Anesthetic experience of methemoglobinemia detected during general anesthesia for gastrectomy of advanced gastric cancer -A case report-

Abstract

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.

Methemoglobinemia Due to Isosulfan Blue Used for Sentinel Lymph Node Mapping

“…(8) Perioperative methemoglobinemia is often overlooked as a cause of low O 2 saturation, such as due to inadequate ventilation, atelectasis or preexisting lung diseases; but it also may occur due to toxic effects of some drugs, such as nitroglycerine, amyl nitrite, ethyl nitrite, sodium nitrite, bismuth subnitrate, silver nitrate, quinones, sulfonamide, sulfathiazole, sulfapyridine, sulfathiazole, aniline dyes, acetanilide, aminobenzenes, aminophenol, benzocaine, prilocaine and phenacetine. (8) The symptoms of methemoglobinemia are usually related to the methemoglobin levels, but cardiovascular and respiratory function and total hemoglobin in blood could also affect the symptoms. Methemoglobin levels above 15 % cause blackbrown colored blood and cyanosis.…”

“…(8) First choice of the treatment is methylene blue 1-2 mg/ kg, which acts as an accelerator of methemoglobin breakdown and a co-factor of methemoglobin reductase which converts methemoglobin to leukomethylene blue in the presence of nicotinamide adenine dinucleotide phosphate and provides nonenzymatic reduction of MetHb. (10) Some cases could also respond to ascorbic acid, however ascorbic acid acts slowly than methylene blue.…”

“…The patient was administered 3 L/min O 2 with nasal CPAP mask and iv 500 mg ascorbic acid was given. (7,8) Totally eight arterial blood gas analyses were performed (Table I). The patient was transferred to the general surgery ward 24 hours later with normal methemoglobin values.…”

Methemoglobinemia in the Operating Room and Intensive Care Unit: Early Recognition, Pathophysiology, and Management

“…Methemoglobinemia is characterized by elevated blood levels of hemoglobin (Hb) containing oxidized ferric (?3) iron (Fe) rather than ferrous (?2) Fe [4]. Hb with ferric Fe cannot reversibly bind oxygen (O 2 ) and has increased affinity for the O 2 bound to the other functional ferrous heme groups, further preventing delivery of O 2 to tissue [5,6]. Because methemoglobin cannot effectively deliver O 2 to peripheral tissue and organs, the oxyhemoglobin dissociation curve is shifted left and hypoxia results [7].…”

“…Hypoxia and cyanosis in the setting of discrepancy between the SpO2 and the SaO2 that is refractory to oxygen therapy should elevate methemoglobinemia on the differential list. In addition to this ''saturation gap,'' signs and symptoms classically associated with methemoglobinemia include cyanosis refractory to oxygen therapy, decreased SpO2 often with a nadir of 85%, chocolate-colored [12] or black/ brown blood [6,8,9], physiologically appropriate PaO2 on ABG, acidosis and tachycardia [12]. These are described in Table 2 [1].…”