1/5. Methaemoglobinaemia after cardiac catheterisation: a rare cause of cyanosis.Two young women had unexpected cyanosis a few hours after cardiac catheterisation for electrophysiological investigation. The first patient had atrioventricular septal defect, had undergone repeated surgical interventions, and was referred because of atrial flutter. The second patient had ablation of an accessory pathway in wolff-parkinson-white syndrome. Local anaesthesia was performed with 40 ml prilocaine 2%. cyanosis with oxygen saturation of 85% developed in both patients a few hours after the electrophysiological investigation. The patients were transferred to the intensive care unit and for the first patient a considerable diagnostic effort was made to rule out morphological complication. Finally methaemoglobinaemia of 16.7% and 33.4%, respectively, was found. cyanosis resolved within 24 hours and did not reappear. Underlying glucose-6-phosphate dehydrogenase deficiency and erythrocyte-methaemoglobin reductase deficiency were ruled out. physicians should be aware of this rare side effect of local anaesthetics in patients with unexpected cyanosis.- - - - - - - - - - ranking = 1keywords = anaesthesia (Clic here for more details about this article) |
2/5. Anaesthetic management of Osler-Weber-Rendu syndrome with coexisting congenital methaemoglobinaemia.A 9-year-old cyanosed child suffering from Osler-Weber-Rendu syndrome with bilateral pulmonary arteriovenous malformations (PAVMs) was posted for cerebral angiography under general anaesthesia. Careful preanaesthetic evaluation led to the diagnosis of coexisting congenital methaemoglobinaemia. There is no previous report of Osler-Weber-Rendu syndrome coexisting with congenital methaemoglobinaemia. This report emphasizes that a second contributory cause of cyanosis must be suspected and meticulously looked for if the symptomatology in a patient cannot be explained by a single established diagnosis. Positive-pressure ventilation was associated with reduction in arterial oxygenation despite an increasing inspired oxygen concentration, which returned to preanaesthetic levels only after extubation and resumption of spontaneous respiration.- - - - - - - - - - ranking = 1keywords = anaesthesia (Clic here for more details about this article) |
3/5. Methaemoglobinemia induced by a low dose of prilocaine during interscalenic block.Methaemoglobinemia is a rare but well known complication of the use of prilocaine in locoregional anaesthesia. We report a case of methaemoglobinemia following the administration of a low dose of prilocaine for an interscalenic bloc. We suggest some hypotheses to explain this phenomenon. This case illustrates the necessity of pulse oximetry monitoring in all patients receiving prilocaine during locoregional anaesthesia.- - - - - - - - - - ranking = 2keywords = anaesthesia (Clic here for more details about this article) |
4/5. Congenital methaemoglobinaemia detected by preoperative pulse oximetry.Methaemoglobinaemia is an unusual cause of cyanosis whether it is congenital or acquired. Hence, the diagnosis may not be immediately obvious and appropriate treatment may be delayed. The case described shows that it should be considered when pulse oximetry and arterial blood gas analysis appear to give conflicting results. A healthy 24-yr-old woman was found to have a pulse oximeter reading of 82% prior to induction of anaesthesia for minor surgery. Clinical examination confirmed cyanosis but no other abnormality was detected. She had no important medical history and was not receiving any medications. Arterial blood gas analysis with the patient breathing air showed PaO2 12.03 kPa (90 mmHg). Co-oximeter analysis of this sample revealed a methaemoglobin content of 13.4% and she was subsequently found to have congenital methaemoglobin reductase deficiency. Anaesthesia was induced and maintained with incremental doses of propofol and fentanyl. A spontaneously breathing technique with oxygen in nitrous oxide was employed uneventfully. No specific treatment for methaemoglobinaemia was given. Perioperative pulse oximetry is one of the major advances in patient monitoring in recent years but unexpected results should not be accepted uncritically. A knowledge of the working principles of oximetry is essential to enable appropriate management in the presence of dyshaemoglobins.- - - - - - - - - - ranking = 1keywords = anaesthesia (Clic here for more details about this article) |
5/5. NADH-diaphorase deficiency identified in a patient with congenital methaemoglobinaemia detected by pulse oximetry.We report on a young woman with congenital methaemoglobinaemia detected by a pulse oximeter during anaesthesia. Investigation of the patient and her family showed that the methaemoglobinaemia resulted from a recessive deficiency of NADH-diaphorase enzyme. A knowledge of the working principles and limitations of pulse oximetry is essential to determine appropriate management in desaturation episodes during the perioperative period.- - - - - - - - - - ranking = 1keywords = anaesthesia (Clic here for more details about this article) |