Abstract
Objective—To evaluate a combined transcutaneous carbon dioxide pressure (tcPCO2) and pulse oximetry sensor in sheep and dogs.
Animals—13 adult sheep and 11 adult dogs.
Procedures—During inhalation anesthesia, for the first 10 minutes following sensor placement, arterial blood gas was analyzed and tcPCO2 was recorded every 2 minutes. Subsequently, the animals were hyper-, normo-, and hypoventilated. The simultaneously obtained tcPCO2 and PaCO2 values were analyzed by use of Bland-Altman statistical analysis.
Results—Mean ± SD overall difference between tcPCO2 and PaCO2 10 minutes after sensor application was 13.3 ± 8.4 mm Hg in sheep and 8.9 ± 12 mm Hg in dogs. During hyper-, normo-, and hypoventilation, mean difference (bias) and precision (limits of agreement [bias ± 2 SD]) between tcPCO2 and PaCO2 values were 13.2 ± 10.4 mm Hg (limits of agreement, −7.1 and 33.5 mm Hg) in sheep and 10.6 ± 10.5 mm Hg (limits of agreement, −9.9 and 31.2 mm Hg) in dogs, respectively. Changes in PaCO2 induced by different ventilation settings were detected by the tcPCO2 sensor with a lag (response) time of 4.9 ± 3.5 minutes for sheep and 6.2 ± 3.6 minutes for dogs.
Conclusions and Clinical Relevance—The tcPCO2 sensor overestimated PaCO2 in sheep and dogs and followed changes in PaCO2 with a considerable lag time. The tcPCO2 sensor might be useful for noninvasive monitoring of changes but cannot be used as a surrogate measure for PaCO2.
