ABSTRACT
Objective:To investigate the effects of different phototherapy intensities on the levels of malondialdehyde, a peroxidation product of intralipid, vitamin C and vitamin E in parenteral nutrition for premature infants.Methods:The parenteral nutrition for premature infants was prepared under strict aseptic condition and was divided into four groups based on different phototherapy intensities in simulated clinical settings, which were indoor light group, single-, double-, and three-sided phototherapy group. According to whether the nutrient solution shielded for light or not, each group was further divided into two subgroups: exposure or non-exposure group. The levels of malondialdehyde, vitamin C and vitamin E in all groups before phototherapy and 6, 12, 18, and 24 h after phototherapy were measured. Ten samples of parenteral nutrient solutions were prepared for each group, of which 2 ml were extracted for test at different time points. Repeated measurement analysis of variance was used for data analysis and the results were adjusted using Greenhouse-Geisser method if failed in Mauchly sphere test.Results:With the increase of phototherapy time, the malondialdehyde level increased in the exposure and the non-exposure subgroups in the one-sided phototherapy group [before phototherapy: (3.777±0.112) vs (3.746±0.141) nmol/ml; phototherapy for 6 h: (3.808±0.122) vs (3.715±0.145) nmol/ml; 12 h: (4.546±0.138) vs (4.507±0.136) nmol/ml; 18 h: (6.116±0.151) vs (5.239±0.156) nmol/ml; 24 h: (7.569±0.136) vs (5.300±0.200) nmol/ml; all P<0.05], but the level of vitamin C [before phototherapy: (62.507±0.205) vs (62.341±0.144)μg/ml; phototherapy for 6 h: (51.211±0.086) vs (58.128±0.076) μg/ml; 12 h: (43.288±0.084) vs (55.351±0.050) μg/ml; 18 h: (35.758±0.113) vs (51.215±0.093) μg/ml; 24 h: (33.473±0.075) vs (48.473±0.080)μg/ml] and vitamin E decreased [before phototherapy: (4.101±0.132) vs (4.084±0.141) μg/ml; phototherapy for 6 h: (3.761±0.119) vs (3.904±0.075) μg/ml; 12 h: (3.654±0.092) vs (3.729±0.087) μg/ml; 18 h: (3.385±0.102) vs (3.582±0.119) μg/ml; 24 h: (3.313±0.127) vs (3.438±0.113) μg/ml, all P<0.05]. The same situation was also observed in indoor light group, double-, and three-sided phototherapy groups. The malondialdehyde level at different time in the exposure subgroups were higher but the vitamin C and vitamin E levels were lower than those in the non-exposure subgroups, regardless of the phototherapy intensities (all P<0.001). (2) The analysis of all exposure phototherapy subgroups showed that the higher the intensity of light therapy, the higher the malondialdehyde level, and the lower the level of vitamin C and vitamin E, with statistical significance differences in any pairwise comparison. Analysis of all non-exposure subgroups showed statistically significant differences in the malondialdehyde level in any pairwise comparison (all P<0.05) except for the comparison between indoor light group and single-sided phototherapy group ( F=2.383. P=0.140). Moreover, the greater the phototherapy intensities, the lower vitamin C level, with statistically significant differences in any pairwise comparison. And statistical significance differences were observed in the vitamin E level in any pairwise comparison (all P<0.05) except for the comparison between double- and three-sided phototherapy groups ( F=1.358, P=0.259). Conclusions:Phototherapy can increase the malondialdehyde level in parenteral nutrient solution for premature infants and the degree of intralipid peroxidation, but can also lead to vitamin C and vitamin E loss in the parenteral nutrient and weaken its antioxidant capacity.