Cardiovascular Effects of Tramadol in Dogs Anesthetized with Sevoflurane

Abstract

ABSTRACT. Cardiovascular effects of tramadol were evaluated in dogs anesthetized with sevoflurane. Six beagle dogs were anesthetized twice at 7 days interval. The minimum alveolar concentration (MAC) of sevoflurane was earlier determined in each dog. The dogs were then anesthetized with sevoflurane at 1.3 times of predetermined individual MAC and cardiovascular parameters were evaluated before (baseline) and after an intravenous injection of tramadol (4 mg/kg). The administration of tramadol produced a transient and mild increase in arterial blood pressure (ABP) (P=0.004) with prolonged increase in systemic vascular resistance (SVR) (P<0.0001). Compared with baseline value, mean ABP increased significantly at 5 min (119% of baseline value, P=0.003), 10 min (113%, P=0.027), and 15 min (111%, P=0.022). SVR also increased significantly at 5 min (128%, P<0.0001), 10 min (121%, P=0.026), 30 min (114%, P=0.025), 45 min (113%, P=0.025) and 60 min (112%, P=0.048). Plasma concentrations of tramadol were weakly correlated with the percentage changes in mean ABP (r=0.642, P<0.0001) and SVR (r=0.646, P<0.0001). There was no significant change in heart rate, cardiac output, cardiac index, stroke volume, pulmonary arterial pressure, right atrial pressure and pulmonary capillary wedge pressure.In conclusion, the administration of tramadol produces a prolonged peripheral vascular constriction in dogs anesthetized with sevoflurane, which is accompanied with a transient and mild increase in arterial blood pressure. It also indicated that the degree of vasoconstriction might depend on the plasma concentration of tramadol.KEY WORDS: canine, cardiovascular effects, sevoflurane, tramadol.J. Vet. Med. Sci. 73(12): 1603-1609, 2011 Treatment with analgesic drugs reduces the amount of anesthetics required to produce surgical anesthesia, helps to stabilize anesthesia, and decreases overall patient morbidity associated with surgery and anesthesia [17]. Opioid administration decreases the amount of volatile anesthetics required to produce general anesthesia, as evidenced by decreases in the minimum alveolar concentration (MAC) of volatile anesthetics [10,19].Tramadol is a centrally acting 'atypical' opioid analgesic and widely used in humans for control of acute and chronic pain [6,25]. Tramadol is less likely to induce tolerance in animals and humans compared with morphine because of its non-opioid mechanism of action [15]. Use of tramadol in dogs has gained popularity among veterinarians because the drug is perceived to be an effective analgesic, in easily administered, and has a longer duration of action and fewer adverse effects than most other opioids. It was demonstrated that tramadol administration decreased in the MAC of volatile anesthetics [28] and its preoperative administration provided an early pain control after ovariohysterectomy in dogs [13]. Tramadol produces a synergistic analgesic effect provided by a μ-opioid receptor affinity coupled with inhibitions of synaptic reuptake of monoamine neurotransmitters such as 5-hydroxyt...

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

“…Giorgi et al [6] reported that the minimum effective plasma concentration of tramadol as calculated for humans had been maintained for about 6-7 hr following a single IV administration of 4 mg/kg tramadol in dogs. We previously reported [10] that the plasma concentration of tramadol gradually decreased over time from approximately 2,000 ng/ml at 5 min to 500 ng/ml at 120 min after a single IV dose of 4 mg/kg tramadol in older dogs (8-10 years old) anesthetized with sevoflurane 1.3 MAC. In these dogs, the plasma concentration of M1 showed a peak (332 ng/ml) at 15 min and then gradually decreased to approximately 200 ng/ml at 120 min after the tramadol administration.…”

“…However, it should be remembered that sevoflurane causes dose-dependent hypotension, hypoventilation, impaired cardiac contractility and hypothermia in dogs [27]. On the other hand, it has been reported that tramadol is a mild myocardial depressant in dogs anesthetized with sevoflurane [10]. A sparing effect on anesthetic requirement provided by the preemptive administration of tramadol is expected to convey the advantage of preserving cardiovascular function in patients anesthetized with sevoflurane.…”

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

“…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).…”

Effects of epidural anesthesia with tramadol, ropivacaine or tramadol-ropivacaine combination, in bitches undergoing ovariohysterectomy under anesthesia with isoflurane

“…It is capable of providing analgesia and muscle relaxation in the retroumbilical region (SOUZA et al, 2013) and causes minimal cardiorespiratory changes. It also improves control over postoperative pain, reduces transoperative stress (ALBUQUERQUE et al, 2010), is safe and efficient, and can reduce the concentration of inhaled anesthetic required for the maintenance of proper anesthesia (VALVERDE, 2008;ITAMI et al, 2011;BOSMANS et al, 2011;NATALINI et al, 2011).…”

“…Epidural morphine, fentanyl, methadone, and tramadol are commonly administered. Tramadol is an atypical opiate, which in addition to binding to the opioid receptors, inhibits the reuptake of norepinephrine and serotonin (GUEDES et al, 2002;BASSO et al, 2008;BORGES et al, 2008;MCMILLAN et al, 2008;SILVA et al, 2008;ITAMI et al, 2011). It also exhibits local anesthetic action by blocking the sodium channels in nociceptive C fibers and A-delta (BASSO et al, 2008;KARGI et al, 2008).…”