Cardiovascular changes during multiple vertebroplasty with and without vent-hole: an experimental study in sheep.

STUDY DESIGN: An experimental study of cardiovascular complications arising during vertebroplasty (VP) of multiple levels. OBJECTIVES: To investigate the cardiovascular changes during multiple VP and whether a vent-hole has a preventive effect. SUMMARY OF BACKGROUND DATA: An experimental study and clinical reports showed that fat embolism (FE) and acute hypotension occur during VP. There is the concern that these complications may worsen during VP of multiple levels. Vent-holes may prevent FE during VP. METHODS: In twenty-two sheep, four vertebral bodies were augmented with polymethylmethacrylate (PMMA). In ten sheep, a vent-hole was drilled into the pedicle contralateral to the injection site. Heart rate, arterial, central venous and pulmonary artery pressure, cardiac output and blood gas values were recorded. The lungs were subjected to histologic evaluation at postmortem. RESULTS: The consecutive augmentation of four vertebral bodies with PMMA induced a cumulative FE that gradually deteriorated baseline mean arterial blood pressure (MABP) and blood gas values. The deterioration of MABP and change in blood gas values were attenuated, when a vent-hole was drilled. The amount of intravascular fat in the lungs after multiple VP (19%) was reduced when a vent-hole was drilled (9%). CONCLUSION: Surgeons should be aware of the potential cardiovascular complications during VP of multiple levels. In the clinical setting, a needle in the contralateral pedicle could be used to decompress the vertebral body during the injection of bone cement.