Heyland D, Bradley C, Mandell L A
Department of Internal Medicine, McMaster University, Hamilton, ON, Canada.
Crit Care Med. 1992 Oct;20(10):1388-94. doi: 10.1097/00003246-199210000-00005.
To evaluate the effect of acidified enteral nutritional formulas (feedings) on gastric colonization and pH in critically ill patients.
Randomized, double-blind trial of three groups: a) regular feedings into the stomach; b) regular feedings into the duodenum; and c) acidified feedings into the stomach. Nasogastric aspirates for gastric pH and microbiological determinations were obtained daily for a mean of 5 days after feeding began.
ICU at a tertiary care hospital.
Thirty-one patients indicated to receive enteral feedings before day 4 in the ICU were randomized. Seven patients had their feedings discontinued because of intolerance, accidental extubation, or tolerance of oral supplementation. One patient received the wrong feedings and was dropped from the study. A total of 23 patients finished the study. They were mostly trauma (n = 15) or neurosurgical (n = 6) patients. The average age was 40 yrs (range 15 to 71).
An enteral formula with a pH of 6.5 was used as the control feeding. Hydrochloric acid was added to the control feeding to titrate the pH to 3.5 and this acidified enteral formula was given to the experimental group. All patients received continuous enteral feedings via an 8-Fr feeding tube.
Seven of eight patients receiving the acidified feedings were sterile (no microbial growth) on receiving feedings compared with five of 15 of those patients receiving regular feedings (p = .027). For those patients initially colonized, four of four patients receiving acidified feedings immediately became sterile and remained so. Only two of ten patients receiving regular feedings remained sterile (p = .021). The mean gastric pH of the acidified group was 3.2 compared with the group receiving regular feedings into the stomach (pH = 4.7) and the group receiving regular feedings into the duodenum (pH = 3.8) (p < .01). There was no evidence of gastrointestinal bleeding in any patient.
Acidified enteral feedings are effective in eliminating and preventing gastric colonization in critically ill patients. Further investigation is needed to assess its effect on nosocomial infection rates.
评估酸化肠内营养配方（喂养）对重症患者胃定植及胃内pH值的影响。
三组的随机双盲试验：a）经胃常规喂养；b）经十二指肠常规喂养；c）经胃酸化喂养。喂养开始后平均5天内，每天采集鼻胃吸出物用于测定胃内pH值和微生物情况。
一家三级护理医院的重症监护病房。
31名预计在入住重症监护病房第4天前接受肠内喂养的患者被随机分组。7名患者因不耐受、意外拔管或口服补充剂耐受而停止喂养。1名患者接受了错误的喂养，被排除在研究之外。共有23名患者完成了研究。他们大多是创伤患者（n = 15）或神经外科患者（n = 6）。平均年龄为40岁（范围15至71岁）。
使用pH值为6.5的肠内配方作为对照喂养。向对照喂养中添加盐酸，将pH值滴定至3.5，并将这种酸化肠内配方给予实验组。所有患者通过一根8Fr喂养管接受持续肠内喂养。
接受酸化喂养的8名患者中有7名在接受喂养时无菌（无微生物生长），而接受常规喂养的15名患者中有5名无菌（p = 0.027）。对于那些最初有定植的患者，接受酸化喂养的4名患者中有4名立即变为无菌并保持无菌状态。接受常规喂养的10名患者中只有2名保持无菌（p = 0.021）。酸化组的平均胃内pH值为3.2，与经胃常规喂养组（pH = 4.7）和经十二指肠常规喂养组（pH = 3.8）相比（p < 0.01）。没有任何患者出现胃肠道出血的证据。
酸化肠内喂养在消除和预防重症患者胃定植方面是有效的。需要进一步研究以评估其对医院感染率的影响。
