Background: In recent years, dexmedetomidine (DEX) has been proposed as a useful vasoconstrictor for local anesthesia because it is less effective in circulation than clonidine of antihypertensive drugs. In addition, DEX is expected to act as a vasoconstrictor during local anesthesia. However, histomorphometric studies demonstrating that DEX exerts vasoconstrictive effects are lacking. This study aimed to clarify whether DEX exerts a histomorphologically vasoconstrictive effect on blood vessels in the mandible of rats. Methods: A total of 12 male Wistar rats were used. General anesthesia was induced and maintained using sevoflurane. Normal saline (0.2 ml) was injected on the left side of the jaw (DEX (-) effect site) and 0.2 ml normal saline containing 12.5 µg/ml DEX was injected on the right side of the jaw (DEX (+) effect site).The puncture point was located on the mesial side of the first molar, 1 mm away from the gingival sulcus.Following decalcification, the specimens were paraffinized and sagittally sliced into 20 μm-thick sections, followed by staining with anti-α smooth muscle actin antibody. The intravascular lumen area was measured in the oral mucosa, periodontal ligament, mandibular bone above the root apex, mandibular bone below the root apex, and dental pulp. The unpaired t-test was used for statistical analysis, and a P value < 0.05 was considered statistically significant. Results: Compared to the DEX (-) effect site, the intravascular lumen area in the oral mucosa and periodontal ligament of the DEX (+) effect site was significantly decreased. No significant difference was observed in the intravascular lumen area between the DEX (-) and DEX (-) effect sites in the mandibular bone above and below the root apex and dental pulp. Conclusion A direct vasoconstrictive effect of DEX was not observed in the intravascular lumen of the mandibular bone above and below the root apex and dental pulp; however, it was observed in the oral mucosa and periodontal ligament.

Background: In recent years, dexmedetomidine (DEX) has been proposed as a useful vasoconstrictor for local anesthesia because it is less effective in circulation than clonidine of antihypertensive drugs. In addition, DEX is expected to act as a vasoconstrictor during local anesthesia. However, histomorphometric studies demonstrating that DEX exerts vasoconstrictive effects are lacking. This study aimed to clarify whether DEX exerts a histomorphologically vasoconstrictive effect on blood vessels in the mandible of rats. Methods: A total of 12 male Wistar rats were used. General anesthesia was induced and maintained using sevoflurane. Normal saline (0.2 ml) was injected on the left side of the jaw (DEX (-) effect site) and 0.2 ml normal saline containing 12.5 µg/ml DEX was injected on the right side of the jaw (DEX (+) effect site).The puncture point was located on the mesial side of the first molar, 1 mm away from the gingival sulcus.Following decalcification, the specimens were paraffinized and sagittally sliced into 20 μm-thick sections, followed by staining with anti-α smooth muscle actin antibody. The intravascular lumen area was measured in the oral mucosa, periodontal ligament, mandibular bone above the root apex, mandibular bone below the root apex, and dental pulp. The unpaired t-test was used for statistical analysis, and a P value < 0.05 was considered statistically significant. Results: Compared to the DEX (-) effect site, the intravascular lumen area in the oral mucosa and periodontal ligament of the DEX (+) effect site was significantly decreased. No significant difference was observed in the intravascular lumen area between the DEX (-) and DEX (-) effect sites in the mandibular bone above and below the root apex and dental pulp. Conclusion A direct vasoconstrictive effect of DEX was not observed in the intravascular lumen of the mandibular bone above and below the root apex and dental pulp; however, it was observed in the oral mucosa and periodontal ligament.

Background: In recent years, dexmedetomidine (DEX) has been proposed as a useful vasoconstrictor for local anesthesia because it is less effective in circulation than clonidine of antihypertensive drugs. In addition, DEX is expected to act as a vasoconstrictor during local anesthesia. However, histomorphometric studies demonstrating that DEX exerts vasoconstrictive effects are lacking. This study aimed to clarify whether DEX exerts a histomorphologically vasoconstrictive effect on blood vessels in the mandible of rats. Methods: A total of 12 male Wistar rats were used. General anesthesia was induced and maintained using sevoflurane. Normal saline (0.2 ml) was injected on the left side of the jaw (DEX (-) effect site) and 0.2 ml normal saline containing 12.5 µg/ml DEX was injected on the right side of the jaw (DEX (+) effect site).The puncture point was located on the mesial side of the first molar, 1 mm away from the gingival sulcus.Following decalcification, the specimens were paraffinized and sagittally sliced into 20 μm-thick sections, followed by staining with anti-α smooth muscle actin antibody. The intravascular lumen area was measured in the oral mucosa, periodontal ligament, mandibular bone above the root apex, mandibular bone below the root apex, and dental pulp. The unpaired t-test was used for statistical analysis, and a P value < 0.05 was considered statistically significant. Results: Compared to the DEX (-) effect site, the intravascular lumen area in the oral mucosa and periodontal ligament of the DEX (+) effect site was significantly decreased. No significant difference was observed in the intravascular lumen area between the DEX (-) and DEX (-) effect sites in the mandibular bone above and below the root apex and dental pulp. Conclusion A direct vasoconstrictive effect of DEX was not observed in the intravascular lumen of the mandibular bone above and below the root apex and dental pulp; however, it was observed in the oral mucosa and periodontal ligament.

Background: We assessed the relationship between patient age and remifentanil dosing rate in patients managed under general anesthesia with spontaneous breathing using low-dose remifentanil in sevoflurane. Methods: The participants were patients with an American Society of Anesthesiologists Physical Status of 1 or 2 maintained under general anesthesia with low-dose remifentanil in 1.5-2.0% sevoflurane. The infusion rate of remifentanil was adjusted so that the spontaneous respiratory rate was half the rate prior to the induction of anesthesia, and γH 　(µg/kg/min) was defined as the infusion rate of remifentanil under stable conditions where the respiratory rate was half the rate prior to the induction of anesthesia for ≥ 15 minutes. The relationship between γH and patient age was analyzed statistically by Spearman's correlation analysis. Results: During dental treatment under general anesthesia using low-dose remifentanil in sevoflurane, a significant correlation was detected between γH and patient age. The regression line of y = − 0.00079 x + 0.066 (y-axis; γH , x-axis; patient's age) was provided. The values of γH provide 0.064 µg/kg/min at 2 years and 0.0186 µg/kg/min at 60 years. Therefore, as age increases, the dosing rate exhibits a declining trend. Furthermore, in the dosing rate of remifentanil when the patient's respiratory rate was reduced by half from the preanesthetic respiratory rate, the dosing rate provided was around 0.88 mL/h in all ages if the remifentanil was diluted as 0.1 mg/mL. EtCO2 showed 51.0 ± 5.7 mmHg, and SpO2 was controlled within the normal range by this method. In addition, all dental treatments were performed without major problems, such as awakening and body movement during general anesthesia, and the post-anesthetic recovery process was stable. Conclusion General anesthesia with spontaneous breathing provides various advantages, and the present method is appropriate for minimally invasive procedures.

Background: Recent animal studies have suggested the role of GABA type A (GABA- A ) receptors in salivation, showing that GABA- A receptor agonists inhibit salivary secretion. This study aimed to evaluate the effects of propofol (a GABA- A agonist) on salivary secretions from the submandibular, sublingual, and labial glands during intravenous sedation in healthy volunteers. Methods: Twenty healthy male volunteers participated in the study. They received a loading dose of propofol 6 mg/kg/h for 10 min, followed by 3 mg/kg/h for 15 min. Salivary flow rates in the submandibular, sublingual, and labial glands were measured before, during, and after propofol infusion, and amylase activity was measured in the saliva from the submandibular and sublingual glands. Results: We found that the salivary flow rates in the submandibular, sublingual, and labial glands significantly decreased during intravenous sedation with propofol (P < 0.01). Similarly, amylase activity in the saliva from the submandibular and sublingual glands was significantly decreased (P < 0.01). Conclusion It can be concluded that intravenous sedation with propofol decreases salivary secretion in the submandibular, sublingual, and labial glands via the GABA- A receptor. These results may be useful for dental treatment when desalivation is necessary.

Objective: To clarify whether early mobilization is a predictive factor for ambulation recovery in elderly patients and/or patients with severe subarachnoid hemorrhage (SAH).Methods: This multicenter retrospective observational study included 471 patients with treated SAH (Group 1). We focused on SAH patients with a poor prognosis, including a subgroup of elderly SAH patients (age>65 years:n=203) (Group 2) and patients with severe SAH (World Federation of Neurological Societies [WFNS] grade IV or V:n=117) (Group 3). The chi-square test and Mann-Whitney U test were used to compare the differences between the ambulation recovery group and the non-recovery group. Multivariable logistic regression analysis modeling was used to estimate odds ratios and 95% confidence intervals of early mobilization for the ambulation-recovered group within 30 days of onset compared with the unrecovered group. Other covariates examined as possible confounders of the outcome were age, sex, location of the ruptured aneurysm, modified Fisher scale score, WFNS grade, mode of treatment (surgical vs. endovascular), duration of cerebrospinal fluid drainage, days on mechanical ventilation, intracerebral hemorrhage, symptomatic cerebral vasospasm, complications, shunt placement for hydrocephalus, and time to start mobilization.Results: Early mobilization was an independent predictive factor for gait recovery in all groups. Furthermore, location of the ruptured aneurysm (anterior circulation), absence of complications, and absence of shunt placement were independent factors for ambulation recovery in all groups.Conclusion: Early mobilization in elder or/and sever patients with SAH may be a predictive factor for ambulation recovery within 30 days of onset.

Objective: To clarify whether early mobilization is a predictive factor for ambulation recovery in elderly patients and/or patients with severe subarachnoid hemorrhage (SAH).Methods: This multicenter retrospective observational study included 471 patients with treated SAH (Group 1). We focused on SAH patients with a poor prognosis, including a subgroup of elderly SAH patients (age>65 years: n=203) (Group 2) and patients with severe SAH (World Federation of Neurological Societies [WFNS] grade IV or V: n=117) (Group 3). The chi-square test and Mann-Whitney U test were used to compare the differences between the ambulation recovery group and the non-recovery group. Multivariable logistic regression analysis modeling was used to estimate odds ratios and 95% confidence intervals of early mobilization for the ambulation-recovered group within 30 days of onset compared with the unrecovered group. Other covariates examined as possible confounders of the outcome were age, sex, location of the ruptured aneurysm, modified Fisher scale score, WFNS grade, mode of treatment (surgical vs. endovascular), duration of cerebrospinal fluid drainage, days on mechanical ventilation, intracerebral hemorrhage, symptomatic cerebral vasospasm, complications, shunt placement for hydrocephalus, and time to start mobilization.Results: Early mobilization was an independent predictive factor for gait recovery in all groups. Furthermore, location of the ruptured aneurysm (anterior circulation), absence of complications, and absence of shunt placement were independent factors for ambulation recovery in all groups.Conclusion: Early mobilization in elder or/and sever patients with SAH may be a predictive factor for ambulation recovery within 30 days of onset.