Flow and airway pressure analysis for detecting ineffective effort during mechanical ventilation in neuromuscular patients

Figures

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  Figure 1.. Example of a preincluded patient who was excluded because the Pes change caused by cardiac contraction (d in the figure) was more than 1/3 of the Pes swing related to the spontaneous breathing effort (D in the figure). Pdi: transdiaphragmatic pressure; Pes: esophageal pressure; Paw: airway pressure.

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  Figure 2.. Example of an ineffective effort (black arrows) classified as a true-positive, followed by a breathing effort assisted by the ventilator (dashed arrows) classified as a true-negative. Pdi: transdiaphragmatic pressure; Pes: esophageal pressure; Paw: airway pressure.

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  Figure 3.. Patient #5: cardiac contractions affecting both airway pressure and flow signals were mistaken for ineffective efforts, leading to a high false-positive rate. Pdi: transdiaphragmatic pressure; Pes: esophageal pressure; Paw: airway pressure.

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  Figure 4.. Example of premature cycling of the ventilator (horizontal black arrows where t represents the insufflation duration and T the inspiratory effort duration) simulating ineffective efforts (false positives) when analyzing only flow and Paw without Pes. Pdi: transdiaphragmatic pressure; Pes: esophageal pressure; Paw: airway pressure

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  Figure 5.. Example of abrupt changes in the expiratory flow signal due to upper airway obstruction during expiration simulating ineffective efforts and therefore leading to a high positive rate, whereas no respiratory effort was detected on the Pes signal. Pdi: transdiaphragmatic pressure; Pes: esophageal pressure; Paw: airway pressure.

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  Figure 6.. Delayed triggering of the ventilator simulating ineffective efforts. The dashed line indicates zero flow. The solid vertical line and black arrow mark the beginning of an inspiratory effort, indicating delayed triggering of the ventilator. Pdi: transdiaphragmatic pressure; Pes: esophageal pressure; Paw: airway pressure.