Where is the gas? A new method to study nitrogen during diving and decompression: FY2019-000313-AS
Abstract
A century of study has not been able to identify the causal mechanism of decompression sickness (DCS). We propose a new quantitative method to study Nitrogen gas (N2) in mammals. Decompression sickness is currently hypothesized to be caused by bubble formation in tissues. However, due to the lack of direct methods to track tissue gas, the field has used indirect methods such as ultrasound of venous gas emboli (VGE) in the heart and mathematical modelling based on empirical testing in human divers. Current methods topredict DCS are based on statistical probability with relative risk factors such as depth and duration. It has not yet been possible to determine the causal mechanisms and explain the intra- and interindividual variability present in DCS, suggesting that a direct method to map tissue gas distribution is a priority, as it has the potential to refine risk assessment and contribute to optimizing diving profiles.We will use a radioactive, positron-emitting isotope of Nitrogen (13N2) that can be breathed in a hyperbaric chamber and monitored in time and space using positron-emission tomography (PET) combined with magnetic resonance imaging (MRI). With 13N2, we can quantitatively measure the Nitrogen distribution in the body. 13N2 has previously been produced and used in normobaric experiments with human volunteers, and a hyperbaric chamber can be constructed to inhale the gas during compression (simulated diving), widening applicability to hyperbaric breathing. We hypothesize that tissue gas bubbles will create bright spots while gas in solution will generate a signal equivalent to that tissues saturation with Nitrogen. This new method would allow to answer the gas localization question, and address the impact of preconditioning on the amount of venous gas emboli after decompression. This approach will open a window to study basic mechanisms and impact of interventions related to DCS in both animals and humans.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 31, 2020
- Source ID
- N000142012763
Entities
People
- Peter Lindholm
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego