That's interesting. I never encountered either a pseudocholinesterase deficiency or MH during my 38 years of residency/attending/private practice.
However — in my first year of residency, during my rotation at the VA, while performing my first brachial plexus block, I unknowingly injected lidocaine into the axillary artery: as the patient began seizing, the attending calmly said "Joe, take out the needle, I'm going to give him some diazepam." Worked!
Never had another intravascular injection (that became symptomatic) doing a regional block.
One of my attendings during residency was Kenyan. In the bush, pediatric anesthesia was lido until they seized. At that point, you knew they could not feel anything.
However — in my first year of residency, during my rotation at the VA, while performing my first brachial plexus block, I unknowingly injected lidocaine into the axillary artery: as the patient began seizing, the attending calmly said "Joe, take out the needle, I'm going to give him some diazepam." Worked!
Never had another intravascular injection (that became symptomatic) doing a regional block.