Nerve Injuries
What is the most commonly injured peripheral nerve in surgical positioning?
Ulnar nerve
Which position improves V/Q matching in patients with ARDS?
Prone
How much does MAP change per inch of height above/below the heart?
2mmHg
What syndrome results from tissue pressure > perfusion pressure, especially in lithotomy?
Compartment
Which nerve is at risk when the lateral leg rests against an unpadded stirrup?
Common peroneal
Injury to which nerve causes wrist drop?
Radial
Trendelenburg position has what effect on FRC?
Decreases FRC
What happens to CO in prone and sitting positions?
Decreases due to venous pooling
What causes central retinal artery occlusion during prone surgery?
External pressure on the globe
Which position should be avoided in patients with anterior mediastinal masses?
Supine
What nerve is compressed against the fibular head in lithotomy?
Common Peroneal
Why should the abdomen hang free in prone position?
To prevent diaphragm compression and preserve lung compliance
Why is Trendelenburg dangerous in CAD patients?
Increases preload and myocardial work
What device can contribute to airway edema intraoperatively?
Esophageal temperature probe
In which position is an axillary roll used to prevent compression?
Lateral decubitus
Which nerve injury causes "hand of benediction"?
Median
In lateral position, which lung is better ventilated?
Nondependent
Which position may falsely elevate MAP in a hypovolemic patient?
Lithotomy
Which complication is caused by air entering venous circulation in sitting position?
Venous air embolism
A patient in steep Trendelenburg develops facial and airway edema. What positioning change should be made?
Reduce tilt angle, head-up adjustment
Which nerve is at risk in lateral decubitus if the patient rolls forward onto the dependent shoulder?
Suprascapular
Which position may cause endobronchial intubation due to diaphragm displacement?
Trendelenberg
What is the cardiovascular risk of extreme hip flexion?
Compression of femoral vessels, reducing venous return
What condition results from hyperflexion of the cervical spine?
Mid-cervical tetraplegia
In robotic surgery, what are two physiologic concerns of prolonged Trendelenburg?
↑ ICP, airway edema; ↓ FRC