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  • Author or Editor: Rainer Vogt x
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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.

Full access
in American Journal of Veterinary Research


Objective—To determine the effect of inhalation of isoflurane at end-tidal concentrations greater than, equal to, and less than the minimum anesthetic concentration (MAC) on bispectral index (BIS) in chickens.

Animals—10 chickens.

Procedures—For each chicken, the individual MAC of isoflurane was determined by use of the toe-pinch method. After a 1-week interval, chickens were anesthetized with isoflurane at concentrations 1.75, 1.50, 1.25, 1.00, and 0.75 times their individual MAC (administered from higher to lower concentrations). At each MAC multiple, a toe pinch was performed and BIS was assessed and correlated with heart rate, blood pressure, and an awareness score (derived by use of a visual analogue scale).

Results—Among the chickens, mean ± SD MAC of isoflurane was 1.15 ± 0.20%. Burst suppression was detected at every MAC multiple. The BIS and awareness score were correlated directly with each other and changed inversely with increasing isoflurane concentration. Median (range) BIS values during anesthesia at 1.75, 1.50, 1.25, 1.00, and 0.75 MAC of isoflurane were 25 (15 to 35), 35 (25 to 45), 35 (20 to 50), 40 (25 to 55), and 50 (35 to 65), respectively. Median BIS value at extubation was 70 ± 9. Values of BIS correlated with blood pressure, but not with heart rate. Blood pressure changed with end-tidal isoflurane concentrations, whereas heart rate did not.

Conclusions and Clinical Relevance—Assessment of BIS can be used to monitor the electrical activity of the brain and the degree of unconsciousness in chickens during isoflurane anesthesia.

Full access
in American Journal of Veterinary Research