The Nitrogen Saturation Myth

I work as a divemaster on a small island. Last weekend some of my coworkers went to the local chamber for “washout treatments,” despite not having any symptoms. We all dive a lot, but I’d never heard of anything like that before. Is that something I should do? 
 There is a misconception among some divers – particularly recreational dive professionals and fisherman divers — that a degree of tissue nitrogen saturation will occur over weeks or months of frequent diving activity. Some of these divers believe they may benefit from occasional “washout treatments” in a hyperbaric chamber, but that is a fallacy. Such a concept is completely at odds with all credible diving and decompression research and is inconsistent with informed clinical practice standards.

 Efforts to determine the origin of this misunderstanding have thus far proven unsuccessful. Similarly, there are reports of chamber operators actually propagating this myth by offering routine “nitrogen desaturation treatments” – for a price, of course. Decompression sickness (DCS) can certainly manifest as musculoskeletal pain, so any such presentation within 24 hours of diving would warrant prompt evaluation and perhaps treatment in a chamber. However, while chronic pain has many possible causes, diving-related trapped nitrogen is not one of them. Inert gas uptake and elimination during air, nitrox and heliox diving will obey both Dalton’s and Henry’s gas laws.

Should bubbles be produced upon decompression (whether there are symptoms of DCS or not), then Boyle’s law also comes into play. Asymptomatic bubbles may remain in tissues for a day or so at most. Throughout the compression phase of a dive and while at depth, the associated increase in inert gas pressure in the breathing gas is delivered to the diver’s lungs (Dalton’s law). From there it is gradually taken up by the blood and delivered to the body’s various tissues (Henry’s law).

The rate of inert gas uptake in the blood and other tissues depends on several variables. Key among them are speed of compression, type of inert gas breathed and its related solubility coefficient, body temperature, inherent tissue perfusion and level of exercise or workload. In recreational diving, nitrogen uptake essentially ends once the diver begins his ascent to the surface. I say “essentially” because the body’s “slower” tissues – those that are less well perfused or are supported by simple diffusion, for instance – may continue to take on nitrogen during the early and intermediate stages of ascent if their nitrogen pressures remain lower than the blood’s.

Thus, nitrogen in the blood will continue to transfer into these tissues until such time that blood nitrogen levels fall to the level of those tissues. It is at this point that slower tissues will begin off-gassing. This is why it is important that ascents be mostly direct and largely linear. Divers who slowly meander back to the surface may accumulate levels of nitrogen in certain tissues in excess of those assumed by decompression tables. In this way, repetitive dives can lessen the protective capabilities of the table in use.

If a diver remains at depth more than 12 to 18 hours (in a seafloor habitat or a commercial oilfield saturation-diving complex, for example), all of their tissues – fast, intermediate and slow – will re-equilibrate with nitrogen (or helium) at the new depth. This is called saturation diving. Except for tiny variations that may occur with body temperature fluctuations, it is physiologically impossible for any additional inert gas to be taken up without further change in depth. When a diver ascends from a saturation dive, inert gas elimination occurs in the same manner as it does at the end of a recreational dive, as described by Henry’s and Dalton’s gas laws.

Once a diver has returned to the surface, regardless of whether the dive was a short recreational dive or a long saturation dive, all tissue inert gas in excess of normal atmospheric pressure will be eliminated over the following 12 to 18 hours (in other words, his body’s tissue nitrogen levels will be re-equilibrated to the ambient atmospheric pressure). After that period, no additional nitrogen above normal atmospheric (sea level) pressure will remain in the body. Residual nitrogen is never “trapped” in the body, so there is absolutely no basis to treat divers for chronic nitrogen saturation. It is a misunderstanding at best, and a hoax perpetrated on divers at worst. Don’t fall for this. -  Dick Clarke, President, National Baromedical Services

Article from Alert Diver Lite 2018-2019


After anaesthesia Air Quality Air exchange centre Air hose failure Altitude changes Altitude sickness Ama divers Anaerobic Metabolism Annual renewal Apnea Apnoea Arterial gas embolism Arthroscopic surgery Aurel hygiene BCD Badages Bag valve mask Bandaids Barbell back squat Bench press Blood flow Bouyancy compensators Boyle's Law Boyle\'s Law Bradycardia Brain Breast Cancer Breath Hold Diving Breath hold Breath-hold Breathing Gas Breathing Bruising Buoyancy Burnshield CGASA CMAS CO2 Cabin pressure Camera settings Cancer Remission Cancer treatments Cancer Cannabis and diving Cannabis Cape Town Dive Festival Carbon dioxide Cardio health Cardiomyopathy Chamber Safety Charles' Law Charles\' Law Charles\\\' Law Charles\\\\\\\' Law Charles\\\\\\\\\\\\\\\' Law Chemotherapy Cleaning products Coastalexcursion Cold Water Cold care Cold Compressed gas Conservation Contaminants Contaminated air Corals Courtactions Crohns disease Crystal build up Crystallizing hoses Cutaneous decompression DAN Courses DAN Profile DAN Researchers DAN medics DAN report DCI DCS Decompressions sickness DCS DM training DReams Dalton's Law Dalton\'s Law Dalton\\\'s Law Dalton\\\\\\\'s Law Dalton\\\\\\\\\\\\\\\'s Law Deco dives Decompression Illness Decompression Sickness Decompression illsnes Decompression treatment Decompression Diaphragms Diseases Dive Chamber Dive Industry Dive Instruction Dive Instructor Dive Pros Dive Research Dive Training Dive accidents Dive buddies Dive computers Dive gear Dive health Dive medicines Dive medicine Dive safety Dive staff Diveleader training Diveleaders Diver Profile Divers Alert Diving Kids Diving career Diving emergencies Diving guidelines Diving injuries Diving suspended Diving Domestic Donation Dr Rob Schneider Drysuit diving Drysuit valves Drysuits EAPs EAP Ear pressure Ear wax Ears injuries Education Emergency action planning Emergency decompression Emergency plans Emergency underwater Oxygen Recompression Emergency Enviromental Protection Environmental factors Environmental impact Environmental managment Equipment care Evacuation Exercise Extended divetime Extinguisher Extreme treatments Eye injuries FAQ Failures Fatigue Faulty equipment Fire Coral Fire Safety Firefighting First Aid Equipment First Aid Training First Aid kits Fish Fitness Flying Francois Burman Free diving Free flow Freedive Training Freediver Freediving performance Gas Density Gas laws Gas mixes GasPerformance Gases Gastric bypass Gear Servicing Gordon Hiles HELP HIRA Haemorhoid treatment Hazard Description Hazardous Marine life Health practitioner Heart Health Heart Helium High temperatures Hot Humans Hydrate Hydrogen Hydroids Hydrostatic pressure Hyperbaric Chamber Hyperbaric research Hypothermia Immine systems In Water Recompression Indemnity form Indian Ocean Inert gas Infections Instinct Instructors Insurance Integrated Physiology International travel International Irritation Kidneys Kids scubadiver Labour laws Legal advice Legislation Leukemis Liability Risks Liability releases Liability Life expectancy Lifestyle Low blood pressure Low pressure deterioration Low volume masks Lung function Lung injuries Lung MOD Maintenance Mammalian Dive Response Mammalian effect Master scuba diver Maximum operating depth Medical Q Medical questionaire Medical statement Middle ear pressure Mike Bartick Military front press Mixed Gas Mono Fins Mooring lines More pressure Muscle pain Mycobacterium marinum Nautilus Nitrogen build up Nitrox No-decompression Non-rebreather Mask Normal Air Nosebleeds O2 providers O2 servicing OOxygen maintenance Ocean pollution Orbital implants Oronasal mask Oxygen Cylinder Oxygen Units Oxygen deficit Oxygen deicit Oxygen ears Oxygen equipment Oxygen masks Oxygen supply Oxygen therapy Oxygen P J Prinsloo PFI PJP Tech Part 3 Photography Pistons Planning Plastic Pneumothorax Pollution Pool Diving Preparation Prepared diver Press Release Professional rights Provider course Pulmanologist Pulmonary Bleb Purge RAID South Africa RCAP Radio communications Rashes Recompression chamber Recompression Recycle Regulator failure Regulators Regulator Remote areas Renewable Report incidents Rescue training Resume diving Risk Assessments Risk assesments Risk elements Risk management SABS 019 Safety Stop Safety Saturation Diving Save our seas Science Scuba Air Quality Scuba Injury Scuba children Scuba dive Scuba health Scubalearners Sealife Skin Bends Skin outbreak Skin rash Snorkeling Snorkels Sodwana Bay Splits Squeezes Standars Supplemental oxygen Surgeries Surgery Tattoes Technical Diving The Bends The truth Thermal Notions Tides Tips and trick Transplants Travel tips Travel Tweezers Unconsciousness Underwater photographer Underwater pho Vaccines Vagus nerve Valsalva manoeuvers Vape Vaping Vasvagal Syncope Venting Volatile fuels Washout treatments Wastewater Water Weakness Wetsuit fitting White balance Winter Woman in diving Work of Breathing Wound dressings Wreck dive Wreckdiving Youth diver abrasion air-cushioned alert diver altitude anemia antibiotics antiseptics bandages bent-over barbell rows body art breathing air calories burn cardiovascular checklist chemo port child clearances closed circuit scuba currents cuts dead lift decompression algorithms decongestants dehydration dive injuries dive medicing dive ready child dive reflex dive tribe diver rescue diver training dive diving attraction doctors domestic travel dri-suits dry mucous membranes dry suits dry e-cigarettes ear spaces elearning electrolyte imbalance electroytes emergency action plans emergency assessment equalizing exposure injuries eyes fEMAL DIVERS fire rescue flexible tubing frediving gas bubble health hospital humidity immersion pulmonary edema (IPE join DAN knee longevity lower stress marine pathogens medical issues medical procedures medical risk assesment mental challenge minor illness mucous membranes nasal steroids nasal nematocysts newdivers nitrogen bubbles off-gassed operating theatre operations orthopeadic outgas pain perforation phillippines physical challenges pinched nerves plasters polyester-TPU polyether-TPU post dive preserve prevention rebreather mask rebreathers retinal detachment risk areas safety stops saturation scissors scuba equipment scuba single use sinus infections smoking snorkeling. spearfishing stings strength sub-aquatic swimmers ears tattoo care tecnical diver thermal protection training trimix unified standards vision impaired warmers water quality