Mechanical Ventilation-Induced Reverse-Triggered Breaths: A Frequently Unrecognized Form of Neuromechanical Coupling

doi:10.1378/chest.12-1817

Chest

Volume 143, Issue 4, April 2013, Pages 927-938

https://doi.org/10.1378/chest.12-1817 Get rights and content

Background

Diaphragmatic muscle contractions triggered by ventilator insufflations constitute a form of patient-ventilator interaction referred to as “entrainment,” which is usually unrecognized in critically ill patients. Our objective was to review tracings, which also included muscular activity, obtained in sedated patients who were mechanically ventilated to describe the entrainment events and their characteristics. The term “reverse triggering” was adopted to describe the ventilator-triggered muscular efforts.

Methods

Over a 3-month period, recordings containing flow, airway pressure, and esophageal pressure or electrical activity of the diaphragm were reviewed. Recordings were obtained from a series of consecutive heavily sedated patients ventilated with an assist-control mode of ventilation for ARDS. The duration of entrainment, the entrainment ratio, and the phase difference elapsing between the commencement of the ventilator and neural breaths were evaluated.

Results

The tracings of eight consecutive patients with ARDS were reviewed; they all showed different forms of entrainment. Reverse triggering occurred over a portion varying from 12% to 100% of the total recording period. Seven patients had a 1:1 mechanical insufflation to diaphragmatic contractions ratio; this coexisted with a 1:2 ratio in one patient and 1:2 and 1:3 ratios in another. One patient exhibited only a 1:2 ratio. The frequency of reverse-triggered breaths had a mean coefficient of variability of < 5%, very close to the variability of mechanical breaths.

Conclusions

To our knowledge, this is the first time that the presence of respiratory entrainment in sedated, critically ill adult patients who are mechanically ventilated has been documented. The “reverse-triggered” breaths illustrate a new form of neuromechanical coupling with potentially important clinical consequences.

Section snippets

Materials and Methods

This study was approved by the ethics committee of Geneva University Hospital (Comité départemental d'éthique NAC, NAC 12–032R). Because of the descriptive character of the study, informed consent from the patients was not required.

Patient Characteristics

Recordings of Pes or EAdi activity were available in eight patients. All had a diagnosis of ARDS and were deeply sedated as indicated by the RASS. They were ventilated with either volume assist-control (VAC) or pressure assist-control modes. The ventilators used were Evita XL (Dräger) and Servo-I (MAQUET Holding GmbH & Co KG). An esophageal balloon was inserted into six patients with the objective of selecting ventilator settings according to lung mechanical properties. To optimize monitoring

Discussion

In this observational study, we documented the presence of respiratory entrainment in critically ill adults who were mechanically ventilated. We consecutively observed, in eight deeply sedated patients with ARDS, neural efforts entrained by the ventilator at three different ratios: 1:1, 1:2, and 1:3. We defined these neural efforts apparently triggered by the ventilator as “reverse-triggered breaths.” They occurred mainly around the transition phase from mechanical inspiration to expiration,

Conclusions

In this observational study, we documented, for the first time to our knowledge, the presence of “reverse triggering” in deeply sedated, critically ill adult patients under volume or pressure assist-control mechanical ventilation for ARDS. In the context of entrainment, “reverse-triggered” breaths constitute an unclassified and unrecognized form of patient-ventilator interaction. They can be totally overlooked, leading to erroneous assumptions regarding the patient's respiratory status. The

Acknowledgments

Author contributions: Dr Richard is the guarantor of the manuscript and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Dr Akoumianaki: contributed to the identification of the phenomenon, data recording, data analysis and interpretation, and writing of the manuscript.

Dr Lyazidi: contributed to the data collection, statistical analysis, creation of images and tables, and review of the manuscript.

Dr Rey: contributed to the recruitment of patients, data

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Reverse triggering during mechanical ventilation: Diagnosis and clinical implications
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Esta revisión aborda el fenómeno «trigger reverso», una asincronía que se presenta en pacientes sedados o en transición de despertar, con una prevalencia en estos grupos del 30% al 90%. Los mecanismos fisiopatológicos aún no están claros, pero se propone el «entrainment» como uno de ellos. Detectar esta asincronía es complejo y se han usado métodos como inspección visual, presión esofágica, ecografía diafragmática y métodos automáticos. El trigger reverso puede tener efectos en la función pulmonar y diafragmática, mediados porbablemente por el nivel de esfuerzo respiratorio y la activación excéntrica del diafragma. El manejo óptimo no está establecido y puede incluir ajuste de parámetros ventilatorios, frecuencia respiratoria, nivel de sedación y en casos extremos, bloqueo neuromuscular. Es importante comprender su significación, su detección e incrementar la investigación para mejorar su manejo clínico y sus potenciales efectos en los pacientes críticamente enfermos.
This review addresses the phenomenon of “reverse triggering”, an asynchrony that occurs in deeply sedated or patients in transition from deep to light sedation. Reverse triggering has been reported to occur between 30% and 90% of ventilated patients. The pathophysiological mechanisms are still unclear, but “entrainment” is proposed as one of them. Detecting this asynchrony is crucial, and methods such as visual inspection, esophageal pressure, diaphragmatic ultrasound, and automatic methods have been used. Reverse triggering may have effects on lung and diaphragm function, probably mediated by the level of breathing effort and eccentric activation of the diaphragm. The optimal management of reverse triggering is not established and may include adjustment of ventilatory parameters as well as sedation level, and in extreme cases, neuromuscular blockade. It is important to understand the significance of this condition, its detection, but also to conduct dedicated research to improve its clinical management and its potential effects in critically ill patients.
Reverse triggering neural network and rules-based automated detection in acute respiratory distress syndrome.
2023, Journal of Critical Care
Dyssynchrony may cause lung injury and is associated with worse outcomes in mechanically ventilated patients. Reverse triggering (RT) is a common type of dyssynchrony presenting with several phenotypes which may directly cause lung injury and be difficult to identify. Due to these challenges, automated software to assist in identification is needed.
This was a prospective observational study using a training set of 15 patients and a validation dataset of 13 patients. RT events were manually identified and compared with “rules-based” programs (with and without esophageal manometry and reverse triggering with breath stacking), and were used to train a neural network artificial intelligence (AI) program. RT phenotypes were identified using previously defined rules. Performance of the programs was compared via sensitivity, specificity, positive predictive value (PPV) and F1 score.
33,244 breaths were manually analyzed, with 8718 manually identified as reverse-triggers. The rules-based and AI programs yielded excellent specificity (>95% in all programs) and F1 score (>75% in all programs). RT with breath stacking (24.4%) and mid-cycle RT (37.8%) were the most common phenotypes.
Automated detection of RT demonstrated good performance, with the potential application of these programs for research and clinical care.
Ventilation of denervated transplanted lung at risk for overdistention by reverse triggering and breath stacking: a role for the paradoxical reflex of Head. Comment on Br J Anaesth 2022; 129: e1–4
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Expiratory Muscle Relaxation-Induced Ventilator Triggering: A Novel Patient-Ventilator Dyssynchrony
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In critically ill patients receiving mechanical ventilation, expiratory muscles are recruited with high respiratory loading and/or low inspiratory muscle capacity. In this case report, we describe a previously unrecognized patient-ventilator dyssynchrony characterized by ventilator triggering by expiratory muscle relaxation, an observation that we termed expiratory muscle relaxation-induced ventilator triggering (ERIT). ERIT can be recognized with in-depth respiratory muscle monitoring as (1) an increase in gastric pressure (Pga) during expiration, resulting from expiratory muscle recruitment; (2) a drop in Pga (and hence, esophageal pressure) at the time of ventilator triggering; and (3) diaphragm electrical activity onset occurring after ventilator triggering. Future studies should focus on the incidence of ERIT and the impact in the patient receiving mechanical ventilation.

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Funding/Support: The authors have reported to CHEST that no funding was received for this study.

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Original ResearchCritical CareMechanical Ventilation-Induced Reverse-Triggered Breaths: A Frequently Unrecognized Form of Neuromechanical Coupling

Background

Methods

Results

Conclusions

Section snippets

Materials and Methods

Patient Characteristics

Discussion

Conclusions

Acknowledgments

J Theor Biol

Respir Physiol

Respir Physiol

Early Hum Dev

Gait Posture

Early Hum Dev

Effects of Mechanical ventilation on control of breathing

Respiratory phase locking during mechanical ventilation in anesthetized human subjects

Am J Physiol

Entrainment of respiratory rhythm by periodic lung inflation: effect of airflow rate and duration

Am J Physiol

Phase locking of the respiratory rhythm in cats to a mechanical ventilator

Can J Physiol Pharmacol

Vagal feedback in the entrainment of respiration to mechanical ventilation in sleeping humans

J Appl Physiol

Entrainment of respiration in humans by periodic lung inflations. Effect of state and CO2

Am J Respir Crit Care Med

A theory for phase locking of respiration in cats to a mechanical ventilator

Am J Physiol

Respiratory oscillator entrainment by periodic vagal afferentes: an experimental test of a model

Biol Cybern

The Richmond Agitation-Sedation Scale: validity and reliability in adult intensive care unit patients

Am J Respir Crit Care Med

Pressure-time product during continuous positive airway pressure, pressure support ventilation, and T-piece during weaning from mechanical ventilation

Am Rev Respir Dis

Effects of flow triggering on breathing effort during partial ventilatory support

Am J Respir Crit Care Med

Original Research
Critical Care
Mechanical Ventilation-Induced Reverse-Triggered Breaths: A Frequently Unrecognized Form of Neuromechanical Coupling

Entrainment of respiration in humans by periodic lung inflations. Effect of state and CO₂