Mediastinoscopy: vascular compression

Mediastinoscopy provides access to the mediastinal lymph nodes and is used to establish either the diagnosis or the resectability of intrathoracic malignancies. Anesthesia for mediastinoscopy involves multiple considerations. One frequent complication involves compression of the innominate artery by the scope. This can produce “apparent cardiac arrest” as subclavian flow is prevented. Because the innominate artery also supplies cerebral blood flow, cerebral ischemia may result from prolonged compression. A way to monitor for compression and therefore prevent cerebral ischemia is to place the pulse ox and/or arterial line on the right arm and the noninvasive cuff on the left arm. The pulse ox/arterial line may clue you to compression, as evidenced by apparent arrest or hypotension on the arterial line but a normal blood pressure on the left arm via the NIBP. It should then be communicated to the surgeon that innominate compression is likely occurring. Keep in mind that vagally mediated reflex bradycardia can also occur from compression of the trachea or great vessels during mediastinoscopy, as well as sudden massive hemorrhage.