Lofaso F, Brochard L, Hang T, Lorino H, Harf A, Isabey D
Institut National de la Santé et de la Recherche Médicale INSERM U 296, Services de Physiologie-Explorations Fonctionnelles et de Réanimation Médicale, Hôpital Henri Mondor, Créteil, France.
Am J Respir Crit Care Med. 1996 May;153(5):1591-9. doi: 10.1164/ajrccm.153.5.8630607.
A bench study using an artificial lung model and a clinical study in patients were performed to evaluate six commercially available home pressure support devices. Six devices were tested in the in vitro study, including five designed for home use and one designed for use in intensive care units. Minimal positive end-expiratory pressure (PEEP) varied across home devices, from 0.5 cm H2O to 4.3 cm H2O. Work imposed during exhalation varied up to six-fold across devices. A substantial rebreathing volume has present for the three home devices with a common inspiratory and expiratory line. This rebreathing volume decreased with increasing PEEP level, as expected, but remained substantial at the widely used PEEP level of 5 cm H2O. Use of a non-rebreathing valve increased both the work imposed by the circuit during the exhalation phase and the time required to attain the relaxation equilibrium. Except for two home devices and a bilevel positive airway pressure (BiPAP) device equipped with a non-rebreathing valve, differences in inspiratory trigger sensitivities were small between home and intensive care devices. During pressure support, the total work performed by the machines did not differ by more than 15% between devices, whereas differences of more than 300% were observed in flow acceleration. Only one home device gave a flow acceleration similar to or better than that obtained with the intensive care device. In a randomized, crossover clinical study, we compared a home device to a device specially designed for intensive care use in seven intubated patients during weaning from mechanical ventilation. The main differences between the two devices were trigger sensitivity and initial flow acceleration. For the same level of pressure support, there were no significant differences in arterial PCO2, tidal volume, respiratory rate, or minute ventilation between these two devices. However, the esophageal pressure-time product was 30% higher with the home device (165 +/- 93 versus 119 +/- 80 cm H2O/min, p < 0.05). In conclusion, differences exist between devices in terms of occurrence of rebreathing, speed of attainment of stable pressure support level, and expiratory resistance. These differences characterizing the delivery of pressure support may have clinical impact on the inspiratory effort of patients.
开展了一项使用人工肺模型的实验研究以及一项针对患者的临床研究，以评估六种市售家用压力支持设备。在体外研究中测试了六种设备，其中包括五种设计用于家庭使用的设备和一种设计用于重症监护病房的设备。家用设备的呼气末正压（PEEP）最小值各不相同，从0.5厘米水柱到4.3厘米水柱不等。不同设备在呼气过程中施加的功相差高达六倍。对于三种具有共用吸气和呼气管道的家用设备，存在大量的重复呼吸量。正如预期的那样，随着PEEP水平的升高，这种重复呼吸量会减少，但在广泛使用的5厘米水柱的PEEP水平下，其仍然很大。使用无重复呼吸阀会增加呼气阶段回路施加的功以及达到松弛平衡所需的时间。除了两种家用设备和一种配备无重复呼吸阀的双水平气道正压（BiPAP）设备外，家用设备和重症监护设备之间的吸气触发敏感度差异很小。在压力支持期间，不同设备之间机器执行的总功差异不超过15%，而在流量加速方面观察到的差异超过300%。只有一种家用设备的流量加速与重症监护设备获得的流量加速相似或更好。在一项随机交叉临床研究中，我们在七名机械通气撤机期间的插管患者中，将一种家用设备与一种专门为重症监护设计的设备进行了比较。这两种设备之间的主要差异在于触发敏感度和初始流量加速。对于相同水平的压力支持，这两种设备在动脉PCO2、潮气量、呼吸频率或分钟通气量方面没有显著差异。然而，家用设备的食管压力 - 时间乘积高30%（165±93对119±80厘米水柱/分钟，p<0.05）。总之，不同设备在重复呼吸的发生、达到稳定压力支持水平的速度以及呼气阻力方面存在差异。这些表征压力支持输送的差异可能会对患者的吸气努力产生临床影响。
