Clinical Trial: Impact of Proportional Assisted Ventilation on Dyspnea and Asynchrony in Mechanically Ventilated Patients

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title: Impact of Proportional Assisted Ventilation on Dyspnea and Asynchrony in Mechanically Ventilated Patients

Brief Summary:

Rational. The mismatch between the activity of the respiratory muscles and the assistance delivered by the ventilator results in patient-ventilator disharmony, which is commonly observed in ICU patients and is associated with dyspnea and patient-ventilator asynchrony. Both dyspnea and asynchrony are in turn associated with a worse prognosis. Unlike conventional modes of mechanical ventilation, such as pressure support ventilation (PSV) that deliver a constant level of assistance regardless of the patient effort, Proportional Assisted Ventilation (PAV) adjusts the level of ventilator assistance to the activity of respiratory muscles. To date, data on the impact of PAV on dyspnea and patient ventilator asynchrony are scarce and most studies have been conducted in healthy subjects or in ICU patients who had no severe dyspnea nor severe asynchrony. To our knowledge, there are no data in patients with severe patient-ventilator dysharmony.

Study Aim. To evaluate the impact of PAV on dyspnea and patient-ventilator asynchrony in ICU mechanically ventilated patients in intensive care with severe patient-ventilator disharmony defined as either severe dyspnea or severe patient-ventilator asynchrony.

Patients and Methods. Will be included 24 ICU mechanically ventilated patient exhibiting severe patient-ventilator dysharmony with PSV. The intensity of dyspnea will be assessed by the VAS, the ICRDOSS and by the electromyogram of extradiaphragmatic inspiratory muscles and pre inspiratory potential collected from the electroencephalogram. The prevalence of patient-ventilator asynchrony will be quantified.

Expected results. It is anticipated that the switch from PSV to PAV will decrease the prevalence and severity of dyspnea and the prevalence of patient-ventilator asynchrony.

Detailed Summary:

Rational As opposed to controlled mechanical ventilation, partial modes of assisted ventilation maintains a certain level spontaneous activity of respiratory muscles. As a consequence, assisted ventilation may contribute to prevents ventilator induced diaphragm dysfunction (1-3), improves gas exchanges (4), reduces the use of sedative agents, which can ultimately shorten weaning from mechanical ventilation (5).

The most widely used partial ventilatory assistance mode is pressure support ventilation (PSV) (6), in which a constant preset level of pressure assists each inspiration regardless of the patient's inspiratory effort. Mismatching between patient demand and level of assistance, which the investigators will term patient-ventilator dysharmony in the present project is therefore possible and can be potentially harmful. On the one hand, underassistance may induce respiratory discomfort and dyspnea (7), which is an immediate cause of suffering, generates anxiety and is a source of delayed neuropsychological sequelae such as dark respiratory recollections and post-traumatic stress disorders(8-12). One the other hand, overassistance may cause lung overdistension and volutrauma (13). Finally, both underassistance and overassistance may generate patient-ventilator asynchrony that is associated with poorer clinical outcomes (14). Of notice, underassistance is likely to be associated with an asynchrony named double-triggering while over assistance is more commonly associated with ineffective efforts(15).

Proportional modes of mechanical ventilation have been designed to overcome this weakness of (PSV). Indeed, as opposed to PSV that delivers a constant level of assistance regardless of the patient inspiratory effort, proportional modes of ventilation adjust the amount of assistance delivered with respect to the patient's effort
Sponsor: Association pour le Développement et l'Organisation de la Recherche en Pneumologie et sur le So

Current Primary Outcome: Quantification of dyspnea [ Time Frame: in real time, during the procedure ]

Original Primary Outcome: Same as current

Current Secondary Outcome:

• Airway pressure [ Time Frame: in real time, during the procedure ]
  The airway pressure will be also measured at the Y-piece by a differential pressure transducer (Validyne, Northridge, USA).
• Electromyography (EMG) of extra inspiratory diaphragmatic muscles [ Time Frame: in real time, during the procedure ]
  The amplitude of the EMG signal of extradiaphragmatics inspiratory muscles is proportional to the intensity of dyspnea. EMG will be collected by self-adhesive surface electrodes of the same type as those commonly used to collect the ECG signal in critically ill patients. A distance of 2 cm will separate the two electrodes. The position of the electrodes will depend on the recorded muscle.
• Electroencephalogram (EEG) in search of a pre-inspiratory potential [ Time Frame: in real time, during the procedure ]
  The application of an inspiratory resistive load to healthy subjects results in the activation of the pre-motor cortex detected by EEG recording. This EEG activity is named pre-inspiratory potential (PIP).
• Arterial blood gas [ Time Frame: in real time, during the procedure ]
  For patients with an arterial catheter, the measurement of blood gases using an arterial blood sample of a volume of less than 1ml be performed at the end of each condition.
• Patient-ventilator asynchrony [ Time Frame: in real time, during the procedure ]
  Asynchrony will be detected by visual inspection of the recordings. The investigators will investigate patterns of two major asynchronies that are easily detected on pressure and flow recordings: ineffective triggering and double triggering. Ineffective triggering will be defined as an abrupt airway pressure drop (≥ 0.5 cmH2O) simultaneous to a flow decrease (in absolute value) and not followed by an assisted cycle during the expiratory period. Double-triggering will be defined as two cycles separated by a very short expiratory time, defined as less than one-half of the mean inspiratory time, the first cycle being patient-triggered.
• Flow [ Time Frame: in real time, during the procedure ]
  Airway flow will be measured with a pneumotachograph (Hans Rudolph, Kansas City, USA) inserted between the Y-piece and the endotracheal tube and connected to a differential pressure sensor (Validyne, Northridge, USA).
• Quantification of dyspnea [ Time Frame: in real time, during the procedure ]
  Dyspnea will be quantified with a dyspnea-VAS from 0 (no discomfort) to 10 (maximum breathing)

Original Secondary Outcome:

• Airway pressure [ Time Frame: in real time, during the procedure ]
  The airway pressure will be also measured at the Y-piece by a differential pressure transducer (Validyne, Northridge, USA).
• Electromyography (EMG) of extra inspiratory diaphragmatic muscles [ Time Frame: in real time, during the procedure ]
  The amplitude of the EMG signal of extradiaphragmatics inspiratory muscles is proportional to the intensity of dyspnea. EMG will be collected by self-adhesive surface electrodes of the same type as those commonly used to collect the ECG signal in critically ill patients. A distance of 2 cm will separate the two electrodes. The position of the electrodes will depend on the recorded muscle.
• Electroencephalogram (EEG) in search of a pre-inspiratory potential [ Time Frame: in real time, during the procedure ]
  The application of an inspiratory resistive load to healthy subjects results in the activation of the pre-motor cortex detected by EEG recording. This EEG activity is named pre-inspiratory potential (PIP).
• Arterial blood gas [ Time Frame: in real time, during the procedure ]
  For patients with an arterial catheter, the measurement of blood gases using an arterial blood sample of a volume of less than 1ml be performed at the end of each condition.
• Patient-ventilator asynchrony [ Time Frame: in real time, during the procedure ]
  Asynchrony will be detected by visual inspection of the recordings. We will investigate patterns of two major asynchronies that are easily detected on pressure and flow recordings: ineffective triggering and double triggering. Ineffective triggering will be defined as an abrupt airway pressure drop (≥ 0.5 cmH2O) simultaneous to a flow decrease (in absolute value) and not followed by an assisted cycle during the expiratory period. Double-triggering will be defined as two cycles separated by a very short expiratory time, defined as less than one-half of the mean inspiratory time, the first cycle being patient-triggered.
• Flow [ Time Frame: in real time, during the procedure ]
  Airway flow will be measured with a pneumotachograph (Hans Rudolph, Kansas City, USA) inserted between the Y-piece and the endotracheal tube and connected to a differential pressure sensor (Validyne, Northridge, USA).
• Quantification of dyspnea [ Time Frame: in real time, during the procedure ]
  Dyspnea will be quantified with a dyspnea-VAS from 0 (no discomfort) to 10 (maximum breathing)

Dates:
Date Received: May 6, 2016
Date Started: February 2016
Date Completion: October 2017
Last Updated: February 15, 2017
Last Verified: January 2017