HYPOTENSION DURING CEMENTED ARTHROPLASTY - RELATIONSHIP TO CARDIAC-OUTPUT AND FAT-EMBOLISM

An episode of hypotension is common during cemented joint replacement, and has been associated with circulatory collapse and sudden death. W e studied the mechanism of hypotension in two groups of six dogs after simulated bilateral cemented arthroplasty. In one group, with no lava ge, the insertion of cement and prosthesis was followed by severe hypo tension, elevated pulmonary artery pressure, decreased systemic vascul ar resistance and a 21% reduction in cardiac output. In the other grou p, pulsatile intramedullary lavage was performed before the simulated arthroplasties. Hypotension was less, and although systemic vascular r esistance decreased, the cardiac output did not change. The severity o f the hypotension, the decrease in cardiac output and an increase in p rostaglandin metabolites were related to the magnitude of pulmonary fa t embolism. Pulsatile lavage prevents much of this fat embolism, and h ence the decrease in cardiac output. The relatively mild hypotension a fter lavage was secondary to transient vasodilatation, which may accen tuate the hypotension caused by the decreased cardiac output due to a large embolic fat load. We make recommendations for the prevention and management of hypotension during cemented arthroplasty.