Anesthesia for Thoracic Surgery

Question 1

What are some complications with lateral decubitus positioning?

Answer 1

• coughing, tachycardia, HTN during turn to lateral decubitus position
• hypotension from blood pooling in dependent portions
• VQ mismatching = hypoxemia
• interstitial edema of dependent lung
• brachial plexus and peroneal nerve injury
• monocular blindness
• outer ear ischemia
• axillary artery compression

Question 2

In the awake patient in the upright position spontaneously breathing with a closed chest, where is ventilation and perfusion greatest?

Answer 2

• apex of lungs maximally dilated
• most ventilation occurs at the base of the lungs
• perfusion also favors the base of the lungs
• VQ matching is preserved during spontaneous respirations

Question 3

Where is perfusion and ventilation better in the awake patient in the lateral decubitus position with spontaneous respirations and closed chest?

Answer 3

• VQ matching is preserved

- dependent lung receives more ventilation and perfusion than the upper lung (non-dependent) lung

Question 4

Where is ventilation and perfusion greatest in the anesthetized patient in the lateral decubitus position, paralyzed, with a closed chest?

Answer 4

• undergoing positive pressure ventilation
• decrease in FRC
• VQ mismatching increases
• dependent lung has greater perfusion
• non-dependent lung has greater ventilation

Question 5

What happens in the anesthetized patient in the lateral decubitus position with an open chest?

Answer 5

• VQ mismatching
• perfusion remains greater in dependent lung
• Upper lung collapse leads to progressive hypoxemia (mediastinal shift and paradoxical respirations because gas flow moves from dependent lung to upper airway during respiration)