摘要目的探讨结、直肠手术后早期肠内营养的可行性，比较肠内与肠外营养的代谢效应，并观察肠内营养对结肠粘膜组织学的影响.方法结直肠术后随机分为早期肠内营养(enteral nutrition，EN)和全肠外营养(TPN)组，各15例．EN组术后24h内经鼻肠管滴注能全力(nutrison fiber)，TPN组经外周静脉进行，两组基本等热量，各7d．术前及术后8d进行人体测量，生化监测、留取结肠粘膜标本行光镜及透射电镜观察，并比较肠功能恢复及住院费用等.结果EN组15例均完成肠内营养计划，未发生吻合口瘘和腹腔感染．两组术后体重、三头肌皮褶厚度、上臂周径、清蛋白均较术前略低(P＜0.01)，两组总淋巴细胞计数、前清蛋白营养支持前后无显著差异(P＞0.05)，转铁蛋白TPN组术后8d(2.3±1.1)g/L显著低于术前水平(3.4±1.6)g/L，P＜0.01，而EN支持组仍维持在术前水平．碱性磷酸酶TPN组术后(163±120)U/L高于术前(125±97)U/L，P＜0.05，而EN支持前后无明显改变，术后乳酸脱氢酶TPN组(635±377)U/L高于EN组(418±147)U/L，P＜0.05，转氨酶组间比较无显著差异，总胆红素TPN，EN前后均无显著改变．两组术后氮监测1wk均表现为负氮平衡，且累积氮平衡TPN组略低于EN组(P＞0.05)．EN组肠功能恢复快(P＜0.05)．两组伤口愈合情况、住院天数无差异(P＞0.05)．平均住院费用 /药物费用EN组低于TPN组(P＜0.05)．EN前后结肠粘膜层厚度、腺体分布没有明显变化，细胞的超微结构保存良好，TPN组术后标本镜下表现为粘膜层变薄，腺体排列稀疏，细胞超微结构除微绒毛稀少，细胞器的发达程度略受影响外，其余变化不明显.结论结、直肠术后早期肠内营养是安全可行的．EN和TPN均可改善患者营养状况，降低蛋白质分解，术后短期应用代谢效应相似．与TPN相比，EN促进肠功能恢复，降低住院费用，减少对肝功能的影响，维持肠粘膜组织结构的完整，有助于保护肠粘膜屏障.

中国图书馆分类号R656.9

Early enteral nutrition after colorectal resections: a prospective clinical trial

WU Wen-Xi，XU Qin，HUA Yi-Bing and SHEN Li-Zhong

(Department of Gastroenterologic Surgery，the First Affiliated Hospital of Nanjing Medical University，Nanjing 210029，Jiangsu Province，China)

AbstractAIMTo evaluate the feasibility of early postoperative enteral nutrition (EN) in colorectal surgery and compare the metabolic effects and histologic changes of colonic mucosa following EN or total parenteral nutrition (TPN).METHODSPatients undergone open elective colorectal resections were randomized to either early EN or control (TPN) group．Fifteen patients in EN group had a nasal-jejunal tube inserted during the operation．The enteral feeding with a formula containing fiber started within the first 24 hours postoperatively and continued for consecutive 7 days．The full load of EN provided 0.18ng/(kg·d) and 104.5kJ/(kg·d) of non-protein energy．Fifteen patients in control group received total parenteral nutrition via peripheral vein postoperatively and provided 0.10ng/(kg·d) and 101kJ/(kg·d) of non-protein energy for 7 days．Anthropometric，biochemical parameters and visceral functions were monitored．Colonoscopic examination with mucosa biopsy were taken in 6 patients of EN group and 4 patients of parenteral nutrition (PN) group preoperatively and followed up for 8 days postoperatively．The microstructure of the colonic mucosa was studied.RESULTSPatients in each group were well matched with sex，age，type and duration of operations．All patients in EN group tolerated the early feeding．Total lymphocyte and prealbumin level maintained stable after the nutrition support in both groups．Serum transferrin maintained stable in EN group，however，decreased significantly in TPN group．By the end of the study cumulated nitrogen balance in EN and TPN groups was (-19.2±15.7)gN/7d and (-27.6±12.4)gN/7d，respectively (P＞0.05)．On the 8th day the serum level of lactate dehydrogenase (LDH) was significantly higher in TPN group than that of EN group (635±376 vs 418±147，P＜0.05)．An increased alkaline phosphatase (AKP) level was observed after TPN support，but not in EN group．No difference was found in total bilirubin and transaminase level in the two groups．No bowel anastomosis leakage was found in both groups．There were no statistical differences in wound healing，infective complications and duration of hospitalization between the two groups．The overall cost of enteral nutrition was significantly lower than that of TPN group (P＜0.05)．The audible bowel sounds and bowel movement recovered earlier in EN group than that in the control group (P＜0.05)．Histologic examination showed the colonic mucosa thickness and glands density decreased after seven days of TPN，but unchanged after EN．Postoperatively no significant changes were observed in ultrastructure of the colon epithelial cell in the two groups except for reduced microvilli，less mucus secretion and water transport in TPN group.CONCLUSIONThe early postoperative enteral nutrition was well tolerated in the patients undergone colorectal surgery．In comparison with TPN the metabolic effect was similar in EN with less disturbance of liver function．The early enteral feeding with formula containing fiber may help to maintain the bowel functions and gut integrity.

Subject headingscolorectal resections; enteral nutrition; prospective study

0引言

胃肠道手术后，消化道功能受影响，术后常需禁食，围手术期营养支持受到关注．近年来消化道动力学研究的深化，使术后早期肠内营养(EN)受到重视，但仍有问题有待探讨：结、直肠手术后消化道远端肠吻合口的存在，使术后早期EN的安全性、有效性及临床价值有进一步探究的必要．术后早期EN，肠外营养(PN)对结肠粘膜组织学的影响，报告甚少．我们以大肠癌术后患者为对象，比较术后早期EN与PN的临床效果，并观察大肠粘膜组织结构的变化.

1材料和方法

1.1材料选自1998-09/1999-02间我科收治的结、直肠癌手术患者30例，男20例，女10例；平均年龄56.4岁±14.6岁．无明显肝、肾功能障碍及代谢性疾病．患者按序随机分为早期肠内营养组(EN组)和全肠外营养组(TPN组)，各15例．两组性别、年龄、手术种类无差异.

1.2方法病例经3d常规术前肠道准备后手术，手术当日常规静脉补液，术后1d起开始EN或TPN．EN组：术中将鼻肠管送过幽门置于十二指肠降部以远，术后24h内开始肠内营养．使用液体型含有纤维的肠内营养制剂能全力，术后1d经鼻肠管滴入生理盐水500mL，及能全力500mL，速度50mL/h～75mL/h．术后2d能全力1000mL，75mL/h～100mL/h．3d～7d能全力1500mL/d～2000mL/d，100mL/h～150mL/h．利用重力或输注泵匀速滴注．不足之液体与能量由外周静脉补给.

TPN组经外周静脉进行，由500g/L葡萄糖及300g/L Intralipid分别提供约55%和45%的非蛋白热量，氮源为70g/L Vamin，多种维生素及微量元素，100g/L氯化钾30mL～40mL，胰岛素按1U∶5g～6g葡萄糖给予，混合于3L输液袋，约18h内均匀输入，共7d.

EN组中任择6例，TPN组中任择4例，分别于术前、术后8d通过纤维结肠镜留取距离肛门15cm左右处肠粘膜标本，分别以100mL/L福尔马林、50mL/L戊二醛固定，以供镜检．实验设计经医院伦理委员会核准，入组患者均签署知情同意书.

监测内容：术前及术后8d测量三头肌皮褶厚度(TSF)，上臂周径(MAC)及体重，检测血清清蛋白(ALB)、转铁蛋白(TF)、前清蛋白(PAB)、肝功能、总淋巴细胞计数等，每日留24h尿测尿素氮，计算氮平衡：EN组氮平衡(g/d)＝氮摄入量-［尿尿素氮(g/d)+4］，TPN组氮平衡(g/d)＝氮摄入量-［尿尿素氮(g/d)+3］．术后观察肠功能恢复时间，记录住院时间及费用．甲醛固定的标本常规石蜡切片，HE染色，光镜观察，并测量粘膜层厚度、计数高倍视野下腺体数目^［1］．戊二醛固定的标本制成电镜标本，用EM400型透射电镜观察结肠粘膜超微结构.

统计学处理全部数据采用均数±标准差表示，并用自身配对和两样本均数t检验进行统计分析.

2结果

EN组实际提供非蛋白热量(103.0±14.6)kJ/(kg·d)，氮(0.18±0.03)g/(kg·d)，非蛋白热量：氮=572.2kJ∶1g．TPN组实际提供非蛋白热量101kJ/(kg·d)±9kJ/(kg·d)，氮(0.10±0.02)g/(kg·d)，非蛋白热量：氮=983.6kJ∶1g．体重、TSF、MAC两组术后数值均低于术前(P＜0.01)，组间比较无统计学差异(P＞0.05)．淋巴细胞计数、PAB两组营养支<