新流感的重症治療經驗 Cohort Study
JAMA 這期連續刊出 美國加州，墨西哥，加拿大，澳洲與紐西蘭的病例彙整報告，來看看幾個有興趣的資料。
（一）
美國加州這篇彙整今年4~8月份登錄到加州官方機構的1088個新流感病例資料，值的注意的幾個數據：
1.住入加護病房的比率，為住院數中的31%
2.住院死亡率為11%
3.有21%病人沒有接受克流感藥物治療，一半的病人無法在48小時內投藥
4.併發繼發性細菌肺炎者只有4%
5.約有1/3的假陰性快篩率
Factors Associated With Death or Hospitalization Due to Pandemic 2009 Influenza A(H1N1) Infection in California. JAMA. 2009;302(17):1896-1902.
（二）
加拿大這篇，彙整證實confirmed與可能probable 168個新流感重症患者資料。
1.90.5%有接受抗流感藥物治療Neuraminidase Inhibitors
2.重症患者28天死亡率為14.3％，90天死亡率為17.3％
3.繼發性肺炎的發生率為24.4%，但抗生素的使用率卻高達98.8%
4.接受ECMO治療者4.2%
5. 有一半的病人接受corticosteroid的治療（是否為了原來的內科疾病COPD asthma 未披露）
Critically Ill Patients With 2009 Influenza A(H1N1) Infection in Canada.JAMA. 2009;302(17):1872-1879
（三）
墨西哥這個全球流感的源頭，發表58例證實，可能，及懷疑的重症患者(佔所有案例的6.5%)
1. 60天重症死亡率41.4%
2.95%使用抗生素，69％使用corticosteroids
3.都沒有使用ECMO
4.只有4例（4/58 < 8%)繼發性肺炎
Critically Ill Patients With 2009 Influenza A(H1N1) in Mexico. JAMA. 2009;302(17):1880-1887
（四）
紐西蘭與澳洲這篇最有意思，他是彙整使用6~8三個月的ECMO治療經驗。
首先他的ECMO的使用率，68/201，超過30%，是目前新流感重症患者中最高的一個報告，而他的入選條件與目前正在進行ARDS患者是否使用ECMO的RCT Trial 一樣。（All of the patients fulfilled the ARDS severity criteria for enrollment in a recently reported randomized controlled trial (the CESAR study16) of ECMO treatment.）。
文獻上的報告，ARDS使用ECMO的死亡率為30~48%，而本系列為21％，這只能說反應viral pneumonia本來就有比較好的預後（較低的死亡率），而對比其他系列報告的死亡率（墨西哥除外）14-17%，以及他本身非ECMO組的死亡率13％，ECMO並沒有突出他的治療價值，尤其是當你再注意看他的死亡原因，竟然有多數死於bleeding。而出血的併發症高達50％
Hemorrhagic complications occurred in 37 patients (54%) during ECMO therapy, with the most common sources being ECMO cannulation sites in 15 patients (22%), gastrointestinal tract in 7 patients (10%), respiratory tract in 7 patients (10%), vaginal bleeding in 6 patients (9%), and intracranial hemorrhage in 6 patients (9%).
The median (IQR) amount of blood administered per patient was 1880 (904-3750) mL. Infective complications occurred in 42 patients (62%) during ECMO therapy, with the most common sites being respiratory tract in 30 patients (44%), bloodstream in 14 patients (21%), non-ECMO catheter-related in 13 patients (19%), and ECMO cannulae-related in 7 patients (10%).
依照以上三個cohort的報告資料，有80%的重症患者需要呼吸器治療，而重症死亡率約在15%計算，201/0.8=251，接近252本系列的所有重症患者，而251*0.15 約有37死亡病例，而本系列的死亡數ECMO 14 + NonECMO 17 =31也大致符合。
因此，目前個人來看，ECMO並無比較優勢，是否使用，需要臨床醫師就個案來綜合考量。
參考：Efficacy and economic assessment of conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR): a multicentre randomised controlled trial.Lancet. 2009 Oct 17;374(9698):1351-63
INTERPRETATION: We recommend transferring of adult patients with severe but potentially reversible respiratory failure, whose Murray score exceeds 3.0 or who have a pH of less than 7.20 on optimum conventional management, to a centre with an ECMO-based management protocol to significantly improve survival without severe disability.
另外有三篇之前的報告一併列出參考。
1.Michigan 10 severe ICU cases:大胖子，pulmonary embolism
Intensive-Care Patients With Severe Novel Influenza A (H1N1) Virus Infection --- Michigan, June 2009
2.Critical care services and 2009 H1N1 influenza in Australia and New Zealand [published online October 8, 2009]. N Engl J Med.
3.Hospitalized patients with 2009 H1N1 influenza in the United States, April-June 2009 [published online October 8, 2009]. N Engl J Med.
沒有回答的問題：
1.合併多種抗流感藥物？
2.Steroid的使用？
3.非傳統，未證實的治療方法：immunoglobulin infusion, cytokine inhibitors treatment
編輯觀點：
The rapid onset of refractory hypoxemia, together with multisystem organ failure and hypotension, suggests that clinical outcomes will depend on clinicians' ability to apply sophisticated mechanical ventilatory support and adjunct therapies.
Clinicians and hospitals should take note that the rescue therapies used in these studies have the potential to cause harm if not implemented in a coordinated manner.
Many US hospitals may not have adequate numbers of physicians with this expertise, or staffing structures to facilitate timely treatment at any time of day or night.
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