I'm not positive on the injectable sedation drug but I'm thinking where I work, the vets use either DexDormitor, Torbitrol or Ketamine or even a combination of those. I'll have to ask sometime.

I know for a fact that the gas anethetic is IsoFlurane though.

As for being 3 kinds of anesthetic I'm thinking your vet may be referring to the method of giving it; IM (intramuscular), SubQ (subcutaneous), or Inhalation, could possibly be 4 if you count IV method. Not sure exactly what your vet is referring to.

Was the additional test a T4 by any chance? If so that would be a thryroid test, but it's not new though, and overactive thyroid is common in older cats. Or the EDT4 which is also thyroid.

The only newest test I can think of would be the Feline Triple Snap Test that Idexx offers that does FELV/FIV/Heartworm. Or possibly the Istat EC4 tests which are like electrolytes.

Death or complications from anesthetic is very low when monitored properly and pre-anesthetic testing is done. Either way I'm sure your vet does proper monitoring and regardless of which anesthetic he uses, if it's in his best judgement and experience to use that one, I'm sure your kitty will be fine.