Anaesthesia in surgery for aneurysm of the descending thoracic or thoracoabdominal aorta

Aneurysm of the descending thoracic or thoracoabdominal aorta was repaired in 12 cases during simple aortic cross-clamping. The regimen for anaesthesia and general monitoring is presented. It includes thoracic epidural analgesia with intravenous general anaesthesia, use of a double-lumen endotracheal tube, continuous registration of ECG, body temperature, urinary output, systemic and pulmonary arterial pressures and central venous pressure, and intermittent measurement of pulmonary capillary wedge pressure (PCWP), cardiac output, blood gases and haemoglobin. Mannitol (25-40 g) is infused prior to aortic cross-clamping, and infusion of sodium nitroprusside and possibly nitroglycerin is begun just before clamping to control left ventricular afterload and preload. Sodium bicarbonate is given to maintain positive base excess. Before declamping, ventilation is increased by 50% and rapid infusion of blood, plasma and crystalloids is begun in order to raise PCWP by 3-5 mmHg. The clamp is gradually released, and small doses of vasopressor may be required to stabilize the circulation. The operation was uncomplicated in 11 cases, but a patient with ruptured aneurysm died of myocardial infarction.