An air embolism, also known as a  gas embolism, is a blood vessel blockage caused by one or more bubbles of air or other gas in the circulatory system. Air can be introduced into the circulation during surgical procedures, lung over-expansion injury, decompression, and a few other causes. Air embolisms may also occur in the xylem of vascular plants, especially when suffering from water stress. Divers can develop arterial gas embolisms as a consequence of lung over-expansion injuries. Breathing gas introduced into the venous system of the lungs  due to pulmonary barotrauma will not be trapped in the alveolar capillaries, and will consequently be circulated to the rest of the body through the systemic arteries, with a high risk of embolism. Inert gas bubbles arising from decompression are generally formed in the venous side of the systemic circulation, where inert gas concentrations are highest, these bubbles are generally trapped in the capillaries of the lungs where they will usually be eliminated without causing symptoms. If they are shunted to the systemic circulation through a patent foramen ovale they can travel to and lodge in the brain where they can cause stroke, the coronary capillaries where they can cause myocardial ischaemia or other tissues, where the consequences are usually less critical. The first aid treatment is to administer oxygen at the highest practicable concentration, treat for shock and transport to a hospital where therapeutic recompression and hyperbaric oxygen therapy are the definitive treatment.
A study comparing nabilone with metoclopramide, conducted before the development of modern 5-HT3 antagonist anti-emetics such as ondansetron, revealed that patients taking cisplatin chemotherapy preferred metoclopramide, while patients taking carboplatin preferred nabilone to control nausea and vomiting.Nabilone is sometimes used for nightmares in post-traumatic stress disorder, but there have not been studies longer than nine weeks, so effects of longer-term use are not known. Nabilone has also been used for medication overuse headache. Side effects
Nabilone can increase – rather than decrease – postoperative pain. In the treatment of fibromyalgia, adverse effects limit the useful dose. Adverse effects of nabilone include, but are not limited to: dizziness/vertigo, euphoria, drowsiness, dry mouth, ataxia, sleep disturbance, dysphoria, headache, nausea, disorientation, depersonalization, and asthenia. Pharmacology
Pharmacokinetics
Nabilone is given in 1 or 2 mg doses multiple times a day up to a total of 6 mg. It is completely absorbed from oral administration and highly plasma protein bound. Multiple cytochrome P450 enzymes extensively metabolize nabilone to various metabolites that have not been fully characterized. Chemistry
Nabilone is a racemic mixture consisting of (S,S)-(+)- and (R,R)-(−)-isomers. History
Nabilone was originally developed by Eli Lilly and Company; Lilly received FDA approval in 1985 to market it, but withdrew that approval in 1989 for commercial reasons. Valeant Pharmaceuticals acquired the rights from Lilly in 2004.