Pressure sores: a biochemical test for early detection of tissue damage.

This study was undertaken to seek biochemical indicators in blood associated with the onset of early tissue damage which may progress to the formation of a pressure sore. Changes in serum creatinine phosphokinase (CPK), inorganic phosphate, and lactate dehydrogenase in systemic blood of pigs were investigated before, during, and after local indentation. Pressures of 540mmHg and 700mmHg were applied for six hours on both sides of the scapula and backs of five anesthetized animals. Two hours after release of indentation, serum CPK levels showed marked elevation and remained elevated even after one week. The elevated levels of CPK were shown to correspond to defined pathology of the tissue as determined histologically. On the other hand, inorganic phosphate began to decrease after release of indentation and recovered to the preindentation level after one day. Lactate dehydrogenase did not change significantly throughout the experiment. These results offer important evidence of the potential of CPK as a systemic indicator of muscle damage at an early stage of pressure sore formation.