Nitrous oxide for monitoring fluid absorption in volunteers
2007 (English)In: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 98, no 1, 53-59 p.Article in journal (Refereed) Published
BACKGROUND: We studied whether nitrous oxide (N(2)O) added to a fluid allows the infused volume to be quantified by measuring N(2)O in the expired air during normal breathing. If so, N(2)O might serve as a tracer of fluid absorption during endoscopic surgery.
METHODS: Twelve male volunteers received continuous and intermittent i.v. infusions (5-45 min) of fluid containing 40 ml litre(-1) of N(2)O. Breath N(2)O and CO(2) concentrations were measured every second via a flared nasal cannula, a standard nasal cannula, or a Hudson mask.
RESULTS: An expression for the amount of infused fluid was obtained by calculating the area under the N(2)O concentration-time curve for samples representative for exhalation (CO(2)>median) and then dividing this area by the median CO(2) for the remaining samples. The N(2)O method then estimated fluid volumes of between 50 and 1400 ml within a 95% prediction interval of +/-200 ml. There were differences of up to 14% in results between the airway devices tested, but the volunteers preferred the flared nasal cannula. N(2)O showed a distinctly higher 3 min variability during intermittent infusion, which could indicate whether fluid absorption is directly intravascular or extravascular. No adverse effects were seen.
CONCLUSIONS: N(2)O method does not require forced end-expiratory breath sampling but still predicts an administered fluid volume with high precision. N(2)O variability can probably be used to distinguish immediately between intravascular and perivesical fluid absorption during surgery.
Place, publisher, year, edition, pages
Oxford University Press, 2007. Vol. 98, no 1, 53-59 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-100188DOI: 10.1093/bja/ael311PubMedID: 17142823OAI: oai:DiVA.org:liu-100188DiVA: diva2:660684