Relationship between succinylcholine-induced apnea and dibucaine number in patients with genetic deficiency of plasma cholinesterase

ABSTRACT

In this study, a commercially available kit in which propionylthiocholine is used as a substrate and a dibucaine solution to determine the variants of the enzyme were utilized. Plasma cholinesterase activity of 151 patients who underwent different operations was measured during a period of six months. The mean +/- SD of the enzyme activity in 150 patients was 4.39 +/- 1.17 kU/L. Seventeen patients [11.2%] were found to have a serum cholinesterase activity of less than normal [<3 kU/L], but the period of apnea and the dibucaine number [DN] were found to be normal. Eight patients [5.3%] displayed an increased sensitivity to succinylcholine. Six of these patients [4%] were heterozygous for atypical enzyme with a mean period of apnea of 18.6 min [range 12-35 minutes] and had a dibucaine number of less than normal [<80%]. The DN of the other two patients [1.3%] who were homozygotes and had an exceedingly low atypical enzyme allele was 10% and 24%. The mean +/- SD DN value, in the 149 out of 151 patients was 84.41 +/- 2.91%, and the DN ranged from 10-90% in these patients. The mean +/- SD apnea period in the 149 patients was 6.37 +/- 4.28 min