title: Mechanical ventilation-induced reverse-triggered breaths: a frequently unrecognized form of neuromechanical coupling.
abstract: BACKGROUND
  Diaphragmatic muscle contractions triggered by ventilator insuffl ations 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 fl ow, 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 insuffl ation 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 coeffi cient of variability of , 5%, very close to the variability of mechanical breaths.
  
  
  CONCLUSIONS
  To our knowledge, this is the fi rst 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.
authors.affiliation: Intensive Care Unit Division, Anesthesiology Pharmacology and Intensive Care Department, Geneva, Switzerland.
authors.forename: Evangelia
authors.initials: E
authors.lastname: Akoumianaki
authors.affiliation: Intensive Care Unit Division, Anesthesiology Pharmacology and Intensive Care Department, Geneva, Switzerland; School of Medicine, University of Geneva, Geneva, Switzerland.
authors.forename: Aissam
authors.initials: A
authors.lastname: Lyazidi
authors.affiliation: Intensive Care Unit Division, Anesthesiology Pharmacology and Intensive Care Department, Geneva, Switzerland.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rey
authors.affiliation: Intensive Care Unit Division, Anesthesiology Pharmacology and Intensive Care Department, Geneva, Switzerland.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Matamis
authors.affiliation: Intensive Care Unit Division, Anesthesiology Pharmacology and Intensive Care Department, Geneva, Switzerland.
authors.forename: Nelly
authors.initials: N
authors.lastname: Perez-Martinez
authors.affiliation: Intensive Care Unit Division, Anesthesiology Pharmacology and Intensive Care Department, Geneva, Switzerland.
authors.forename: Raphael
authors.initials: R
authors.lastname: Giraud
authors.affiliation: Hospital Sant Pau, Servei de Medicina Intensiva, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Mancebo
authors.affiliation: Intensive Care Unit Division, Anesthesiology Pharmacology and Intensive Care Department, Geneva, Switzerland; School of Medicine, University of Geneva, Geneva, Switzerland.
authors.forename: Laurent
authors.initials: L
authors.lastname: Brochard
authors.affiliation: Intensive Care Unit Division, Anesthesiology Pharmacology and Intensive Care Department, Geneva, Switzerland; School of Medicine, University of Geneva, Geneva, Switzerland. Electronic address: jcm.richard@hcuge.ch.
authors.forename: Jean-Christophe Marie
authors.initials: JM
authors.lastname: Richard
mesh_terms: D000328:Adult; D000368:Aged; D016638:Critical Illness / Q000628:therapy; D003964:Diaphragm / Q000503:physiopathology; D005260:Female; D006801:Humans; D015994:Incidence; D001239:Inhalation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D012121:Respiration, Artificial / Q000009:adverse effects*; D012128:Respiratory Distress Syndrome / Q000503:physiopathology* / Q000628:therapy*; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000503:physiopathology*; D012189:Retrospective Studies; D013997:Time Factors