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Carbon Monoxide to Prevent Lung Inflammation

This study has been completed.
Information provided by (Responsible Party):
National Institutes of Health Clinical Center (CC) Identifier:
First received: October 16, 2004
Last updated: April 19, 2017
Last verified: April 19, 2016

This study will examine in healthy volunteers how breathing carbon monoxide (CO) affects lung inflammation. Severe lung inflammation sometimes develops in patients with pneumonia or patients who develop serious blood stream infections. Studies in the laboratory and in animals show that CO can decrease lung inflammation.

Healthy volunteers between 18 and 40 years of age who do not smoke, are not taking any medications, do not have asthma, are not allergic to sulfa- and penicillin-based drugs, and are not pregnant may be eligible for this study. Candidates are screened with a medical history and physical examination, blood and urine tests, electrocardiogram (EKG), and chest x-ray. Subjects are enrolled in either a pilot study or the main study.

Participants undergo bronchoscopy and bronchoalveolar lavage to study the effects of endotoxin (a component of bacteria that causes inflammation similar to that in patients with lung infections) on lung function. Before the procedure, a small plastic tube (catheter) is placed in a vein to collect blood samples and another is placed in an artery to check blood pressure. For the bronchoscopy, the mouth and nasal airways are numbed with lidocaine, and a bronchoscope (thin flexible tube) is passed through the nose into the airways of the lung. A small amount of salt water is squirted through the bronchoscope into one lung and then salt water containing endotoxin is squirted into the other lung.

Following the bronchoscopy, subjects are treated with either CO or room air (placebo) for 6 hours. (Subjects in the pilot study receive treatment for only 3 hours). The gas is delivered through a cushioned mask placed over the nose and mouth. The amount of exhaled CO is measured before, during, and after inhalation of the gas. For this measurement, subjects take a deep breath to fill up their lungs and slowly exhale into a mouthpiece connected to a measuring device until they feel their lungs are empty.

After the CO treatment, a second bronchoscopy is done to examine how the lung responded to the CO or room air. This is studied in two ways. To sample the air, a large needle is used to withdraw air through the bronchoscope over about 3 seconds. Then the areas of the lung that were squirted with salt water alone and with endotoxin and salt water and are rinsed (lavage) and cells and secretions are collected.

Condition Intervention Phase
Respiratory Distress Syndrome, Adult
Procedure: Bronchoscopy
Procedure: Bronchoalveolar lavage
Drug: Endotoxin
Drug: Carbon Monoxide
Phase 1

Study Type: Interventional
Study Design: Allocation: Randomized
Masking: Single Blind (masked role unspecified)
Primary Purpose: Treatment
Official Title: Effects of Inhaled Carbon Monoxide on Pulmonary Inflammatory Responses Following Endotoxin Instillation

Resource links provided by NLM:

Further study details as provided by National Institutes of Health Clinical Center (CC):

Enrollment: 35
Study Start Date: October 13, 2004
Study Completion Date: March 11, 2010
Primary Completion Date: March 11, 2010 (Final data collection date for primary outcome measure)
Detailed Description:

Acute respiratory distress syndrome (ARDS) is a major cause of morbidity and mortality. Of the many potential predisposing factors, sepsis and pneumonia represent the two main causes of ARDS. In spite of an increase in survival in recent years mortality in patients with ARDS is still estimated around 30 to 40%. In this context, development of effective preventive strategies in patients at high risk of development of ARDS is of paramount importance. Unfortunately, the results of studies evaluating prophylactic regimens for ARDS have been mostly disappointing.

The gaseous molecule carbon monoxide (CO) has been traditionally viewed as a toxic metabolic and industrial waste. However, recent studies have demonstrated an important physiologic role of CO in many biological systems. Specifically, strong anti-inflammatory, anti-oxidant and anti-thrombotic effects of CO gas administration and heme oxygenase activation (the enzyme that generates endogenous CO gas) have been demonstrated in several animal models.

Previous studies conducted in our department have demonstrated that bronchoscopic instillation of endotoxin (LPS) in healthy volunteers elicits a compartmentalized pulmonary inflammatory response, serving as an excellent model to evaluate interventions directed towards suppression of lung inflammation at its earliest stages.

In the current single blinded, randomized, placebo controlled study, we are planning to evaluate the effects of inhaled carbon monoxide on local pulmonary inflammatory responses following endotoxin administration. Healthy subjects will undergo local endotoxin instillation, breathe CO or room air through a mask for 6 hours, and then a repeat bronchoscopy with lavage will be done at 6 hours to assess the ability of CO to suppress local inflammation in the lung.


Ages Eligible for Study:   18 Years to 40 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

All volunteer subjects, employees and non-employees, must 18 to 40 years of age and must be able to provide informed, written consent for participation in this study. We will not directly advertise the study to employees to avoid the potential for coercion. Eligibility in the study is determined prior to enrollment on the basis of the following inclusion and exclusion criteria.

Normal screening examination including:

  1. medical history and physical examination, nonsmoker, no concurrent medications including aspirin or nonsteroidal anti-inflammatory drugs, no active medical problems
  2. complete blood count with differential and platelet counts
  3. serum chemistries including creatinine, blood urea nitrogen, glucose, liver enzymes and function tests, electrolytes, prothrombin time, partial thromboplastin time, carboxyhemoglobin measured by venous co-oxymetry.
  4. urinalysis
  5. female subjects must have negative urine pregnancy test within one week of participation (this will be repeated immediately prior to beginning the screening procedures due to radiation exposure from the chest x-ray)
  6. electrocardiogram
  7. chest radiograph

Sexually active females not using contraceptive methods will be instructed to abstain from sexual activity or use barrier contraception methods from the time of last negative pregnancy test to 24 hours after completion of the study.


  1. active tobacco use
  2. baseline caroxyhemoglobin greater than 2%
  3. pregnancy
  4. lactation
  5. medical history of recent clinically significant asthma allergy to both sulfa- and penicillin-based drugs
  6. Allergy to both sulfa- and penicillin-based drugs.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00094406

United States, Maryland
National Institutes of Health Clinical Center, 9000 Rockville Pike
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
National Institutes of Health Clinical Center (CC)
Principal Investigator: Anthony F Suffredini, M.D. National Institutes of Health Clinical Center (CC)
  More Information

Responsible Party: National Institutes of Health Clinical Center (CC) Identifier: NCT00094406     History of Changes
Other Study ID Numbers: 050012
Study First Received: October 16, 2004
Last Updated: April 19, 2017

Keywords provided by National Institutes of Health Clinical Center (CC):
Lung Permeability
Endotoxin Tolerance
Carbon Monoxide Inhalation

Additional relevant MeSH terms:
Carbon Monoxide
Respiratory Distress Syndrome, Newborn
Respiratory Distress Syndrome, Adult
Acute Lung Injury
Lung Diseases
Respiratory Tract Diseases
Respiration Disorders
Infant, Premature, Diseases
Infant, Newborn, Diseases
Lung Injury
Molecular Mechanisms of Pharmacological Action
Neurotransmitter Agents
Physiological Effects of Drugs processed this record on April 24, 2017