Tanios Maged A, Nevins Michael L, Hendra Katherine P, Cardinal Pierre, Allan Jill E, Naumova Elena N, Epstein Scott K
UCLA School of Medicine, Pulmonary and Critical Care Medicine, St. Mary Medical Center Long Beach, California and Long Beach Memorial Medical Center, Long Beach, CA, USA.
Crit Care Med. 2006 Oct;34(10):2530-5. doi: 10.1097/01.CCM.0000236546.98861.25.
Weaning predictors are often incorporated in protocols to predict weaning outcome for patients on mechanical ventilation. The predictors are used as a decision point in protocols to determine whether a patient may advance to a spontaneous breathing trial. The impact of including predictors in a weaning protocol has not been previously studied. We designed a study to determine the effect of including a weaning predictor (frequency-tidal volume ratio, or f/Vt) in a weaning protocol.
Randomized, blinded controlled trial.
Academic teaching hospitals.
Three hundred and four patients admitted to intensive care units at three academic teaching hospitals.
Patients were screened daily for measures of oxygenation, cough and secretions, adequate mental status, and hemodynamic stability. Patients were randomized to two groups; in one group the f/Vt was measured but not used in the decision to wean (n = 151), but in the other group, f/Vt was measured and used, using a threshold of 105 breaths/min/L (n = 153). Patients passing the screen received a 2-hr spontaneous breathing trial. Patients passing the spontaneous breathing trial were eligible for an extubation attempt.
Groups were similar with regard to gender, age, and Acute Physiology and Chronic Health Evaluation II score. The median duration for weaning time was significantly shorter in the group where the weaning predictor was not used (2.0 vs. 3.0 days, p = .04). There was no difference with regard to the extubation failure, in-hospital mortality rate, tracheostomy, or unplanned extubation.
Including a weaning predictor (f/Vt) in a protocol prolonged weaning time. In addition, the predictor did not confer survival benefit or reduce the incidence of extubation failure or tracheostomy. The results of this study indicate that f/Vt should not be used routinely in weaning decision making.
撤机预测指标常被纳入方案中，用于预测机械通气患者的撤机结果。这些预测指标在方案中作为决定患者是否可进入自主呼吸试验的依据。此前尚未研究过在撤机方案中纳入预测指标的影响。我们设计了一项研究，以确定在撤机方案中纳入撤机预测指标（频率-潮气量比值，即f/Vt）的效果。
随机、盲法对照试验。
教学医院。
三家教学医院重症监护病房收治的304例患者。
每天对患者进行氧合、咳嗽及分泌物、精神状态良好及血流动力学稳定情况的评估。患者被随机分为两组；一组测量f/Vt但不用于撤机决策（n = 151），另一组测量f/Vt并使用，阈值为105次呼吸/分钟/升（n = 153）。通过筛查的患者接受2小时自主呼吸试验。通过自主呼吸试验的患者有资格尝试拔管。
两组在性别、年龄和急性生理与慢性健康状况评分II方面相似。未使用撤机预测指标的组撤机时间中位数显著更短（2.0天对3.0天，p = 0.04）。在拔管失败、院内死亡率、气管切开或意外拔管方面无差异。
在方案中纳入撤机预测指标（f/Vt）会延长撤机时间。此外，该预测指标未带来生存获益，也未降低拔管失败或气管切开的发生率。本研究结果表明，f/Vt不应常规用于撤机决策。
