机械通气的撤离

机械通气的撤离邵逸夫医院呼吸治疗科

葛慧青

To weaning, or Not to weaning

⏹Phoa LL.Singapore Med J.2002Oct;43(10):504-8.

312patients received mechanically ventilated in MICU.

UE accounted for8.7%.The rate of reintubation after failed UE was58.3%.

⏹Epstein SK.Am J Respir Crit Care Med.2000

Jun;161(6):1912-6.75patients with unplanned extubation.Forty-two(56%)patients required reintubation after unplanned extubation(74% immediately,86%within12h).

撤机前需具备的一般临床参数⏹呼吸衰竭的诱因和机械通气的原因已经解决或显著改善⏹停用镇静肌松药物

⏹神经恢复到正常状态

⏹无脓毒症或显著发热

⏹稳定的心血管状态（休克、心力衰竭和严重心律失常已纠

正）

⏹电解质、代谢功能紊乱和酸碱失衡已纠正

⏹预期近期没有需要全麻的外科操作

⏹适当的气体交换（动脉血氧合）：FiO2≤0.4和

PEEP≤5cmH2O情况下，PaO2≥60mmHg(SaO2>90%);

PaO2/FiO2≥200; PaO2/PAO2≥0.35; A-aDO2<350mmHg

⏹适当的呼吸泵功能

⏹呼吸力学指标

➢呼吸频率（Rr）：<30 bpm >6 bpm

➢潮气量（VT）：>5 ml/kg

➢肺活量（VC）：>10-15 ml/kg

➢静态顺应性（Static compliance）：>25 ml/cmH2O ➢浅快呼吸指数（f/VT）：<105

⏹呼吸肌强度指标

➢最大吸气压（PImax）：<-20~-30cmH2O

Egan’s , Fundamentals of respiratory care. seventh edition .976

⏹呼吸驱动（通气需求）

➢分钟通气量（VE for normal PCO2）：<10L/min ➢0.1秒末闭合气道压（P0.1 ）：<6cmH2O

⏹呼吸功（WOB）

➢自主呼吸功：<1.6kg.m/min

➢压力时间指数：<0.15-0.18

⏹通气储备

➢最大分钟通气量（MVV）：>20L/min或>2*VE ⏹综合指标：压力（CROP）指数

Egan’s , Fundamentals of respiratory care. seventh edition .976

⏹Yang KL, N Engl J Med. 1991 May 23; 324 (21) : 1445-50.

–the area under the ROC curve: f/VT ratio 0.89, CROP

index 0.78, (P < 0.05), Plmax 0.61, (P<0.001), and VE

0.40, (P <0.001).

–结论：f/VT具有更好的预测价值，测定较复杂的指

标并没有保证比f/VT比率有更好的价值。

⏹Yang KL. Intensive Care Med. 1993;19(4):204-8.

–The combined usage of rapid shallow breathing index

and PI/PImax ratio provided the highest accuracy with

sensitivity of 0.81 and specificity of 0.93.

–结论：PI/PImax 和f/VT 结合可提高撤机预测的准

确性。

⏹Sassoon CS, Mahutte CK. Am Rev Respir Dis. 1993 Oct;148(4 Pt 1):860-6.

–P0.1*f/VT，sensitivity 0.97 ，Specificity 0.60；P0.1，

sensitivity 0.97 ，Specificity 0.40；f/VT，sensitivity 0.97 ，Specificity 0.40

–结论：P0.1*f/VT只能轻度改善特异性

⏹Mohsenifar Z，etal.Ann Intern Med. 1993 Oct 15;119(8):794-8.

–PHi，sensitivity 1.00 ，Specificity 1.00

–结论：PHi操作简单、迅速，对预测撤机后果可能具有

临床实用价值

⏹STUDY OBJECTIVES :Serial measurements of the RSBI as a predictor of

weaning outcome in elderly medical patients (≥70 years old) .

⏹DESIGN: Prospective observational (49，f/VT ≤130,) study using parameters

suggested from retrospective analysis (10，f/VT ≤105).

⏹RESULTS: Using an f/VT < or =130 as the threshold value for prospectively

predicting successful weaning, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value increased from 84%, 92%, 57%, 87%, and 67%, respectively, when measured at the beginning of the weaning trial to 92%, 93%, 89%, 97%, and 80%, respectively, when measured 3

h later. The area under the receiver operating characteristic curve for f/VT also

improved from 0.81 to 0.93.

⏹结论：自主呼吸下连续监测f/VT（≤130）在老年患者中具有很好的

预测价值

Krieger BP,etal. Chest. 1997 Oct;112(4):1029-34.