Alexopoulou C, Kondili E, Vakouti E, Klimathianaki M, Prinianakis G, Georgopoulos D
Department of Intensive Care Medicine, University Hospital of Heraklion, University of Crete, Heraklion, 711 10, Crete, Greece.
Intensive Care Med. 2007 Jul;33(7):1139-1147. doi: 10.1007/s00134-007-0630-2. Epub 2007 Apr 26.
Proportional-assist ventilation with load-adjustable gain factors (PAV+) automatically adjusts the flow and volume assist to represent constant fractions of resistance and elastance of the respiratory system, respectively. Resistance and elastance are calculated at random intervals of 4-10 breaths, by applying a 300 ms pause maneuver at the end of selected inspirations.
To determine whether the large number of end-inspiratory occlusions during PAV+ operation influences sleep quality in critically ill patients who exhibited good patient-ventilator synchrony during pressure support (PS, baseline).
One and two nights' polysomnography was performed in sedated (protocol A, n=11) and non-sedated (protocol B, n=9) patients, respectively, while respiratory variables were continuously recorded. In each protocol the patients were ventilated with PAV+ and PS at two levels of assist (baseline and high).
In both protocols sleep quality did not differ between the modes of support or the assist levels. In sedated patients sleep efficiency was slightly but significantly higher with PAV+ than with high PS, while it did not differ between modes in non-sedated patients. The two modes of support had comparable effects on respiratory variables. Independent of the mode of support and particularly at high assist, a significant proportion of patients developed periodic breathing during sleep (27% in protocol A and 44% in protocol B).
In patients exhibiting good patient-ventilator synchrony during PS, the large number of short-term end-inspiratory occlusions with PAV+ operation did not adversely influence sleep quality. With both modes high assist may cause unstable breathing during sleep.
具有负荷可调增益因子的比例辅助通气（PAV+）会自动调整流量和容积辅助，分别代表呼吸系统阻力和弹性的恒定分数。通过在选定吸气结束时应用300毫秒的暂停操作，以4 - 10次呼吸的随机间隔计算阻力和弹性。
确定在压力支持（PS，基线）期间患者 - 呼吸机同步性良好的重症患者中，PAV+操作期间大量的吸气末阻塞是否会影响睡眠质量。
分别对接受镇静（方案A，n = 11）和未接受镇静（方案B，n = 9）的患者进行一到两晚的多导睡眠图检查，同时持续记录呼吸变量。在每个方案中，患者分别以两种辅助水平（基线和高）接受PAV+和PS通气。
在两个方案中，支持模式或辅助水平之间的睡眠质量没有差异。在接受镇静的患者中，PAV+时的睡眠效率略高于高PS时，但差异显著，而在未接受镇静的患者中，两种模式之间没有差异。两种支持模式对呼吸变量的影响相当。无论支持模式如何，特别是在高辅助水平时，相当比例的患者在睡眠期间出现周期性呼吸（方案A中为27%，方案B中为44%）。
在PS期间患者 - 呼吸机同步性良好的患者中，PAV+操作期间大量的短期吸气末阻塞不会对睡眠质量产生不利影响。两种模式下高辅助水平都可能导致睡眠期间呼吸不稳定。
