BACKGROUND The impact of anemia and red blood cell (RBC) transfusion on weaning from mechanical ventilation is not known. In theory, transfusions could facilitate liberation from the ventilator by improving oxygen transport capacity. In contrast, retrospective studies of critically ill patients showed a positive correlation of transfusions with prolonged mechanical ventilation, increased mortality rates, and increased risk of nosocomial infections, which in turn could adversely affect weaning outcome. METHODS Retrospective, observational study on prolonged mechanically ventilated, tracheotomized patients (n = 378), admitted to a national weaning center over a 5 year period. Medical records were reviewed to obtain data on patients' demographics, comorbidities, blood counts, transfusions, weaning outcome, and nosocomial infections, defined according to the criteria of the U.S. Centers for Disease Control and Prevention. The impact of RBC transfusion on outcome measures was assessed using regression models. RESULTS Ninety-eight percent of all patients showed anemia on admission to the weaning center. Transfused and non-transfused patients differed significantly regarding disease severity and comorbidities. In multivariate analyses, RBC transfusion, but not mean hemoglobin concentration in the course of weaning, was independently correlated with weaning duration (adjusted β 12.386, 95% CI 9.335-15.436; p <  0.001) and hospital length of stay (adjusted β 16.116, 95% CI 8.925-23.306; p <  0.001); there was also a trend toward increased hospital mortality (adjusted odds ratio [OR] 2.050, 95% CI 0.995-4.224; p = 0.052), but there was no independent correlation with weaning outcome or nosocomial infections. In contrast, hemoglobin level on the day of admission to the weaning center was independently associated with hospital mortality (adjusted OR 0.956, 95% CI 0.924-0.989; p = 0.010), appearing significantly elevated at values below 8.5 g/dl (AUC 0.670, 95% CI 0.593-0.747; p <  0.001). CONCLUSIONS A high percentage of prolonged mechanically ventilated patients showed anemia on admission to the weaning center. RBC transfusion was independently correlated with worse outcomes. Since transfused patients differed significantly regarding their clinical characteristics and comorbidities, RBC transfusion might be an indicator of disease severity rather than directly impacting patient prognosis.

中文翻译：

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在专门的断奶中心接受长期机械通气的患者中的贫血和红细胞输血实践：一项观察性研究。

背景技术贫血和红细胞（RBC）输血对机械通气断奶的影响尚不清楚。从理论上讲，输血可以通过提高氧气的输送能力来促进从呼吸机中的释放。相反，对重症患者的回顾性研究显示，输血与长时间机械通气，死亡率增加和医院感染的风险呈正相关，这反过来可能对断奶结果产生不利影响。方法回顾性观察性研究针对5年内进入国家断奶中心接受长期机械通气，气管切开术的患者（n = 378）。审查了病历，以获取有关患者的人口统计学，合并症，血球计数，输血，断奶结果和医院感染的数据，根据美国疾病控制与预防中心的标准进行定义。使用回归模型评估了RBC输血对结局指标的影响。结果所有患者中有98％在进入断奶中心时表现出贫血。输血和非输血患者在疾病严重程度和合并症方面存在显着差异。在多变量分析中，RBC的输血（而非断奶过程中的平均血红蛋白浓度）与断奶持续时间（调整后的β12.386、95％CI 9.335-15.436； p <0.001）和住院时间（调整后的β16.116， 95％CI 8.925-23.306; p <0.001）; 医院死亡率也有增加的趋势（调整后的优势比[OR] 2.050，95％CI 0.995-4.224； p = 0.052），但与断奶结果或医院感染没有独立的相关性。相比之下，断奶中心入院当天的血红蛋白水平与医院死亡率独立相关（校正后的OR 0.956，95％CI 0.924-0.989； p = 0.010），在低于8.5 g / dl的值下明显升高（AUC 0.670） ，95％CI 0.593-0.747； p <0.001）。结论高比例的机械通气时间较长的患者入院时出现贫血。RBC输血与预后差独立相关。由于输血患者的临床特征和合并症存在显着差异，因此RBC输血可能是疾病严重程度的指标，而不是直接影响患者的预后。进入断奶中心当天的血红蛋白水平与医院死亡率独立相关（校正后的OR 0.956，95％CI 0.924-0.989； p = 0.010），在低于8.5 g / dl的值下明显升高（AUC 0.670，95％ CI 0.593-0.747； p <0.001）。结论高比例的机械通气时间较长的患者入院时出现贫血。RBC输血与预后差独立相关。由于输血患者的临床特征和合并症存在显着差异，因此RBC输血可能是疾病严重程度的指标，而不是直接影响患者的预后。进入断奶中心当天的血红蛋白水平与医院死亡率独立相关（校正后的OR 0.956，95％CI 0.924-0.989； p = 0.010），在低于8.5 g / dl的值下明显升高（AUC 0.670，95％ CI 0.593-0.747； p <0.001）。结论高比例的机械通气时间较长的患者入院时出现贫血。RBC输血与预后差独立相关。由于输血患者的临床特征和合并症存在显着差异，因此RBC输血可能是疾病严重程度的指标，而不是直接影响患者的预后。在低于8.5 g / dl的值时，其浓度显着升高（AUC 0.670，95％CI 0.593-0.747; p <0.001）。结论高比例的机械通气时间较长的患者入院时出现贫血。RBC输血与预后差独立相关。由于输血患者的临床特征和合并症存在显着差异，因此RBC输血可能是疾病严重程度的指标，而不是直接影响患者的预后。在低于8.5 g / dl的值时，其浓度显着升高（AUC 0.670，95％CI 0.593-0.747; p <0.001）。结论高比例的机械通气时间较长的患者入院时出现贫血。RBC输血与预后差独立相关。由于输血患者的临床特征和合并症存在显着差异，因此RBC输血可能是疾病严重程度的指标，而不是直接影响患者的预后。