Esophageal Balloon Guided Weaning of the Morbidly Obese Patient

Study Overview
=================
Brief Summary
-----------------
This is a study to evaluate whether PEEP adjusted by use of an esophageal balloon to overcome negative transpulmonary pressure; or adjusted by use of CStat to achieve the best effective static compliance will have any effect on outcomes with respect to ventilator weaning in tracheotomized morbidly obese patients (BMI >=40) with at least one failed prior weaning attempt.

Detailed Description
-----------------
Tracheotomized morbidly obese patients (BMI >= 40) who had failed an initial attempt at ventilator weaning (defined in the investigators study as ventilator dependent) were randomly assigned to one of two methods for setting Positive End Expiratory Pressure (PEEP). Patients randomized to the esophageal balloon arm (ESO group) had their PEEP adjusted to overcome negative transpulmonary pressure and maintain a positive transpulmonary pressure (Ptp) of 0 to 10 cm H20 - targeting as close to zero as possible. Patients randomized to the static effective compliance arm (CStat group) had their PEEP adjusted to achieve the best static effective compliance as automatically calculated and displayed on the graphic interphase of the hamilton G5 or Galileo ventilator. For this group, the PEEP was adjusted in increments of 3 cm H20 until there was a less than 5% observed improvement in the static effective compliance. the PEEP with the best Cstat was chosen. At the end of the intervention period, this intervention cohort (termed PEEP intervention cohort) will be compared to a group of historical controls to compare the efficiency of a PEEP-based weaning protocol to traditional weaning methods. The investigators hypothesized that PEEP levels titrated by use of an esophageal balloon to maintain a positive transpulmonary pressure between 0 to 10 cm H20, would lead to improved outcomes with respect to ventilator weaning in this subset of patients.

Official Title
-----------------
Esophageal Balloon Guided Weaning of the Morbidly Obese Patient

Conditions
-----------------
Morbid Obesity

Intervention / Treatment
-----------------
* Device: Esophageal Balloon
* Other: Cstat


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Morbidly obese patients with BMI of 40 or greater Ventilator dependent patients (defined as at least one prior failure at weaning) Tracheotomized No active underlying lung disease that would preclude ventilator weaning Stable hemodynamics Patient/ family able to give consent No naso-facial abnormalities that would interfere with placement of an esophageal balloon Fio2 <= 60% Patient able to tolerate Pressure Support ventilation Exclusion Criteria: Lack of consent Patient deemed not weanable from mechanical ventilation as per the clinical judgement of the pulmonary physician Significant lung, heart or neuromuscular disease that would interfere with or preclude ventilator weaning, including an active ongoing lung infection. Contraindications to placement of an esophageal pressure monitoring device - such as ulcerations, tumors, diverticulitis, uncontrolled bleeding varices, sinusitis, epistaxis or recent nasopharyngeal surgery

Ages Eligible for Study
-----------------
Minimum Age: 19 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Esophageal balloon Arm<br>Patients in this arm were randomly assigned to have their PEEP adjusted to maintain a positive transpulmonary pressure (0 to 10 cm H20). | Device: Esophageal Balloon<br>* Esophageal balloon was used to measure esophageal pressure (Paux) which was used as an estimate of pleural pressure. Transpulmonary pressure (Ptp) was calculated as the difference between airway pressure (Pao) and Paux. Applied PEEP was then adjusted to overcome negative Ptp which we maintained between 0 to 10 cm H20. All measurements were made at end-expiration.<br>|
| Active Comparator: Cstat Arm<br>Patients in this arm had their PEEP adjusted to achieve the best static effective compliance (CStat). | Other: Cstat<br>* PEEP was adjusted to achieve the best CStat in this group of patients<br>|
| No Intervention: Historic Controls<br>These were historic controls with similar patient characteristics weaned by traditional methods in the 2-year period prior to the start of the study. | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of patients weaned by day 30 | A patient was considered successfully weaned and ventilator independent if they were spontaneously breathing without ventilator support for at least 24 hours, and remained off the ventilator by day 30. If ventilator support was subsequently required, the patient was returned to their original group and considered not weaned. The patients were considered to be weaned or not, after a period of thirty days. | 30-days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to wean | The time to wean/ time to achieve ventilator independence was measured from the date of randomization to the date of final successful liberation from mechanical ventilation. If patient had an unsuccessful initial wean, he was not considered weaned. Only patients who were considered weaned by day 30 accrued time to ventilator independence. | 30-days | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Transpulmonary pressure, Esophageal balloon, Esophageal pressure monitoring device, Cstat, Static effective compliance, Ventilator weaning, Morbidly Obese Ventilator Dependent Tracheotomized Patients