Pulmonary and Intensive Care Department, Rouen University Hospital & UPRES EA 3830 (IFR MP23), Institute for Biomedical Research, Rouen, France.
Respiration. 2010;80(3):198-206. doi: 10.1159/000264606. Epub 2009 Dec 2.
Ineffective inspiratory triggering efforts are a major cause of poor patient-ventilator interactions during mechanical ventilation, but their routine identification requires the insertion of an esophageal catheter.
We developed a mathematical analysis of ventilatory tracings recorded under noninvasive pressure ventilation in order to identify ineffective triggering efforts and their consequences without recording esophageal pressure.
We assessed 2,183 cycles from 44 pressure support tracings in 14 children with cystic fibrosis treated by noninvasive home ventilation. Airway pressure, flow and esophageal pressure time series were visually analyzed and manually counted. Airway pressure versus time and flow versus time were then analyzed using a dedicated algorithm written by us. Esophageal pressure was only used for validation.
A mathematical treatment of flow time series allowed us to draw phase portraits that had specific periodic trajectories for triggered ventilatory cycles and ineffective triggering efforts. From flow and pressure tracings, our algorithm correctly identified 100% of triggered cycles and 53/56 (94.6%) of ineffective triggering efforts. Ineffective triggering was associated with a significant reduction in minute ventilation, inspiratory flows and a significant increase in inspiratory efforts.
A noninvasive analysis of flow and airway pressure can reliably identify ineffective triggering efforts during noninvasive pressure support ventilation. This approach may be a valuable tool for evaluating patient-ventilator interactions and their consequences during long-term recordings.
无效的吸气触发努力是机械通气期间患者-呼吸机交互作用不良的主要原因，但常规识别需要插入食管导管。
我们开发了一种对无创压力通气下记录的通气轨迹的数学分析方法，以便在不记录食管压力的情况下识别无效的触发努力及其后果。
我们评估了 14 例囊性纤维化患儿在无创家庭通气治疗下的 44 个压力支持轨迹中的 2183 个循环。气道压力、流量和食管压力时间序列进行了视觉分析和手动计数。然后使用我们编写的专用算法对气道压力与时间和流量与时间进行了分析。仅使用食管压力进行验证。
流量时间序列的数学处理使我们能够绘制出触发通气循环和无效触发努力具有特定周期性轨迹的相图。从流量和压力轨迹中，我们的算法正确识别了 100%的触发循环和 56 次无效触发努力中的 53 次（94.6%）。无效触发与分钟通气量、吸气流量显著降低以及吸气努力显著增加有关。
无创压力支持通气时，对流量和气道压力的非侵入性分析可以可靠地识别无效的触发努力。这种方法可能是评估长期记录期间患者-呼吸机相互作用及其后果的有价值工具。
