High Inspired Oxygen Fraction and Surgical Site Infection
the partial pressure of oxygen (PO2) in wounds is important for healing.8 PO2 is low in surgical wounds as a result of injury, coagulation, inflammation, and, in large measure, the sympathetic nervous system stimulation and consequent vasoconstriction caused by hypothermia,9 hypovolemia,10 and pain.11
麻醉術中處置,對手術病人預後的影響,是麻醉醫師介入圍術期照護的跳板,可惜,能影響病人的預後的因素太多,而麻醉手段,至目前為止,好像是杯水車薪,螞蟻撼樹,起不了多大的波瀾, SSI surgical site infection 也是外科術後關注的議題,提高術中吸氧濃度可以降低SSI 的發生率嗎?先前的累積證據 12% vs. 9% ,可以降低3%,減少25% 的可能性。而最近的JAMA文章,研究14間荷蘭醫院1400剖腹探查病人的SSI, 發現 80% vs. 30% 吸氧濃度,不會改變SSI的發生率,19% vs. 20%。
就基礎理論來看,組織氧氣攜帶量DO2與 心輸出量,氧飽和度,與血紅素有正相關 (DO2=[1.34*Hb*SaO2+0.0034*PaO2]*cardiac output,動脈氧氣分壓所佔的比率,微乎其微,幾乎可以省略,所以不是要看高濃度吸氧能帶來多少好處,而是要看低濃度吸氧會不會造成組織帶氧量的減少,似乎是比較合理的解釋。
1.High Inspired Oxygen Fraction and Surgical Site Infection.JAMA. 2009;302(14):1588-1589.
2.Supplemental perioperative oxygen to reduce the incidence of surgical-wound infection. N Engl J Med. 2000;342(3):161-167.