Background: A high incidence (40–73%) of postoperative nausea and vomiting (PONV) has been reported following orthognathic surgery, and various risk factors have been associated with it. Identifying PONV risk factors based on initial onset time will help establish preventive measures. This study aimed to identify factors that are significantly related to PONV based on the initial onset time after orthognathic surgery. Methods: This study included 590 patients who underwent orthognathic surgery. Multivariate logistic regression analysis was performed to identify the risk factors that are significantly related to PONV. The objective variables were classified into three categories: no PONV, early PONV (initial onset time: 0–2 h after anesthesia), and late PONV (initial onset time: 2–24 h after anesthesia). The explanatory variables included relevant risk factors for PONV, as considered in previous studies. Results: Total intravenous anesthesia with propofol was a significant depressant factor for early PONV (adjusted odds ratio [aOR] = 0.340, 95% confidence interval [CI] = 0.209–0.555) and late PONV (aOR = 0.535, 95% CI = 0.352–0.814). The administration of a combination of intraoperative antiemetics (vs. no administration) significantly reduced the risk of early PONV (aOR = 0.464, 95% CI = 0.230–0.961). Female sex and young age were significant risk factors for late PONV (aOR = 1.492, 95% CI = 1.170–1.925 and unit aOR = 1.033, 95% CI = 1.010–1.057, respectively). Conclusion We identified factors that are significantly related to PONV based on the initial onset time after orthognathic surgery. Total intravenous anesthesia with propofol significantly reduced the risk of PONV not only in the early period (0–2 h after anesthesia) but also in the late period (2–24 h after anesthesia).

We provided general anesthesia management to a patient with advanced atrioventricular block, which was discovered in the remote period after open-heart surgery. A 21-year-old man with Noonan syndrome was scheduled to undergo excision of a median intramandibular tumor. At 2 months of age, the patient underwent endocardial repair for congenital heart disease. During our preoperative examination, an atrioventricular block was detected, which had not been previously noted. Emergency drugs were administered, and a transcutaneous pacemaker was placed. During anesthesia induction, mask ventilation was easy, and intubation was performed smoothly using a video laryngoscope. The transcutaneous pacemaker was activated in demand mode at a pacing rate of 50 cycles/min approximately throughout the anesthesia time, and the hemodynamic status remained stable. The effect of intraoperatively administered atropine was brief, lasting only a few seconds. Although body movements due to thoracoabdominal muscle spasm were observed during pacemaker activation, they did not interfere with surgery. In postoperative patients with congenital heart disease, an atrioventricular block may be identified in the remote period, and preoperative evaluation should be based on this possibility. In addition, during anesthesia management, it is important to prepare multiple measures to maintain hemodynamic status.

Methemoglobinemia is a blood disorder in which an abnormal amount of methemoglobin is produced, and prilocaine is one of the drugs that can cause this disorder. The maximum recommended dose of prilocaine is 8 mg/kg. We report a case of methemoglobinemia caused by the administration of 4.2 mg/kg of prilocaine without other methemoglobinemia-inducing drugs during general anesthesia. A 17-year-old girl with hyperthyroidism and anemia was scheduled to undergo maxillary sinus floor elevation and tooth extraction. The patient’s peripheral oxygen saturation (SpO 2 ) decreased from 100% at arrival to 95% after receiving prilocaine with felypressin following induction of general anesthesia. However, the fraction of inspired oxygen was 0.6. Blood gas analysis showed that the methemoglobin level was 3.8% (normal level, 1%–2%), fractional oxygen saturation was 93.9%, partial pressure of oxygen was 327 mmHg, and arterial oxygen saturation was 97.6%. After administration of 1 mg/kg of methylene blue, her SpO 2 improved gradually to 99%, and the methemoglobin value decreased to 1.2%. When using prilocaine as a local anesthetic, it is important to be aware that methemoglobinemia may occur even at doses much lower than the maximum recommended dose.

Methemoglobinemia is a blood disorder in which an abnormal amount of methemoglobin is produced, and prilocaine is one of the drugs that can cause this disorder. The maximum recommended dose of prilocaine is 8 mg/kg. We report a case of methemoglobinemia caused by the administration of 4.2 mg/kg of prilocaine without other methemoglobinemia-inducing drugs during general anesthesia. A 17-year-old girl with hyperthyroidism and anemia was scheduled to undergo maxillary sinus floor elevation and tooth extraction. The patient’s peripheral oxygen saturation (SpO 2 ) decreased from 100% at arrival to 95% after receiving prilocaine with felypressin following induction of general anesthesia. However, the fraction of inspired oxygen was 0.6. Blood gas analysis showed that the methemoglobin level was 3.8% (normal level, 1%–2%), fractional oxygen saturation was 93.9%, partial pressure of oxygen was 327 mmHg, and arterial oxygen saturation was 97.6%. After administration of 1 mg/kg of methylene blue, her SpO 2 improved gradually to 99%, and the methemoglobin value decreased to 1.2%. When using prilocaine as a local anesthetic, it is important to be aware that methemoglobinemia may occur even at doses much lower than the maximum recommended dose.

Cohen syndrome is a rare genetic disorder associated with mutations in the VPS13B gene. Individuals with this disorder present with diverse clinical manifestations, including muscle hypotonia, intellectual disabilities, and typical facial characteristics, such as prominent upper central incisors and micrognathia. General anesthesia was administered to a 23-year-old man with Cohen syndrome. Although we observed prominent upper central incisors, an overjet of 10 mm, micrognathia, and thyromental distance of 4 cm, hypotonia was not observed in the patient. Intubation was rendered difficult when performing a direct laryngoscopy. However, smooth intubation was achieved using a video laryngoscope. The patient’s train of four (TOF) count remained zero close to 60 min after rocuronium administration, suggesting that the drug’s muscle-relaxant effect may have been prolonged. A TOF ratio of 0.79 was confirmed 130 min after rocuronium administration, and a TOF ratio of 1.0 was confirmed after administration of 150 mg of sugammadex. The patient’s respiration remained stable after extubation, and no recurarization of muscle relaxation was observed. As demonstrated in this case report, it is important to closely monitor recovery from muscle relaxation and prepare multiple techniques for airway management in general anesthesia management of patients with Cohen syndrome.

Postpolio syndrome (PPS) is widely known to manifest as muscle weakness in patients affected by poliomyelitis in early childhood. This is caused by the long-term overwork of motor nerves regenerated from surviving nerve cells. We report a characteristic delay in recovery from muscle relaxation after administering rocuronium to a patient with PPS under general anesthesia with desflurane. A 59-year-old woman was scheduled to undergo surgical debridement for jaw osteonecrosis. She had a history of poliomyelitis at the age of 2 years, and was diagnosed with PPS at the age of 51 years. General anesthesia was induced with 80 mg propofol, 50 µg fentanyl, and 30 mg (0.69 mg/kg) rocuronium, and maintained with desflurane and remifentanil. The durations of train-of-four (TOF) count 0 and 1 were 96 and 37 min, respectively. Five minutes after discontinuing desflurane, the TOF count was 4. Three minutes after administering 200 mg sugammadex, the TOF ratio was 0.83, and the tracheal tube was subsequently removed. In summary, the effect of a single dose of rocuronium on twitch in TOF monitoring was significantly prolonged in a patient with PPS, which may have been exacerbated by desflurane.