校正的脉搏压变异度对自主呼吸脓毒症患者液体反应性的评估

目的:研究在自主呼吸患者深吸气时潮气量（Vt DI）对脉搏压力变异度（ΔPP DI）的影响,并验证是否以Vt DI校正ΔPP DI可进一步提高预测液体反应性（fluid responsiveness，FR）的能力。 方法:前瞻性纳入2017年10月至2019年10月于武警特色医学中心和南京市高淳人民医院ICU确诊的、符合第三版国际共识诊断标准的自主呼吸的脓毒症和脓毒性休克患者，20 min内静脉输注生理盐水500 mL进行容量扩张（volume expansion，VE），VE后每搏输出量变化率（ΔSV）≥15％为液体反应者,否则为液体无反应者。VE开始前，在平静呼吸以及深吸气时测量脉搏压力变异度（ΔPP TB和ΔPP DI）和潮气量（Vt TB和Vt DI）。采用多元线性回归分析ΔPP DI与Vt DI、ΔSV的关系，应用受试者工作特征曲线（ROC）下面积（AUC）以及灰区范围评估参数预测FR能力，并计算灰区范围误分类代价比（R）的不同而变化的情况。 结果:最终纳入31例患者，17例为液体反应者；液体反应者的ΔPP DI显著高于无反应者（19.1±7.4）% vs（11.2±4.5）%， P=0.001]。ΔPP DI预测FR的AUC为0.832显著高于ΔPP TB的0.580（ P<0.05）。多元回归分析显示Vt DI和ΔSV均是ΔPP DI的独立影响因素（ P<0.01）；经Vt DI校正的ΔPP DI （ΔPP DI/Vt DI）的AUC显著高于单独使用ΔPP DI （ P=0.03）。采用正常液体策略时（R=1），ΔPP DI/Vt DI的灰区范围为12.7~14.5，包含19%的患者；采用限制性液体策略时（R=2），ΔPP DI/Vt DI灰区范围为12.8~14.5，仅包含6.5%的患者。 结论:在完全自主呼吸的脓毒症患者中，ΔPP DI预测FR具有中度的准确度，以Vt DI校正ΔPP DI后可进一步提高其预测价值。

Ability of adjusted pulse pressure variation in predicting fluid responsiveness in spontaneously breathing patients with sepsis

Objective:To investigate the effect of tidal volume (Vt DI) on pulse pressure variation (ΔPP DI) during deep inspiration maneuvers in spontaneously breathing patients with sepsis and to test if adjusting ΔPP DI by Vt DI can further improve its ability in predicting fluid responsiveness (FR). Methods:Spontaneously breathing, nonintubated sepsis or septic shock patients who were admitted to the Intensive Care Unit of the Characteristic Medical Center of Chinese People's Armed Police Force and Nanjing Gaochun People's Hospital were prospectively enrolled from October 2017 to October 2019. Volume expansion (VE) was performed by infusing 500 mL saline over 20 min. Prior to VE, measurements including pulse pressure variation and tidal volume were obtained during quiet spontaneous breathing (ΔPP TB and Vt TB, respectively) and during the deep inspiration maneuver (ΔPP DI and Vt DI, respectively). Patients were classified as responders if stroke volume (SV) increased ≥ 15% after VE, otherwise non-responders. Multiple linear regression analysis was conducted to investigate the correlation of ΔPP DI with Vt DI and VE-induced percentage changes in SV (ΔSV). Receiver operating characteristic (ROC) curve analysis and the gray zone approach were used to assess the ability of each index to predict FR. Changes in gray zone limits according to the cost ratio (R = costfalse positive (FP)]/costfalse negative (FN)]) were also evaluated. Results:Of the included 31 patients, 17 were responders. There was no significant difference in ΔPP TB between fluid responders and non-responders ( P>0.05), whereas ΔPP DI was significantly higher in responders than in non-responders (19.1±7.4)% vs (11.2±4.5)%; P=0.001]. The area under the ROC curve (AUC) of ΔPP DI predicted FR was 0.832, sensitivity of 76.47% and specificity of 71.43%, which was significantly higher than ΔPP TB (AUC=0.580, sensitivity of 47.06% and specificity of 71.43%; P<0.05). Multiple linear regression analysis showed that both Vt DI and ΔSV were independently associated with ΔPP DI ( P<0.01), the AUC of ΔPP DI adjusted by Vt DI was signigicantly higher than that of ΔPP DI alone ( P=0.03). Among the ΔPP TB, ΔPP DI and ΔPP DI/Vt DI, ΔPP DI/Vt DI had the narrowest gray zone (12.7-14.5) for the normal fluid policy (R=1), which only included 19% of the patients. When applying "restrictive" fluid management (R=2), the gray zone for ΔPP DI/Vt DI was 12.8-14.5 and included only 2 patients (6.5%). Conclusions:In spontaneously breathing, nonintubated patients with sepsis or septic shock, the ΔPP value obtained during the deep inspiration maneuver predicts FR with moderate accuracy. Given the close correlation between Vt DI and ΔPP DI, ΔPP DI adjusted by Vt DI performs better than ΔPP DI alone in predicting FR.