Nitric Oxide Production by High Voltage Electrical Discharges for Medical Uses: A Review

Nitric oxide (NO) is a vasodilator and antihypertensive agent as well as a universal anti-microbial factor killing bacteria, fungi and parasites without killing human cells provided that an appropriate dose level and treatment time are applied. Exogenous NO is often employed in inhalation therapies for treating pulmonary hypertension in children and adults. NO generation from air in high voltage electrical discharges is being developed for medical uses because it is technologically simple, economical and portable. The related literature is reviewed here. The plasma can be a thermal plasma, where the temperature is of the order of 10,000 K, or it can be a non-thermal plasma, where the electron temperature is very high but the average gas temperature can vary over a wide range from close to room temperature to thousands of degrees above room temperature. The plasma temperature has significant effects on the chemical composition of the treated gas. These effects are explained based on the chemical reaction mechanism. Further, NO generated by electrical discharges is usually contaminated with nitrogen dioxide and sometimes with ozone and particulate matter. The techniques that have been successfully hybridized with the electrical discharge devices or that can potentially be hybridized for the purification of NO are also reviewed. Recent successful testing of electrical discharge-based NO generators for inhalation therapy on animal models in the US and routine use of them in Russia and east Europe for wound decontamination and fast heeling suggests that the technique has a great potential for applications in future.