Location
Weber State University
Start Date
5-8-2017 9:34 AM
End Date
5-8-2017 12:00 AM
Description
Anesthesia care providers routinely deliver supplemental O2 during monitored anesthesia care to prevent hemoglobin desaturation. The existing method of delivery, however, contributes to complications including respiratory depression and fire hazard. Patient variability also makes delivering O2 difficult. We have developed a demand oxygen delivery system that only gives oxygen during early inspiration. We designed a volunteer study to evaluate patient monitoring and to compare continuous flow to demand delivery. We hypothesized that ceasing oxygen delivery during expiration will facilitate reliable capnography in non-intubated patients. We also hypothesized that delivering oxygen on demand leads to higher alveolar oxygen concentrations and higher hemoglobin saturation. Methods: We recruited thirty healthy volunteers. We asked volunteers to lie down in a hospital bed and fitted them with a nasal cannula and a pulse oximeter. Our prototype system delivered both constant and demand oxygen delivery, one at a time, of flows between 0 and 10 L/min. Each flow rate and mode combination was delivered for two minutes. At the end of each two-minute period, oxygen flow was turned off and the expired oxygen and carbon dioxide was sampled for three breaths. Results: When using demand delivery, the observed etCO2 value was within ±0.57 mm Hg for all flow rates. When using constant mode, the error increased as the supplemental O2 flow rate increased. Statistical analysis showed no significant difference when monitoring etCO2 using demand delivery. A statistically significant (P < 0.05) difference in etCO2 measurement was observed for all rates when monitoring etCO2 during constant flow. ETO2 values were significantly higher (P < 0.05) during demand delivery than during continuous flow. Higher SpO2 values were also observed during demand delivery. For flow rates of 1-4 L/min, less than 40% percent of constant flow oxygen values were needed to obtain equivalent ETO2 concentrations when using demand oxygen delivery. Discussion: EtCO2 can be monitored accurately when supplemental O2 delivery is interrupted during expiration. Demand delivery is useful for delivering O2 while still ensuring accurate etCO2 readings on exhalation. Higher ETO2 concentrations and SpO2 values can be achieved using demand oxygen delivery. These findings are consistent with prior evaluation of demand oxygen delivery systems used for long-term oxygen therapy. This study has shown that our intelligent oxygen flowmeter can obtain ETO2 and SpO2 values equivalent to or higher than continuous flow oxygen delivery while providing the benefits of demand oxygen delivery including reduced operating room fire hazard
Included in
Testing an Oxygen Demand Delivery Device
Weber State University
Anesthesia care providers routinely deliver supplemental O2 during monitored anesthesia care to prevent hemoglobin desaturation. The existing method of delivery, however, contributes to complications including respiratory depression and fire hazard. Patient variability also makes delivering O2 difficult. We have developed a demand oxygen delivery system that only gives oxygen during early inspiration. We designed a volunteer study to evaluate patient monitoring and to compare continuous flow to demand delivery. We hypothesized that ceasing oxygen delivery during expiration will facilitate reliable capnography in non-intubated patients. We also hypothesized that delivering oxygen on demand leads to higher alveolar oxygen concentrations and higher hemoglobin saturation. Methods: We recruited thirty healthy volunteers. We asked volunteers to lie down in a hospital bed and fitted them with a nasal cannula and a pulse oximeter. Our prototype system delivered both constant and demand oxygen delivery, one at a time, of flows between 0 and 10 L/min. Each flow rate and mode combination was delivered for two minutes. At the end of each two-minute period, oxygen flow was turned off and the expired oxygen and carbon dioxide was sampled for three breaths. Results: When using demand delivery, the observed etCO2 value was within ±0.57 mm Hg for all flow rates. When using constant mode, the error increased as the supplemental O2 flow rate increased. Statistical analysis showed no significant difference when monitoring etCO2 using demand delivery. A statistically significant (P < 0.05) difference in etCO2 measurement was observed for all rates when monitoring etCO2 during constant flow. ETO2 values were significantly higher (P < 0.05) during demand delivery than during continuous flow. Higher SpO2 values were also observed during demand delivery. For flow rates of 1-4 L/min, less than 40% percent of constant flow oxygen values were needed to obtain equivalent ETO2 concentrations when using demand oxygen delivery. Discussion: EtCO2 can be monitored accurately when supplemental O2 delivery is interrupted during expiration. Demand delivery is useful for delivering O2 while still ensuring accurate etCO2 readings on exhalation. Higher ETO2 concentrations and SpO2 values can be achieved using demand oxygen delivery. These findings are consistent with prior evaluation of demand oxygen delivery systems used for long-term oxygen therapy. This study has shown that our intelligent oxygen flowmeter can obtain ETO2 and SpO2 values equivalent to or higher than continuous flow oxygen delivery while providing the benefits of demand oxygen delivery including reduced operating room fire hazard