Chest Wall Influence on Respiratory System Mechanics in Morbidly Obese Patients

March 24, 2015 updated by: Robert M. Kacmarek, Massachusetts General Hospital

The goal of this study is to describe the influence of the chest wall on the respiratory system mechanics in morbidly obese patients and in patients with high intra-abdominal pressure.

The effects of increasing and decreasing positive end-expiratory pressure (PEEP) on chest wall and total respiratory system mechanics, lung volumes and gas exchange will be evaluated, both during controlled and assisted mechanical ventilation.

Patients will be studied, first, during the acute phase of respiratory failure, when requiring intubation and controlled mechanical ventilation. Then, patients will be evaluated again during weaning from the ventilator to assess the influence of PEEP in assisted ventilation prior to extubation.

Study Overview

Status

Completed

Detailed Description

The goal of this study is to describe the influence of the chest wall on the respiratory system mechanics. Investigators want to describe how extreme obesity and Intra-Abdominal Hypertension (IAH) affect normal respiratory system behavior. The effects of increasing and decreasing positive end-expiratory pressure (PEEP) on respiratory system mechanics, lung volumes and gas exchange will be evaluated, both during controlled and assisted mechanical ventilation.

Investigators will record and compare lung volumes, airway and transpulmonary pressure, gas exchange and hemodynamic changes caused by variations of PEEP. Patients will be studied, first, during the acute phase of respiratory failure, when requiring intubation and controlled mechanical ventilation. Patients will then again be evaluated during weaning from the ventilator to assess the influence of PEEP in assisted ventilation prior to extubation.

Investigators believe that assessment of the transpulmonary pressure and lung volumes is essential to correctly evaluate respiratory system function in patients in which the relationship between the lung and chest wall is altered. Improper mechanical ventilation leads to lung damage. High ventilatory volume/pressure are associated with lung overdistension, while low volume/pressure leads to lung collapse and cyclic opening and closing of alveoli. All of these mechanisms have been associated with ventilator induced lung injury and poorer outcomes. Adequate PEEP and transpulmonary pressure are fundamental in preventing this vicious cycle.

Study Type

Observational

Enrollment (Actual)

14

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • Massachusetts
      • Boston, Massachusetts, United States, 02114
        • Massachusetts General Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Probability Sample

Study Population

We will enroll morbidly obese intubated patients and/or patients affected by intraabdominal hypertension admitted to medical ICUs and surgical ICUs at Massachusetts General Hospital. Patients with contraindication to esophageal balloon placement or with severe respiratory failure will be excluded from the study.

Description

Inclusion Criteria:

  • 18 years or older
  • Requiring intubation and mechanical ventilation
  • BMI≥40 kg/m2 or IAP≥12 mmHg

Exclusion Criteria:

  • Known presence esophageal varices
  • Recent esophageal trauma or surgery
  • Severe thrombocytopenia (PTL≤10,000/mm3)
  • Severe coagulopathy (INR≥2)
  • Presence of pneumothorax
  • Pregnancy
  • Patients with diagnosed moderate to severe ARDS or with poor oxygenation index (PaO2/FiO2 < 200 mmHg)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Case-Only
  • Time Perspectives: Prospective

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Obese

We will enroll patients with BMI≥40 kg/m2 to describe the impact of obesity on chest wall compliance and respiratory mechanics.

Respiratory mechanics assessment: We will assess respiratory mechanics through different end expiratory pressure settings and recording airway and esophageal pressure tracings.

Data collection on respiratory mechanics, end expiratory lung volumes, gas exchanges, work of breathing. Data will be obtained by setting different end expiratory pressures and recording esophageal and airways pressure tracings.
Intraabdominal Hypertension

We will enroll patients with IAP≥12 mmHg to describe the impact of intraabdominal hypertension on chest wall compliance and respiratory mechanics.

Respiratory mechanics assessment: We will assess respiratory mechanics through different end expiratory pressure settings and recording airway and esophageal pressure tracings.

Data collection on respiratory mechanics, end expiratory lung volumes, gas exchanges, work of breathing. Data will be obtained by setting different end expiratory pressures and recording esophageal and airways pressure tracings.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
End Expiratory Lung Volumes
Time Frame: 2 hours
EELV variation at different levels of PEEP in mechanically ventilated and sedated morbidly obese patients and patients with intraabdominal hypertension
2 hours

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Respiratory mechanics
Time Frame: 24 hours
Evaluation of effects of PEEP level set by ICU staff on respiratory mechanics after 24 hours from enrollment Evaluation of PEEP level set by ICU staff
24 hours
Work of breathing
Time Frame: 20 minutes
Evaluation of work of breathing variation at different level of PEEP during spontaneous breathing and ventilation weaning in morbidly obese patients
20 minutes
Respiratory mechanics
Time Frame: 2 hours
Respiratory mechanics variation at different levels of PEEP in mechanically ventilated and sedated morbidly obese patients and patients with intraabdominal hypertension
2 hours
Gas Exchange
Time Frame: 2 hours
Gas exchange variation at different levels of PEEP in mechanically ventilated and sedated morbidly obese patients and patients with intraabdominal hypertension
2 hours
Respiratory mechanics
Time Frame: 20 minutes
Evaluation of respiratory mechanics at different level of PEEP during spontaneous breathing and ventilation weaning in morbidly obese patients
20 minutes
Gas exchange
Time Frame: 20 minutes
Evaluation of gas exchange variation at different level of PEEP during spontaneous breathing and ventilation weaning in morbidly obese patients
20 minutes
End Expiratory Lung Volume
Time Frame: 24 hours
Evaluation of effects of PEEP level set by ICU staff on EELV after 24 hours from enrollment
24 hours
Gas Exchange
Time Frame: 24 hours
Evaluation of effects of PEEP level set by ICU staff on gas exchange after 24 hours from enrollment
24 hours

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Investigators

  • Principal Investigator: Robert M Kacmarek, PhD RRT, Massachusetts General Hospital

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

August 1, 2013

Primary Completion (Actual)

January 1, 2015

Study Completion (Actual)

March 1, 2015

Study Registration Dates

First Submitted

February 12, 2014

First Submitted That Met QC Criteria

April 2, 2014

First Posted (Estimate)

April 7, 2014

Study Record Updates

Last Update Posted (Estimate)

March 25, 2015

Last Update Submitted That Met QC Criteria

March 24, 2015

Last Verified

March 1, 2015

More Information

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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