ABSTRACT
Cyanosis is typically a sign of a potentially life-threatening condition in the emergency department and requires immediate workup and treatment. This case report highlights the diagnostic reasoning and clinical approach to cocaine- and volatile nitrite-induced methemoglobinemia (MHG). MHG is a rare, life-threatening cause of cyanosis. The diagnosis must be suspected in the emergency department in the presence of hypoxia and cyanosis disproportionate to cardiopulmonary repercussions and refractory to oxygen supplementation. Acquired causes are more prevalent than genetics, and recreational drugs should be highly suspected. Despite the rarity of this situation, cyanosis precipitants and the specificities of each hemoglobinopathy are reviewed in this article.
ABSTRACT
BACKGROUND: 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) has emerged as a useful diagnostic tool for suspected infective endocarditis (IE) in patients with prosthetic valves or implantable devices. However, there is limited evidence regarding use of 18F-FDG-PET/CT for the diagnosis of native valve endocarditis (NVE). METHODS: Between 2014 and 2017, 303 episodes of left-sided suspected IE (188 prosthetic valves/ascending aortic prosthesis and 115 native valves) were studied. 18F-FDG-PET/CT accuracy was determined in the subgroups of patients with NVE and prosthetic valve endocarditis (PVE)/ascending aortic prosthesis infection (AAPI). Associations between inflammatory infiltrate patterns and 18F-FDG-PET/CT uptake were investigated in an exploratory ad hoc histological analysis. RESULTS: Among 188 patients with PVE/AAPI, the sensitivity, specificity, and positive and negative predictive values of 18F-FDG-PET/CT focal uptake were 93%, 90%, 89%, and 94%, respectively, while among 115 patients with NVE, the corresponding values were 22%, 100%, 100%, and 66%. The inclusion of abnormal 18F-FDG cardiac uptake as a major criterion at admission enabled a recategorization of 76% (47/62) of PVE/AAPI cases initially classified as "possible" to "definite" IE. In the histopathological analysis, a predominance of polymorphonuclear cell inflammatory infiltrate and a reduced extent of fibrosis were observed in the PVE group only. CONCLUSIONS: Use of 18F-FDG-PET/CT at the initial presentation of patients with suspected PVE increases the diagnostic capability of the modified Duke criteria. In patients who present with suspected NVE, the use of 18F-FDG-PET/CT is less accurate and could only be considered a complementary diagnostic tool for a specific population of patients with NVE.
