Safe Anesthesia Induction in Patients with Anterior Mediastinal Mass Using Muscle Paralysis

Abstract

Available reports suggest that an anterior mediastinal mass causing more than 50% narrowing of the trachea and compressing the great vessels can cause further narrowing of the airway and cardiovascular collapse after the administration of muscle relaxants. Accordingly, inhalation induction of general anesthesia or awake intubation is used to avoid the use of muscle relaxation.The following two case reports describe the stepwise safe anesthetic induction of two patients with anterior mediastinal masses using total intravenous anesthesia followed by tailored positive pressure ventilation and administration of muscle relaxant. Case 1A 68-year-old female with recurrent large B-cell lymphoma after multiple rounds of chemotherapy and palliative radiation. The patient developed progressive shortness of breath over a 3-month period. The patient also complained of a choking sensation, hoarseness, dysphagia, and orthopnea along with increasing neck size [1][2][3][4].Computed tomography showed a large anterior mediastinal mass measuring 9.3 cm. The mass encased the great vessels and the aortic arch, narrowing the tracheal luminal diameter to 7 mm (Figures 1a and 1b). The patient was scheduled for a rigid bronchoscopy for placement of tracheal stent. Preoperative assessment revealed hoarseness, audible stridor and palpable supraclavicular mass with engorgement of superficial neck veins. Pre-procedure vital signs were heart rate 116, blood pressure 109/59, respiratory rate 16, and saturation 97% on 5 L nasal cannula.Electrocardiogram showed sinus tachycardia. Pre-procedure echocardiogram showed mild concentric left ventricular hypertrophy, an ejection fraction of 45-50%, and mild global hypokinesis of the left ventricle. Consent for general anesthesia was obtained. AnesthesiaThe patient was taken to the bronchoscopy suite and was placed in a sitting position. Preoxygenation with non-rebreather facemask was started under standard American Society of Anesthesiologists monitoring. Additionally, a Bispectral index (BIS) and non-invasive arterial blood pressure monitoring were utilized. Propofol infusion at 250 µg/kg/min, and 50 µg of fentanyl were given. As the BIS reading dropped to the 60s positive pressure ventilation was initiated with tidal volume in the range of 500s ml with a peak airway pressure of 20 cm