ACCS Technological and Procedural Proficiency 3 — Questions and Answers
Question 1: A patient undergoing prone positioning for severe ARDS develops worsening oxygenation after 2 hours. The MOST appropriate initial action is:
- Immediately return to supine position
- Increase FiO2 to 1.0
- Assess endotracheal tube position and secretion clearance (Correct answer)
- Increase PEEP by 5 cmH2O
Correct answer: Assess endotracheal tube position and secretion clearance
Endotracheal tube displacement and secretion accumulation are the most common reversible causes of oxygenation decline during prone positioning and should be assessed first.
Question 2: Which parameter from an esophageal pressure catheter most directly guides PEEP titration in ARDS?
- Esophageal pressure at end-expiration
- Transpulmonary pressure at end-expiration (Correct answer)
- Esophageal pressure swing during tidal breath
- Peak esophageal pressure
Correct answer: Transpulmonary pressure at end-expiration
End-expiratory transpulmonary pressure (airway pressure minus esophageal pressure) guides PEEP titration to maintain alveolar patency without overdistension.
Question 3: During an arterial blood gas draw from a radial arterial line, the specimen appears bright red and the pO2 is 450 mmHg on room air. What error has most likely occurred?
- Venous contamination
- Air bubble contamination (Correct answer)
- Clot in the sample
- Metabolic alkalosis artifact
Correct answer: Air bubble contamination
Air bubbles in an ABG sample equilibrate with atmospheric O2 (~150 mmHg), falsely elevating pO2; the bright red color and very high pO2 on room air indicate air contamination.
Question 4: In high-frequency oscillatory ventilation (HFOV), oxygenation is primarily controlled by adjusting:
- Frequency (Hz)
- Amplitude (ΔP)
- Mean airway pressure (mPaw) (Correct answer)
- Inspiratory time percentage
Correct answer: Mean airway pressure (mPaw)
Mean airway pressure determines alveolar recruitment and oxygenation in HFOV, while amplitude controls CO2 elimination.
Question 5: A critically ill patient requires extracorporeal membrane oxygenation (ECMO). The circuit shows a sudden drop in pump flow with normal RPM. The MOST likely cause is:
- Oxygenator thrombosis
- Hypovolemia causing inlet cannula collapse (chatter) (Correct answer)
- Circuit air embolism
- Pump head failure
Correct answer: Hypovolemia causing inlet cannula collapse (chatter)
Decreased pump flow at constant RPM with visible cannula vibration (chatter) indicates inadequate venous return due to hypovolemia or cannula malposition.
Question 6: Which complication is MOST specific to femoral vein central venous catheter placement compared to subclavian placement?
- Air embolism
- Arterial puncture
- Higher infection and thrombosis rates (Correct answer)
- Pneumothorax
Correct answer: Higher infection and thrombosis rates
Femoral CVCs carry significantly higher rates of deep vein thrombosis and catheter-related bloodstream infections compared to subclavian sites.
Question 7: During point-of-care ultrasound assessment for pneumothorax, which finding CONFIRMS the absence of pneumothorax at the examined site?
- Presence of A-lines
- Lung sliding sign (Correct answer)
- Absence of B-lines
- Hyperechoic pleural line
Correct answer: Lung sliding sign
Lung sliding (movement of visceral against parietal pleura during respiration) confirms pleural apposition and excludes pneumothorax at the probe location.
ACCS Technological and Procedural Proficiency 3
A patient undergoing prone positioning for severe ARDS develops worsening oxygenation after 2 hours.
The MOST appropriate initial action is: