It is annoying and dangerous to have a patient coughing (“bucking”… I hate that term) or moving after intubation. Don’t let this happen by waiting for the twitch to return after succinylcholine before giving a nondeplarizing relaxant.
I have been doing anesthesia for more than thirty years and I have yet to have personally given succinylcholine to a pseudocholinesterase deficient patient. That gives some indication as to the rarity of this condition and why the practice of waiting for the return of twitch after succinylcholine is unnecessary.
The dogma is to wait for return of twitch function after giving succinylcholine so as to avoid giving a nondepolarizing relaxant to a pseudocholinesterase deficient patient.
But why should giving a nondepolarizing relaxant to a pseudocholinesterase deficient patient be any more of a problem than giving succinylcholine alone?
While it is true that nondepolarizing muscle relaxants, unlike succinylcholine, undergo metabolism by the liver/kidney, their action is terminated by redistribution away from the neuromuscular junction. Therefore, in the pseudocholinesterase deficient patient, succinylcholine will outlast any moderate dose of nondepolarizing relaxant.
Immediately after intubation with succinylcholine (and without waiting for return of the twitch), I dose with an adequate but not excessive amount of vecuronium (depends on the anticipated length of the operation, e.g., 5 mg for a laparoscopic cholecystectomy). This allows me to do the other things that are necessary after the intubation and it keeps the patient from coughing/moving when the succinylcholine has worn off and I am distracted (busy) with other tasks.
During the operation, I keep the etCO2 high enough (see post on etCO2) so that the patient will try to breath when the nondepolarizing relaxant is waning. If the patient doesn’t attempt to breath (breathing is the first indication of needing to re-dose the muscle relaxant) then there is no need to give more nondepolarizing relaxant.
In this way, ALL patients can be kept from coughing/moving AND the rare patient with pseudochonlineterase deficiency will be detected. In the pseudocholinerase deficient patient, the succinylcholine will last much longer than the moderate dose of vecuronium.
When there has been no indication to re-dose the vecuronium beyond the time anticipated for the vecuronium to have worn off, then a pseudocholinesterase deficiency should be entertained. In this case, there will be no twitch, the patient will not meet extubation criteria, and the they will require ventilation in the PACU. However, this will be due to persisting succinylcholine blockade, NOT BECAUSE A MODERATE DOSE OF VECURONIUM WAS GIVEN TO A PSEUDOCHOLINESTERASE DEFICIENT PATIENT BEFORE THE RETURN OF THE TWITCH.