二氧化碳反应与机械通气撤机时间。

CO2 response and duration of weaning from mechanical ventilation.

机构信息

Intensive Care Unit, Hospital Universitario Son Dureta, Palma de Malorca, Illes Balears, Spain.

出版信息

Respir Care. 2011 Aug;56(8):1130-6. doi: 10.4187/respcare.01080. Epub 2011 Apr 15.

DOI:10.4187/respcare.01080

PMID:21496366

Abstract

BACKGROUND

The CO2 response test measures the hypercapnic drive response (which is defined as the ratio of the change in airway-occlusion pressure 0.1 s after the start of inspiratory flow [ΔP(0.1)] to the change in P(aCO2) [ΔP(aCO2)]), and the hypercapnic ventilatory response (which is defined as the ratio of the change in minute volume to ΔP(aCO2)).

OBJECTIVE

In mechanically ventilated patients ready for a spontaneous breathing trial, to investigate the relationship between CO2 response and the duration of weaning.

METHODS

We conducted the CO2 response test and measured maximum inspiratory pressure (P(Imax)) and maximum expiratory pressure (P(Emax)) in 102 non-consecutive ventilated patients. We categorized the patients as either prolonged weaning (weaning duration > 7 d) or non-prolonged weaning (≤ 7 d).

RESULTS

Twenty-seven patients had prolonged weaning. Between the prolonged and non-prolonged weaning groups we found differences in hypercapnic drive response (0.22 ± 0.16 cm H2O/mm Hg vs 0.47 ± 0.22 cm H2O/mm Hg, respectively, P < .001) and hypercapnic ventilatory response (0.25 ± 0.23 L/min/mm Hg vs 0.53 ± 0.33 L/min/mm Hg, respectively, P < .001). The optimal cutoff points to differentiate between prolonged and non-prolonged weaning were 0.19 cm H2O/mm Hg for hypercapnic drive response, and 0.15 L/min/mm Hg for hypercapnic ventilatory response. Assessed with the Cox proportional hazards model, both hypercapnic drive response and hypercapnic ventilatory response were independent variables associated with the duration of weaning. The hazard ratio of weaning success was 16.7 times higher if hypercapnic drive response was > 0.19 cm H2O/mm Hg, and 6.3 times higher if hypercapnic ventilatory response was > 0.15 L/min/mm Hg. Other variables (P(0.1), P(Imax), and P(Emax)) were not associated with the duration of the weaning.

CONCLUSIONS

Decreased CO2 response, as measured by hypercapnic drive response and hypercapnic ventilatory response, are associated with prolonged weaning.

摘要

背景

CO2 反应测试测量高碳酸血症驱动反应（定义为吸气流量开始后 0.1 秒时气道阻塞压的变化[ΔP(0.1)]与 P(aCO2)的变化[ΔP(aCO2)]之比）和高碳酸血症通气反应（定义为分钟通气量的变化与ΔP(aCO2)之比）。

目的

在准备进行自主呼吸试验的机械通气患者中，研究 CO2 反应与脱机时间的关系。

方法

我们对 102 例非连续通气患者进行了 CO2 反应测试和最大吸气压力（P(Imax)）和最大呼气压力（P(Emax)）测量。我们将患者分为脱机时间延长（脱机时间>7 天）和非延长（≤7 天）。

结果

27 例患者脱机时间延长。在脱机时间延长和非延长组之间，我们发现高碳酸血症驱动反应（分别为 0.22±0.16 cm H2O/mm Hg 和 0.47±0.22 cm H2O/mm Hg，P<.001）和高碳酸血症通气反应（分别为 0.25±0.23 L/min/mm Hg 和 0.53±0.33 L/min/mm Hg，P<.001）存在差异。区分脱机时间延长和非延长的最佳截断值为高碳酸血症驱动反应 0.19 cm H2O/mm Hg，高碳酸血症通气反应 0.15 L/min/mm Hg。用 Cox 比例风险模型评估，高碳酸血症驱动反应和高碳酸血症通气反应均为与脱机时间相关的独立变量。如果高碳酸血症驱动反应>0.19 cm H2O/mm Hg，脱机成功率的危险比增加 16.7 倍；如果高碳酸血症通气反应>0.15 L/min/mm Hg，脱机成功率的危险比增加 6.3 倍。其他变量（P(0.1)、P(Imax)和 P(Emax)）与脱机时间无关。