日本新生児成育医学会雑誌　第29巻　第1号　59～64頁（2017年）

日本新生児成育医学会雑誌　29(1)：59-64；2017　

受付日：平成28．03．25

受理日：平成28．06．20

当院NICU入院児におけるビタミンK予防内服の検討

Vitamin K Prophylaxis for Neonates in the NICU

北海道立子ども総合医療・療育センター　新生児内科

Department of Neonatology, Hokkaido Medical Center for Child Health and Rehabilitation

野口聡子・石川　淑・浅沼秀臣・新飯田裕一

Satoko NOGUCHI，Shuku ISHIKAWA，Hideomi ASANUMA，Yuichi NIIDA

Key Words：vitamin K deficiency，vitamin K prophylaxis，PIVKAⅡ，hepaplastin test，antibiotics

　当院NICU では2011年3月に発表されたガイドラインに準じ，全症例に生後3か月まで週1回ビタミンK製剤投与を継続している。2012年1月から6月までの6か月間に入院した34症例について，この方法でのビタミンK欠乏状態の有無とリスク要因，ビタミンK 製剤継続投与の効果について後方視的に検討した。
　生後1か月では23％の児でPIVKAⅡが陽性で，全例に抗菌薬投与歴があった。抗菌薬投与歴のある児全体では41％が陽性で，陽性例のうち43％は混合または人工栄養児であった。生後3か月でPIVKA Ⅱ陽性例はなかった。
　生後1か月のヘパプラスチンテスト（HPT：％）値は抗菌薬投与歴のある児で低い傾向があった。栄養方法との関連はなかった。HPT（％）の平均値は生後3か月までに有意に上昇し出血症状を認めた症例はなかった。抗菌薬投与歴をもつ児は生後1か月でPIVKAⅡ陽性を呈しやすいが，ビタミンK 製剤の投与を生後3か月まで継続することで改善効果が期待できる。

　Neonates in the NICU are at an increased risk of vitamin K deficiency bleeding（ VKDB） compared with healthy term neonates. In our NICU, all patients routinely receive 2mg of vitamin K2 at birth followed by 2mg of weekly supplementation starting on the 5th day until the end of the 14th week according to the “Revised Guidelines for VKDB in infants and neonates” published in 2011.
　To assess the necessity for this prophylactic regimen and to identify risk factors for vitamin K deficiency in neonates with various underlying disorders in the NICU, patient clinical background, plasma PIVKAⅡ levels, and hepaplastin tests measured at birth, and the 1st and 3rd month after birth were evaluated. Between January and July 2012, 34 patients were included in the study. The PIVKAⅡ positive rate was 23% the 1st month, higher than the previously reported rate in healthy term babies. Patients who used antibiotics had lower hepaplastin values, with a significantly higher PIVKAⅡ positive rate in the 1st month （p＜0.01） than patients without antibiotics. The hepaplastin values increased in the 1st month （p＜0.001）, and continued to increase in the 3rd month （p＜0.001） compared with the value at birth. The PIVKAⅡ positive rate was 0% in the 3rd month. No patients were affected by VKDB.
　When antibiotics are used for neonates in the NICU, careful attention should be paid to the possibility of vitamin K deficiency and vitamin K2 prophylaxis should be continuously administered. This three-month prophylactic regimen is effective for neonates in the NICU despite the administration of antibiotics.