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We bilaterally injected 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle of rats and developed bilateral Parkinson's disease (PD) model rats in order to experimentally investigate the neural mechanisms underlying the alteration of nociception in the orofacial region of patients with PD. We explored the effects of dopamine depletion on nociception by investigating behavioral responses (face rubbing) triggered by subcutaneous administration of formalin into the vibrissa pad. We also assessed the number of c-Fos-immunoreactive (c-Fos-IR) cells in the superficial layers of the trigeminal spinal subnucleus caudalis (Vc). Subcutaneous formalin administration evoked a two-phase increase in face rubbing. We observed the first increase 0-5 min after formalin administration (first phase) and the second increase 10-60 min after administration (second phase). The number of face rubbing behaviors of 6OHDA-injected rats did not significantly change compared with saline-injected rats in both phases. Significant increase of c-Fos-IR cells in the Vc was found in 6-OHDA-injected rats after formalin administration compared with those in saline-injected rats after formalin administration. We also assessed expression of c-Fos-IR cells in the paraventricular nucleus (PVN), and significant decrease of c-Fos-IR cells in the PVN of 6-OHDA-injected rats was found. Taken together, these findings suggest that bilateral dopaminergic denervation evoked by 6-OHDA administration causes hyperalgesia in the trigeminal region and the PVN may be involved in the hyperalgesia.

While the descending dopaminergic control system is not fully understood, it is reported that the hypothalamic A11 nucleus is its principle source. To better understand the impact of this system, particularly the A11 nucleus, on neuropathic pain, we created a chronic constriction injury model of the infraorbital nerve (ION-CCI) in rats. ION-CCI rats received intraperitoneal administrations of quinpirole (a dopamine D2 receptor agonist). ION-CCI rats received microinjections of quinpirole, muscimol [a gamma-aminobutyric acid type A (GABAA) receptor agonist], or neurotoxin 6-hydroxydopamine (6-OHDA) into the A11 nucleus. A von Frey filament was used as a mechanical stimulus on the maxillary whisker pad skin; behavioral and immunohistochemical responses to the stimulation were assessed. After intraperitoneal administration of quinpirole and microinjection of quinpirole or muscimol, ION-CCI rats showed an increase in head-withdrawal thresholds and a decrease in the number of phosphorylated extracellular signal-regulated kinase (pERK) immunoreactive (pERK-IR) cells in the superficial layers of the trigeminal spinal subnucleus caudalis (Vc). Following 6-OHDA microinjection, ION-CCI rats showed a decrease in head-withdrawal thresholds and an increase in the number of pERK-IR cells in the Vc. Our findings suggest the descending dopaminergic control system is involved in the modulation of trigeminal neuropathic pain.

Mandibular advancement in the supine position may influence swallowing during dental treatment under intravenous sedation. This study investigated the influence of mandibular advancement in the supine position on swallowing ability, compared with head extension and mouth opening. The water swallowing test was performed in 13 healthy, awake, supine, adult subjects under four head and mandibular positions. An electromyogram of the suprahyoid muscles was recorded; the duration and peak amplitude were examined. A greater volume of water remained in the mouth during mouth opening and mandibular advancement relative to the neutral position; the volume in the mandibular advancement position was larger and smaller than that in the head extension position and during mouth opening, respectively. The duration of the electromyogram in the head extension position was longer than that in the mandibular advancement position, without differences in the amplitude. Thus, swallowing ability in the supine position was more impaired with mandibular advancement, relative to neutral and head extension positions, but less than that observed with mouth opening. Although unconfirmed by electromyogram, our findings suggest that head extension might improve airway patency by reducing the impairment of swallowing ability compared with mandibular advancement.

Background The insertion of inappropriately sized uncuffed endotracheal tubes (ETTs) with a tight seal or presence of air leakage may be necessary in children. This study aimed to analyze the frequency of the requirement of inappropriately sized uncuffed ETT insertion, air leakage after the ETT was replaced with one of a larger size, and factors associated with air leakage after ETT replacement. Methods Patients under 2 years of age who underwent oral surgery under general anesthesia with uncuffed ETTs between December 2013 and May 2015 were enrolled. The ETT size was selected at the discretion of the attending anesthesiologists. A leak test was performed after intubation. The ETT was replaced when considered necessary. Data regarding the leak pressure (P Leak ) and inspiratory and expiratory tidal volumes were extracted from anesthesia records. We considered a P Leak of 10 < P Leak  ≤ 30 cmH 2 O to be appropriate. The frequencies of the requirement of inappropriately sized ETTs, absence of leakage after ETT replacement, ETT size difference, and leak rate were calculated. A logistic regression was performed, with P Leak , leak rate, and size difference included as explanatory variables and presence of leakage after replacement as the outcome variable. Results Out of the 156 patients enrolled, 109 underwent ETT replacement, with the requirement of inappropriately sized ETTs being observed in 25 patients (23%). ETT replacement was performed in patients with P Leak  ≤ 10 cmH 2 O; leakage was absent after replacement (P Leak  < 30 cmH 2 O) in 52% of patients (25/48). In the multivariate logistic model, the leak rate before ETT replacement was significantly associated with the presence of leakage after replacement ( p  = 0.021). Conclusions Inappropriately sized ETTs were inserted in approximately 23% of the patients. The leak rate may be useful to guide ETT replacement.

Preformed cuffed oral endotracheal tubes are widely used to intubate children undergoing oral surgery. To evaluate the efficacy and safety of oral Ring-Adair-Elwyn (RAE) Microcuff® pediatric endotracheal tubes, we retrospectively investigated the endotracheal tube exchange rate and associated complications in Japanese children younger than 2 years of age undergoing cheiloplasty or palatoplasty. The exchange rate was 3.5%, and although unplanned extubations occurred in 2 patients, no severe complications were observed. Our results suggest that oral RAE Microcuff® tubes are effective and safe for intubating Japanese children younger than 2 years of age, with a low tube exchange rate and minor complications.

The swallowing function is often compromised immediately after general anesthesia owing to the effects of anesthetic agents. Consequently, pharyngeal residue may accumulate, which increases the risk of aspiration during the perioperative period. Therefore, we designed a single-arm, open-label study, developing an artificial intelligence (AI)-based acoustic analyzer for quantifying pharyngeal residues and evaluating its efficacy. A sample of 30 patients aged ≥18 years scheduled for jaw deformity surgery will be enrolled in this study. Immediately after tracheal tube extubation, adventitious sounds from pharyngeal residues, such as saliva and blood, will be measured and quantified using an AI acoustic analysis system. Subsequently, the residual pharyngeal fluid will be suctioned and quantified by measuring the change in container weight before and after collection. The primary outcome measure will be the comparison of adventitious sounds before and after pharyngeal suction, and the secondary outcome will be the correlation between pharyngeal residue volume and adventitious sounds. The results of this study are expected to be drawn by 2025 upon its completion. This study will demonstrate the feasibility of AI-based acoustic monitoring for quantifying increased pharyngeal residues during perioperative management. This approach has the potential to reduce the risk of postoperative aspiration with a simple and inexpensive method.

Background This study aims to validate our previously reported prediction technique for uncuffed tracheal tube (TT) sizes in children younger than 2 years of age based on a calculated outer diameter (OD Cal , mm) in each patient according to the regression equation OD Cal  = 0.00223 × age (day) + 4.88 and to investigate a better method to select initial TT sizes to decrease re-intubation frequency, especially since large tubes can damage the trachea. Methods We included patients younger than 2 years of age who underwent oral surgery under general anesthesia with tracheal intubation between July 2011 and December 2016 at the Osaka University Dental Hospital. The OD of the actual TT and the age in days were extracted from anesthesia records. Agreement rates, estimated numbers of required tubes, and size reduction frequencies were compared to obtain recommended OD (OD Rec ) values in 2 selection groups: “average selection” in the range “nearest to the OD Cal value (OD Cal - 0.35 < OD Rec ≤ OD Cal + 0.35)” and “safe selection” in the range “nearest to the value below OD Cal (OD Cal - 0.7 < OD Rec ≤ OD Cal )”. Results The agreement rates for an OD Rec in the average selection and safe selection groups were 60.8 and 55.1%, respectively ( P  = 0.001). The estimated number of required tubes per patient were 1.40 ± 0.51 and 1.47 ± 0.55 ( P  < 0.001), respectively. The estimated frequencies of size reductions were 13.3 and 4.0% ( P  < 0.001), respectively. Conclusions Because the size reduction frequency is lower despite a slightly higher number of required TTs, selecting an OD Rec based on “safe selection” parameters is desirable to avoid complications due to intubation with larger TTs.

Background Anaphylaxis is difficult to diagnose in the absence of skin or mucosal signs and symptoms. We report two cases of anaphylaxis under general anesthesia, in which the initial presentation was in the form of respiratory signs, followed by skin manifestations 10–15 min later. Diagnosis of anaphylaxis was delayed because skin symptoms were absent early on in the presentation. Case presentation In the first case, a 23-year-old male patient with jaw deformity was scheduled to undergo maxillary alveolar osteotomy. After intubation, auscultation indicated a sudden decrease in breath sounds, together with severe hypotension. Approximately 10 min later, flushing of the skin and urticaria on the thigh appeared and spread widely throughout the body. In the second case, a 21-year-old female patient with jaw deformity was scheduled to undergo maxillomandibular osteotomy. Twenty minutes after the start of dextran infusion, her lungs suddenly became difficult to ventilate, and oxygen saturation decreased to 90%. Approximately 15 min later, flushing of the skin and urticaria were observed. Conclusion In both cases, there was a time lag between the appearance of respiratory and skin symptoms, which resulted in a delay in the diagnosis, and hence, treatment of anaphylaxis. Our experience highlights the fact that it is difficult to diagnose anaphylaxis under general anesthesia.

To determine which nostril is more suitable for nasotracheal intubation in patients with normal patency of both nostrils. Prospective, randomized clinical trial. Operating room of a university medical center. 191 ASA physical status 1 and 2 patients scheduled for elective oral surgery requiring general anesthesia with nasotracheal intubation. Patients were randomized to two groups to undergo nasotracheal intubation through the right nostril (Group R; n = 96) or the left nostril (n = 95). Standard traditional nasotracheal intubation was performed using the Macintosh laryngoscope. Tube rotation was attempted for alignment toward the glottis, and Magill forceps were then used to assist intubation, as necessary. Epistaxis was inspected in the pharynx after the tube tip was passed through the nasal cavity and 15 minutes after nasotracheal intubation was completed. Intubation time was the interval between when the anesthesiologist opened the patient’s mouth with the cross finger maneuver and when the tube was connected to the anesthetic circuit after nasotracheal completion. The frequency of epistaxis was significantly lower in Group R than Group L (P = 0.0006). Although there was no significant difference in nasal passage time between two groups, the intubation time in Group R (24.5 ± 9.4 sec) was shorter than in Group L (30.5 ± 15.6 sec; P = 0.0015). Nasal intubation via the right nostril is more safely performed than with the left nostril. Because of less epistaxis and faster intubation.

To identify the factors that predict blood pressure (BP) changes during induction of general anesthesia, and the relationship between the level of arteriosclerosis and BP changes during anesthesia induction. Prospective, case-control observational study. Operating room of a university hospital. Seventy-two patients who received general anesthesia for oral and maxillofacial surgery. Brachial-ankle pulse wave velocity (baPWV) and central BP were measured. The primary variable was the parameters affecting BP changes during the induction of general anesthesia. For additional analyses, the parameters were compared between high and low PWV groups (1606 cm/s was the cutoff value of baPWV). To measure the relationships between the parameters and BP changes, bivariate and multiple linear regression analyses were performed. Seventy-two patients (including 41 men) with a mean age of 61.7 years and a median baPWV value of 1606 cm/s were evaluated. Significantly higher values for age, central BP, preoperative systolic BP (SBP), amount of decrease in SBP and diastolic BP, and number of patients with diabetes mellitus (DM) and hypertension were observed in the high PWV group. Multiple linear regression analysis demonstrated that age, baPWV, and DM were factors independently associated with the amount of decrease in SBP. In patients 40 years and older, age, baPWV, and DM are thought to be effective predictors of the amount of decrease in SBP during induction of general anesthesia.