Detection of embolized material in the right atrium during cementation in hip arthroplasty

Precordial Doppler ultrasound, hemodynamic changes and end-tidal carbon dioxide (ETCO2) were monitored in 36 patients undergoing hip surgery in general anesthesia. Changes in Doppler ultrasound indicative of embolization were recognized in 22 out of 36 patients during femoral cementation. The character of the ultrasound was suggestive of air emboli, though simultaneous embolization of bone marrow could not be excluded. Embolization was associated with a fall in arterial oxygen tension (PaO2). Both embolization and reduction of PaO2 were influenced by the cementation technique. Digital anterograde insertion and insertion by syringe of acrylic bone cement into the femoral cavity caused ultrasound changes in 92% and 75% respectively, whereas retrograde insertion of low viscosity bone cement was accompanied by ultrasound activity in only one patient (9%). The blood levels of monomeric methylmethacrylate (MMA) released from the low viscosity bone cement ranged from 0.04 to 7.01 micrograms/ml-1. Doppler ultrasound monitoring gave valuable help during cementation, as the ultrasound change immediately signalled a warning of embolism and an imminent decrease in PaO2.