Background: Patients who undergo general anesthesia may experience respiratory failure postoperatively because of respiratory depression or upper airway obstruction.Aim: We investigated whether a piezoelectric sensor (AYA-P sensor) can be used to detect upper airway obstruction in patients undergoing intravenous sedation.Methods: This prospective observational study included 26 patients who underwent dental treatment under sedation at a dental clinic. Participants were evaluated using a newly defined airway obstruction score (AOS). The AYA-P sensors were attached to the suprasternal notch and the midpoint between the umbilicus and xiphoid process. The patient's respiratory status was classified into four categories based on thoracic movements, capnography, and breathing sounds from recorded data (S1: no airflow, S2: hypoventilation, S3: normal breathing, and S4: artifact). The data obtained from the AYA-P sensors were processed using a 0.4-Hz low-pass filter, calculated using the moving standard deviation (MSD) method, and further processed using a 0.1-Hz low-pass filter (fMSD). Next, these data were differentiated (D-fMSD). We defined the positive predictive value (PPV) as fMSD or D-fMSD values higher than a threshold alpha in categories S1 and S2. PPV(alpha MAX) was defined as the maximum PPV, and the negative predictive value (NPV[alpha MAX]) was defined using the same alpha MAX.Results: We compared each of the apnea-hypopnea time ratio (AHT%) and AOS with PPV(alpha MAX) and NPV(alpha MAX). The AHT% and AOS were correlated with PPV(alpha MAX) and NPV(alpha MAX) in the neck and abdomen, respectively. These findings suggest that an AYA-P sensor attached to the neck and abdomen can detect a patient's respiratory status.Conclusion: Processed data obtained from AYA-P sensors can predict upper airway obstruction in patients, and the predicted data may be dependent on individual anatomical differences.Clinical trial registration: This study was registrated in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) clinical trial: Unique ID: UMIN000047007.

Orthognathic surgery may induce hemorrhage resulting from nasal mucosal injury or from maxillary osteotomy sites, and if severe, the hemorrhage may cause airway obstruction. The patient in this case report was a 27-year-old woman who underwent Le Fort I and bilateral sagittal split osteotomies under general anesthesia. There were no abnormal intraoperative vital signs. However, immediately after the patient was returned to the ward, significant bleeding that required frequent suctioning was observed in the oral cavity. As the bleeding persisted, the surgeon attempted to insert epinephrine-soaked gauze and polyvinyl acetal sponges into both nasal cavities, but hemostasis was difficult to obtain. To achieve hemostasis by compression/closure at the choana and maintain nasal patency, we inserted a modified cuffed endotracheal tube to serve as a transnasal airway and a choanal hemostatic balloon. This method resulted in hemostasis. The volume of blood loss after returning to the ward was approximately 420 mL. The transnasal airway and choanal balloon was useful for airway management and the prevention of intranasal bleeding into the lower pharyngeal regions. Furthermore, the method was simple and minimally invasive, suggesting its clinical usefulness in similar situations.

Background. The role of perioperative pain management is not only to reduce acute postoperative pain (POP) but also to prevent chronic POP. It would be important to know the usefulness of nerve blockade for perioperative management. However, it has not been extensively studied in orofacial surgery. The objective of the study was to investigate whether perioperative nerve blockade reduces acute POP after orthognathic surgery. Methods. Patients scheduled for orthognathic surgery were retrospectively reviewed (“preblock group”: the nerve blockade was performed before emergence from general anesthesia, and “no preblock group”: the nerve blockade was not performed before emergence from general anesthesia). The visual analog scale (VAS; 0–100 mm)-POP intensity, the VAS-POP areas under the curves (VASAUCs (mm × day)) in addition to VASAUCs for postoperative hours 6 (VASAUC_6), 12 (VASAUC_12), 18 (VASAUC_18), and 24 (VASAUC_24), the analgesic requirement period (day), and the number of days with pain (day) were analyzed. Data are presented as median (interquartile range) values. Results. Fifty-six patients (preblock group, 22; no preblock group, 34) were included (21 males, 35 females; age: 22.0 [21.0–28.0] years). VASAUC_6, VASAUC_12, VASAUC_18, and VASAUC_24 in the preblock group were significantly smaller than those in the no preblock group (3.5 [2.0–7.2] vs. 7.4 [5.1–10.0], p = 0.0007; 9.5 [6.4–13.7] vs. 15.0 [7.2–22.9], p = 0.042; 15.7 [10.3–23.1] vs. 29.3 [18.9–37.2], p = 0.0002; and 17.6 [12.7–27.2] vs. 39.5 [22.9–46.9], p = 0.001, respectively). There were no significant differences between the 2 groups in VASAUC, the analgesic requirement period, and the number of days with pain (p > 0.05). Conclusions. Perioperative nerve blockade reduces POP after orthognathic surgery, especially for the acute postoperative period.

Objectives: High intensity and longer duration of acute postoperative pain are generally associated with a higher risk of developing chronic postoperative pain. Therefore, it is important to identify the preoperative predictors for acute postoperative pain. Preoperative evaluation of offset analgesia (OA) and the Pain Catastrophising Scale (PCS) may be potential predictors for acute postoperative pain. This study aimed to investigate the relationship between preoperative OA, PCS, and acute postoperative pain following orthognathic surgery.Methods: Thirty patients (19 females) scheduled to undergo orthognathic surgery were included in this study. OA and PCS were evaluated preoperatively, and the patients reported their postoperative pain intensity using the visual analogue scale [0-100 mm] until it reached zero (number of days with pain). OA was induced on the dominant forearm via three consecutive painful heat pulses delivered for 5 s (T1=46 ?), 5 s (T2=47 ?), and 20 s (T3=46 ?). Subsequently, the associations between OA, PCS, and the number of days with pain were analysed.Results: The median duration of postoperative pain was 10.3 days. Multiple linear regression analysis showed a significant (p=0.0019) predictive value of OA (p=0.008) for the number of days with pain. The PCS-magnification component was positively correlated with the number of days with pain (R=0.369, p=0.045), with no predictive values of PCS-total and PCS-subscale scores observed.Conclusions: Preoperative evaluation of OA may be a new individualised, predictive tool for the number of days with acute postoperative pain following orthognathic surgery; hence, a possible biomarker for the patient's vulnerability to developing chronic postoperative pain.Ethical committee number: The study was approved by the Ethics Committee of Meikai University (A1624, A2113).Trial registry number: This study was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) Clinical Trial (Unique ID: UMIN000026719, UMIN000046957).

To examine the effects of photobiomodulation (PBM) in healthy volunteers using photonic stimulation of acupuncture points on conditioned pain modulation (CPM), temporal summation of pain (TSP), and offset analgesia (OA), which reflect some aspects of endogenous pain modulation. We included 15 men and 15 women (age, 31.5 [27.3–37.0], body mass index, 25.7 [24.4–27.1], Fitzpatrick skin typing, II: 20, III: 8, IV: 2). CPM, TSP, and OA were evaluated after a sham procedure (control session) and after acupuncture point stimulation (LI4 and LI10 on the non-dominant forearm) using linear polarized near-infrared light irradiation (LPNILI; wavelengths peaked at approximately 1000 nm, output: 1.4 W/cm2, spot diameter: 10 mm, spot size: 1.02 cm2, maximum temperature: 40.5 °C, pulse width: 1 s, frequency: 0.2 Hz) (PBM session). Differences in CPM, TSP, and OA between the two sessions were evaluated by the paired t-test and Fisher’s exact test (statistical significance: p < 0.05). Values indicate median [interquartile range]. LPNILI significantly increased CPM in all participants (control session: 12.1 [−4.5–37.4], PBM session: 23.9 [8.3–44.8], p < 0.05) and women (control session: 16.7 [−3.4–36.6], PBM session: 38.7 [24.6–52.1], p < 0.05). The CPM effect increment was significantly higher in women than in men (p = 0.0253). LPNILI decreased TSP in participants with higher TSP ratios (p = 0.0219) and increased OA in participants with lower OA scores (p = 0.0021). LPNILI enhanced endogenous pain modulation in healthy volunteers, particularly in women, as evaluated using CPM. CPM, TSP, and OA evaluations are potentially useful for discriminating PBM responders from non-responders.

Abstract Objectives Paradoxical sensations, known as thermal pain illusions, can be evoked by painful cold-heat pulse stimulation. They may provide diagnostic value; however, the possible interaction between conditioned pain modulation and thermal pain illusions has not been explored. The present study examined: (1) whether conditioned pain modulation could be induced by alternating tonic painful cold-heat pulse stimulation; and (2) whether the presence of thermal pain illusions during the conditioning stimulus influences the degree of conditioned pain modulation. Methods This study was approved by the Ethics Committee of Meikai University (A1507). Conditioned pain modulation was provoked using alternating painful cold-heat pulses delivered at 20-s intervals applied to the forearm. Thermal pain illusions were qualitatively evaluated, and conditioned pain modulation was assessed quantitatively using the pressure pain threshold as a test stimulus. Differences in the conditioned pain modulation effect between the participants who experienced thermal pain illusions and those who did not were analysed using Student’s t-test. Results A significant positive conditioned pain modulation effect (51.0 ± 4.7%, overall effect) was detected. There was no significant difference in conditioned pain modulation between the participants who experienced thermal pain illusions and those who did not (44.3 ± 6.0% and 55.5 ± 6.8%, respectively; p = 0.255). Conclusions Conditioned pain modulation induced by alternating painful conditioning cold-heat pulse stimulation was identical during the conditioning stimulation in volunteers with and without thermal pain illusions. Conditioning cold-heat pulse stimulation is useful to evaluate conditioned pain modulation. Moreover, conditioned pain modulation is not influenced by the presence of thermal pain illusions, indicating partially different underlying supraspinal, neuronal networks.

Introduction: The incidence and severity of chronic postoperative pain (POP) are major clinical challenges, and presurgical conditioned pain modulation (CPM) and pain catastrophizing scale (PCS) assessments have exhibited predictive values for POP. However, whether CPM and PCS assessments are also predictive of acute POP is unknown. Objectives: We aimed to investigate the relationship between preoperative CPM and PCS and acute POP severity after orthognathic surgery by assessing preoperative CPM and PCS in 43 patients. Methods: The pressure pain threshold and tonic painful cold-heat pulse stimulation (applied with a pain intensity score of 70 on a visual analogue scale [VAS 0-100]) were used as the test and conditioning stimuli, respectively. The pain area under the postoperative VAS area under the curve (VASAUC) was estimated. The associations between CPM, PCS, and VASAUC were also analyzed. Results: No patient experienced chronic POP after 1 month. Negative and positive CPM effects (test stimulus threshold was 0% > and 0% <= during conditioning stimulation, respectively) were detected in 36 and 7 patients, respectively. For patients with negative CPM effects (CPM responders), multiple regression analysis revealed a prediction formula of log (VASAUC) = (-0.02 x CPM effect) + (0.13 x PCS-magnification) + 5.10 (adjusted R-2 = 0.4578, P = 0.00002, CPM effect; P = 0.002, PCS-magnification; P = 0.0004), indicating that a weaker CPM and higher PCS scores were associated with more acute POP after surgery. Conclusion: CPM and PCS can predict acute POP after orthognathic surgery.

Limited information is currently available on methemoglobinemia caused by the administration of prilocaine in children undergoing dental procedures in Japan. This case report presents the development of methemoglobinemia due to prilocaine overdose. The patient was a female aged 5 years 8 months with Noonan syndrome who also had pulmonary valve stenosis and hypertrophic cardiomyopathy. She presented with severe dental caries affecting 12 total teeth and required general anesthesia due to a lack of cooperation during dental treatment. General anesthesia was performed, during which 3% prilocaine with 0.03 IU/mL felypressin was administered intraoperatively via infiltration. Her SpO2 gradually decreased after 30 minutes, and cyanosis was observed postoperatively. Several assessments including a 12-lead electrocardiogram, an anteroposterior chest radiograph, and venous blood gas analysis were performed to identify potential causes. However, there were no indications of acute respiratory or cardiovascular abnormalities. It was noted that a total of 192 mg prilocaine was administered during the procedure, and methemoglobinemia was suspected to have developed because of overdose. Further testing revealed an elevated serum methemoglobin of 6.9%, supporting methemoglobinemia as the cause of her decreased SpO2. In dental procedures that require the use of prilocaine to treat multiple teeth, particularly for pediatric patients, it is important to carefully manage prilocaine dosing, as an overdose may lead to methemoglobinemia.

PURPOSE/AIM:The thermal grill illusion is a paradoxical pain sensation induced by simultaneous exposure to spatially separated, non-painful, cold, and warm stimuli. This study aimed to determine whether paradoxical sensations are also evoked by simultaneous exposure to painful cold-heat stimuli and whether the mechanism involves modulation by segmental and extra-segmental spatial integration.MATERIALS AND METHODS:Sensory perceptions were triggered by simultaneous application of painful cold-heat pulse stimuli using a developed bedside tool equipped with quantitative thermal stimulator devices. Four conditions were investigated: (1) one device placed on the forearm (condition 1, control); (2) two devices placed on the forearm (condition 2, ipsilateral segmental integration); (3) two devices placed on the forearm and ipsilateral thigh (condition 3, extra-segmental integration); and (4) two devices placed bilaterally on the forearms (condition 4, contralateral segmental integration). The evoked perceptions of paradoxical heat sensation and the loss of cold or heat sensation were evaluated.RESULTS:The aforementioned phenomena were experienced by 11(35.4%), 3(9.7%), 3(9.7%), and 0(0.0%) subjects for conditions 1-4, respectively. Fisher's exact test revealed significant differences (p=.001) among the four conditions. However, Bonferroni post hoc analysis revealed significant differences only between conditions 1 and 4 (p=.005).CONCLUSIONS:Simultaneous painful cold-heat pulse stimulation can induce paradoxical sensations similar to those shown for non-painful thermal (cold and heat) stimuli. They were predominantly evoked by ipsilateral integration. Paradoxical sensations have diagnostic value, and quantifying them using a simple bedside tool may be useful in the clinical setting.