• Journal of Veterinary Clinics
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• v.27 no.6
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• pp.668-673
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• 2010

This study was to evaluate the effects of tramadol and medetomidine administration on minimum alveolar concentration (MAC) of isoflurane in dogs. MAC of isoflurane was determined in four occasions; 1 ml saline (Control), $2{\mu}g$/kg medetomidine (M2), 4 mg/kg tramadol (T4), $2{\mu}g$/kg medetomidine-4 mg/kg tramadol combination (M2T4). Heart rate, blood pressure, respiratory rate, end-tidal carbon dioxide concentration, saturation of hemoglobin with oxygen and body temperature were recorded. After administration of M2 ($0.81{\times}0.18%$), T4 ($0.81{\times}0.14%$) and M2T4 ($0.62{\times}0.12%$), less isoflurane was required than the control value ($1.13{\times}0.19%$). Significantly lower heart rate than the control value was detected after treatment of M2, T4, and M2T4. When only M2T4 was administered, blood pressure was significantly higher than the control value. In conclusion, administrations of tramadol, medetomidine and medetomidine-tramadol combination decreased the MAC of isoflurane in dogs. Especially, medetomidine-tramadol combinations could be useful as a premedication because of the anesthetic sparing effect and moderate changes in cardiovascular system.

• Journal of Veterinary Science
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• v.23 no.4
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• pp.53.1-53.9
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• 2022

Background: Problems associated with using inhalational anaesthesia are numerous in veterinary anaesthesia practice. Decreasing the amount of used inhalational anaesthetic agents and minimising of cardiorespiratory disorders are the standard goals of anaesthetists. Objective: This experimental study was carried out to investigate the sparing effect of intravenous tramadol, lidocaine, dexmedetomidine and their combinations on the minimum alveolar concentration (MAC) of sevoflurane in healthy Beagle dogs. Methods: This study was conducted on six beagle dogs. Sevoflurane MAC was determined by the tail clamp method on five separate occasions. The dogs received no treatment (control; CONT), tramadol (TRM: 1.5 mg kg^-1 intravenously followed by 1.3 mg kg^-1 h^-1), lidocaine (LID: 2 mg kg^-1 intravenously followed by 3 mg kg^-1 h^-1), dexmedetomidine (DEX: 2 ㎍ kg^-1 intravenously followed by 2 ㎍ kg^-1 h^-1), and their combination (COMB), respectively. Cardiorespiratory variables were recorded every five minutes and immediately before the application of a noxious stimulus. Results: The COMB treatment had the greatest sevoflurane MAC-sparing effect (67.4 ± 13.9%) compared with the other treatments (5.1 ± 25.3, 12.7 ± 14.3, and 40.3 ± 15.1% for TRM, LID, and DEX treatment, respectively). The cardiopulmonary variables remained within the clinically acceptable range following COMB treatment, although the mean arterial pressure was higher and accompanied by bradycardia. Conclusions: Tramadol-lidocaine-dexmedetomidine co-infusion produced a remarkable sevoflurane MAC-sparing effect in clinically healthy beagle dogs and could result in the alleviation of cardiorespiratory depression caused by sevoflurane. Cardiorespiratory variables should be monitored carefully to avoid undesirable side effects induced by dexmedetomidine.

• Journal of Yeungnam Medical Science
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• v.36 no.1
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• pp.50-53
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• 2019

Awareness during general anesthesia occurs in approximately 0.1-0.2% of cases; nevertheless, particular attention is required because it can lead to critical complications including insomnia, depression, anxiety, and post-traumatic stress disorder. To prevent these complications, bispectral index (BIS) and end-tidal anesthetic gas (ETAG) concentration monitoring are commonly used to examine patient consciousness during surgery. In the present case, an 80-year-old man was scheduled for total gastrectomy. Anesthesia was maintained using desflurane 4.0-5.0% vol, oxygen, and nitrous oxide. The authors simultaneously monitored BIS, which was maintained between 37 and 43, and ETAG, which was maintained between 0.9 and 1.2 minimum alveolar concentration (MAC). After the operation, however, the authors were surprised to learn that the patient complained of awareness during anesthesia. Although BIS and ETAG concentration monitoring are useful in preventing awareness during anesthesia, they cannot be completely trusted. Even though BIS was maintained at approximately 40 and ETAG at 0.7-1.3 MAC, awareness during anesthesia occurred.

• Journal of Veterinary Clinics
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• v.32 no.4
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• pp.308-312
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• 2015

This study was aimed to evaluate the effects of tramadol hydrochloride on the minimum alveolar concentration of isoflurane ($MAC_{ISO}$) in dogs. Six healthy, female German shepherd dogs (aged 1-2 years) were used in this study. Anesthesia was induced by mask induction and maintained with isoflurane in oxygen. Mechanical ventilation maintained the end-tidal $CO_2$ partial pressure ($P_{ET}CO_2$) from 35 to 45 mmHg throughout the study. A baseline $MAC_{ISO}$ ($MAC_{ISO}B$) was determined starting 45 minutes after induction of anesthesia by clamping a pedal digit until gross purposeful movement was detected. After $MAC_{ISO}B$ determination, dogs received a tramadol loading dose of 3 mg/kg followed by a continuous rate infusion (CRI) of 2.6 mg/kg/h. The determination of $MAC_{ISO}$ after administration of tramadol ($MAC_{ISO}T$) began 20 min after the start of the CRI. Arterial blood pressure and heart rate were recorded continuously and arterial blood samples for blood gas analysis were collected at the end of the equilibration period. Mean ${\pm}$ SD values for the $MAC_{ISO}B$ and $MAC_{ISO}T$ were $1.33{\pm}0.04%$ and $1.23{\pm}0.04%$, respectively. The $MAC_{ISO}B$ decreased significantly by $7.5{\pm}0.2%$ (P < 0.05) after administration of tramadol. The mean heart rate and arterial blood pressure of six dogs were not changed significantly after tramadol administration. The blood gas levels remained constant during the study. In conclusion, tramadol could significantly reduce $MAC_{ISO}$ without depression of cardiorespiratory function. Thus, the use of tramadol on inhalation anesthesia with isoflurane in dogs can improve the stability of anesthesia and the quality of recovery.

• Journal of Veterinary Clinics
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• v.19 no.3
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• pp.283-289
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• 2002

The effects of electroacupuncture (EA) at SP-6 with different durations on the minimum alveolar concentration (MAC) and on the cardiovascular system were evaluated in dogs under isoflurane anesthesia. Eight healthy male beagles were randomly assigned to four study groups (n = 5/group) with washout period of 7 days for recovery and anesthetic withdrawal between experiments. Four study groups were control, nonacupoint electrical stimulation (NA), EA for 30 minutes (SP-6) and continuous EA for 70 or 90 minutes (SP-6C). For the nonacupoint electrical stimulation group, needles were inserted into the nonacupoint at the muscle bellies of left triceps brachii and right quadriceps femoris. MAC and cardiovascular parameters were determined after EA at SP-6 acupoint and at nonacupoint. Thirty minutes of EA and continuous EA until re-determination of MAC at SP-6 acupoint lowered the MAC of isoflurane by 21.3$\pm$8.0% and 16.1$\pm$4.6%, respectively (p<0.05). The decrements in MAC values were not significantly different between two EA groups. However, electrical stimulation of nonacupoint did not induce a significant change in MAC. In SP-6 and SP-6C groups, significant changes in cardiovascular parameters were not observed. These results indicate that EA at SP-6 have an advantage in isoflurane anesthesia in terms of reducing the requirement for anesthetics and minimizing cardiovascular side effects. EA for 30 minutes at maximum might be the sufficient time to produce acupuncture analgesia.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.381-388
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• 1996

The hemodynamic changes in septic patients produced by inhalational anesthetics are sufficient to threaten the anesthesiologists. The effect of hydroxocobalamin, a vitamin $B_{12a}$, on contractile responses to phenylephrine during administration of inhalational anesthetics were evaluated in aortic ring preparations obtained from LPS-treated rats. The sepsis was developed by intraperitoneal injection of LPS (1.5 mg/kg for l8h) and confirmed by iNOS expression using RT-PCR. Statistical significances (P<0.05) were analyzed by Student's t-test or paired t-test according to data characteristics. The blood pressure, but not heart rate, was decreased in LPS-treated rats as compared to control rats. The contractile response to phenylephrine were dose-dependently increased from the doses of $10^{-8}\;M$ to that of $10^{-5}$ and were attenuated in LPS-treated rings. Both halothane and enflurane, at the doses of 1 MAC, decreased the contractile responses to phenylephrine while isoflurane did not significantly affect the contractile responses. Hydroxocobalamin ($10^{-5}$ M) significantly potentiated the contractile responses in the LPS-treated aortic ring preparations during administration of each inhalational anesthetic or not. From these results, it is suggested that hydroxocobalamin may improve the hemodynamics of septic patients during inhalational anesthesia. Abbreviations: LPS, lipopolysaccharide; RT-PCR, reverse transcription-polymerase chain reaction; MAC, minimum alveolar concentration; iNOS, inducible nitric oxide synthase; GAPDH, glyceraldehyde 3-phosphate dehydrogenase