oxygen toxicity

Do Viagra and other PDE5 Inhibitors Increase the Risk of DCS in Humans?

Phosphodiesterase type 5 (PDE5) inhibitors — such as Viagra, Cialis, Levitra, Vivanza, Mvix and Lodenafil — are a class of popular drugs prescribed to treat erectile dysfunction and are often sold on the black market as sexual-function enhancers. It is reasonable to assume that many divers use PDE5 inhibitors while on a diving vacation, although the drugs’ possible effects on decompression safety have not been studied previously. In a recent paper, Blatteau et al.1 presented the results of a study on rats treated with sildenafil (Viagra) and then exposed to a simulated dive.


Sensors and Senses

In January 2015 engineers from the Creativity Lab at Samsung Electronics introduced a prototype of a smartphone application and device called the Early Detection Sensor & Algorithm Package (EDSAP) as a stroke-detection tool. After two years of development, they are close to delivering the product. EDSAP’s sensors, which are applied to the head via a headset, collect electrical waves caused by brain activity and wirelessly transfer the information to a smartphone application that analyzes the data and determines the threat of stroke. The developers hope the data can provide additional health information such as stress levels, anxiety and quality of sleep.


Can Crystalline Salt Reduce the Size of Scuba Equipment?

safe diver quiz

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.”

Sex and Sensitivity to Oxygen Toxicity


The most feared manifestation of acute oxygen toxicity is a loss of consciousness and tonic-clonic convulsions (seizures). The threat of oxygen-induced seizures in scuba diving becomes real when the partial pressure of the breathing gas exceeds 1.6 bars. It is known that exercise, carbon dioxide and immersion increase risk of seizures; thus, the working diver should limit oxygen in their breathing gas to 1.2 bars.

The recent paper by Heather Held, “Female rats are more susceptible to central nervous system oxygen toxicity than male rats,” presents data of an experimental study on rats which shows that females have a lower threshold for oxygen convulsions. Age, weight and hormonal status did not show obvious effect on sensitivity to oxygen toxicity.