摘要
我们比较了三种提供不同工作机制的辅助无创通气设备在室内空气呼吸和二氧化碳诱导过度通气时的效果。在7名健康志愿者中,对呼吸模式、呼吸肌活动和舒适度进行了评估:在通过呼吸器(SB)进行无辅助自主呼吸时;在辅助呼吸时使用提供吸气压力支持(IPS)的设备;以及两个提供间歇性正压呼吸(IPPB)的设备,Monaghan 505 (IPPB1)和cpu1呼吸机(IPPB2)。所有三个装置都设置在10 cmH2O的最大压力下。在室内空气呼吸过程中,以功率表示的呼吸功,两种IPPB设备明显大于其他两种模式(IPPB1和IPPB2分别为7.3 +/- 5.2和7.2 +/- 6.2 J.min-1,而SB和IPS分别为2.4 +/- 0.7和2.3 +/- 3.3 J.min-1)。压力-时间乘积(PTP)的差异没有达到统计学意义。在IPPB模式下,不适感也更大。在co2诱导的过度通气过程中,两种IPPB设备与其他两种模式之间的呼吸功率存在相当大的差异。IPPB的PTP也高得多。 Transdiaphragmatic pressure was significantly smaller during IPS than during the three other modes (IPS 18 +/- 2.6 cmH2O versus SB 22 +/- 2.6, IPPB1 32 +/- 5.2, and IPPB2: 28 +/- 5.2). Maximal discomfort was observed during the IPPB modes and was correlated with the magnitude of transdiaphragmatic pressure (r = 0.60). Despite similarities in their operational principles, IPS and IPPB had very different effects on respiratory muscle activity in healthy non-intubated subjects. IPPB machines not only failed to reduce patient's effort but also induced a significant level of extra work by comparison to spontaneous ventilation at ambient pressure. Great caution is, therefore, needed in the use of patient-triggered devices for non-intubated patients with acute respiratory failure.