Methemoglobinemia is a rare but clinically important condition that should be considered among differential diagnosis' in cyanosis. The conventional treatments of methemoglobinemia are high flow oxygen and methylene blue therapies. We present a 52-year-old male patient who admitted to emergency room with severe cyanosis and dyspnea after he was exposed to paint thinner and zinc phosphate solution. The patient was diagnosed with methemoglobinemia with a MetHb level of 49.1mm/Hg in his arterial blood gas test. Patient's symptoms and increased MetHb levels were resistant to high flow oxygen and methylene blue therapies so hyperbaric oxygen therapy (HBO) as an alternative treatment was initiated and the patient was cured promptly. In this case presentation, we aim to discuss the alternative treatment modalities in methemoglobinemia patients with persistent hypoxia and cyanosis, who are unresponsive to standard methylene blue treatment.

Background and Objectives: Contrast-induced nephropathy (CIN), is acute renal damage due to contrast agents. This study is conducted to evaluate serum and renal heterodimeric nuclear transcription factor (HIF)-2 alpha levels and its tissue expression in contrast-induced nephropathy, and in N-acetyl cysteine (NAC)-and Sildenafil-treated rat models. Materials/Methods: This randomized, controlled, interventional animal study was conducted on Wistar rats. Rats (n = 36) were randomly assigned to four groups: control (n = 9), CIN group (n = 9), CIN + NAC group (n = 9), and sildenafil (n = 9). The rat model was used to form iohexol-originated CIN. During the modeling, prophylactic treatment was performed at the 24th and 48th h. After 48 h of modeling, blood, urine, and tissue samples were obtained for biochemical analyses. HIF-2-α levels were measured in renal tissue, serum, and urine samples. Renal sections were also performed for histopathologic and immunohistochemical evaluations of renal injury and HIF-2-α expression. Results: In the CIN model, HIF-2α levels and other biochemical parameters were significantly increased (p < 0.01). Both sildenafil and NAC efficiently decreased renal damage due to contrast agents, as shown in histopathologic examinations (p < 0.05). Similarly, after treatment with sildenafil and NAC, HIF-2α levels were significantly decreased (p < 0.05). Conclusions: The current study shows that serum and tissue HIF-2α levels decrease in CIN. Besides, the levels and tissue expression of HIF-2α decrease with both NAC and sildenafil treatments. With further studies, HIF-2α can be investigated as a biomarker of CIN and can be used in the follow-up of patients with CIN.