A new method for determining levels of sedation in dogs: A pilot study with propofol and a novel neuroactive steroid anesthetic

Evaluation of the electroencephalogram in awake, sedated, and anesthetized dogs

Sedation and anesthesia alter the raw electroencephalogram (EEG). Interpretation of the EEG is facilitated by measuring the patient state index (PSI), visual inspection of density spectral arrays (DSA), and power density analysis of the delta (0.1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), and beta plus gamma (12-40 Hz) frequency bands. Baseline data were recorded in six male intact Beagles before sedation with intravenous acepromazine (0.03 mg/kg) and hydromorphone (0.1 mg/kg). Anesthesia was induced and maintained for five minutes with intravenous propofol (1.5 mg/kg over five seconds followed by 12 mg/kg/h). Additional propofol (0.5-1.0 mg/kg and up to 16.7 mg/kg/h) was administered within this time frame if the PSI was above 50. The effects of sedation and anesthesia were evaluated with a mixed-effect model followed by Dunnett's test (alpha = 0.05). The average baseline PSI (95% confidence interval) was 93.0 (91.4-94.6) and decreased on sedation [88.7 (86.0-91.3); p = 0.039] and anesthesia [44.5 (40.8-48.2); p < 0.001]. The awake DSA showed dense power in all bands. The power density decreased with sedation. During anesthesia, the power density was reduced in frequencies above 12 Hz. The baseline power density on the delta, theta, alpha, and beta plus gamma bands was higher than sedation (p < 0.007). Compared to baseline, anesthesia had lower power on delta, and beta plus gamma bands (p < 0.002). The interpretation in awake, sedated, and anesthetized dogs of the EEG can be facilitated by processing and generating PSI and DSA.

Evaluation of the effects of gabapentin on the physiologic and echocardiographic variables of healthy cats: a prospective, randomized and blinded study

OBJECTIVES

The aim of this study was to evaluate, using echocardiography, the effects of oral administration of a single dose of gabapentin on the physiologic variables (heart rate [HR], respiratory rate [RR] and systolic blood pressure [SBP]) and systolic and diastolic cardiac function of healthy cats.

METHODS

This was a prospective, randomized and blinded study with 40 healthy cats aged between 6 months and 2 years. The cats' health status was assessed on the first appointment (T1) when they underwent a physical examination, complete blood count, biochemical profile, assessment of physiologic variables and echocardiogram. The echocardiogram was used to measure the left ventricle's (LV) internal diameter during systole and diastole, isovolumic relaxation time, transmitral flow, E-wave deceleration time and HR. The cats were randomly divided into two groups: (1) a treatment group with 20 cats that received a single oral dose of gabapentin (100 mg/cat); and (2) a control group with 20 cats that received a single oral dose of placebo. All variables of the physiologic and echocardiographic variables were re-evaluated 1-3 weeks after T1 (T2), 90 mins after medication or placebo administration.

RESULTS

There was no difference in the physiologic variables evaluated in both groups. The proportion of cats in the treatment group that had their ventricular filling waves fused on T1 but did not have them fused on T2 was significantly higher (45%) compared with cats in the control group (15%; P = 0.0384).

CONCLUSIONS AND RELEVANCE

There was no difference between the groups in regard to SBP, HR, RR and echocardiographic variables. Gabapentin improved evaluation of diastolic function on echocardiogram because it reduced the fusion of ventricular filling waves during the evaluation of the diastolic function of the LV. Gabapentin did not cause adverse effects on the cardiovascular hemodynamics of young healthy cats.