Center for Functional MRI In the Department of Radiology

7T How To: Anesthesia Procedures

Initial steps

These are the first things to do and check.

  • Secure animals and check animals for signs of injury or distress
  • Provide adquate food and water for waiting animals
  • Start the physio heating system -- it takes a long time to warm up
  • Check the oxygen tank level -- if it is lower than 500psi switch to the backup tank and alert staff to order another

 

Isoflurane setup

  • Please check Oxygen and Isoflurane levels daily
  • Oxygen should be no lower than 500psi.  If at or below, switch over to a fresh oxygen tank and order a new one.
  • The vaporizer should be at least half full of Isoflurane.  
  • If not, please set vaporizer to “0”, unscrew the small cap at the fill port part way, and carefully pour Isoflurane into the basin.  
  • Have a paper towel ready in case of any spills, and make sure to wash hands afterward.  
  • Once the gauge shows full, tighten screw and use as normal.
  • Isoflurane is stored in an eye-level cabinet near the door of the console room.

 

Physio computer start-up procedure

1. Turn the switch box to OFF 
2. Turn on the physio computer computer (restart if the computer is already on) 
3. Start the PC-SAM software by double-clicking the icon on the desktop of the physio computer 
4. The temperature probe should be in place for the heating system to work properly 
5. Check that the heater and the blower are plugged in and switched on 
6. Check that the rechargeable battery is plugged into the temp/ecg unit

  • Note: When starting up the physio computer the switchbox on the table should be OFF. When running the physio software, it should be turned to ON.
  • Note: If the pointer is jumping around the screen on the physio computer, turn the switch box OFF, restart the physio computer, start the software and turn

Prepare the anesthesia jar

1. Clean the animal anesthesia chamber with soap and water before and after the study 
2. Place a clean paper towel at the bottom for the animal to stand on. 
3. Plug in heater and let it warm up. 
4. Check animals for any signs of injury or distress.  

Preparation for anesthesia

 Prepare the oxygen flow 
Open the main valve to the Oxygen tank.   
Do not change the flow rate or the pressure!   
If the pressure gauge has been inadvertently moved, please adjust so that the needle on the gauge is in-line with the tape. 
If the flow rate is accidentally adjusted, turn the knob until the silver ball is hovering at 30.

 Prepare the isoflurane flow 
Turn the Isoflurane vaporizer to “3”.  Give the chamber a few minutes to fill with gas. 
Make sure that both the anesthesia line and the exhaust are plugged into animal chamber (see photo near the chamber). 
The anesthesia line is the smaller tubing near the bottom of the chamber.   
This line will be removed and placed on the coil to keep the animal asleep during the procedure.

 Anesthetize 
Place animal in the chamber and monitor for unconsciousness.   
Animals will appear to go to sleep at first, but may quickly recover somewhat.  Wait a few minutes then lightly pinch their tail or a toe.   
If there is no response, the animal is under. 
If there is a response, leave the animal alone in the chamber for a few more minutes.

 Re-route anesthesia to the scanner 
Change the stopcocks as indicated in the photo near the anesthesia chamber

 Move the animal to the scanner 
Quickly place the animal in the coil with its muzzle in the nose cone by placing the animal’s incisors on the bite bar. 
Be sure not to cover the small hole in the tooth bar -- this is the outlet for anesthesia 
Secure the animal to the coil, making sure the body is place directly over the respiration lead to monitor respiration.   
The animal should be taking about 30 breaths per minute. 
Respiration should never drop below 20 per minute and never go above 50.   
If it does, decrease/increase Isoflurane slightly until breathing returns to a safe level. 
Cover eyeballs with an ocular lube to prevent eyes from drying out.

 Connect the monitors 
The respiratory bellows should be under the animal 
The temperature thermistor should be in position 
The ECG small gold leads should be connected the animal’s back feet using a small amount of conductive gel to get a good connection 
Do not tape the leads too tightly 
The ECG ratings vary from species to species.  Please refer to a veterinary source for details.

 Afterwards

  • When the procedure is finished, unplug all leads and remove all tape.
  • Monitor the animal for at least 5 minutes to make sure that it is recovering.
  • Cage mates may pick on unconscious animals. To prevent injury, observe and separate if necessary.
  • Provide water as the anesthetic may dehydrate the animal.
  • Keep the animal warm.  A heating pad set on low or hot water bottle filled with warm water may be needed if the animal is alone.
  • Animals should make a full recovery within an hour
  • Clean the animal bed and anesthesia chamber