Critical Care Medicine-Pulmonary Disorders>>>>>Thromboembolic Disease and Hemoptysis
Question 2#

Which of the following statements regarding monitoring modalities for venous air embolism (VAE) is MOST accurate?

A. Precordial Doppler is the most sensitive monitoring modality available for the detection of VAE
B. Changes in end tidal nitrogen occur earlier than changes in end tidal carbon dioxide
C. Pulmonary artery catheter is the most sensitive monitor for the detection of VAE
D. Mill-wheel murmur auscultated with an esophageal stethoscope is an early sign of VAE

Correct Answer is B

Comment:

Correct Answer: B

Transesophageal echocardiography (TEE) is the most sensitive monitoring modality to detect venous air embolism. TEE can detect as little as 0.02 mL/kg of air. Precordial Doppler is the most sensitive noninvasive monitoring modality with the ability to detect 0.05 mL/kg of air. Other available monitoring modalities for the detection of VAE include transcranial Doppler, esophageal stethoscope, pulmonary artery catheter, end tidal carbon dioxide and nitrogen. Changes in end tidal nitrogen are seen to occur 30 to 90 seconds prior to the changes in end tidal carbon dioxide. Although their sensitivities seem equivalent, for large volume entrainment, the sensitivity of end tidal nitrogen might exceed that of end tidal CO₂ . Pulmonary artery catheters are fairly insensitive monitors for this purpose. The mill-wheel murmur auscultated with an esophageal stethoscope has a low sensitivity and is not an early sign (1.7 mL/kg/min).

References:

1. Mirski M, Lele A, Fitzsimmons L, Toung T. Diagnosis and treatment of vascular air embolism. Anesthesiology. 2007;106: 164-177.
2. Shaikh N, Ummunisa F. Acute management of vascular air embolism. J Emerg Trauma Shock. 2009;2(3):180-185.