Microparticles in Scuba Divers With Decompression Sickness

Study Overview
=================
Brief Summary
-----------------
The investigators hypothesize that membrane microparticles (MPs) are liberated into the blood stream in response to decompression stress and that certain MPs characteristics initiate inflammatory responses that contribute to the clinical syndrome the investigators call decompression sickness. The research goal is to evaluate the number, type and time-course for elevations in MPs in sport SCUBA divers who present for treatment of decompression sickness. Blood samples are to be taken from consenting patients before and after they undergo treatment for decompression sickness and at a follow-up clinic visit from 1 to 3 weeks later (three samples total).

Detailed Description
-----------------
Microparticles (MPs) are small membrane bound vesicles shed from the surface of a variety of cells by what appear to be well regulated processes. They are elevated in many physiological and disease states and in some instances have been associated with organ injury. Shear stress - as can be caused by intravascular bubbles - is one of the stimuli known to cause cells to release microparticles. Most sport SCUBA dives have been shown to generate intravascular bubbles - even safe dives well within limits established by the US Navy and sports authorities. The investigators have reported elevations in several sub-types of MPs in a group of individuals undergoing a well monitored series of open-water SCUBA dives. There is no information of the occurrence of MPs in injured divers. The investigators have published results using a murine model which demonstrated that mice subjected to varying decompression stresses exhibit progressive elevations in circulating MPs derived from leukocytes, erythrocytes, platelets and endothelial cells. Using novel interventions the investigators demonstrated that MPs cause intravascular neutrophil activation and inflammatory perivascular injuries. Therefore, there is pathophysiological information to suggest that one or more element of MPs (number and/or pro-inflammatory subtype) may be proximal elements that precipitate the clinical syndrome the investigators call decompression sickness.

Official Title
-----------------
Phase 1 Study Investigating Alterations of Circulating Microparticles in Scuba Divers With Decompression Sickness

Conditions
-----------------
Decompression Sickness, Dysbarism

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients who are given the diagnosis of decompression sickness will be offered entry into this study Exclusion Criteria: Inability to provide informed consent

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Divers with decompression sickness<br>The sole group under study is SCUBA divers who have sustained decompression sickness | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Microparticle elevations in injured divers | We will quantify microparticles in plasma by standard flow cytometry techniques. | four years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Microparticle sub-types in injured divers | We will evaluate sub-types of microparticles to determine their cells of origin. | four years | 
| Neutrophil activation in injured divers | We will evaluate presence of neutrophil activation in injured divers. | four years | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
decompression, intravascular bubbles, neutrophil activation