Sources of nitrogen in the anesthesia circuit

Air embolism during posterior spinal fusion

A 12-year-old healthy girl underwent a 13-level posterior spinal fusion with Harrington rod, Luque instrumentation and Drummond spinous process wires for scoliosis repair. Her anaesthetic induction and initial intraoperative course were completely uneventful until a precipitous blood pressure drop occurred accompanied by a significant decrease in heart rate. The Harrington rod was being manipulated at the same time as bone chips were being removed from the iliac crest. Although more common intraoperative events were presumed and treatment initiated, venous air embolism (VAE) was considered the aetiology of these events when a transient decrease in the end-tidal carbon dioxide (ETCO2) and an increase in the end-tidal nitrogen (ETN2) was noted by mass spectrometry. This transient episode resolved within a relatively narrow window of time, and the case proceeded without further incident, including a wake-up test, to the conclusion of surgery.