CARDIOVASCULAR CHANGES DURING FAT EMBOLISM CAUSED BY MULTIPLE VERTEBROPLASTY IN SHEEP

Abstract

Introduction: Vertebroplasty (VP) is a new prophylactic treatment for preventing osteoporotic compression fractures of vertebral bodies. During this procedure polymethylmethacrylate (PMMA) is injected into several vertebral bodies. It has been shown that fat embolism (FE) with acute cardiopulmonary deterioration occurs during VP as it does in a variety of other orthopaedic procedures (e.g. knee and hip replacements).

Aim: To investigate the cardiovascular changes during FE caused by multiple VP using an animal model.

Method: PMMA was injected unilaterally, into L1 – L6 in six sheep, with 10 minutes between injections. Arterial, venous and pulmonary arterial pressure, cardiac output and blood gas values were recorded before injection and again after the injection at one, three, five and 10 minutes. The lungs were harvested post mortem and the histopathologic score (percentage of lung fields occupied by intravascular fat globules as the field of the microscope) was calculated.

Results: The sequential injection of bone cement into six vertebral bodies from values before injection of L1 to 10 minutes after injection of L6 resulted in significant falls in arterial blood pressure (P< 0.0001), cardiac output (P=0.0049), pO² (P< 0.0001) and pH (P< 0.0001). There were also significant rises in pulmonary arterial pressure (P=0.0005) and pCO2 (P< 0.0001), but no significant change in central venous pressure. The histopathological score was 19.1±1.94%,

Conclusions: This study clearly showed that multiple VP in sheep leads to FE with major cardiovascular reactions. Arterial blood pressure showed a stepwise, cumulative fall and was clearly the best parameter to demonstrate these reactions. This suggests that in human patients, particular attention should be paid to falls in arterial blood pressure during multiple VP.