骨盤位に対する帝王切開時の臍帯血液ガス状態, 頭位のそれとの比較  [in Japanese] Umbilical Blood-gas Status at Cesarean Section for Breech Presentation: A Comparison with That for Vertex Presentation  [in Japanese]

骨盤位経膣分娩では周産期罹病率・死亡率が高いので, 骨盤位に対する帝王切開(以下「帝切」)・施行率が増加している. 今回, 骨盤位児の帝切娩出の安全性を確認するため, 酸素投与下の脊椎麻酔による帝切で娩出した骨盤位例(25例)と頭位例(25例)の臍帯血液ガス値を比較した. 産婦はすべて妊娠38〜39週, 陣痛未発来で, 合併症がなく, 児の先天異常, 胎盤・臍帯の異常もなかつた. 骨盤位の臍動脈血(UA)酸素値(Po_2:18.9mmHg<平均値>, So_2<酸素飽和度>: 37.3%, Co_2<酸素含有量>:7.6ml/dl)は頭位のそれ(Po_2:24.3mmHg, So_2:51.5%, Co_2:10.5ml/dl)よりも有意に低かった. 低酸素化症例は骨盤位7例, 頭位0例で有意差があつた. 他の臍帯酸-塩基値は骨盤位と頭位の間に有意差がなく, 両者とも正常であつた. 骨盤位児のoxygen extraction(49.0%:平均値)は頭位児のそれ(32.9%)よりも有意に高く, 骨盤位での臍帯血流量の減少が示唆される.骨盤位児の生後1分のdepression発生率(24%)は頭位児のそれ(0%)よりも有意に高かった.骨盤位では子宮切開から児娩出までの所要時間が延長すると, UAが代謝性アシドーシスに傾き, 1分Apgar scoreが低くなる傾向がみられた. 骨盤位帝切時には, 的確で十分な切開と巧妙な娩出技術によつて, 臍帯圧迫の軽減と児娩出遅延の回避を図らねばならない.

Umbilical blood-gas status at elective cesarean section with oxygen inhalation for breech presentation (25 cases) was compared with that for vertex presentation (25 cases), so as to confirm the security of full-term breech fetuses delivered by cesarean section under spinal anesthesia. Umbilical arterial oxygen levels were significantly lower in the breech group (Mean Po_2 : 18.9mmHg ; So_2 : 37.3% ;Oxygen content : 7.6ml/dl). The number of hypoxemic fetuses was significantly higher in the breech group (the breech : 7 ; the vertex ; 0). The other umbilical blood-gas values revealed no significant differences between the breech and vertex groups, and were within normal limits in both groups. Oxygen extraction in the breech (Mean : 49.0%) was higher than that in the vertex (32.9%). Therefore decreased umbilical blood flow in the breech was suggested. The incidence of depression at 1 minute after delivery in the breech infants (24%) was significantly higher than that in the vertex infants (0%). It became obvious in the breech that as the interval between the uterine incision and delivery increased, umbilical arterial blood tended to acidosis and the 1 minute Apgar score decreased. Cesarean section for breech presentation requires sufficient and optimal incisions of the abdominal wall and uterus as well as a skilful manual delivery technique, because the fetus or neonate should be protected against asphyxia resulting from umbilical compression and prolonged delivery interval.