"Warning card" as a prevention of prolonged apnea in children.

Human butyrylcholinesterase (EC 3.1.1.8) (BChE) is present in serum mainly as "usual UU" form, but it has also been found in variant forms known as "atypical" BChE. The most important predictive value of BChE phenotype is for anesthetist to prevent prolonged apnea. BChE has an important role in the hydrolysis of neuromuscular relaxant succinylcholine (suxamethonium, scoline) used during anesthesia. In order to detect atypical variants of BChE and give these findings to the anesthetists-surgeons before an operation to avoid the prolonged apnea, we phenotyped 542 sera of children before tonsillectomies. Total BChE activity was measured using butyrylthiocholine as substrate and dibucaine, fluoride, urea and dimethylcarbamate Ro 02-0683 were used as inhibitors. The frequencies of phenotypes in 542 children were: UU, UA, US, SS, AS and AA--92.25%, 7.01%, 0.18%, 0.18%, 0.18%, 0.18% respectively. Once established phenotype of BChE does not change during the lifetime. Therefore the carriers of atypical phenotype of BChE received a "Warning card", which is a permanent warning for succinylcholine application, as well as a sign to the members of the families to test their own phenotype of BChE. In our study three "Warning cards" were given: two to the carriers of atypical phenotype and third to a child presented as SS phenotype with low total activity of BChE. The present study is the first clinical evaluation of this genetic abnormality in the Republic of Croatia.