Nilsson A, Engberg G, Henneberg S, Danielson K, De Verdier C H
Department of Anaesthesiology, University Hospital, Uppsala, Sweden.
Br J Anaesth. 1990 Jan;64(1):72-6. doi: 10.1093/bja/64.1.72.
We have measured plasma concentrations of local anaesthetics, and the substance fraction of methaemoglobin (MetHb), in infants less than 3 months of age, after application of a lignocaine-prilocaine cream (EMLA). A total of EMLA 2 g was applied over four different skin areas, totalling 16 cm2, for 4 h before anaesthesia for a minor surgical procedure. Sampling was carried out before and 4, 8 and 12 h after application. Maximum MetHb values (median = 2.24%) were obtained usually at 8 h and were significantly (P less than 0.001) higher than before application (median 1.32%). The plasma concentrations of local anaesthetics were low (maximum values: prilocaine 78 ng ml-1, lignocaine 412 ng ml-1). The activity of erythrocyte MetHb reductase (cytochrome b5 reductase) was analysed. Data from a previously studied group of infants aged 3-12 months were included also. Enzyme activity did not reach adult levels until after the age of 3 months. It showed a good inverse correlation with the maximum MetHb values after application of EMLA. Although the MetHb concentrations in the infants younger than 3 months were small, the enzyme capacity may be overloaded when EMLA is administered at the same time as other MetHb-inducing agents. It is concluded that the use of EMLA should be restricted in this age group.
我们测量了小于3个月龄婴儿在使用利多卡因-丙胺卡因乳膏（EMLA）后血浆中局部麻醉药的浓度以及高铁血红蛋白（MetHb）的物质分数。在进行小型外科手术麻醉前，将总共2 g的EMLA涂抹在四个不同的皮肤区域，总面积为16 cm²，持续4小时。在涂抹前以及涂抹后4、8和12小时进行采样。最大MetHb值（中位数 = 2.24%）通常在8小时时获得，且显著高于涂抹前（中位数1.32%，P < 0.001）。局部麻醉药的血浆浓度较低（最大值：丙胺卡因78 ng/ml，利多卡因412 ng/ml）。分析了红细胞MetHb还原酶（细胞色素b5还原酶）的活性。还纳入了先前研究的一组3至12个月龄婴儿的数据。酶活性直到3个月龄后才达到成人水平。它与涂抹EMLA后的最大MetHb值呈现良好的负相关。虽然小于3个月龄婴儿的MetHb浓度较低，但当EMLA与其他诱导MetHb的药物同时使用时，酶的能力可能会过载。结论是该年龄组应限制使用EMLA。
