow further manipulation after a few minutes of the injection.
- Following sedation, use the marginal (lateral) ear veins as access to anesthetize the rabbits with an intravenous injection of pentobarbital sodium (28 mg/kg).
- Monitoring:
- To avoid insufficient anesthesia or excessive depression of cardiac and respiratory functions, monitor the following parameters. To assess the depth of anesthesia, perform a toe pinch test.
- Ensure that the mucous membrane is pink. Blue or grey shades indicate hypoxia.
- Ensure that the heart rate is between 120-135 beats/min and that the body temperature does not drop below 36.5 °C.
- Animal placement:
- Shave the rabbit's torso and place the animal on the operating table in the supine position. Place the ventilation system near the table, behind the rabbit's head, to permit connecting the cannula quickly after tracheotomy to avoid tissular damage.
- Incision and tracheotomy:
- Dissect the skin with a ventral median line incision of 3-5 cm from the diaphragm up to the neck.
- With the operating scissors, cut the anterior 2/3 of the trachea between two cartilage rings to insert the tracheal cannula through the tracheal fibrous membrane.
- Insert a 5 mm (outer diameter; OD) tracheal cannula through the tracheal fibrous membrane and use a 4-0 silk suture to fix it carefully.
- Place either forceps or tweezers underneath the trachea to ensure the cannula did not bend against the trachea.
