Exhaled Nitric Oxide-2 (NOA-2) - 08.20.14
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Decompression sickness (gas bubbles in the bloodstream) is a concern and common occurrence in scuba divers. It is unknown if astronauts experience the same type of phenomenon from extravehicular activities (EVA). NOA-2 is designed to compare the amount of nitric oxide that is exhaled before and after an EVA to determine if the astronauts experience decompression sickness.
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What do scuba diving and extravehicular activity (EVA) in space have in common? Perhaps a risk of decompression sickness, or gas bubbles in the bloodstream. An increase in nitric oxide exhaled by astronauts after EVA could indicate the presence of such bubbles. This investigation measured nitric oxide exhaled by astronauts before and after EVA to establish a baseline for the effect of microgravity. This will be of use in the future for diagnosing and treating airway inflammation. Future experiments will examine nitric oxide turnover with multiple exhalation flows and whether wearing a US space suit on an EVA affects exhaled nitric oxide.
Aerocrine, Solna, , Sweden
Karolinska Institute, Stockholm, , Sweden
Sponsoring Space Agency
European Space Agency (ESA)
ISS Expedition Duration
October 2005 - October 2008
Previous ISS Missions
This experiment has also been known as ESANO-2.
- Decompression sickness or gas emboli (bubbles in the bloodstream) can occur without symptoms following resurfacing for scuba divers. It is unknown if astronauts experience the same following extravehicular activities (EVA).
- The objective of this investigation is to test the amount of nitric oxide (NO) exhaled before and after an EVA. (An elevated NO level indicates that they are experiencing decompression sickness.)
- Determining if the astronauts experience gas emboli will lead to countermeasure to ensure the health of the crew following EVAs.
In scuba divers the presence of gas emboli (bubbles) in the bloodstream as a result of decompression is well-known and can be common after normal dives with no subjective signs of decompression sickness. The occurrence of decompression sickness in astronauts following decompression in connection with extravehicular activity (EVA) is not known. It has though been demonstrated that using the corresponding decompression techniques on the ground gives rise to symptoms of decompression sickness in approximately 6% of the cases. This suggests a much higher frequency of gas emboli without clear symptoms of decompression sickness. A non-invasive and simple technique for assessing current decompression techniques before and after EVA would be beneficial.
In this experiment astronauts will perform a simple inhalation-exhalation procedure (as in the NOA-1 protocol) as late as possible before starting standard EVA preparations and again as soon as possible after completing the EVA. An increased level of expired Nitric Oxide compared to pre-procedure levels will indicate the presence of gas emboli, suggesting a need for adaptation of existing EVA procedures. (Description provided by ESA: Astrolab Mission)
Karlsson LL, Kerckx Y, Gustafsson LE, Hemmingsson TE, Hemmingsson TE, Linnarsson D. Microgravity Decreases and Hypergravity Increases Exhaled Nitric Oxide. Journal of Applied Physiology. 2009: 1431-1437.
Karlsson LL, Blogg SL, Lindholm P, Gennser M, Hemmingsson TE, Hemmingsson TE, Linnarsson D. Venous gas emboli and exhaled nitric oxide with simulated and actual extravehicular activity . Respiratory Physiology and Neurobiology. 2009 October; 169: s59-s62. DOI: 10.1016/j.resp.2009.04.003. PMID: 19442591.
Ground Based Results Publications
Kerckx Y, Karlsson LL, Linnarsson D, Van Muylem A. Effect of blood redistribution on exhaled and alveolar nitric oxide: A hypergravity model study. Respiratory Physiology and Neurobiology. 2010 May; 171(3): 187-192. DOI: 10.1016/j.resp.2010.04.005. PMID: 20385259.
The information on this page is provided courtesy of the ESA Erasmus Experiment Archive.
The Platon device is used to detect Nitric Oxide in the NOA-2 experiment. Image courtesy of ESA.
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NASA Image: ISS012E24271- The Planton Unit and Medical kits in the Zvezda Service Module (SM). The Platon unit, Nitric Oxide Analyzer (NOA), used in the European Space Agency Nitric Oxide 1 (ESANO 1) experiment is in the mid-left of the image. This image was taken during Expeditions 12/13 Joint Operations.
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