EUBS 2017 has left us with more questions than answers, on the topic of post-dive bubbles.
Ballestra presented the preliminary results of an exploratory study of the effects of sonic vibrations on post-dive venous gas emboli detected by transthoracic echocardiography1. (more…)
Recompression treatment and hyperbaric oxygen (HBOT) are standard treatment for decompression illness. While it is generally accepted that sooner recompression is associated with better outcomes, the urgency of treatment may not be same for all cases. Looking for practical guidelines we regularly consult published case series. Three case series presented at EUBS 2017 may be used to illustrate problems with such approach. (more…)
Immersion pulmonary edema (IPE) continues to be a central focus of dive medicine researchers and clinicians. Late last week, at the 2017 EUBS Annual Meeting, four scientists presented five different studies on the subject.
It appears that IPE is significantly more common than previously reported. In a two year period (2014-16) one hyperbaric facility in Cozumel diagnosed 40 cases of IPE among recreational scuba divers1. On the other side of the world, there were 21 cases of IPE reported among French military rebreather divers in a six year period2. (more…)
Decompression sickness is caused by gas bubbles that form in the body during and after decompression. The current thought is that gas bubbles originate on the venous side and pass to the arterial side either through intra-cardiac (PFO) or intra-pulmonary shunt (arteriovenous anastomoses). A group of scientists proposed recently a third mechanisms: the evolution of bubbles in the distal arteries, independent of venous gas bubbles.(1) They presented their work at the EUBS 2017 meeting (2) in Ravenna. (more…)
Apple Inc. recently announced the release of ResearchKit, an open-source software framework that is expected to enhance medical research. Apple claims its product enables everyone to take part in research that will advance medical knowledge and that it is “taking research out of the lab and into the real world.”
Mobile health technology, including wearable sensors and mobile applications, has been available for some time. Companies have been developing mobile medical applications (MMAs) for so long that the U.S. Food and Drug Administration (FDA) has already established their classifications and safety-monitoring rules and the Federal Communications Commission (FCC) has established rules and the frequency band for use with wireless body sensors. While it appears that Apple actually was lagging behind, it is encouraging that it finally joined the trend.
A popular article over last few days is one about crystalline salt that can uptake and store oxygen in high concentration. It was published in Chemical Science by Jonas Sundberg and coauthors from University of Southern Denmark.1 The article describes a synthetized crystalline containing cobalt combined with an organic compound, which has some properties of biological carriers of oxygen like iron-based hemoglobin in mammals or similar copper-based carriers in other animals.
The most significant property of this crystalline is that it binds oxygen reversibly – it can uptake oxygen and release it – and that this process may be controlled. Professor Christine McKenzie, the leader of the team that synthetized the crystalline, told the Science Daily2 that among other applications: “When the material is saturated with oxygen, it can be compared to an oxygen tank containing pure oxygen under pressure – the difference is that this material can hold three times as much oxygen. This could be valuable for lung patients who today must carry heavy oxygen tanks with them. But also divers may one day be able to leave the oxygen tanks at home and instead get oxygen from this material as it “filters” and concentrates oxygen from surrounding air or water. A few grains contain enough oxygen for one breath, and as the material can absorb oxygen from the water around the diver and supply the diver with it, the diver will not need to bring more than these few grains.”
(more…)
Office of Naval Research 2014
While vacationing in Croatia, I heard a story about a diver who fits the description of people I sometimes call “robo-divers.” The story’s hero is a famous Croatian sponge diver, with whom I share an acquaintance. My friend, who is one of his teammates, described this robo-diver’s practice, which is similar to previously described empirical dive practices of other local sponge divers: Reportedly, he does four descents per day to extreme depths, after each of which he ascends very slowly without decompression stops. After the last dive of the day, he quickly takes his boat to shallow waters (within approximately 10 minutes) and descends for about two hours of decompression, split between stops at nine, six and three meters (30, 20 and 10 feet).
I don’t know about his decompression sickness history, but I do know that he is 64 years old now, and the fact that he has survived this long following those types of dive practices make me think of him more as a robot than as a man of flesh and bone. At very least, it is unlikely that this diver has a PFO.
Last April, a Canadian woman named Stacey Yepes experienced stroke symptoms, but by the time she made it to the hospital her symptoms were gone. Because her physicians could not find any signs of stroke, they believed that she was displaying symptoms of stress and released her home. A few days later, she had a similar attack and used her phone to tape herself during an episode in which she suffered from facial drooping and slurred speech. The video helped her doctors diagnose her with TIA (transient ischemic attack).
In many cases of diseases with transitory symptoms, physicians are unable to diagnose patients and opportunities for early treatments are missed. In the case of TIA, it is especially important to establish an early diagnosis and provide treatment to prevent the progression of symptoms and permanent loss of brain tissue. TIA can lead to blood clotting in the brain, but early administration of thrombolytic medication can prevent clotting and brain damage. Because of the transitory nature of TIA symptoms, some hospitals offer stroke telemedical consultations to enhance diagnosis of and establish early eligibility for thrombolytic medication. By using video connections, they establish a correct diagnosis in 96% of cases, as compared with only 83% of cases in which symptoms are only reported by phone.
During the ONR-NAVSEA Progress Review Meeting that took place in Durham from July 15-17 this summer, Stephen Thom summarized the current status of his research on circulating microparticles (MPs), which are small fragments shed by various cells that have been exposed to stress. These MPs can be found in subjects with inflammation or injury and in divers after diving.
Between July 15-17, the Office of Naval Research (ONR) and the Naval Sea Systems Command (NAVSEA) hosted an undersea medicine progress review meeting in Durham, North Carolina. The presentations focused primarily on topics of interest for the Navy, but most of the research also benefits recreational and technical divers. One topic I found particularly interesting concerns the combined effect of increased carbon dioxide levels (CO2) in breathing gas and the breathing resistance that breathing apparatuses impose on divers.
If breathing is unimpeded, slightly increased levels of CO2 pose no problem. However, the more CO2 that is inhaled, the less CO2 can be added, and a larger breathing volume per unit of time will be required to wash out the same amount of CO2. This increase of breathing volumes occurs automatically, successfully washing out the metabolic CO2 and maintaining a nearly normal level of CO2 in arterial blood (even during exercise when the internal metabolic production of CO2 is increased).
The Dive Lab 