Mirtallo J M, Fabri P J, Radcliffe K, Shaw-Regan C, Johnson J A, Ruberg R L
JPEN J Parenter Enteral Nutr. 1983 Mar-Apr;7(2):136-41. doi: 10.1177/0148607183007002136.
This two phase study evaluates nitrogen utilization by the body as a function of fixed caloric intake but different nitrogen loads. Nitrogen use by the body was estimated from measures of nitrogen balance, net protein utilization, and urea accumulation rate. Phase 1 of this study included 411 measurements of nitrogen use in 120 patients assigned, according to clinical condition, to receive one of the four following therapies: dextrose (D) 25%, amino acids (CAA) 4.25% (Group 1); D 35%, CAA 4.25% (Group 2); D 25%, CAA 21.3% (Group 3); or D 35%, CAA 21.3% (Group 4). Forty patients in Phase 2 were assigned in a randomized, prospective, double blind manner, to receive one of the following regimens; D 35%, CAA 2.75% (Group 5); D 25%, CAA 2.75% (Group 6); D 35%, CAA 4.25% (Group 7); or D 25%, CAA 4.25% (Group 8). In Phase 1, positive nitrogen balance was achieved with the exception of Group 3 where neither the estimated caloric nor nitrogen needs of the patients were met. It appeared that protein utilization was maximal in patients receiving the therapy of highest calorie:nitrogen ratio (Group 4). Phase 2 patients achieved positive nitrogen balance to the same extent (p greater than 0.05) and although net protein utilization improved from 53 to 71%/d as the calorie:nitrogen ratio was increased, the differences were not significant (p greater than 0.05). There was a significant improvement in total iron binding capacity in Phase 2 patients (p less than 0.01) that was most prominent at the lower concentrations of amino acids (high cal:n ratio) (Groups 5 and 6). Smaller amounts of nitrogen appear adequate in producing a positive nitrogen balance and may be better utilized in hospitalized patients if the patients' caloric requirements are achieved.
这项两阶段研究评估了在固定热量摄入但不同氮负荷情况下身体对氮的利用情况。通过氮平衡、净蛋白质利用率和尿素积累率的测量来估算身体对氮的使用情况。本研究的第一阶段包括对120名患者进行411次氮使用情况的测量，这些患者根据临床状况被分配接受以下四种疗法之一：25%葡萄糖（D）、4.25%结晶氨基酸（CAA）（第1组）；35%葡萄糖、4.25%结晶氨基酸（第2组）；25%葡萄糖、21.3%结晶氨基酸（第3组）；或35%葡萄糖、21.3%结晶氨基酸（第4组）。第二阶段的40名患者以随机、前瞻性、双盲的方式被分配接受以下方案之一：35%葡萄糖、2.75%结晶氨基酸（第5组）；25%葡萄糖、2.75%结晶氨基酸（第6组）；35%葡萄糖、4.25%结晶氨基酸（第7组）；或25%葡萄糖、4.25%结晶氨基酸（第8组）。在第一阶段，除第3组外均实现了正氮平衡，在第3组中患者的热量和氮需求均未得到满足。似乎接受热量:氮比值最高疗法的患者（第4组）蛋白质利用率最高。第二阶段的患者在相同程度上实现了正氮平衡（p大于0.05），尽管随着热量:氮比值的增加，净蛋白质利用率从53%/天提高到了71%/天，但差异不显著（p大于0.05）。第二阶段患者的总铁结合能力有显著改善（p小于0.01），在较低氨基酸浓度（高热量:氮比值）时最为明显（第5组和第6组）。在实现患者热量需求的情况下，较少量的氮似乎足以产生正氮平衡，并且在住院患者中可能得到更好的利用。
