Carotid body tumour excision: Anaesthetic challenges and review of literature
A 38-year-old female weighing 47 kg presented with history of swelling on the right side of neck near the angle of jaw since 4 years. The lump was slow growing, painless, soft and non-pulsatile, of 6 × 3 × 4.5 cm in size. The patient visited our hospital as she developed weakness of tongue on the right side, after attempted biopsy. There were no other pathological findings. She was normotensive; her indirect laryngoscopy showed normal vocal cord movements, and there was no extension of tumour in hypopharynx. Computed tomography (CT) scan of neck showed well-defined oval soft-tissue mass pushing the right-sided carotid vessels slightly medially and anteriorly. Magnetic resonance imaging (MRI) angiography showed a large well-defined soft-tissue lesion just above the right carotid artery bifurcation splaying internal and external carotid arteries and being fed by branches of these vessels []. A diagnosis of Shamblin type II CBT was made and excision under general anaesthesia was planned.\nHer preoperative biochemical investigations, urinary vanillyl mandelic acid (VMA), ECG and X-ray chest were within normal limits. Preoperatively vascular and neurosurgeon were consulted, cerebral protection therapy was discussed, and synthetic graft material was made available. In the operation theatre, patient was connected to multi-para monitor IV midazolam 1 mg, fentanyl 60 μg was given, and radial artery cannulation was done. Conventional general anaesthesia with controlled ventilation technique was used. Intraoperative induced hypotension was achieved with infusion of nitroglycerine (NTG) 0.5 mcg/kg/min and clonidine 2 mcg/kg/h and adjusted to maintain the mean blood pressure (BP) 80-90 mmHg and pulse 70-80 beats/min. Operation theatre temperature was kept at 22°C with patient temperature 34-35°C for mild hypothermia. At the time of tumour dissection, there was an episode of bradycardia that was treated with IV atropine 0.6 mg and local infiltration of lignocaine 2%. While separating the mass from carotid artery, there was injury to the external carotid artery with torrential blood loss of 1500 ml with hypotension. NTG and clonidine were immediately stopped and 1000 ml of colloid was infused. The artery was clamped, and sutured with Gortex graft. Bypass shunt was used to maintain circulation across the cross clamp. Four units of packed cells were infused to maintain the blood volume and mean arterial BP 80-90 mmHg for adequate cerebral perfusion. A single dose of thiopentone 300 mg was given IV. As there was a catastrophic event of blood loss and the risk of neurological involvement, patient was electively ventilated in the intensive care unit with electroencephalograph (EEG) monitoring. Thiopentone infusion was started 3-5 mg/kg/h. Mean arterial BP was maintained in the range of 80-90 mmHg by adjusting the infusion rate. Patient was weaned off after confirming cerebration and extubated after 24 h. There were no additional cranial nerve palsies, and her vocal cord movements were normal with a good deglutition reflex. Patient was discharged on 10th postoperative day without additional neurological deficit though her tongue weakness persisted.