雙驅動 (double triggering，DT) 常見於病人與呼吸器的不協調。臨床上如果沒有藉助食道球，胃球或肌電圖的協助，對於區辨真假雙驅動 (pseudo-double-triggering，PDT) 會有困擾。本研究以在吸氣延遲期 (inspiratory trigger delay) 呼吸道壓力 (airway pressure) 的下降和呼吸道氣流 (airway flow) 的上升變化量為依據，來區分出真假雙驅動。共有14位病人符合條件被納入分析，所有的病人都有放置食道球，且呼吸器的設定都是氣流啟動 (flow trigger 2 L/min)。呼吸器的帶動為輔助/控制型換氣 (assisted controlled ventilation) 或壓力支持型換氣 (pressure support ventilation)。如果連續兩次的呼吸週期間隔小於平均吸氣期的一半，伴隨食道球壓力下降大於1公分則意謂第一個呼吸週期由病人自己帶動，稱之為雙驅動。若是第一個呼吸週期伴隨食道球壓力下降小於1公分且週期時間和呼吸器的設定相吻合，稱之為假雙驅動—控制型 (PDT-C)。若是第一個呼吸週期伴隨食道球壓力下降小於1公分且週期時間小於呼吸器的設定，稱之為假雙驅動—自我引動型 (PDT-A)。我們總共分析507個真假雙驅動；其中271個屬於PDT-C，50個為PDT-A，186個為DT。呼吸道壓力在0.1秒吸氣延遲期的下降 (PD0.1，從吸氣延遲期最低點往前推算) 於PDT-C，PDT-A，DT三組分別為0.13 ± 0.10 (平均值 ± 標準差)、0.20 ± 0.13以及1.17 ± 0.63公分水柱 (cm H2O)；呼吸道壓力在0.13秒吸氣延遲期的下降 (PD0.13，從最低點往前推算) 則分別為0.16 ± 0.12、0.25 ± 0.17以及1.34 ± 0.67公分水柱。同區段呼吸道氣流在0.1秒的上升 (F0.1) 分別為1.87 ± 2.24、2.26 ± 1.87以及14.69 ± 7.26 升/分 (L/min)。同區段呼吸道氣流在0.13秒的上升 (F0.13) 分別為2.11 ± 2.31、2.64 ± 2.07以及16.51 ± 8.02升/分。根據Yuden index (敏感度+特異度-1) 來選取區辨真假雙驅動的最佳標準，都有相當不錯的結果，其值分別為PD0.1: 0.45公分水柱 (敏感度 98%，特異度97% )、F0.1: 5.69升/分 (敏感度 90%，特異度 94 %)、PD0.13: 0.49公分水柱 (敏感度 98%，特異度97%) 以及F0.13: 6.12升/分 (敏感度91%，特異度94%)。此分析證明吾人可用呼吸道壓力的下降和呼吸道氣流的上升變化量來分辨真假雙驅動。

Introduction: Double triggering (DT, two consecutive ventilator cycles separated by a short expiratory time) is one of the most common types of patient-ventilator asynchrony. Confusion with pseudo-double-triggering (PDT, in which the first breath could be either controlled or autotriggered) may be a problem for critical care physicians. We hypothesize that DT and PDT could be differentiated using either pressure or flow change in the phase of inspiratory trigger delay.
Methods: Fourteen mechanically ventilated patients with DT and PDT were included in this study and all had esophageal balloon placed. All patients are flow triggered (sensitivity 2 L/min) and receiving either assisted controlled or pressure support ventilation. Breaths in which the first breath is associated with a drop of greater than 1 cm H2O in esophageal pressure were defined as DT. Breaths in which the first breath occurred at the ventilator set cycle and without esophageal pressure drop of greater than 1 cm H2O were defined as PDT with first breath controlled (PDT-C). Those breaths in which the first breath occurred earlier than the ventilator set cycle without esophageal pressure drop of greater than 1 cm H2O were defined as PDT with first breath autotriggered (PDT-A). The pressure drop (PD0.1, PD0.13) and flow change (F0.1, F0.13) in 0.1s and 0.13s in the phase of inspiratory trigger delay (retrogradely computed from the nadir of airway pressure tracing and concomitant flow tracing) were determined in all breaths with DT and PDT.
Results: There were a total of 507 breaths with DT and PDT among 14 patients. Two hundred and seventy-one breaths belonged to PDT-C, 50 breaths were PDT-A and 186 breaths were DT. PD0.1 for PDT-C, PDT-A and DT was 0.13 ± 0.10 (mean ± SD), 0.20 ± 0.13, and 1.17 ± 0.63 cm H2O respectively. F0.1 for PDT-C, PDT-A and DT was 1.87 ± 2.24, 2.26 ± 1.87, and 14.69 ± 7.26 L/min. PD0.13 for PDT-C, PDT-A and DT was 0.16 ± 0.12, 0.25 ± 0.17, and 1.34 ± 0.67 cm H2O. F0.13 for PDT-C, PDT-A and DT was 2.11 ± 2.31, 2.64 ± 2.07, and 16.51 ± 8.02 L/min. The best discriminating criteria for differentiating DT and PDT based on Yuden index (sensitivity +specificity-1) was PD0.1: 0.45 cm H2O (sensitivity 98%, specificity 97% ), F0.1: 5.69 L/min (sensitivity 90%, specificity 94 %), PD0.13: 0.49 cm H2O (sensitivity 98%, specificity 97%), and F0.13: 6.12 L/m (sensitivity 91%, specificity 94%).
Conclusion: DT and PDT could be reliably classified using airway pressure and flow deflection in the phase of trigger delay in ventilated patients.

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