Henzler Dietrich, Pelosi Paolo, Bensberg Ralf, Dembinski Rolf, Quintel Michael, Pielen Veronica, Rossaint Rolf, Kuhlen Ralf
Department of Anesthesiology, Aachen University Hospital, Germany.
Crit Care Med. 2006 Jun;34(6):1738-45. doi: 10.1097/01.CCM.0000218809.49883.54.
The early phase of acute respiratory distress syndrome (ARDS) is characterized by impaired respiratory mechanics, ventilation-perfusion mismatch, and severe hypoxemia. Partial ventilatory support can effectively unload the respiratory workload and improve pulmonary gas exchange with less hemodynamic compromise. The partial ventilatory support mode most indicated in early phases of ARDS has not been determined. This study compares the effects of assisted ventilatory techniques on breathing pattern, gas exchange, hemodynamic function, and respiratory effort with those of controlled mechanical ventilation in similarly sedated subjects.
Prospectively randomized crossover animal study.
Animal research laboratory.
Eleven anesthetized and mechanically ventilated pigs.
Acute lung injury was induced by lung lavage. Pressure-controlled ventilation (PCV), pressure-controlled assisted ventilation (P-ACV), bilevel positive airway pressure (BIPAP), and pressure support ventilation (PSV) with equal airway pressures and sedation were applied in random order.
Gas exchange, respiratory effort, and hemodynamic function were measured, and ventilation-perfusion distributions were calculated by multiple inert-gas-elimination techniques. The results revealed that partial ventilatory support was superior to PCV in maintaining adequate oxygenation and hemodynamic function with reduced sedation. The effects of P-ACV, BIPAP, and PSV were comparable with respect to gas exchange and hemodynamic function, except for a more pronounced reduction in shunt during BIPAP. P-ACV and PSV were superior to BIPAP to reduce respiratory drive and work of breathing. PSV affected the pattern of breathing and deadspace to a greater degree than did P-ACV.
In acute lung injury, P-ACV preserves oxygenation and hemodynamic function with less respiratory effort compared with BIPAP and reduces the need for sedation compared with PCV.
急性呼吸窘迫综合征（ARDS）早期的特征为呼吸力学受损、通气-灌注不匹配及严重低氧血症。部分通气支持可有效减轻呼吸负荷，并在对血流动力学影响较小的情况下改善肺气体交换。ARDS早期最适用的部分通气支持模式尚未确定。本研究比较了在同样接受镇静的受试者中，辅助通气技术与控制机械通气对呼吸模式、气体交换、血流动力学功能及呼吸功的影响。
前瞻性随机交叉动物研究。
动物研究实验室。
11头麻醉并接受机械通气的猪。
通过肺灌洗诱导急性肺损伤。以随机顺序应用气道压力和镇静程度相同的压力控制通气（PCV）、压力控制辅助通气（P-ACV）、双水平气道正压通气（BIPAP）及压力支持通气（PSV）。
测量气体交换、呼吸功及血流动力学功能，并采用多种惰性气体清除技术计算通气-灌注分布。结果显示，在维持充分氧合及血流动力学功能且减少镇静的情况下，部分通气支持优于PCV。在气体交换和血流动力学功能方面，P-ACV、BIPAP及PSV的效果相当，但BIPAP期间分流减少更为明显。P-ACV和PSV在降低呼吸驱动力和呼吸功方面优于BIPAP。PSV对呼吸模式和死腔的影响程度大于P-ACV。
在急性肺损伤中，与BIPAP相比，P-ACV在减少呼吸功的情况下可维持氧合和血流动力学功能，与PCV相比，可减少镇静需求。
