Lisboa Thiago, Seligman Renato, Diaz Emili, Rodriguez Alejandro, Teixeira Paulo J Z, Rello Jordi
Critical Care Department, Joan XXIII University Hospital, University Rovira & Virgili, Institut Pere Virgili, CIBER Enfermedades Respiratorias, Tarragona, Spain.
Crit Care Med. 2008 Jan;36(1):166-71. doi: 10.1097/01.CCM.0000297886.32564.CF.
Appropriateness of antibiotic therapy is associated with reduction of bacterial load in ventilator-associated pneumonia. C-reactive protein is a valid biochemical surrogate. The objective was to determine the correlation of bacterial load, measured by quantitative tracheal aspirate (QTA), with serum C-reactive protein as an indicator of inflammatory response in episodes of ventilator-associated pneumonia and association of its variation with antibiotic appropriateness.
Prospective, observational cohort study.
Two medical-surgical intensive care units at large urban hospitals affiliated with teaching institutions.
Sixty-eight intubated patients with monomicrobial ventilator-associated pneumonia.
None.
QTA and serum C-reactive protein were measured in patients with suspected ventilator-associated pneumonia on diagnosis (baseline) and 96 hrs afterward (follow-up). Its logarithm value (logQTA) was calculated. LogQTA correlated positively with serum C-reactive protein (rho = 0.46, p < .05), temperature (rho = 0.20, p = .05), and white blood cell count (rho = 0.22, p < .05). LogQTA decreased significantly more from baseline to follow-up in patients receiving appropriate empirical antibiotic therapy compared with those with inappropriate treatment (logQTA ratio 0.77 +/- 0.22 vs. 1.02 +/- 0.27, p < .05). Mean serum C-reactive protein levels showed a similar pattern, decreasing from baseline to follow-up in patients receiving appropriate empirical antibiotic treatment but not in episodes with inappropriate treatment (C-reactive protein ratio 0.58 +/- 0.32 vs. 1.36 +/- 1.11, p < .05). There was a positive correlation between serum C-reactive protein and logQTA variations (r2 = .59, p < .05). Adjusted mean serum C-reactive protein levels by analysis of covariance on follow-up were significantly lower in patients with appropriate antibiotic treatment than in those with inappropriate empirical treatment (103 +/- 10 mg/L vs. 192 +/- 14 mg/L, p < .05). A C-reactive protein ratio of 0.8 at 96 hrs was a useful indicator of appropriateness of antibiotic therapy (sensitivity 77%; specificity 87%; area under the receiver operating characteristic curve 0.86 [0.75-0.96]).
C-reactive protein is a useful biochemical surrogate of bacterial burden in patients with ventilator-associated pneumonia. Follow-up measurements of serum C-reactive protein anticipate the appropriateness of antibiotic therapy.
抗生素治疗的合理性与呼吸机相关性肺炎中细菌载量的降低相关。C反应蛋白是一种有效的生化替代指标。目的是确定通过定量气管吸出物（QTA）测量的细菌载量与血清C反应蛋白之间的相关性，血清C反应蛋白作为呼吸机相关性肺炎发作时炎症反应的指标，以及其变化与抗生素治疗合理性的关联。
前瞻性观察队列研究。
教学机构附属的大型城市医院的两个内科-外科重症监护病房。
68例插管的单微生物呼吸机相关性肺炎患者。
无。
对疑似呼吸机相关性肺炎的患者在诊断时（基线）和之后96小时（随访）测量QTA和血清C反应蛋白。计算其对数值（logQTA）。LogQTA与血清C反应蛋白（rho = 0.46，p < 0.05）、体温（rho = 0.20，p = 0.05）和白细胞计数（rho = 0.22，p < 0.05）呈正相关。与接受不适当治疗的患者相比，接受适当经验性抗生素治疗的患者从基线到随访时LogQTA下降更为显著（LogQTA比值0.77±0.22 vs. 1.0(2)±0.27，p < 0.05）。平均血清C反应蛋白水平呈现类似模式，接受适当经验性抗生素治疗的患者从基线到随访时下降，而在不适当治疗的发作中则没有下降（C反应蛋白比值0.58±0.32 vs. 1.36±1.11，p < 0.05）。血清C反应蛋白与LogQTA变化之间存在正相关（r2 =.59，p < 0.05）。通过协方差分析调整后的随访时平均血清C反应蛋白水平，接受适当抗生素治疗的患者显著低于接受不适当经验性治疗的患者（103±10 mg/L vs. 192±14 mg/L，p < 0.05）。96小时时C反应蛋白比值为0.8是抗生素治疗合理性的有用指标（敏感性77%；特异性87%；受试者操作特征曲线下面积0.86 [0.75 - 0.96]）。
C反应蛋白是呼吸机相关性肺炎患者细菌负荷的有用生化替代指标。血清C反应蛋白的随访测量可预测抗生素治疗的合理性。
