論文No1516
Oxygenation Saturation Index Predicts Clinical Outcomes in ARDS
Katherine DesPrez, J. Brennan McNeil, Chunxue Wang, Julie A. Bastarache, Ciara M. Shaver, Lorraine B. Ware
CHEST, Volume 152, Issue 6, Pages 1151–1158, 2017.
＜背景＞
Pao2/Fio2のようなARDSの重症度判定は臨床予後を正確に予測しないかもしれない。
酸素化指数 (OI [Fio2 × 平均気道内圧 × 100)/Pao2])はARDS重症度をより正確に反映するが血液ガス測定を要する。
我々は酸素飽和度指数(OSI [Fio2 × 平均気道内圧 × 100)/パルスオキシメーターによる 酸素飽和度(Spo2)])がARDS患者の院内死亡、人工呼吸不要の日数(VFDs)に関連するOIの非侵襲的な信頼しうる代替になるのではないかと考えた。
＜方法＞
前向きコホート研究に登録された重症患者がICU滞在最初の4日以内にARDS(ベルリン基準）となった場合に、平均気道内圧、Spo2/Fio2, Pao2/Fio2をARDS診断初日に記録した（329名）。
最高平均気道内圧、最低Spo2/Fio2, Pao2/Fio2を使用してOI, OSIを計算した。
OI、OSIと院内死亡、VFDにてついてロジスティック回帰、線形回帰分析で解析した。
死亡に対するROC曲線下面積(AUC)をOI, OSI, Spo2/Fio2, Pao2/Fio2,Acute Physiology and Chronic Health Evaluation II scores(APACHE Ⅱ）とで比較した。
＜結果＞
OI, OSIは強い関連性があった (rho = 0.862; P < .001)。
OSIは院内死亡に独立して関連していた(OR per 5-point increase in OSI, 1.228 [95% CI, 1.056-1.429]; P = .008)。
OI, OSIはそれぞれVFDの減少に関連していた (OI, P = .023; OSI, P = .005)。
死亡予測のAUCはAPACHE Ⅱ (AUC, 0.695; P < .005)、OSI (AUC, 0.602; P = .007)で最も高かった。
OSIのAUCは４０歳未満でより高かった(AUC, 0.779; P < .001)。
＜感想＞
ARDS患者で、OSIはOIと強い関連性があったようです。
死亡予測にも有用で非侵襲性でもあり、
OSI [Fio2 × 平均気道内圧 × 100)/(Spo2)]はARDS予後の有用な予測因子となりうるようです。
Background
Traditional measures of ARDS severity such as Pao2/Fio2 may not reliably predict clinical outcomes. The oxygenation index (OI [Fio2 × mean airway pressure × 100)/Pao2]) may more accurately reflect ARDS severity but requires arterial blood gas measurement. We hypothesized that the oxygenation saturation index (OSI [Fio2 × mean airway pressure × 100)/oxygen saturation by pulse oximetry (Spo2)]) is a reliable noninvasive surrogate for the OI that is associated with hospital mortality and ventilator-free days (VFDs) in patients with ARDS.
Methods
Critically ill patients enrolled in a prospective cohort study were eligible if they developed ARDS (Berlin criteria) during the first 4 ICU days and had mean airway pressure, Spo2/Fio2, and Pao2/Fio2 values recorded on the first day of ARDS (N = 329). The highest mean airway pressure and lowest Spo2/Fio2 and Pao2/Fio2 values were used to calculate OI and OSI. The association between OI or OSI and hospital mortality or VFD was analyzed by using logistic regression and linear regression, respectively. The area under the receiver-operating characteristic curve (AUC) for mortality was compared among OI, OSI, Spo2/Fio2, Pao2/Fio2, and Acute Physiology and Chronic Health Evaluation II scores.
Results
OI and OSI were strongly correlated (rho = 0.862; P < .001). OSI was independently associated with hospital mortality (OR per 5-point increase in OSI, 1.228 [95% CI, 1.056-1.429]; P = .008). OI and OSI were each associated with a reduction in VFD (OI, P = .023; OSI, P = .005). The AUC for mortality prediction was greatest for Acute Physiology and Chronic Health Evaluation II scores (AUC, 0.695; P < .005) and OSI (AUC, 0.602; P = .007). The AUC for OSI was substantially better in patients aged < 40 years (AUC, 0.779; P < .001).
Conclusions
In patients with ARDS, the OSI was correlated with the OI. The OSI on the day of ARDS diagnosis was significantly associated with increased mortality and fewer VFDs. The findings suggest that OSI is a reliable surrogate for OI that can noninvasively provide prognostic information and assessment of ARDS severity.