Effects of a Single Bolus Intravenous Dose of Tramadol on Minimum Alveolar Concentration (MAC) of Sevoflurane in Dogs

Abstract

ABSTRACT. Tramadol is an atypical opioid analgesic widely used in small animal practice. This study was designed to determine the effect of a single intravenous (IV) dose of tramadol on the minimum alveolar concentration (MAC) of sevoflurane in dogs. Six beagle dogs were anesthetized twice to determine the sevoflurane MAC with or without an administration of tramadol (4 mg/kg, IV) at 7 days interval. The sevoflurane MAC was determined using a tail clamp method in each dog ventilated with positive pressure ventilation. The tramadol administration produced a significant reduction in the sevoflurane MAC by 22.3 ± 12.2% (1.44 ± 0.28% with tramadol versus 1.86 ± 0.30% without tramadol, P=0.010). This MAC reduction had been determined from 122 ± 19 to 180 ± 41 min following the tramadol administration. During this period, the plasma concentrations of tramadol and its metabolite, O-desmethyltramadol (M1), decreased from 429 ± 64 to 332 ± 55 ng/ml and from 136 ± 24 to 114 ± 68 ng/ml, respectively, but these changes were not statistically significant. There was no significant difference in heart rate, mean arterial blood pressure and SpO 2 between the control and tramadol treatment. The dogs that received tramadol treatment sometimes breathed spontaneously. Therefore, their respiratory rates significantly increased, and PETCO 2 decreased during the MAC determination. In conclusion, the single IV dose of tramadol produced a significant reduction in the sevoflurane MAC in dogs.

Comparison of continuous intravenous infusion of tramadol and tramadol-lidocaine-ketamine in the sevoflurane requirement in dogs

“…The MAC reduction found in this study is similar to the one reported by Itami et al (2013), who obtained MAC reduction of 1.86 to 1.44 vol%, (approximately 22%) after the administration of tramadol in a single dose. In a study with rats (Wolff et al 1999), it was observed that tramadol could reduce the MAC of isoflurane.…”

“…Several studies have evaluated the effect of drugs combinations administered by continuous IV infusion on the requirement for inhalational agents. Studies with sevoflurane have obtained different basal MAC: 2.2-2.3 vol% (Matsubara et al 2009, Columbano et al 2012) and 1.82-1.9 vol% (Wilson et al 2008, Itami et al 2011, Itami et al 2013, Moran-Muñoz et al 2014. This variation may be due to methodological differences, since various stimuli can be applied, such as electrical stimulation, surgical incisions, digital pressure, tail clamping or movement of the endotracheal tube (Ebert & Schmid 2004).…”

“…The response to the stimulus was considered positive if the animal made any gross movement of the head or limbs (Ewing et al 1993). The ETsevo set for the first animal of the TRA group was defined as 1.8 vol% and for the first animal in the TLK group was 1.4 vol% (Wilson et al 2008, Itami et al 2013. When the animal responded negatively (no movement), the ETsevo for the next animal was reduced by 0.1 vol%.…”

“…There is little information regarding the use of a continuous infusion of tramadol combined with lidocaine and ketamine, however some studies have suggested that IV or epidural use of tramadol reduced the MAC of inhaled anesthetic agent and/or allowed adequate analgesia (Seddighi et al 2009;Itami et al 2013).…”

2015 AAHA/AAFP Pain Management Guidelines for Dogs and Cats

“…[45][46][47][48] Pharmacodynamic studies demonstrate the anesthestic-sparing and pain-modifying effect of parenteral tramadol in dogs. [49][50][51][52][53] Convincing evidence for a painmodifying effect of oral tramadol, however, remains elusive, and already low plasma levels quickly diminish with sequential administration. [54][55][56][57] one small study of oral tramadol did report a statistically significant increase of mechanical threshold levels in dogs, but only at the 5 and 6 h time points.…”