Dexmedetomidine Dose Dependently Decreases Oral Tissue Blood Flow During Sevoflurane and Propofol Anesthesia in Rabbits

Effects of dexmedetomidine on the onset and duration of action in non-depolarizing neuromuscular relaxant rocuronium

To determine the impact of two varying doses of dexmedetomidine (DEX) on the onset and duration of neuromuscular blockade of rocuronium (ROC) under the condition of sevoflurane anesthesia. Eighty-one patients, American Society of Anesthesiologists Class I–II, were stochastically allocated to control group (group C) and two DEX groups (group D1 and group D2). In group D1 and group D2, DEX (0.5 and 1.0 µg/kg, respectively) was administrated 10 min before induction of general anesthesia. In group C, equivalent saline was infused by the same way. We monitored heart rate (HR), blood pressure, and train-of-four (TOF) values of all subjects in the period of anesthesia. We recorded times to reach TOF value 0 (T0, from injection of ROC to disappearance of all four twitches) as the onset time and TOF value 25% (T25, ratio of fourth twitch to first twitch,) as clinical duration of neuromuscular blockade. A total of 81 patients were randomized, 75 of whom accepted treatment, including group D1 ( n = 25), D2 ( n = 25), and C ( n = 25). T0 time of three groups was found to be similar. The duration of action for ROC in group D2 was 62.76 ± 6.33 min, which was much longer than that in group D1 and group C, which were 42.64 ± 3.92 and 42.56 ± 4.04 min ( p < 0.05), respectively. At T2 (after DEX administration) and T4 time point (10 min after trachea intubation), compared with group C, the changes of heart rate (HR) and blood pressure in DEX groups (group D1 and group D2) show greatly differences. Otherwise, there were no obvious differences among different groups at the other monitoring point-in-time. DEX infusion in general anesthesia has no obvious effect on the onset of ROC, but it is capable of prolonging its clinical effect time, which can provide reference for rational application of DEX and ROC in general anesthesia.

[Practical potentials of using dexmedetomidine in oral and maxillofacial surgery]

Dexmedetomidine is a selective α₂ adrenoreceptor agonist. The drug has a set of useful properties due to wide prevalence of the receptors in a body. The article presents review of the literature of using dexmedetomidine in anesthetic practice of various surgery fields which positive results may be extrapolated to dentistry and maxillofacial surgery to solve important anesthesiologic problems. Inclusion of the drug in routine oral and maxillofacial surgery anesthesia can bring a significant amount of benefits: safe sedation for dental interventions, sedation for compromised airways without respiratory depression, improvement of intraoperative and postoperative analgesia, reduction of postoperative nausea, vomiting and postoperative shivering incidence, nephroprotection and stability of hypotensive hemodynamics, decrease of intraoperative blood loss. Thus, the dexmedetomidine may be a useful agent for anesthesia in oral and maxillofacial surgery that increases anesthesia safety and quality of medical care.

Application of dexmedetomidine-remifentanil in high-intensity ultrasound ablation of uterine fibroids: a randomised study

OBJECTIVE

To compare the effects of dexmedetomidine-remifentanil with the traditional analgesia and sedation regimen midazolam-remifentanil during HIFU treatment of uterine fibroids.

DESIGN

A randomised controlled trial.

SETTING

Department of Anesthesia in a single hospital.

POPULATION

Patients with uterine fibroids.

METHODS

A total of 80 patients diagnosed with uterine fibroids and scheduled for selective HIFU treatment were randomly divided into the dexmedetomidine group (the D group) and midazolam group (the M group). At 20 minutes before the HIFU procedure, patients in the D group received a loading dose of 0.8 μg/kg dexmedetomidine, followed by a continuous intravenous infusion of 0.2 μg/kg/hour until the end of the operation. Patients in the M group were given a corresponding amount of 0.9% saline. Patients in the M group received a slow intravenous infusion of 0.03 mg/kg midazolam before the procedure, an intravenous injection of 0.02 mg/kg 30 minutes later, another 0.02 mg/kg 60 minutes later, followed by 0.02 mg/kg at 40-minutes intervals. Patients in the D group were given a corresponding amount of 0.9% saline. During the HIFU procedure, patients in both groups were administered remifentanil at an effect site concentration of 1.0 ng/ml. Sedation and analgesia were rated using the Ramsay Sedation Scale (RSS) and Visual Analogue Scale (VAS) before drug administration (T1), after drug administration but before HIFU (T2), at the beginning of HIFU (T3), 15 minutes later (T4), 45 minutes later (T5), 75 minutes later (T6), and at the end of HIFU (T7). Patient satisfaction score and Steward recovery score survey were conducted 30 minutes after surgery.

MAIN OUTCOME MEASURES

Different effects of the traditional midazolam-remifentanil regimen and dexmedetomidine-remifentanil.

RESULTS

All patients in both groups underwent a successful HIFU procedure without developing serious complications during the postoperative period. However, the D group reported significantly fewer cases of respiratory depression than the M group during HIFU treatment (P < 0.05). The pause during HIFU ablation in the D group was significantly shorter than that in the M group. HIFU ablation intensity, the number of patients with an RSS of 3 or 4 measured at different time points, and the number of patients with an RSS of 3 or 4 measured at arousal were significantly greater in the D than the M group (P < 0.05). Likewise, the D group scored significantly higher in the evaluation of patient satisfaction, recovery score, and surgeon satisfaction (P < 0.05).

CONCLUSIONS

Both dexmedetomidine-remifentanil and midazolam-remifentanil met the requirements and ensured the safety of HIFU treatment of uterine fibroids. However, compared with the traditional midazolam-remifentanil regimen, dexmedetomidine-remifentanil was associated with more stable sedation in patients, more efficient HIFU treatment and higher degree of patient comfort.

TWEETABLE ABSTRACT

Dexmedetomidine-remifentanil is associated with more stable sedation in patients, more efficient HIFU treatment and higher degree of patient comfort than is midazolam-remifentanil.

Effects of Volatile Anesthetics on Oral Tissue Blood Flow in Rabbits: A Comparison Among Isoflurane, Sevoflurane, and Desflurane

PURPOSE

The aim of this study was to compare the concentration-dependent effects of isoflurane, sevoflurane, and desflurane on oral tissue blood flow.

MATERIALS AND METHODS

Thirty male Japan White rabbits were randomized to receive 1 of 3 volatile anesthetics: isoflurane (group Iso), sevoflurane (group Sevo), or desflurane (group Des). The end-tidal concentration of each volatile anesthetic was regulated to 0.5, 1, and 1.5 minimum alveolar concentrations (MACs). The observed variables were heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, common carotid arterial blood flow, tongue mucosal blood flow, mandibular bone marrow blood flow (BBF), masseter muscle blood flow (MBF), upper alveolar tissue blood flow, and lower alveolar tissue blood flow (LBF).

RESULTS

The blood pressure in each group tended to decrease depending on the concentration of each volatile anesthetic, with the smallest effect in group Des. BBF and MBF in group Iso were higher than those in group Des at 1 MAC, and MBF and LBF in group Iso were highest at 1.5 MAC.

CONCLUSION

The results of this study suggest that each volatile anesthetic produced unique effects on blood flow in oral tissues and circulatory parameters. Among the 3 volatile anesthetics, desflurane produced the smallest effects on oral tissue blood flow.

Effect of changes in end-tidal carbon dioxide tension on oral tissue blood flow during dexmedetomidine infusion in rabbits

A decrease in arterial carbon dioxide tension induces an increase in masseter muscle blood flow and a decrease in mandibular bone marrow blood flow during general anesthesia. In addition, dexmedetomidine infusion reduces oral tissue blood flow. In this study we investigated how end-tidal carbon dioxide tension (ET-CO2 ) changes influence on oral tissue blood flow during continuous dexmedetomidine infusion in rabbits. Eleven male Japan White rabbits were anesthetized with sevoflurane. Then, ET-CO2 was set at 30 mmHg and adjusted to 40 and 60 mmHg, and heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, common carotid artery blood flow, mandibular bone marrow blood flow, masseter muscle blood flow, and blood flow in other oral tissues were measured. Following this, the ET-CO2 was returned to 30 mmHg and dexmedetomidine was infused over 60 min. The measurements were repeated. Most parameters increased, regardless of whether or not dexmedetomidine was present, and heart rate and masseter muscle blood flow decreased in an ET-CO2 -dependent manner. Dexmedetomidine infusion suppressed ET-CO2 -dependent masseter muscle blood flow change. Masseter muscle blood flow during ET-CO2 at 30 mmHg with dexmedetomidine was the same as that during ET-CO2 at 40 mmHg without dexmedetomidine. Our findings suggest that dexmedetomidine infusion and slight hypocapnia under general anesthesia suppress an increase in masseter muscle blood flow as well as reducing mandibular bone marrow blood flow. These results may be of significance for decreasing bleeding during oral and maxillofacial surgery.