Abstract
BACKGROUND: One century after the introduction of the oxygen flow meter into clinical practice, we have developed a device, FreeO2, that automatically titrates the oxygen flow delivered to spontaneously breathing patients, with the aim of maintaining a stable SpO2. We evaluated this system in healthy subjects during induced hypoxemia.
METHODS: Hypoxemia was induced in 10 healthy subjects while breathing a gas mixture of variable FIO2 (air + nitrogen). Each subject performed 3 hypoxemic challenges with the addition, in a random order, of either: air with constant flow (1.5 L/min); oxygen with constant flow (1.5 L/min); or automatic oxygen flow titration. Subjects were blinded to the intervention. Oxygen flow, SpO2, end-tidal CO2, respiratory rate, and heart rate were recorded every second. The primary outcome was the time with SpO2 between 92% and 96%.
RESULTS: The SpO2 target (92–96%) was achieved a median of 26.0%, 36.8%, and 66.5% (P < .001) of the time with air, constant oxygen, and automated oxygen titration, respectively. Severe oxygen desaturations (SpO2 < 88%) were respectively observed at a median of 33.7%, 12.7%, and 0.4% of the time (P < .001). Hyperoxia was present a median of 4.1%, 39.1%, and 14.5% of the time (P < .001). Tachycardia was present with air and with constant oxygen flow, but not while using automated oxygen titration. These results were obtained with a mean and maximal oxygen flow of 1.3 L/min and 7.6 L/min with the automated titration.
CONCLUSIONS: In this model of induced hypoxemia, the FreeO2 system that automatically titrates the oxygen flow was more efficient at maintaining the SpO2 target, while ensuring a statistically significant reduction in the rates of severe hypoxemia and hyperoxia, in comparison with air or constant oxygen flow. These beneficial results were obtained with less oxygen, in comparison to a constant oxygen flow.
Footnotes
- Correspondence: François Lellouche MD PhD, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, 2725 Chemin Sainte-Foy, Ville de Québec, Québec, Canada G1V 4G5. E-mail: francois.lellouche{at}criucpq.ulaval.ca.
Drs Lellouche and L'Her are co-inventors of the FreeO2 system and have disclosed relationships with Oxynov. This research was partly supported by the Canadian Foundation for Innovation Leaders Opportunity Fund and by Fonds de Recherche en Santé du Québec.
Dr Lellouche presented a version of this paper at the meeting of the European Society of Intensive Care Medicine, held October 11–14, 2009, in Vienna, Austria, and at the International Conference of the American Thoracic Society, held May 14–19, 2010, in New Orleans, Louisiana.
- Copyright © 2012 by Daedalus Enterprises Inc.