Alfaxalone

To evaluate the accuracy, agreement, and trending ability of the pulse contour cardiac output (PulseCO) system calibrated with echocardiography-derived cardiac output (CO) in sevoflurane-anesthetized healthy dogs during 8 hours of general anesthetic.

Prospective, randomized, blinded experimental study.

A total of five healthy Beagle dogs, three intact females and two intact males.

Dogs were anesthetized using intravenous alfaxalone for induction and sevoflurane in 100% oxygen for maintenance for 8 hours. CO was estimated using three methods: pulmonary artery catheter thermodilution (PAC-TD)-derived CO (CO_PAC-TD), Doppler-based echocardiography-derived CO (CO_Echo), and PulseCO-derived CO (CO_PulseCO). The PulseCO monitor was calibrated at baseline using CO_Echo and not recalibrated during the anesthetic. Measurements were taken at baseline and at intervals up to 8 hours. All CO values were converted to cardiac index (CI) by indexing to body surface area. Statistical analysis included Bland-Altman and linear regression analyses for agreement assessment and Critchley's four-quadrant and polar plots for trending analysis.

A total of 100 paired CI measurements were obtained. Bland-Altman analysis revealed a mean bias of -0.1 L minute^-1 m^-2 and percentage error of 28.3% for CI_PAC-TDversus CI_PulseCO, and a mean bias of 0.01 L minute^-1 m^-2 with a percentage error of 24.9% for CI_PAC-TDversus CI_Echo. Trending analysis between CI_PAC-TD and CI_PulseCO showed a concordance rate of 98.2% in the four-quadrant plot and a mean angular bias of 2.6 ° with radial limits of agreement ranging from -21.47 ° to 26.67 ° in the polar plot.

The results indicate that the PulseCO system has acceptable accuracy, agreement, and trending ability compared with the traditional reference method of PAC-TD. This highlights the potential of the PulseCO system as a minimally invasive and practical monitoring tool in sevoflurane-anesthetized dogs.

To evaluate the sedative effects of intramuscular (IM) alfaxalone 4% combined with butorphanol or dexmedetomidine in healthy dogs.

Experimental, randomized, blinded, crossover study.

A total of six healthy adult dogs of mixed breeds.

Alfaxalone 4% (3 mg kg^-1) was combined with either butorphanol 0.4 mg kg^-1 or dexmedetomidine 5 μg kg^-1 injected IM, with a minimum 3 day washout. Sedation variables (onset, duration, quality including composite scoring, onset, and recovery), cardiorespiratory variables [heart rate (HR), respiratory rate (f_R), oxygen saturation of haemoglobin (SpO₂), mean arterial pressure (MAP)], and response to cephalic venous catheterization [on a 4-point scale (0-3)] were recorded. Data are shown as median and interquartile range or mean ± standard deviation, p < 0.05.

All dogs achieved sedation with good to excellent recovery [scores: alfaxalone-butorphanol 3.5 (3.25-4), alfaxalone-dexmedetomidine 4 (4-4)]. Duration of sedation was 88.9 ± 63.7 minutes and 95.8 ± 43.7 minutes (p = 0.831) and quality of sedation was 21 (19-22) and 22 (18-25.5) out of 27 (p = 0.249). Catheter placement was successful in all dogs with minimal resistance [score 3 (3-3)]. HR decreased from baseline in both groups: alfaxalone-butorphanol (110 ± 30 to 63 ± 12 beats minute^-1; p = 0.003) and alfaxalone-dexmedetomidine (99 ± 16 to 59 ± 15 beats minute^-1; p = 0.001). f_R decreased from baseline with alfaxalone-butorphanol (25 ± 3 to 18 ± 5 breaths minute^-1; p = 0.031). Mild hypoxaemia (SpO₂ 90-94%) occurred in both groups: alfaxalone-butorphanol (3/6), alfaxalone-dexmedetomidine (5/6). MAP was higher following alfaxalone-dexmedetomidine than alfaxalone-butorphanol (104 ± 13 mmHg and 79 ± 8 mmHg, respectively) (p ≤ 0.020).

IM alfaxalone 4% at 3 mg kg^-1 combined with butorphanol or dexmedetomidine provided sufficient sedation for IV catheterization. Supplemental oxygen is recommended with both protocols.