Methemoglobinemia is an uncommon but potentially fatal disorder. Most cases have no adverse clinical consequence and require no treatment, but methemoglobinemia is often overlooked as a cause of low oxygen saturation, and often mistaken for the more common causes of hypoxia by anesthesiologists despite simple bedside tests that indicate the presence of this treatable abnormality. We present a 68-year-old female patient who underwent gastrectomy for advanced gastric cancer with bleeding. In the preoperative period, the patient showed cyanosis and oxygen saturation was 85% by pulse oximeter, but oxygen saturation by arterial blood gas analysis was 100%. After tracheal intubation, the methemoglobin level was 18.3%. Ascorbic acid and methylene blue were administered. During preanesthetic evaluation, the patient had not informed the anesthesiologist that she had been taking dapsone.

Tracheal compression by vascular anomalies in adults is uncommon and most related reports are of children. A 79-year-old woman without any respiratory history underwent a lumbar spine surgery under general anesthesia. She suddenly developed airway obstruction after a position change from supine to prone. A fiberoptic bronchoscopy showed the obstruction of endotracheal tube. The obstruction was relieved after we changed the depth of endotracheal tube and supported the patient's neck with a cotton roll. The surgery ended without any other event and the patient recovered safely. A computed tomography revealed the rightward tracheal deviation and tortuous innominate artery contact with trachea. The patient didn't manifest any respiratory related symptoms during postoperative period, and she was discharged without any treatment.

A 48-year-old healthy woman was admitted in our hospital for elective hemorrhoidectomy. She developed sudden headache and chest pain, and showed sinus bradycardia, arrhythmia and hypotension forty minutes after spinal anesthesia with 0.5% hyperbaric bupivacaine. An EKG showed ST depression and an transthoracic echocardiogram performed in PACU demonstrated mild LV dysfunction with hypokinesia of LV inferolateral wall. An coronary angiography on postoperative day 1 revealed normal coronary vessel and akinesia of LV inferior wall. Levels of CK-MB and Troponin I were mildly elevated. With medical therapy, the patient's symptoms improved and recovered without any complication.

A patient had respiratory difficulty and hoarseness following total thyroidectomy due to bilateral vocal cord palsy. The patient was a 60-year-old man who underwent total thyroidectomy for papillary carcinoma of the thyroid. He had no laryngeal symptoms prior to the operation. Anesthesia lasted 3.5 hours and was uneventful. Spontaneous respiration resumed after reversal of the neuromuscular blockade. After arriving at the post-anesthesia care unit, he complained of respiratory difficulty and hoarseness. We confirmed bilateral vocal cord palsy by fiberoptic laryngoscopy. It is necessary to perform a complete and thorough search for the underlying cause of vocal cord palsy.