Clinical trials showed that using perflubron with ordinary ventilators improved outcomes as much as using high frequency oscillating ventilation (HFOV). But because perflubron was not better than HFOV, the FDA did not approve perflubron, and Alliance is no longer pursuing the partial liquid ventilation application. Whether perflubron would improve outcomes when used with HFOV or has fewer long-term consequences than HFOV remains an open question. In 1996 Mike Darwin and Steven B. Harris proposed using cold liquid ventilation with perfluorocarbon to quickly lower the body temperature of victims of cardiac arrest and other brain trauma to allow the brain to better recover. The technology came to be called gas/liquid ventilation (GLV), and was shown able to achieve a cooling rate of 0.5 °C per minute in large animals. It has not yet been tried in humans. Most recently, hypothermic brain protection has been associated with rapid brain cooling. In this regard, a new therapeutic approach is the use of intranasal perfluorochemical spray for preferential brain cooling. The nasopharyngeal (NP) approach is unique for brain cooling due to anatomic proximity to the cerebral circulation and arteries. Based on preclinical studies in adult sheep, it was shown that independent of region, brain cooling was faster during NP-perfluorochemical versus conventional whole body cooling with cooling blankets. To date, there have been four human studies including a completed randomized intra-arrest study (200 patients). Results clearly demonstrated that prehospital intra-arrest transnasal cooling is safe, feasible and is associated with an improvement in cooling time. Proposed uses Diving Gas pressure increases with depth, rising 1 bar () every 10 meters to over 1,000 bar at the bottom of the Mariana Trench. Diving becomes more dangerous as depth increases, and deep diving presents many hazards. All surface-breathing animals are subject to decompression sickness, including aquatic mammals and free-diving humans (see taravana). Breathing at depth can cause nitrogen narcosis and oxygen toxicity. Holding the breath while ascending after breathing at depth can cause air embolisms, burst lung, and collapsed lung. Special breathing gas mixes such as trimix or heliox reduce the risk of nitrogen narcosis but do not eliminate it. Heliox further eliminates the risk of nitrogen narcosis but introduces the risk of helium tremors below about . Atmospheric diving suits maintain body and breathing pressure at 1 bar, eliminating most of the hazards of descending, ascending, and breathing at depth. However, the rigid suits are bulky, clumsy,