I'm a recreational scuba diver and medical doctor in Anaesthesia and Intensive care. I've recently become interested in free diving and particularly the medical issues and physiology. Was interested to hear if anyone was using heliox or trimix prior to NLT dives. From my reading of the AIDA regulations in NLT diving the only rule with regards to breathing gases reads "Any inhalation of oxygen and/or highly oxygenated mixtures 60 minutes prior to the athlete's performance is forbidden." Therefore to my reading a diver could breathe heliox with a normal oxygen level eg 21% O2/79% helium prior to a dive. This should reduce substantially the risk of nitrogen narcosis and DCS. An additional advantage is that helium is of such low density it flows through small passages much more easily and so is significantly easier to equalize via the eustachian tubes.
Are there any reasons i've missed either physiological/medical or due to the sport's rules and regulations that prevent NLT divers from using such methods or make them inadvisable?
Are there any reasons i've missed either physiological/medical or due to the sport's rules and regulations that prevent NLT divers from using such methods or make them inadvisable?