科研之友
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摘要
BACKGROUND: Accurately measuring the partial pressure of end-tidal CO2 (P-ETCO2) in nonintubated patients is problematic due to dilution of expired CO2 at high O-2 flows and mask designs that may either cause CO2 rebreathing or inadequately capture expired CO2. We evaluated the performance of 2 capnographic O-2 masks (Cap-ONE and OxyMask) against a clinically expedient method using a standard O2 mask with a flow-directed nasal cannula used for capnography (CapnoLine) in a spontaneous breathing model of an adult and child under conditions of normal ventilation, hypoventilation, and hyperventilation. METHODS: An ASL-5000 simulator was attached to a manikin face with a catheter port, through which various CO2/air mixtures were bled into the ASL-5000 to achieve a P-ETCO2 of 40, 65, and 30 mm Hg. Both P-ETCO2 and inspired P-CO2 were measured at O-2 flows of 5, 10, 15, and 20 L/min (adult model) and 2, 4, 6, 8, and 10 L/min (pediatric model). RESULTS: P-ETCO2 decreased to varying degrees as O-2 flow increased, depending upon the breathing pattern. Although all devices appeared to perform reasonably well under normal and hyperventilation conditions, the clinically expedient method was associated with substantially more CO2 rebreathing. P-ETCO2 usually deteriorated more under simulated hypoventilation, regardless of the measurement method. CONCLUSIONS: Both of the specially designed O-2 capnography masks provided reasonably stable P-ETCO2 without significant CO2 rebreathing at the commonly used O-2 flows. Because of their open design, P-ETCO2 measured at high O-2 flows may produce artificially lower readings that may not reflect arterial CO2 levels compared with lower O-2 flows.
- 出版日期2017-1
