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Learn about venous air embolism (VAE) in positioning surgeries, its complications, monitoring techniques, detection methods, and treatment options in clinical neuroanesthesia.
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Venous Air Embolism Pekka Talke, MD University of California, San Francisco 2009
Procedures in Sitting Position • Cervical laminectomies • Posterior fossa surgeries • Becoming relatively uncommon but associated with high rates of complications
Benefits of Sitting Position • Better surgical exposure • Less tissue retraction • Less bleeding • Less cranial nerve damage
Complications of Sitting Position • Spinal cord infarct • Ulnar nerve compression • Sciatic nerve damage • Lateral peroneal nerve compression • Cardiovascular changes • Airway obstruction -tube kinking, migration • Tension pneumocephalus • Venous Air Embolism (VAE) (40%)
VAE detection,sensitivity • Doppler, TEE • ET N2 • PaO2 • ET CO2, PAP • PaCO2 • CVP • CO • BP • ECG, esoph. steth.
Monitoring for Sitting Position • ECG • Temperature • Muscle relaxation • Pulse oximeter • ET CO2, ET anesthetic agent, ET N2 • Arterial blood pressure (cpp) • Central venous pressure (cvp, pap) • Precordial Doppler • Esophageal stethoscope
Monitoring for Sitting Position • ECG • Temperature • Muscle relaxation • Pulse oximeter • ET CO2, ET anesthetic agent, ET N2 • Arterial blood pressure (cpp) • Central venous pressure (cvp, pap) • Precordial Doppler • Esophageal stethoscope
Doppler (VAE) • Very sensitive • 3-6 th interspace, right of sternum • 2.2 MHz probe • Blood, wall motion, air • Early detection/prevention
Doppler probe 2.25 MHz flat probe 3/4’’ ultrasound beam at surface
Doppler equipment Model 915-BL or Model 614-B 2 MHz flat probe
ET CO2 changes with VAE • Sudden decrease in ET CO2 within a few breaths after VAE • ET CO2 decrease proportional to VAE magnitude • ET CO2 starts to recover once VAE stops
CVP catheter (VAE) • Positioning: ECG, X-ray, pressure tracing • Positioning in sitting position - migration • Can be used to confirm Doppler placement • Aspiration: confirmation of VAE, treatment? • (PA catheter: diagnosis, resolution)
Placement of CVP Catheter From Clinical Neuroanesthesia, Cucchiara et al
Placement of CVP Catheter From Clinical Neuroanesthesia, Cucchiara et al
VAE Detection - Awake • Cough • Chest pain • Bronchospasm • Hypoxia
Rapid, Large VAE • Rare • Catastrophic • Air lock in right heart • Right sided heart failure • Reduced CO • Cardiovascular collapse
Slow, Continuous VAE • Common • Air bubbles entrapped in pulmonary circulation • Local hypoxemia/obstruction • Sympathetic reflex vasoconstriction • Pulmonary HTN, hypoxemia, CO2 retention, increased dead space, decreased ET CO2 • Bronchoconstriction
M&M from VAE • Right heart failure • Hypoxia - immediate, delayed (ARDS) • Paradoxical Air Embolus (PAE) • incidence unknown • potential for neurologic deficits • PFO (20-30%)
Treatment of VAE • 100% O2 • Flood field, bone wax • Jugular pressure • Volume, vasopressors, supine • CPR
Venous Air Embolism • Prevention - avoid hypovolemia, good surgical technique • Early detection • Treatment
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