CNOR Patient Positioning and Physiological Monitoring 1 — Questions and Answers
Question 1: When placing a patient in the lateral decubitus position, which structure is at greatest risk for pressure injury if padding is not applied correctly?
- Medial malleolus
- Common peroneal nerve at the fibular head (Correct answer)
- Femoral artery
- Brachial plexus at the axilla
Correct answer: Common peroneal nerve at the fibular head
The common peroneal nerve wraps around the fibular head and is vulnerable to compression injury in the lateral position if the lower leg is not properly padded.
Question 2: Which physiological complication is most associated with prolonged Trendelenburg positioning?
- Hypotension and decreased venous return
- Increased intracranial pressure and airway edema (Correct answer)
- Peripheral neuropathy of the lower extremities
- Hypothermia due to vasodilation
Correct answer: Increased intracranial pressure and airway edema
Prolonged Trendelenburg position causes cephalad fluid shift, increasing intracranial pressure and causing facial and airway edema.
Question 3: A patient is positioned in lithotomy. Both legs should be raised and lowered simultaneously to prevent which complication?
- Deep vein thrombosis
- Lumbar spinal injury
- Hemodynamic instability from sudden blood volume shifts (Correct answer)
- Sciatic nerve stretch injury
Correct answer: Hemodynamic instability from sudden blood volume shifts
Raising or lowering both legs simultaneously prevents sudden shifts in blood volume that can cause hemodynamic instability.
Question 4: Which monitoring parameter is MOST important to assess continuously during a procedure performed in the sitting (beach chair) position?
- Pulse oximetry waveform
- Cerebral perfusion pressure via mean arterial pressure at head level (Correct answer)
- Core body temperature
- End-tidal CO2
Correct answer: Cerebral perfusion pressure via mean arterial pressure at head level
In the sitting position, the head is elevated above the heart, so mean arterial pressure must be measured and interpreted at the level of the head to ensure adequate cerebral perfusion.
Question 5: Which position is associated with the highest risk of air embolism during a neurosurgical procedure?
- Supine
- Prone
- Sitting (beach chair) (Correct answer)
- Lateral decubitus
Correct answer: Sitting (beach chair)
The sitting position creates a negative pressure gradient between the surgical site and the right heart, allowing air to enter open venous sinuses and cause air embolism.
Question 6: When positioning a patient prone, the eyes must be checked frequently because prolonged prone positioning can cause:
- Corneal abrasions and pressure-related vision loss (Correct answer)
- Increased intraocular pressure from drainage
- Pupil dilation from parasympathetic stimulation
- Subconjunctival hemorrhage from Valsalva
Correct answer: Corneal abrasions and pressure-related vision loss
Corneal abrasions and ischemic optic neuropathy leading to vision loss are serious complications of prone positioning due to direct pressure and decreased ocular perfusion.
Question 7: Capnography (end-tidal CO2) monitoring provides which of the following critical safety functions in the OR?
- Measures arterial oxygen saturation
- Confirms correct endotracheal tube placement and detects disconnection (Correct answer)
- Quantifies depth of neuromuscular blockade
- Monitors cardiac output continuously
Correct answer: Confirms correct endotracheal tube placement and detects disconnection
Capnography provides real-time confirmation of endotracheal tube placement and immediately detects ventilator disconnection, esophageal intubation, or airway obstruction.
CNOR Patient Positioning and Physiological Monitoring 1
When placing a patient in the lateral decubitus position, which structure is at greatest risk for pressure injury if padding is not applied correctly?