A topic near and dear to me
The reason narcotics are such a great idea toward the end of the case is that they work wonderfully to suppress the cough reflex. If you ever get a horrible upper resp. infection with intractable coughing, have your doctor prescribe a cough syrup with hydrocodone in it and you'll see what I mean. Lidocaine can also suppress the cough reflex as patients lighten at the end of a case, but it will also make them quite sleepy which could prolong your wakeup.
The goal is to keep the patient breathing in a nice smooth pattern right until the moment that you pull the tube. In the absence of narcotic at the end, the patient will blow off the volatile anesthetic and they will eventually get to the stage where they will begin to respond to that big piece of plastic sitting between their vocal cords. They then begin coughing which as you know is not an effective gas exchange. What happens?? - your wakeup comes to a screeching halt because your patient is no longer eliminating their volatile drug via their lungs. Small amounts (25mcg increments of Fentanyl for example) of narcotic once you have a patient back breathing, will allow them to tolerate the tube as they blow off the gas allowing for a much smoother and FASTER wakeup as they can eliminate the volatile drug much more effectively by breathing then you can by squeezing the bag while they're coughing and bucking. The analgesic benefits at the end are also of great value.
This is where the artistry of anesthesia comes into play.
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