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Objective: To evaluate if variation in the end-tidal CO 2 partial pressure (∆Petco 2 ) after a fluid challenge could predict fluid responsiveness with a sensitivity of 75% and a specificity of 70% in healthy anesthetized and mechanically ventilated dogs., Design: Diagnostic accuracy study., Setting: University hospital., Animals: Twenty-seven dogs admitted for neutering., Interventions: To obtain a balanced sample between fluid responder and nonresponder dogs, a 10-mL/kg lactated Ringer's solution was administered over 15 minutes to half of the population before the baseline measurements. All animals then received a fluid challenge of 10 mL/kg lactated Ringer's solution in 5 minutes., Measurements and Main Results: The velocity-time integral of aortic blood flow (VTI Ao ) was evaluated with Doppler echocardiography before and after a fluid challenge to classify the included dogs as fluid responders or nonresponders. Fluid responsiveness was defined as an increase of ≥15% of the VTI Ao after the fluid challenge. Petco 2 was evaluated at 1, 5, and 10 (T1, T5, T10) minutes after fluid expansion. Area under the receiver operating characteristic curve (AUROC) analysis was used to assess the ability of ∆Petco 2 to predict fluid responsiveness at different time points. A total of 13 dogs were fluid responders, and 14 were nonresponders. The best predictive capacity for ∆Petco 2 was observed at T10. The AUROC with its 95% confidence interval (CI) for ∆Petco 2 at T10 was 0.75 (0.56-0.93), with a sensitivity of 84.62% (95% CI, 54.60-98.10), a specificity of 64.29% (95% CI, 35.10-87.20), a positive predictive value of 68.80% (95% CI, 41.30-89.00), and a negative predictive value of 81.80% (95% CI, 48.20-97.70). The optimal cutoff was 1 mm Hg., Conclusions: The current study showed that, although minimal, ∆Petco 2 predicted fluid responsiveness in the dogs studied., (© Veterinary Emergency and Critical Care Society 2024.)

Objective: To evaluate the changes in flow velocities of the middle cerebral artery before and after a carotid compression maneuver using transcranial color-coded duplex sonography (TCCD) in healthy anesthetized dogs under mechanical ventilation., Design: Prospective study., Setting: University teaching hospital., Animals: Eleven healthy adult dogs., Interventions: A 5-second carotid occlusion maneuver was performed to evaluate cerebral autoregulation (CA)., Measurements and Main Results: After 10 minutes of stable anesthesia, the middle cerebral artery was evaluated by TCCD. Dogs were positioned in sternal recumbency with the head raised to the level of the phlebostatic axis. The systolic peak velocity (Vp) was measured using pulsed Doppler mode. CA was evaluated through the transient hyperemia test (THT), which assesses changes in the Vp after a 5-second transient compression of the ipsilateral common carotid artery and is expressed as the ratio between the Vp flow before and after carotid compression. The Vp before and after carotid occlusion was compared using the Wilcoxon signed-rank test. The median Vp of the middle cerebral artery after the carotid compression maneuver was significantly higher than the median Vp before compression (median [interquartile range, IQR]: 47.7 cm/s [34.3] vs 64.1 cm/s [24.4]; P = 0.003). The median THT obtained was 1.20 (IQR: 0.37)., Conclusions: The current study demonstrated a significant increase in the Vp of the middle cerebral artery after a 5-second temporary occlusion of the ipsilateral carotid artery in healthy anesthetized dogs under mechanical ventilation. These findings suggest that the noninvasive TCCD methodology could be valuable for assessing CA in dogs. Additional studies using this technique in neurocritical animals are required to confirm its usefulness., (© Veterinary Emergency and Critical Care Society 2024.)