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Transpulmonary Pressure Gradients in High Frequency Oscillation (TPG in HFO)

This study has been completed.
Information provided by (Responsible Party):
University of British Columbia Identifier:
First received: March 21, 2011
Last updated: March 14, 2014
Last verified: March 2014
Patients with severe lung conditions occasionally require support with a special ventilator (breathing machine) called the High Frequency Oscillator (HFO). Effective ventilation requires that the pressure generated by the ventilator be as high as possible but not too high as this can damage the lungs. In patients on HFO, there is not a well defined way to measure this pressure. We will insert a small probe into the esophagus of patients on HFO to see if this is an accurate way to measure lung pressures for these patients. A better understanding of these pressures could lead to improved patient care.

Condition Intervention
Acute Lung Injury
Other: Esophageal Pressure Monitoring

Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Prospective
Official Title: Transpulmonary Pressure Gradients in High Frequency Oscillation Study

Resource links provided by NLM:

Further study details as provided by University of British Columbia:

Primary Outcome Measures:
  • To demonstrate the proof of concept that esophageal pressures can easily be obtained in patients undergoing HFO. [ Time Frame: 60 minutes ]

Secondary Outcome Measures:
  • To determine the transpulmonary pressure gradient in critically ill patients receiving HFO [ Time Frame: 60 minutes ]

Enrollment: 7
Study Start Date: October 2010
Study Completion Date: March 2013
Primary Completion Date: July 2011 (Final data collection date for primary outcome measure)
Groups/Cohorts Assigned Interventions
Critically Ill patients receiving HFO Other: Esophageal Pressure Monitoring
An esophageal pressure monitor will be placed through the mouth into the esophagus by a study physician. Placement will be confirmed by a bedside chest X-ray. Once placement has been confirmed all air will be evacuated from the balloon by syringe. One ml of air will then be injected to partially inflate the esophageal balloon. Pleural pressure measurements will be recorded after 1 minute without spontaneous breathing or patient care related movement. This measurement will be repeated at 30 minutes and at 60 minutes after the first measurement. Trans-pulmonary pressure is calculated as the difference between esophageal pressure and mouth pressure. Once the measurements have been recorded, the catheter will be removed.

Detailed Description:

Trials have found that the use of lower tidal volumes (6 ml/kg) during conventional mechanical ventilation decreases morbidity and mortality. Compared to conventional ventilation, high frequency oscillation (HFO) is able to provide much smaller tidal volumes (1.1 - 2.5 ml/kg) and thus theoretically may provide additional lung protection. At this time, while trials of HFO in adults have been inconclusive, the use of HFO for the management of ALI/ARDS has become widespread

Patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) are critically ill and have a high mortality associated with their illness (approximately 50%). Currently, esophageal pressure monitors are used to optimize inflation pressures and improve oxygenation in conventional mechanical ventilation in patients with ALI/ARDS. With this in mind, the purpose of this study is twofold: (1) demonstrate that esophageal pressure monitors can easily be inserted in patients undergoing HFO and (2) report the transpulmonary pressures in these patients.


Ages Eligible for Study:   19 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
Critically Ill

Inclusion Criteria:

  • 19 years of age or older
  • Receiving HFO
  • Informed Consent Obtained

Exclusion Criteria:

  • Esophageal lesions or esophageal surgery within the last 6 months
  • Morbid obesity - defined as a Body Mass Index (BMI) > 40
  • Unstable cervical spine injury or cervical spinal cord injury
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Please refer to this study by its identifier: NCT01321398

Canada, British Columbia
Vancouver General Hospital
Vancouver, British Columbia, Canada, V5Z1M9
Sponsors and Collaborators
University of British Columbia
Principal Investigator: William R Henderson, FRCPC Universtiy of British Columbia
  More Information

Responsible Party: University of British Columbia Identifier: NCT01321398     History of Changes
Other Study ID Numbers: H10-02087
Study First Received: March 21, 2011
Last Updated: March 14, 2014

Keywords provided by University of British Columbia:
High Frequency Oscillation
Transpulmonary pressure

Additional relevant MeSH terms:
Acute Lung Injury
Respiratory Distress Syndrome, Adult
Lung Injury
Lung Diseases
Respiratory Tract Diseases
Respiration Disorders
Thoracic Injuries
Wounds and Injuries processed this record on April 24, 2017