We evaluated changes in cardiovascular and renal functions as well as arginine vasopressin (AVP) secretion, with remifentanil and dexmedetomidine administration alone or in combination in sevoflurane-anesthetized dogs. Six healthy adult Beagle dogs received one of the following four treatments in a randomized crossover study: saline (C), remifentanil alone at successively increasing doses (R; 0.15, 0.60, and 2.40 μg/kg/min), dexmedetomidine alone (D; 0.5 μg/kg intravenously for initial 10 min followed by a constant rate infusion at 0.5 μg/kg/hr), and a combination of remifentanil and dexmedetomidine at the above-mentioned doses (RD). Sevoflurane doses were adjusted to 1.5 times of minimum alveolar concentration (MAC) equivalent according to MAC-sparing effects with remifentanil and dexmedetomidine as previously reported. Cardiovascular measurements, renal function data, and plasma AVP concentrations were determined before and every 60 min until 180 min after drug administration as per each treatment. In the R, D and RD, heart rate significantly decreased and mean arterial pressure significantly increased from baseline or with C. Cardiac index significantly decreased and systemic vascular resistance index increased with D and RD.Oxygen extraction ratio, renal blood flow, and glomerular filtration rate were not affected. The plasma AVP concentrations significantly decreased in D and RD, but increased in R. Only in D, the natriuresis was elicited. The combination of remifentanil and dexmedetomidine in sevoflurane-anesthetized dogs was acceptable in terms of the hemodynamics, oxygenation, and renal function. Remifentanil may interfere with dexmedetomidine-induced diuresis and inhibition of AVP secretion.
KEY WORDSarginine vasopressin, cardiovascular and renal effect, dexmedetomidine, dog, remifentanil noted above, no study has documented the combined effects of μ opioid and α2-adrenoreceptor agonists on renal functions.This study aimed to experimentally evaluate the changes in cardiovascular and renal functions as well as AVP secretion with the CRI of remifentanil and dexmedetomidine alone and in combination in dogs anesthetized with sevoflurane.
MATERIALS & METHODS
AnimalsSix healthy, adult neutered Beagle dogs (three males and three females), aged 3.0 ± 0.7 years (mean ± standard deviation [SD]) and weighing 10.2 ± 1.2 kg (mean ± SD), were included in this study. Health status was assessed before the study by physical examination, complete blood count, serum biochemical analysis, and urinalysis. The dogs were housed in cages; food, but not water, was withheld for 12 hr before anesthesia. This study was approved by the Animal Research Committee of Tottori University (no. 16-T-19).
Study designEach dog was randomly anesthetized on four occasions with a ≥4-week washout period and received one of the following four treatments: CRI of saline at 2 ml/kg/min as control (C treatment); CRI of remifentanil (Ultiva, Janssen Pharmaceutical K.K., Tokyo, Japan) at successive dose rates of 0.15, 0.60, and 2.40 μg/kg/min (R treatm...
