We report a case in which intubation/ventilation during anesthesia induction was impossible because of a peripharyngeal hematoma in a patient with a mandibular fracture 2 days after injury. Airway obstruction caused by peripharyngeal hematoma is rare but can cause life-threatening airway complications. A 20-year-old man who sustained a blow to the head and neck while kickboxing was transferred to our hospital. A computed tomography examination of his head and neck revealed a mandibular fracture and a peripharyngeal hematoma, but only a slight narrowing of the upper airway was noted. An open reduction and internal fixation of the mandibular fracture under general anesthesia was scheduled for 2 days later. A general examination before anesthesia induction showed a normal respiratory condition ; the patient did not exhibit dyspnea, his respiratory rate was 12/min, and his SpO₂ was 99%. Based on the above findings, he was scheduled to undergo rapid-induction general anesthesia. Anesthesia was induced via the intravenous injection of propofol, rocuronium, and remifentanil. Ventilation by mask gradually became difficult. We tried to perform intubation using a bronchial fiberscope, but it was difficult to identify the glottis because of the peripharyngeal hematoma and laryngeal edema. We were able to intubate because the tip of the bronchial fiberscope was inserted into the trachea by chance. Airway management may be difficult in patients who have traumatic injuries in the head and/or neck region. Thus, careful consideration is required before the induction of general anesthesia.

  Methemoglobinemia is a rare adverse event during dental treatment. Methemoglobinemia can be critical, leading to hypoxemia. In dental treatment, the amide-type local anesthetic propitocaine, which contains nitrites, can cause methemoglobinemia. We report a case of methemoglobinemia caused by propitocaine during general anesthesia. The patient was a 24-year-old woman (height, 163.3 cm ; weight, 46.5 kg) with WPW syndrome. The removal of a fixation plate after an open reduction of the mandible and wisdom teeth extractions were scheduled to be performed under general anesthesia. We chose propitocaine for local anesthesia to prevent tachycardia. Her SpO₂ gradually decreased from 99% to 93%. We tried to optimize her SpO₂ by increasing PEEP, FIO₂ and/or a lung recruitment maneuver but were unsuccessful. We suspected methemoglobinemia and checked her arterial blood gas levels. Since her partial oxygen tension was 435 mmHg and her O₂Hb was 95%, and a methemoglobin value was 4%. We have noticed methemoglobinemia. The total dose of propitocaine was 540 mg, and methemoglobinemia is typically caused by a dose of more than 400 mg without felypressin. The patient had no clinical signs of cyanosis or dyspnea. After surgery, we monitored the arterial methemoglobin value using pulse spectrophotometry (SpMet^® value ; Masimo Rainbow^®). The peak methemoglobin value was 5.6%, occurring 3 hours after the return of the patient to the ward. Orthtoluidine, a metabolite of methemoglobin, was thought to have contaminated the measured value. The SpO₂ recovered to 97%, and the SpMet^® value decreased to 0.6%. In conclusion, we propose a risk of methemoglobinemia that is caused by overdose of propitocaine. Continuous monitoring using pulse-spectrophotometry (SpMet^®) is useful for confirming the trend of the methohemoglobin value.

  This report describes a case of severe bradycardia caused by assisted mouth opening under general anesthesia. The patient was a 46-year-old woman scheduled for scar revision under general anesthesia because of tendon hyperplasia and aponeurisis of the masticatory muscles. She had previously undergone surgery for masticatory muscle tendon-aponeurosis hyperplasia when she was 28 years old. An electrocardiogram performed during the preoperative examinations was within normal limits. The patient's intraoperative blood pressure and heart rate were stable until after the completion of the bilateral scar revision, at which time the surgeon opened the patient's mouth to evaluate the amount of opening. The patient's blood pressure immediately increased and she developed sinus bradycardia, with her heart rate dropping to 27 times/min. Immediately after closure of the mouth, the electrocardiogram showed a decrease in the of QRS wave. Atropine sulphate (0.5 mg) was administered after preparation for transcutaneous pacing. The heart rate recovered to 80 beats/min, and her sinus rhythm and circulation stabilized, enabling the operation to continue. No further complications occurred during the emergency or throughout the postoperative period. In the present case, the parasympathetic nervous system was tense after remifentanil administration, and a vagal reflex was easily induced. In addition, stimulation from the sinus nodules was thought to have been weakened by the parasympathetic nervous system, which was triggered by the opening load ; an atrial ectopic pacemaker stimulated the sinus nodules, but a QRS wave did not appear.

  Ankylosing spondylitis (AS) is a rare disease. Initially, patients with AS often feel pain in the lumbar and gluteal regions, and their movements gradually become limited. We report the anesthetic management of a 32-year-old male patient with ankylosing spondylitis. The patient has had a medical history of AS since the age of 30 years and had been receiving treatment with infliximab as an outpatient at the Department of Internal Medicine. The patient had difficulty tilting his neck backwards, and he had a restrictive ventilator impairment because of AS. During the operation, we extracted both third molar teeth of the lower jaw under general anesthesia using a laryngeal mask airway (LMA). After the operation, the patient's surgical wound became infected despite the long-term administration of antibiotics. During operations under general anesthesia for patients with AS, 3 important points should be considered : tracheal intubation, respiratory care, and the patient's posture. Tracheal intubation is often difficult to perform in patients with AS because of a rigid neck and temporomandibular joint. In such cases, the use of devices such as an LMA or video intubation system can simplify tracheal intubation. Regarding respiratory care, patients with AS sometimes have restrictive ventilator impairment. During general anesthesia for such patients, the anesthesiologist should pay close attention to the patient's respiratory condition. Finally, patients with AS often have limited mobility. It is important to confirm whether the patient can feasibly maintain the posture required for intubation and surgery prior to the start of general anesthesia and to ensure that the patient's head is held immobile during the operation.

  The presently reported patient developed an infection at the wound site. Thus, infection control in patients taking infliximab should be investigated further.

  Ring 18 syndrome is a rare chromosomal abnormality, with about 70 cases reported worldwide. The clinical manifestations of this syndrome include congenital heart disease, a short height, craniofacial abnormalities such as microcephaly and micrognathia, hypothyroidism, and mental retardation. We report the general anesthetic management of a patient with ring 18 syndrome undergoing dental treatment.

  A 20-year-old male (weight, 28.8 kg ; height, 127 cm) with ring 18 syndrome was scheduled to undergo dental treatment under general anesthesia. The clinical manifestations of this patient included mental retardation, a short height, hypertelorism, a flat nasal bridge, micrognathia, a carp-shaped mouth, aortic valve regurgitation, and pulmonary regurgitation. Because of the anticipated difficulty caused by the patient's mental retardation, he was scheduled to undergo dental treatment under general anesthesia. Prior to entering the operation room, he was sedated with oral midazolam. Upon the induction of general anesthesia, an oral airway, laryngeal mask, video laryngoscope, and broncofiberscope were prepared. General anesthesia was induced with propofol and remifentanil. Since mask ventilation was easy to perform, we administered rocuronium. Fortunately, intubation by visual identification of the larynx and the glottis using a Macintosh laryngoscope was possible. However, nasotracheal intubation was impossible because of the rhinostenosis. General anesthesia was maintained using sevoflurane and remifentanil. To avoid regurgitation, we maintained his heart rate at more than 60 bpm and avoided any increase in systemic vascular resistance. Extubation was performed without difficulty after the patient was fully awake. No complications were observed during or after the general anesthesia.

  When providing anesthesia for patients with ring 18 syndrome, anesthesiologists should evaluate the congenital heart disease preoperatively and prepare for unanticipated airway difficulties.