高酸素の弊害についてのreview
Bench-to-bedside review: the effects of hyperoxia during critical illness.
https://www.ncbi.nlm.nih.gov/pubmed/26278383
Crit Care. 2015 Aug 17;19:284.
<how to control reactive oxygen species>
superoxide dismutase reduces ROS
ROS is also used against several pathogens.
Simply reducing ROS does not solve the inflammation.
In critically ill patients, the level of oxygen toxicity accelerates.
Microcirculation
DAMPs damage-associated molecular pattern molecules alert the innate immune system.
DAMPs activate polymorphonuclear neutrophils (PMNs)
excessive O2 accelerates this process.
Lung in animals
In animal studies, hyperoxia transcends lung injury but time-dependent.
The lung is the most vulnerable organ, it is unknown that the threshold of PaO2 or FiO2 where harm outweighs benefits.
Vessels in animals
hyperoxia induces vasoconstriction in coronary arteries and decreases in heart rate, stroke volume, and cardiac output.
Clinical studies
Among patients with mechanical ventilation, hyperoxia induces high mortality.
Studies of neonate also proved that hyperoxia and hypoxia result in high morbidity.
SpO2 90-95% was the best O2 supply in the post-natal period.
For MI patients, O2 was harmful and
hypoxia was associated with delayed cerebral ischemia after cerebrovascular incidents.
Perioperative O2
WHO recommends that 80% of O2 supply after surgery prevents surgical site infection. But a recent study proved that worse outcomes in 80% O2 supply compared with 30% O2 supply.
心臓手術分野についてどうかというと、ニュージーランドから、2014年に83000人を対照とした大規模コホートstudyで心臓手術24時間の高酸素と死亡率の間には関連はなかったとの報告であった。
心臓手術の場合は他の要素が大きく関連しているので、高酸素の弊害のみを取り出すことが難しいだろうが、83000という大規模データでも差が出なかったということは、あまり臨床的な意義は少ないのかもしれない。
しかし、酸素にしろNOにしろ、何らかのガスにせよ、生体はその利用を状況状況に応じてダイナミックに変化させる。そうした状況依存性（これはモデル作成によって解決できるか）と時間依存性をどのように再現したらいいのだろうか。。。
