A Noninvasive Method to Identify Ineffective Triggering in Patients with Noninvasive Pressure Support Ventilation

Abstract

Background: 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. Objectives: 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. Methods: 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. Results: 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. Conclusions: 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.

Asynchrony and DyspneaDiscussion

“…More recently, several investigators have explored the use of machine learning and pattern recognition to automatically detect asynchrony. [63][64][65][66][67] In most instances these systems specifically address the issue of missed triggers. Chen et al used measurements of flow and pressure deflections to detect missed triggers in 14 mechanically ventilated patients.…”

“…67 They evaluated 14 cystic fibrosis patients receiving nocturnal NIV. These authors evaluated both pressure and flow tracings while comparing the algorithm to esophageal pressure measurements.…”

Patient-Ventilator Interaction During Noninvasive Ventilation

“…Cuvelier et al 46 developed a mathematical analysis of ventilator tracings recorded during NIV to identify ineffective triggering efforts. They retrospectively analyzed tracings that were routinely recorded during the initiation of NIV in children with advanced stable cystic fibrosis lung disease and who had no previous experience with NIV.…”

Realistic human muscle pressure for driving a mechanical lung

“…Patient-ventilator asynchrony is defined as a phase shift between the patient ventilatory cycle and the pressurization cycle delivered by the ventilator. There are various types of asynchrony events [3,4] which can be detected using noninvasive measurements [5]: reducing their incidence allows to decrease the duration for which a patient needs mechanical ventilatory assistance [3]. The quality of the synchronization between the patient ventilatory cycle and the pressurization cycle delivered by the ventilator depends on patient physiological characteristics and on ventilator settings.…”