急性肺障害の少量対十分量経管栄養

急性肺障害で人工呼吸器管理を要する患者に対する、少量の経管栄養と十分量の経管栄養を比較したRCTを紹介します。

The National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network: Initial Trophic vs Full Enteral Feeding in Patients With Acute Lung Injury. The EDEN Randomized Trial. JAMA. Published online February 5, 2012.doi: 10.1001/jama.2012.137

対象は48時間以内に人工呼吸器管理を要する急性肺損傷で経管栄養を開始予定の患者1000人です。少量経管栄養群は、10-20ml/hrの経管栄養で最初の6日間、栄養管理しています。十分量経管栄養群はなるべく早く理想体重の25-30kcal/kg/dayのNPCと1.2-1.6g/kg/dayの蛋白質を目標としています。7日目以降の栄養管理は同じです。

一次アウトカムは人工呼吸器管理から離脱した日数です。両群の平均体重はそれぞれ86kg、87kgで、実際には少量経管栄養群は1日400kcal（実体重の約5kcal/kg/day）程度、十分量経管栄養群は1日1300kcal程度（実体重の約15kcal/kg/day）で管理されました。

結果ですが、両群で人工呼吸器管理から離脱した日数、60日後の死亡率とも統計学的有意差を認めませんでした。消化器合併症は十分量経管栄養群でやや多いという結果でした。以上より、少量経管栄養による人工呼吸器管理から離脱した日数や死亡率の改善は認めないという結論です。

両群とも静脈栄養は行っていませんので、実体重の5kcal/kg/day対15kcal/kg/dayで最初の6日間を栄養管理しているRCTです。15kcal/kg/dayが十分量経管栄養と言えるか微妙ですが。少量経管栄養群も7日目以降は約15kcal/kg/dayです。この範囲なら侵襲時の経管栄養として、どちらも適当な可能性があります。

むしろ5kcal/kg/day以下の過度な飢餓による栄養管理や、25kcal/kg/day以上の過栄養による栄養管理のほうが問題なのではと感じます。最適な投与量はわかりませんが、急性肺障害の初期は5-15kcal/kg/dayで経管栄養で管理する分には、大きな問題はないのではという気がします。

Abstract
Context
The amount of enteral nutrition patients with acute lung injury need is unknown.

Objective
To determine if initial lower-volume trophic enteral feeding would increase ventilator-free days and decrease gastrointestinal intolerances compared with initial full enteral feeding.
 
Design, Setting, and Participants
The EDEN study, a randomized, open-label, multicenter trial conducted from January 2, 2008, through April 12, 2011. Participants were 1000 adults within 48 hours of developing acute lung injury requiring mechanical ventilation whose physicians intended to start enteral nutrition at 44 hospitals in the National Heart, Lung, and Blood Institute ARDS Clinical Trials Network.
 
Interventions
Participants were randomized to receive either trophic or full enteral feeding for the first 6 days. After day 6, the care of all patients who were still receiving mechanical ventilation was managed according to the full feeding protocol.

Main Outcome Measures
Ventilator-free days to study day 28.

Results
Baseline characteristics were similar between the trophic-feeding (n = 508) and full-feeding (n = 492) groups. The full-feeding group received more enteral calories for the first 6 days, about 1300 kcal/d compared with 400 kcal/d (P < .001). Initial trophic feeding did not increase the number of ventilator-free days (14.9 [95% CI, 13.9 to 15.8] vs 15.0 [95% CI, 14.1 to 15.9]; difference, −0.1 [95% CI, −1.4 to 1.2]; P = .89) or reduce 60-day mortality (23.2% [95% CI, 19.6% to 26.9%] vs 22.2% [95% CI, 18.5% to 25.8%]; difference, 1.0% [95% CI, −4.1% to 6.3%]; P = .77) compared with full feeding. There were no differences in infectious complications between the groups. Despite receiving more prokinetic agents, the full-feeding group experienced more vomiting (2.2% vs 1.7% of patient feeding days; P = .05), elevated gastric residual volumes (4.9% vs 2.2% of feeding days; P < .001), and constipation (3.1% vs 2.1% of feeding days; P = .003). Mean plasma glucose values and average hourly insulin administration were both higher in the full-feeding group over the first 6 days.

Conclusion In patients with acute lung injury, compared with full enteral feeding, a strategy of initial trophic enteral feeding for up to 6 days did not improve ventilator-free days, 60-day mortality, or infectious complications but was associated with less gastrointestinal intolerance.