B
Figure 9-4 (cont.)
B, If the prone position is used, it is important to make sure that the chest rolls are optimally placed to prevent an increase in intrathoracic pressure. Before the patient’s head is flexed, it is necessary to confirm that the endotracheal tube is adequately secured. An advantage of the prone position is that the surgeon’s assistant can be involved more actively in the operation instead of standing to the side, which occurs if the patient is in the sitting position. With the sitting position, a central venous catheter, transthoracic Doppler, and transesophageal echocardiography (TEE) are used. If there is Doppler or TEE evidence of a venous air embolus, the anesthesiologist should attempt to aspirate the air through the central venous catheter. At the same time, the surgeon should immediately inspect the operative field to determine the source of the air embolus. The most common sites for air absorption into the venous circulation are through bone diploÍ, veins located laterally
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