9 Clinical Trials for Various Conditions
To evaluate the efficacy of using a pre-dive checklist to prevent the incidence of diving mishaps in recreational divers.
In summary, the investigators propose to study elite Croatian breath-hold and SCUBA divers. The investigators will quantify breath-hold hypoxia- and SCUBA diving-induced pulmonary hypertension and right heart function to investigate the relationships between PFO and IPAVA blood flow. The investigators will use a placebo-controlled intervention (sildenafil) to reduce pulmonary arterial pressure in these subjects to examine the impact of the change in pressure (or absence of change) on the relationships determined above.
The aims of this proposal are to test current USN procedures for adjusting decompression procedures during air diving at 8,000 and 10,000 ft altitude and to provide a decompression algorithm for no-stop dives to 100 feet of sea water (fsw) at 10,000 and 12,000 ft altitude using enriched O2 (PO2=1.3 ATM). Additionally, the experiments will determine whether a period of hyperbaric hyperoxia, such as would be experienced during a dive at altitude, reverses altitude acclimatization, resulting in a return of acute mountain sickness (AMS) symptoms.
SCUBA diving frequently involves repetitive exposures over multiple days. The goal of this study was to see how exercise impacts microparticles (MPs), endothelial function, and venous gas emboli (VGE) over a series of dives. 16 divers in 2 groups each completed 6 dives. One group completed 3 control dives followed by 5 days rest then 3 dives preceded by exercise. The other group completed the opposite protocol. Flow-mediated dilation (FMD) data and blood for MP analysis was collected before and after each dive. VGE were monitored via transthoracic echocardiography 30, 60, and 90 min after surfacing. Exercise before diving consisted of 60 min running outdoors including 8x4 min intervals at 90% VO2max effort.
The purpose of this study is to determine the impact of high intensity,anaerobic exercise, in the form of cycling, on SCUBA diving. Outcomes are determined by the quantification and subtype of circulating microparticles, complete blood counts, and the quantification of venous gas emboli, measured via transthoracic echocardiography, in the cardiac cavities.
This trial is testing the effectiveness of a single oral dose of sildenafil (50 mg) taken 1 hour before a provocative event on the subsequent development of swimming-induced pulmonary edema.
The investigators will simulate the conditions of a working, helmeted diver by using exercising, "head out" immersed subjects to test the following hypotheses: 1. An algorithm can be developed which predicts cognitive performance in immersed exercising divers, based on the exhaled carbon dioxide (PETCO2) and the diver's inspired partial pressures of oxygen and nitrogen (PIO2 and PIN2). 2. PETCO2 using mass spectrometry is an accurate estimate of arterial carbon dioxide (PaCO2) at rest and during immersed exercise and can be used as a PaCO2 surrogate at levels exceeding 50 mmHg and depths up to 158 fsw (gas density 6.4 g/l, similar to 165 fsw density of 6.8 g/l).
This study will determine if newly developed and more standard tests of Eustachian tube function can identify those persons who have ear pain (barotrauma) or develop middle-ear inflammation and/or fluid (barotitis) when they are exposed to rapid changes in air pressure as, for example, during airplane flights or scuba diving. Up to 150 adults and children (10-50 years old) who fly or dive at least 1-2 times and experience ear pain or develop middle-ear fluid during those activities and approximately 60 adults and children who fly or dive but do not experience these problems will undergo Eustachian tube function testing during simulated flight and diving.
Immersion pulmonary edema (IPE) is a condition in which fluid fills the lungs during diving or swimming, particularly in cold water. Some individuals appear to be predisposed to developing IPE. DNA samples will be collected and stored, in order to compare the genetic profiles of individuals who have experienced IPE with those who have not. In a few individuals who have experienced IPE, we plan to measure the effects of cold water immersion on the blood pressure, cardiac output and the pressures in the pulmonary artery. These will be compared with similar measurements already obtained from normal individuals.