Clinical trial NCT01587209: Microparticles in Scuba Divers With Decompression Sickness
Official title: Phase 1 Study Investigating Alterations of Circulating Microparticles in Scuba Divers With Decompression Sickness
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Decompression Sickness
Dysbarism
Keywords: decompression
intravascular bubbles
neutrophil activation
Lead sponsor: University of Pennsylvania
Sponsor class: OTHER
Collaborators: name: Office of Naval Research (ONR)
name: University of Maryland
First posted: 2012-04-30
Enrollment: 1
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: CASE_ONLY
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: SCUBA divers over age 21 that present for evaluation of suspected decompression sickness

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.

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

Primary outcomes:
measure: Microparticle elevations in injured divers
timeFrame: four years
Secondary outcomes:
measure: Microparticle sub-types in injured divers
timeFrame: four years
measure: Neutrophil activation in injured divers
timeFrame: four years
Other outcomes:
Locations:
city: Philadelphia
country: United States
facility: University of Pennsylvania
state: Pennsylvania
Study officials:
affiliation: University of Pennsylvania
name: Stephen R Thom, MD,PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Thom SR, Yang M, Bhopale VM, Huang S, Milovanova TN. Microparticles initiate decompression-induced neutrophil activation and subsequent vascular injuries. J Appl Physiol (1985). 2011 Feb;110(2):340-51. doi: 10.1152/japplphysiol.00811.2010. Epub 2010 Oct 21.
citation: Yang M, Milovanova TN, Bogush M, Uzun G, Bhopale VM, Thom SR. Microparticle enlargement and altered surface proteins after air decompression are associated with inflammatory vascular injuries. J Appl Physiol (1985). 2012 Jan;112(1):204-11. doi: 10.1152/japplphysiol.00953.2011. Epub 2011 Sep 29.
citation: Thom SR, Milovanova TN, Bogush M, Bhopale VM, Yang M, Bushmann K, Pollock NW, Ljubkovic M, Denoble P, Dujic Z. Microparticle production, neutrophil activation, and intravascular bubbles following open-water SCUBA diving. J Appl Physiol (1985). 2012 Apr;112(8):1268-78. doi: 10.1152/japplphysiol.01305.2011. Epub 2012 Feb 9.