Co.De. 1 Compression and Decompression Stress in Diving: How are gases differentially managed in the brains of BHD and SCUBA?
Abstract
During military diving, a mix of immersion techniques can be used to meet specific tactical needs, but personnel can be exposed to several stressors, such as cold water, demanding physical activity, and repetitive compression and decompression. This proposal aims to investigate how single or repeated exposures during BHD VS SCUBA: (1) interact with the lungs and their gas exchange capacity, causing lung parenchymal and arterial partial pressure of oxygen alterations; (2) result in different predispositions to develop decompression illness (DCI); (3) modify gas distribution and management in arterial blood and in the brain, causing cognitive impairment. The project consists of four steps (two at 15 msw, two at 40 msw), over a two-year period and has been already approved by the local ethics committee (HEC-DSB/03-18; addendum 11/2022 included procedures in open waters).The first step will involve 10 healthy and trained breath-hold divers. After warm-up, divers will be asked to perform a 15 msw dive, during which arterial blood samples will be collected: i) immediately before the dive, after the last breath; ii) at 15; iii) at the surface, immediately before the break of apnea with the face still submerged. Then BH-divers will perform five dives at 15 msw for two days. same protocol of the first experimental dive will be performed. In the second step, 10 healthy and trained SCUBA divers breathing compressed air will reach a depth of15 msw (49.2 fsw) and will perform a standardized 10-minute exercise on an underwater bicycle. Blood samples will be collected: i) at the surface, with both body and face submerged, at rest; ii) at the bottom, before the exercise; iii) at the bottom, after the exercise; iv) at the surface. After the exercise at depth, divers will conduct an underwater 5 minute cognitive task. Then SCUBA divers will perform two dives with exercise for two days at 15 msw. Measurements will include arterial pH, O2 and CO2 partial pressures, lactate, brain neurotrametters biomarkers (i.e. glutamate, GABA, dopamine), BDNF, GFAP, pro-inflammatory MPs, neutrophil activation, and biomarkers of local (alveolar epithelial) and systemic inflammation (i.e. IL-6, IL-10, TNF-a; SP-D and sRAGE). MBs formation will be assessed through a portable Doppler apparatus before and after the dives. Chest ultrasound will be performed before, at depth before and after the exercise, and immediately after the dive to detect atelectasis and interstitial pulmonary edema. Continuous measurements of cerebral blood oxygenation, cerebral blood volume, heart rate and SpO2 will be collected via a wearable marinized NIRS device. In step 3 and step 4, breath-hold divers and SCUBA divers (respectively) will perform the same procedures as described in step 1 and step 2 (respectively) but at 40 msw (131.2 fsw), except for lung ultrasound. From previous experiments and from the experience of the research group we expect that: some breath-hold divers will develop a paradoxical relative hypoxemia at the bottom due to lung atelectasis; biomarkers of decompression stress will be different between SCUBA and breath-hold divers, but significantly increased after repetitive diving in both groups; BDNF/glutamate axis alterations and cognitive impairment will be detected at depth in parallel with gas and brain blood distribution derangements. The results will provide insight and allow comparisons between BHD and SCUBA diving, also significantly adding to the understanding of gas exchange and diver safety. Also, insights into repetitive diving, in open seawaters, will shed light and improve the safety of Navy personnel involved in training activities and active duty or deployment. (approved for public release by Prof. G. Bosco)
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2023
- Source ID
- N000142312757
Entities
People
- Gerardo Bosco
Organizations
- Office of Naval Research
- United States Navy
- University of Padua