Hypobaria and Traumatic Pneumothorax

Study Overview
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Brief Summary
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The purpose of this research is to see if people who have had a collapsed lung that has been re-expanded can be safely taken to an elevation that a person might experience while in a commercial airplane without having their lung partially collapse again, or have any symptoms such as feeling short of breath or having oxygen levels in the blood decrease while at the simulated altitude. The investigators hypothesize that subjects who have had a collapsed lung that has been re-expanded will not have any adverse symptoms or signs while subjected to a simulated altitude of 8400 feet (565mm Hg) or 12650 ft (471mm Hg).

Detailed Description
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The investigators will study patients who have been diagnosed with a unilateral traumatic pneumothorax that has been treated. Treatment for pneumothorax may consist of high-flow oxygen therapy in the case of very small or occult pneumothorax, or tube thoracostomy (chest tube) in the case of larger pneumothorax. Treatment for pneumothorax will be at the discretion of the attending trauma surgeon. Once the pneumothorax has radiographically resolved, the chest tube, if used, has been removed, and prior to discharge from the hospital, subjects will undergo a two hour stay in a hypobaric chamber. In the first phase of the study, they will undergo a two hour stay in a hypobaric chamber at a barometric pressure of 565mm Hg, simulating the change in pressure from Salt Lake City to a cruising airliner. If subjects in the first phase do not suffer any adverse events, the investigators will proceed with the second phase. In the second phase of the study, subjects will undergo a two hour stay in the hypobaric chamber at a barometric pressure of 471mm Hg, simulating the change in pressure from sea level to a cruising airliner. Prior to the hypobaric exposure, and at the conclusion of the two hours under hypobaric conditions, single view chest radiographs will be performed.

Official Title
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The Effects of Hypobaric Conditions on Small, Traumatic Pneumothoraces

Conditions
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Pneumothorax

Intervention / Treatment
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* Other: hypobaric chamber


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Inpatient status on trauma surgery service An established diagnosis of pneumothorax with a traumatic etiology (patients with iatrogenic pneumothorax from attempted central venous line placement will be considered to have a traumatic etiology) Age ≥ 18 at the time of injury Exclusion Criteria: Pregnancy Unable to give informed consent Pneumothorax which does not satisfactorily resolve after treatment with tube thoracostomy and requires operative intervention such as video assisted thoracoscopic surgery (VATS) or thoracotomy Pneumothorax requiring tube thoracostomy where the tube has been removed for < 4 or > 48 hours Head injury with GCS < 15 at time of evaluation for study Other injuries or conditions which would preclude participant's ability to remain in chamber for two hours NYHA class III or IV heart failure, active coronary artery disease, arrhythmias, pacemakers, implantable cardiac defibrillator, pulmonary hypertension, claustrophobia Severe obstructive or restrictive lung disease Chronic hypoxemia requiring supplemental oxygen Hypoxemia for any reason (pulmonary contusion, atelectasis, pneumonia, etc.) requiring > 3 liters supplemental oxygen at the time of entry into the study Inability to tolerate the confines of the chamber

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Traumatic Pneumothorax1<br>hypobaric chamber | Other: hypobaric chamber<br>* We will use a large (26 tons) multi-place hyperbaric and hypobaric chamber at IMC in Murray, Utah (elevation 1500m or 4500ft, average ambient barometric pressure 645mm Hg). In the hypobaric study, the barometric pressure will be lowered to 554mm Hg (phase 1) or 471mm Hg (phase 2) over 20 minutes and held there for two hours.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in pneumothorax size | Will document pneumothorax size before simulated altitude, and size after being at simulated altitude for two hours | baseline and 2 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pneumothorax, trauma, commercial air travel