I'm gathering evidence to show that one of the mechanism in which TPVB produces analgesia, apart from direct action over intercostal nerves, is by slowly pumping LA (Local Anesthetics) through the foramen into the Epidural Space. There is some data showing TPV Catheters entering the epidural space and dye injections also spreading to it.
We are trying to show at which extent analgesia is produced by LA acting on the nerve and at which extent they act by passing continuously to the epidural space.
I would like to hear comments on this possibility and on theoretic approaches on the Pharmacokinetics of i.e. a Single Injection TPVB of 25 cc 0,375% Bupivacaine. How long it takes to get it cleared from the PV Space?
Thanks for highlighting this possibilities,but it requires extensive clinical trials before it can really be practiced routinely.
Dr. Shapera, I couldn't agree more with you. I've seen great results with the continuous technique for a wide variety of procedures. From VATS, Mastectomies, Interauricular Comunication Repair through a thoracotomy to Conventional Cholecistectomy among others. And some years ago with the addition of ultrasound this technique has become in my opinionsafer and easier to practice. It has given as a great tool for teaching purposes also. As you said Prof André Boezaart has given a magnificent new kickstart to this forgoten procedure and I have found his work very useful to explain this block, to anesthesia and surgery residents, and also some interested patients.
But my special interest in this case is for the mechanical/PK behavior of a Single Shot TPVB once it is injected in the PV Space. How the local anesthestic distributes locally and what Nervous Structures are affected by this distribution. What amount of contralateral block should we expect, how long it takes for the anesthetic solution to be absorbed and are safe dosages the same as for other type of peripheral blocks? We had a someof cases in which threading a cathether couldn't be performed, and a Single Shot TPVB had very good results.
Thank you for your interest in this topic, and for supporting this useful anesthetic tool.
Dr. Schapera what would be your opinion on trying such a study, on a swine model? In trying to envision a feasible study at our center, I think we could establish a radiopaque ultrasound-guided TPVB and follow it fluoroscopically, between 6-12 hs, to observe the spread.
Apart from the expected limitations from the swine model, do you think this approach is too simplistic?. Would you place a thoracic subarachnoid cathther to dose LA?