Patent blue: a near-miss! Costa, RDiasui (1); Gil, Júlio (2); Ferreira Santos, Carla (3); Valente, Sofia (4); Vaz, Cortez (5); Barros, Inês (3); Albuquerque, Ana (3)(6) (1) Internal Medicine Resident (2) Cardiology Resident (3) Internal Medicine Consultant (4) Anesthesiology Consultant (5) Gynecology Consultant (6) Intensive Care Unit Director At Tondela-Viseu Hospital Center (Portugal) Introduction Blue dyes are an important tool in today’s breast surgery, particularly in patients with a small tumour and non-palpable lymph nodes allowing for a much more conservative and morbidity sparing surgery. They are identified in the early stages of their disease when they still have tumour free sentinel lymph nodes in up to 75% of cases. The use of blue dyes identifies the sentinel lymph nodes with an accuracy that borders 96% and is becoming the standard of care for this type of surgeries. Clinical Case We present a clinical case of a 54-year-old woman with hypertension, dyslipidemia, peripheral vertigo and anxiety disorder. With no know allergies or history of allergic drug reactions. The patient was diagnosed with invasive ductal breast carcinoma and presented for lumpectomy with sentinel lymph node biopsy to evaluate the need for radical axillary node clearance. The surgeon administered intradermally 2 ml of 2.5% patent blue V dye (CAS 3536-49-0) and the anesthesia was induced with propofol, fentanyl and rocuronium. While the airway was being secured some laryngospasm was identified, the endotracheal tube was correctly placed and anesthesia was maintained with sevoflurane in oxygen-enriched air. Due to some bronchospasm and a slight obstructive pattern on the ventilator monitoring, attributed to a small and manageable allergic reaction and a low sedation level, sevoflurane level was increased and methylprednisolone was administered. Subsequently the blood pressure insidiously lowered, interpreted as a consequence of the increased sedation. One hour and ten minutes into the procedure, she became hemodynamically unstable (refractory to fluids), bradycardic and developed an exuberant papular rash primarily in the body and lower extremities. She immediately received adrenaline, hydrocortisone, H1-antihistamines, atropine and repeated bolus of ephedrine followed by a noradrenaline drip. In the next hour the anaphylactic reaction grew worse and she was promptly admitted in the intensive care unit where she presented with severe cardiogenic and distributive shock associated to a significant respiratory failure. For the next twenty-four hours she needed mechanical ventilation, aggressive fluid therapy, vasopressors (noradrenaline), endovenous high-dose corticotherapy and H1-antihistamines. Serum lactates reached 5.8 mmol/L remaining high in the first twelve to sixteen hours. At discharge the patient was referred to an immunology follow-up for further study. Discussion This is an important and severe adverse reaction, particularly relevant for its delayed presentation that might cause a misdiagnosis with potently fatal outcome. The delay in correctly identifying the gravity of the allergic reaction associated with a very insidious presentation, partially caused by the early administration of corticotherapy, hypothetically contributed to the development of such a life threatening anaphylactic reaction, expressed by its exuberant and refractory shock. Although small allergic cutaneous reactions are common with patent blue, such events are rare but they underline the risks of the frequently used blue patent V dye and strategies should be devised in order to avoid or minimize their consequences. It’s our opinion that further consideration should be given to patients’ cutaneous sensibility testing before surgery and, during the procedure, systematically monitoring for the early signs of an anaphylactic reaction. Characters: 2973