The use of pethidine as pre-medication to prevent anoxic spells in patients with tetralogy of Fallot.

Objective: The aim of this study was to determine whether morphine-HCl or pethidine-HCl differ as pre-medication to prevent anoxic spell in patients with tetralogy of Fallot (TOF) at catheterization. Methods: A 3 year retrospective case notes review study of 46 consecutive patients who underwent cardiac catheterization from 1998 to 2001 was conducted. In a prospective 1 year randomized control study, 10 patients diagnosed as TOF and admitted to Tokyo Women's Medical University, The Heart Institute of Japan, Tokyo, in 2002 were randomized to receive morphine or pethidine as pre-medication for cardiac catheterization. The incidence of anoxic spell before and after cardiac catheterization was investigated in both studies. Results: In the case notes review, a total of 10 out of the 46 patients showed anoxic spell study: eight out of 24 patients in the morphine group and two out of 22 in the pethidine group. The difference in the incidence was statistically significant ( P < 0.05, Fisher's exact test). Four patients in the prospective study showed anoxic spell: three out of six in the morphine group and one out of four in the pethidine group (odds ratio = 3.0). Overall, 14 out of 56 patients had anoxic spell: 11 out of 30 in the morphine group and three out of 26 in the pethidine group ( P = 0.03). Conclusion: The incidence of hypoxic spells in patients with TOF undergoing cardiac catheterization is reduced by the use of pethidine-HCl as pre-medication compared to morphine. This has important clinical implications. [ABSTRACT FROM AUTHOR]