Putz G, Mutz N, Baum M, Koller W, Benzer H
Klinik für Anaesthesie und Allgemeine Intensivmedizin, Universität Innsbruck.
Anaesthesist. 1988 Feb;37(2):105-11.
This study was designed to compare the effects of Continuous Positive-Pressure Ventilation (CPPV) and, by using the same unmodified conventional ventilator, High-Frequency Positive-Pressure Ventilation (HFPPVkonv). First, CPPV and HFPPVkonv were studied in a lung model with both normal (R = 5 mbar/1/second) and elevated (R = 20 mbar/1/second) resistance. Our results indicate that in HFPPVkonv the large compressible volume of the conventional ventilator did not influence lung model ventilation at normal resistance. The adjusted (300 ml) tidal volume (VT) and the measured volume of actual expiration (270 ml) were about the same (Fig. 1). However, with elevated resistance air trapping occurred. The large compressible volume influenced model ventilation during both CPPV and HFPPVkonv (Fig. 2). As a second step we evaluated the effects of HFPPVkonv on gas exchange, airway pressure, and hemodynamics in 12 patients (aged 43-69) postoperatively after elective cardiac surgery. After a period of stabilization at the intensive care unit every patient was first ventilated with CPPV. The ventilator settings were: VT = 10-12 ml/kg, inspiratory: expiratory ratio (I:E) = 1:2, frequency (F) = 12/min, V = 60 1/min, PEEP = 5 cm, FiO2 = 40%. After 20 min of CPPV baseline measurements were made (series I). Then the initial ventilator settings of CPPV were switched to HFPPVkonv, the conventional ventilator remaining unmodified. The settings were changed as follows: I:E = 1:3, F = 60/min, V = 120 1/min, PEEP = 5 cm, FiO2 = 40%. During 60 min of HFPPVkonv variables were measured first after 20 min (series II) and again after another 40 min (series III). Minute volume had to be doubled after changing from CPPV to HPFFVkonv to achieve eucapnia. As a result of the new ventilatory settings, VT and hold showed a significant decrease (P less than 0.01) (Table 2).(ABSTRACT TRUNCATED AT 250 WORDS)
本研究旨在比较持续正压通气（CPPV）以及使用同一未改装的传统呼吸机进行高频正压通气（HFPPVkonv）的效果。首先，在正常阻力（R = 5毫巴/升/秒）和高阻力（R = 20毫巴/升/秒）的肺模型中研究了CPPV和HFPPVkonv。我们的结果表明，在HFPPVkonv中，传统呼吸机的大压缩容积在正常阻力下不影响肺模型通气。调整后的潮气量（VT，300毫升）与实际呼出量（270毫升）测量值大致相同（图1）。然而，在高阻力时出现了气体潴留。在CPPV和HFPPVkonv期间，大压缩容积均影响模型通气（图2）。第二步，我们评估了HFPPVkonv对12例择期心脏手术后患者（年龄43 - 69岁）气体交换、气道压力和血流动力学的影响。在重症监护病房稳定一段时间后，每位患者首先采用CPPV通气。呼吸机设置为：VT = 10 - 12毫升/千克，吸呼比（I:E） = 1:2，频率（F） = 12次/分钟，V = 60升/分钟，呼气末正压（PEEP） = 5厘米水柱，吸入氧浓度（FiO2） = 40%。在CPPV 20分钟后进行基线测量（系列I）。然后将CPPV的初始呼吸机设置切换为HFPPVkonv，传统呼吸机保持不变。设置更改如下：I:E = 1:3，F = 60次/分钟，V = 120升/分钟，PEEP = 5厘米水柱，FiO2 = 40%。在HFPPVkonv的60分钟内，分别在20分钟后（系列II）和再过40分钟后（系列III）测量变量。从CPPV转换为HPFFVkonv后，分钟通气量必须加倍以实现正常碳酸血症。由于新的通气设置，VT和屏气时间显著降低（P < 0.01）（表2）。（摘要截选至250字）
