Assessment of Inspiratory Muscles Strength and Endurance Evolution on Difficult to Wean Patients in Intensive Care Unit

Assessment of the Evolution of Force and Endurance of Inspiratory Muscles in Intubated and Mechanically-ventilated ICU Patients With Difficult Weaning

Ventilator-induced diaphragmatic dysfunction appears to contribute to slow weaning from mechanical ventilation. Several trials of inspiratory muscle training to facilitate weaning in intensive care have been performed, with inconsistent results, utilizing different methods of IMT in different populations.

To perform the best IMT program, we need to know the physio-pathology of the diaphragm in difficult to wean patients.

This study proposes to discriminate the two main characteristics of the inspiratory muscles: strength and endurance.

By analyzing the evolution of strength and endurance during all the weaning period, we want to know which characteristic has the more deficiency to adapt in a second time an effective program of IMT.

The main objective of this study is to determinate which characteristic of inspiratory muscles between strength and endurance has more deficiency in difficult to wean patients. In a second time, the results of this study will help to choose the best IMT program to assess his impact on the weaning time.

We are going to conduct an interventional trial because of Peak Pressure measure, which is not measure in care practice. Following 18h of invasive mechanical ventilation in a controlled mode, the failure of the first single breathe trial of 2 hours and the presence of sevrability criterias defined by the European consensus conference in 2007, 80 participants will be included in the medical intensive care unit of Bordeaux's hospital. We'll perform measurements of the Maximal Inspiratory Pressure and Peak Pressure from the inclusion to the extubation.

Inclusion Criteria:

• Patient ventilated more than 18h in a controlled mode;

• First single breathe trial of 2 hours failure;

• Presence of sevrability criterias definied by the European consensus conference in 2007 as usually used:

  • diminution of the sedfative agents ;
  • Patients with spontaneous beath in VAC mode or patient ventilated in a VSAI-PEP mode;
  • PaO2/FiO2 ≥150;
  • Absence d'inotropes ou de vasopresseurs à forte dose ou dose croissante (<1mg/h);
  • SaO2 > 90% with FiO2 ≤ 50%;
  • PEP ≤ 8cmH2O;
  • Corporal température between 36°C and 39°C;
  • Glasgow Score ≥ 8;

• Patient or family consent.

Exclusion Criteria:

• Age < 18 years ;
• medically unstable;
• Poor vital pronostic at very short term;
• Cardiac arrest with a poor neurological prognostic;
• Neuromuscular disease ;
• Tracheostomy ;
• Current pregnancy ;
• Patients with guardianship or trusteeship.