Anaesthesia for Specialty Surgery
This domain asks how systemic disease, surgical position and the operative field change your conduct of anaesthesia. Endocrine, neurosurgical, thoracic and laparoscopic scenarios dominate, and the marks come from anticipating the physiological swing before it happens.
Endocrine surgery
- Pheochromocytoma: alpha blockade with phenoxybenzamine for 10–14 days before surgery, then beta-blockade for reflex tachycardia - never the reverse. Hypertension during tumour handling is treated with sodium nitroprusside, phentolamine or magnesium; hypotension after venous ligation is treated with fluid and noradrenaline.
- Carcinoid: avoid histamine-releasing drugs such as morphine and atracurium, and treat a crisis with octreotide.
Neurosurgery
Cerebral perfusion pressure equals MAP minus ICP. Keep MAP within 20% of baseline, head up 15–30 degrees, normocapnia, and use mannitol 0.25–1 g/kg for raised ICP. Short-term hyperventilation to a PaCO2 of 4.0–4.5 kPa is reserved for impending herniation.
Thoracic surgery and one-lung ventilation
Use a left-sided double-lumen tube and confirm position with fibreoptic bronchoscopy after positioning. For hypoxia during one-lung ventilation: recheck tube position, apply CPAP 2–5 cmH2O to the non-dependent lung, add PEEP to the dependent lung, resume two-lung ventilation intermittently, and clamp the pulmonary artery as a last measure.
Laparoscopy
Carbon dioxide pneumoperitoneum causes hypercapnia, raised intraocular pressure, reduced functional residual capacity and reduced venous return, with vagal bradycardia on insufflation. Adjust minute ventilation and avoid nitrous oxide where bowel distension matters.
Worked example
A 40-year-old with a pheochromocytoma becomes hypertensive at 210/110 mmHg during tumour mobilisation. Deepen anaesthesia, start a sodium nitroprusside infusion, and have noradrenaline drawn up for the drop expected after venous ligation. Beta-blockade is never started before alpha blockade, because unopposed alpha stimulation worsens the hypertensive crisis.
Traps
Beta-blocking before alpha blockade; hyperventilating a head-injured patient as routine; failing to recheck the double-lumen tube after turning the patient; and using nitrous oxide in a prolonged bowel case.