Here's why I like nitrous and isoflurane -- smooth, predictable, and speedy emergences.
It wasn't until I became a CA-3 that I learned how to dial in nitrous at the end of case in order to speed up emergence, minimize time spent in Stage II, and have speedy, predictable and smooth wake ups, especially with isoflurane. If you know when to dial in your nitrous at the end of a case, you can get some pretty superb emergences from GA, especially with iso.
With sevo, although good for induction in kids, there's just way too much emergence delirium and I don't care how insoluble it is, it seems to take forever to get rid of ... end tidals of 0.3, 0.3, 0.2, 0.3, 0.2, (patient holds breath) 0.4, 0.2, 0.2, 0.3 ... You never feel like the patient has adequately exhaled all the agent until end tidal is on the order of 0.1 or less.
Conversely, as the patient breathes off iso, it stays off. End-tidal is remarkably similar to tissue level.
And des is just a fire-cracker -- patients usually wake up with a bug-eyed start -- not very eloquent.
Here's how I tailor the emergence: (assume regular GA abdo case)
1. 0.1 mg/kg morphine given in holding area in addition to any other premeds (versed, glyco, benadryl, pepcid, reglan, neurontin, celebrex, whatever)
2. induction as you see fit
3. keep patient asleep with 50% oxygen and iso, plus or minus nitrous (if short case) or air (if long case).
4. as case draws towards the end: for example, surgeons start to suture fascia, I turn off the iso, run a 70%/30% nitrous/oxygen mixture, and turn flows waaaaaaaaaaayyyyyyyy down in order to prevent iso from being blown off too quickly.
5. When fascia is closed, I give the reversal +/- anti-emetic cocktail. The reversal itself will cause tachycardia which will further slow down gas elimination (remember, high cardiac output slows inhalation induction as well as emergence). At some point, the tachycardia will return back to baseline and the surgeons will start to close subcutaneous tissue/skin. When both of these events arrive, I increase the RR so that end-tidal CO2 is in the low 30's. I don't want the patient to overbreath the vent. I then turn flows up to about 7/3 or 6/4 for nitrous/oxygen in order to get rid of the isoflurane. When isoflurane is 0.2 end-tidal, and when dressings are being applied, I turn off the nitrous and leave oxygen at 3 or 4 liters/min (very high flows might make patient cough). I'm still breathing for the patient. Patient still is not inititiating breaths at this point for a few reasons: narcotics on board plus I'm hyperventilating them. Within 1-2 minutes of turning off the nitrous, end-tidal nitrous levels should be less 20%. At this point, all you have to do is is gently speak into the patient's ear, "Hey buddy, open your eyes. As soon as they patient does, out comes the ETT." No coughing, no fighting, no bucking, no nothing. Many a surgeon has remarked on how smooth the emergence was. Occasionally I give little dollops of propofol here and there if the closure is taking a long time. It adds another nice little anti-emetic effect to the equation.
Sound complicated? Yeah, I guess it is ... particularly if you're the kind who just simply dials the vaporizer to off at case closure. But that coarse method yields coarse wake ups. And anesthesia is an art ...
