Pizov R, Oppenheim A, Eidelman L A, Weiss Y G, Sprung C L, Cotev S
Department of Anesthesiology and Critical Care Medicine, Hadassah-Hebrew University Hospital, Jerusalem, Israel.
Crit Care Med. 1998 Feb;26(2):290-5. doi: 10.1097/00003246-199802000-00029.
To evaluate and compare the effect of tracheal gas insufflation using two gases with different physical properties, helium and oxygen, as an adjunct to conventional mechanical ventilation in patients with respiratory failure.
Prospective, intervention study.
General intensive care unit in a tertiary university medical center.
Seven sedated and paralyzed patients with respiratory failure of various etiologies. All patients were ventilated in the volume-control mode (tidal volume 5 to 7 mL/kg). Inclusion criteria were PaCO2 of > or =50 torr (> or =6.7 kPa), together with peak inspiratory pressure of > or =35 cm H2O and respiratory rate of > or =14 breaths/min.
All patients were intubated with an endotracheal tube that had an additional lumen opening at its distal end, through which tracheal gas insufflation was administered. The tracheal gas insufflation was applied continuously throughout the respiratory cycle at three flow rates (2, 4, and 6 L/min) with two gases, oxygen and helium, while the ventilatory settings were maintained constant.
In addition to airway pressures and arterial blood gases, the relative efficacy of tracheal gas insufflation with each gas was estimated using a "coefficient of efficiency" (which we defined as the change in PaCO2/peak inspiratory pressure) compared with baseline measurements. Tracheal gas insufflation with both gases decreased PaCO2 significantly (p < .05) at all flow rates. This effect was accompanied by an increase in airway pressure with both gases (oxygen and helium). However, at flow rates of 6 L/min, tracheal gas insufflation with helium resulted in lower peak inspiratory pressure than with oxygen. Tracheal gas insufflation with helium was more effective (as estimated by the coefficient of efficiency) than with oxygen at all flow rates (p < .05).
In volume-controlled, mechanically ventilated patients with respiratory failure, tracheal gas insufflation with helium might be suggested as an alternative to oxygen.
评估并比较使用两种具有不同物理性质的气体（氦气和氧气）进行气管内气体吹入作为辅助手段，对呼吸衰竭患者进行常规机械通气的效果。
前瞻性干预研究。
一所三级大学医学中心的综合重症监护病房。
7例因各种病因导致呼吸衰竭的镇静、麻痹患者。所有患者均采用容量控制模式通气（潮气量5至7 mL/kg）。纳入标准为动脉血二氧化碳分压（PaCO2）≥50托（≥6.7千帕），同时吸气峰压≥35厘米水柱，呼吸频率≥14次/分钟。
所有患者均经气管插管，气管导管远端有一个额外的腔口，通过该腔口进行气管内气体吹入。在整个呼吸周期中，以三种流速（2、4和6升/分钟）使用氧气和氦气两种气体持续进行气管内气体吹入，同时通气设置保持不变。
除气道压力和动脉血气外，与基线测量值相比，使用“效率系数（我们将其定义为PaCO2变化值/吸气峰压）”来评估每种气体进行气管内气体吹入的相对疗效。两种气体进行气管内气体吹入均使各流速下的PaCO2显著降低（p<0.05）。两种气体（氧气和氦气）均伴有气道压力升高。然而，在6升/分钟的流速下，氦气进行气管内气体吹入导致的吸气峰压低于氧气。在所有流速下，氦气进行气管内气体吹入比氧气更有效（根据效率系数评估，p<0.05）。
对于采用容量控制、机械通气的呼吸衰竭患者，建议使用氦气进行气管内气体吹入替代氧气。
