Fat embolism and acute hypotension during vertebroplasty: an experimental study in sheep.
METHODS
An experimental study of cardiovascular complications that arise during vertebroplasty was conducted.


OBJECTIVE
To investigate the sequential occurrence of fat embolism and hypotension during vertebroplasty.


BACKGROUND
Vertebroplasty, the augmentation of vertebrae with polymethylmethacrylate, is a technique for treating osteoporotic compression fractures and achieving prophylactic stabilization of osteoporotic vertebral bodies at risk of fracture. However, there is concern that fat embolism and acute hypotension could occur as in a variety of other orthopedic procedures.


METHODS
In six sheep, 6 mL of polymethylmethacrylate was injected unilaterally into L1. Transesophageal echocardiography monitored the pulmonary artery for echodense particles. Heart rate, arterial and venous pressures, and blood gas values were recorded before and for 25 minutes after injection. The lungs were subjected to postmortem histologic evaluation and compared with lung specimens from two sheep that had not undergone vertebroplasty.


RESULTS
Injection of cement elicited a very rapid decrease in heart rate (within 2 +/- 1 seconds) and a rapid increase in venous pressure (within 3 +/- 1 seconds), which was followed by a fall in arterial pressure (within 5 +/- 2 seconds) (phase 1). Thereafter, showers of echogenic material appeared (within 6 +/- 1 seconds) and lasted for 138 +/- 36 seconds. A second more severe fall in arterial pressure was observed beginning at 18 +/- 2 seconds (phase 2). The injection resulted in an increase in partial pressure of carbon dioxide and a decrease in pH. The histology showed intravascular fat globules and bone marrow cells in lung tissue.


CONCLUSIONS
The results suggest that immediately after cement injection, there was a reflex fall in heart rate and arterial pressure. The second fall in arterial pressure was a consequence of fat emboli passing through the heart and getting trapped in the lungs.
Aebli
Nikolaus
N
Departments of Orthopaedic Surgery and Physiology, University of Otago, and the Department of Cardiology, Dunedin Hospital, Dunedin, New Zealand. jean-claude.theis@stonebow.otago.ac.nz
Krebs
Jörg
J
Davis
Gerard
G
Walton
Mark
M
Williams
Michael J A
MJ
Theis
Jean-Claude
JC
D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D004195:Disease Models, Animal; D017548:Echocardiography, Transesophageal; D004620:Embolism, Fat / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007022:Hypotension / Q000175:diagnosis / Q000209:etiology*; D007267:Injections; D008159:Lumbar Vertebrae / Q000601:surgery*; D008168:Lung / Q000473:pathology; D019635:Neurosurgical Procedures / Q000009:adverse effects; D019637:Orthopedic Procedures / Q000009:adverse effects; D019904:Polymethyl Methacrylate / Q000008:administration & dosage / Q000009:adverse effects*; D019736:Prostheses and Implants / Q000009:adverse effects*; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000473:pathology; D011655:Pulmonary Embolism / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000473:pathology; D012756:Sheep; D014690:Venous Pressure / Q000187:drug effects
D019904:Polymethyl Methacrylate