"Hypothetical" protocol for full-proof painless execution by lethal injection?

Over at my Death Penalty Course @ Moritz College of Law blog, we've been talking a lot about execution methods and the role of doctors in lethal injection.  Perhaps inspired by our class efforts, someone calling himself/herself "Provocateur Doctor" posted a comment purporting to set forth a "'Hypothetical' Protocol for Full-Proof Painless Execution by Lethal Injection."  I wonder if anyone informed about this science can weigh in on the doctor's claim that this protocol would result in "full-proof painless executions."

1. ~2-6 hours prior to execution, an emergency or critical care physician, surgeon, or anaesthesiologist inserts a central venous catheter into the femoral, internal jugular, subclavian, axial, or brachial vein (or artery, in that order of preference), by Seldinger technique. Intramuscular or subcutaneous conscious sedation (e.g., fentanyl +/- midazolam) is administered prior to and/or during this procedure, and full local anesthesia (e.g., lidocaine or bupivacaine) is utilized as well. If percutaneous Seldinger technique cannot be utilized in any of the above vessels, the procedure, AND the execution if need be, is delayed until a surgeon, veternarian, or other qualified person can perform surgical cut-down for catheter insertion. The catheter must be sutured in place by no fewer than 12 00 silk sutures passing into the deep subcutaneous tissues. Intravascular placement is confirmed by freely flowing withdrawal of blood from the catheter and functionality is confirmed by free saline flushing.
2. After insertion and until the actual execution, the prisoner is monitored and immobilized if necessary to prevent dislodgement of the catheter. Continued doses of benzodiazepines can be administered for psychological distress. Opioids can be administered for any pain post-procedure.
3. At the time of actual execution, blood is drawn from the catheter to again confirm intravascular placement.
4. At the actual execution, to anesthetize and render completely unconscious the prisoner to absolutely assure that no pain or distress is experienced, a physician directs the administration of sodium thipental at a dose of 5000 mg.
5. The physician or other designated person assures that anaesthesia has been achieved by assessing for apnea or with the use of EEG monitoring (optional).
6. An intravenous mechanically delivered bolus of 160 MEQ of potassium chloride is administered at a rate of 4cc/second (40 seconds required for entire bolus), and cardiac asystole is confirmed by continuous EKG monitoring.