Clinical trial NCT02105220: Chest Wall Influence on Respiratory System Mechanics in Morbidly Obese Patients
Official title: Chest Wall Influence on Respiratory System Mechanics in Morbidly Obese Patients
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Obesity
Intra-Abdominal Hypertension
Keywords: Respiratory mechanics
Esophageal pressure
Functional residual capacity
positive end-expiratory pressure
Lead sponsor: Massachusetts General Hospital
Sponsor class: OTHER
First posted: 2014-04-07
Enrollment: 14
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: CASE_ONLY
Time perspective: PROSPECTIVE
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.

Brief summary: 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.

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.

Eligibility criteria: 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)

Primary outcomes:
measure: End Expiratory Lung Volumes
timeFrame: 2 hours
Secondary outcomes:
measure: Respiratory mechanics
timeFrame: 24 hours
measure: Work of breathing
timeFrame: 20 minutes
measure: Respiratory mechanics
timeFrame: 2 hours
measure: Gas Exchange
timeFrame: 2 hours
measure: Respiratory mechanics
timeFrame: 20 minutes
measure: Gas exchange
timeFrame: 20 minutes
measure: End Expiratory Lung Volume
timeFrame: 24 hours
measure: Gas Exchange
timeFrame: 24 hours
Other outcomes:
Locations:
city: Boston
country: United States
facility: Massachusetts General Hospital
state: Massachusetts
Study officials:
affiliation: Massachusetts General Hospital
name: Robert M Kacmarek, PhD RRT
role: PRINCIPAL_INVESTIGATOR
References: