Dose and cardiopulmonary effects of propofol alone or with midazolam for induction of anesthesia in critically ill dogs

The effect of midazolam co-induction on cardiorespiratory variables, myoclonus and etomidate dose requirements in healthy cats

OBJECTIVE

To evaluate dose requirements of etomidate for endotracheal intubation, with or without midazolam co-induction, and to describe induction quality and associated cardiorespiratory variables in healthy cats.

STUDY DESIGN

Randomized prospective experimental study.

ANIMALS

A group of 24 adult neutered cats (17 females, seven males).

METHODS

Cats were premedicated with intramuscular butorphanol (0.4 mg kg-1) and alfaxalone (2 mg kg-1), and anesthesia was induced with etomidate following midazolam (0.3 mg kg-1) or physiologic saline (0.06 mL kg-1) intravenously. Heart rate, respiratory rate (fR) and arterial blood pressure were measured following premedication, at co-induction, after etomidate administration, and after orotracheal intubation and compared using repeated-measures anova. Pre- and post-etomidate blood samples were assessed for the presence of hemolysis. Etomidate dose requirements and prevalence of myoclonus were compared with Wilcoxon signed ranks test and Fisher's test. Values of p < 0.05 were considered significant.

RESULTS

Mean ± standard deviation etomidate doses required for orotracheal intubation were 0.84 ± 0.26 and 1.39 ± 0.33 mg kg-1 for midazolam and saline co-induction, respectively (p = 0.001). The presence of myoclonus at sedated baseline, co-induction and etomidate was 6/12, 8/12 and 9/12 in the saline group, respectively, and 10/12, 2/12 and 0/12 in the midazolam group. The prevalence of myoclonus was lower in the midazolam group after co-induction and etomidate injection (p = 0.036 and p < 0.001, respectively). Cardiorespiratory variables did not differ between groups at any time point. Compared with baseline, fR decreased in both groups after etomidate injection and intubation. Hemolysis was observed in all post-etomidate plasma samples.

CONCLUSIONS AND CLINICAL RELEVANCE

Etomidate, with or without midazolam co-induction, provides acceptable cardiovascular function in premedicated healthy cats. Midazolam reduces etomidate requirements for orotracheal intubation and improves induction quality in cats premedicated with intramuscular butorphanol-alfaxalone.

The effect of age on the induction dose of propofol for general anesthesia in dogs

OBJECTIVE

In people, the dose of propofol (DOP) required for procedural sedation and anesthesia decreases significantly with age. The objective of this study was to determine if the DOP required to perform endotracheal intubation decreases with age in dogs.

STUDY DESIGN

Retrospective case series.

ANIMALS

1397 dogs.

METHODS

Data from dogs anesthetized at referral center (2017-2020) were analyzed with three multivariate linear regression models with backward elimination using a combination of either absolute age, physiologic age, or life expectancy (ratio between age at the time of anesthetic event and expected age of death for each breed obtained from previous literature) as well as other factors as independent variables, and DOP as the dependent variable. The DOP for each quartile of life expectancy (<25%, 25-50%, 50-75%, 75-100%, >100%) was compared using one-way ANOVA. Significance was set at alpha = 0.025.

RESULTS

Mean age was 7.2 ± 4.1 years, life expectancy 59.8 ± 33%, weight 19 ± 14 kg, and DOP 3.76 ± 1.8 mg kg-1. Among age models, only life expectancy was a predictor of DOP (-0.37 mg kg-1; P = 0.013) but of minimal clinical importance. The DOP by life age expectancy quartile was 3.9 ± 2.3, 3.8 ± 1.8, 3.6 ± 1.8, 3.7 ± 1.7, and 3.4 ± 1.6 mg kg-1, respectively (P = 0.20). Yorkshire Terrier, Chihuahua, Maltese, mixed breed dogs under 10 kg, and Shih Tzu required higher DOP. Status of neutered male, ASA E, and Boxer, Labrador and Golden Retriever breeds decreased DOP, along with certain premedication drugs.

CONCLUSIONS AND CLINICAL RELEVANCE

In contrast to what is observed in people, an age cut-off predictive of DOP does not exist. Percentage of elapsed life expectancy along with other factors such as breed, premedication drug, emergency procedure, and reproductive status significantly alter DOP. In older dogs, the dose of propofol can be adjusted based on their elapsed life expectancy.

Effects of Different Doses of Rimazolam on Oxidative Stress Level Sedation Score and Recovery Time of Patients during Hip Replacement

The effects of Rimazolam on oxidative stress level, sedation score, and recovery time of patients under different doses in hip replacement are investigated. A total of 100 patients who underwent hip arthroplasty in our hospital from September 2020 to May 2022 are selected as the study subjects. According to the random number table method, they are divided into observation group and control group. The observation group is given 0.3 mg/kg Rimazolam, and the control group is given 0.4 mg/kg Rimazolam. Oxidative stress level, hemodynamic indexes at different time after anesthesia, sedation score and sedation depth, Visual Analogue Scale/Score (VAS) score and incidence of adverse reactions are observed in 2 groups. The correlation of sedation score with oxidative stress index and pain degree is analyzed. The experimental results show that Rimazolam has a good anesthesia induction effect in hip replacement, but the low dose (0.3 mg/kg) can reduce the level of oxidative stress in patients, has a better sedation effect and can maintain the stability of patients' hemodynamic indicators, and has a positive effect on relieving postoperative pain in patients. [Clinical Trial Registration Number- ChiCTR2000038548].