Intramuscular pressure and fluid absorption during arthroscopic acromioplasty

During arthroscopic acromioplasty a high level of irrigation fluid pressure is sometimes required to obtain an adequate visual field To evaluate the i nfluence of bursa pressure level on the blood circulation of the shoulder m uscles, we measured he intramuscular pressure (IMP) in the supraspinatus an d deltoid muscles with the microcapillary infusion technique during surgery Eleven patients with impingement syndromes Neer I-III and rotator cuff ten dinitis were examined at subacromial bursa pressures of 100 or 150 mm Hg. I n another 11 patients he amount of irrigation fluid absorbed into he circul atory system was evaluated with the use of 2% ethanol NaCl irrigation fluid . At bursal pressures of 100 or 150 mm Hg, the absorbed volume was calculat ed From he expiratory breath ethanol concentration at he termination of sur gery The IMP in both the supraspinatus and the deltoid muscle varied consid erably regardless of bursal pressure. In 50% of he recordings a considerabl e increase was seen in IMP pressure (>15 mm Hg) when he arthroscope was red irected from the intra-articular position to the subacromial bursa. The mea n IMP in bah muscles was less than 60 mm Hg during the major portion of the bursoscopy regardless of the infusion pressure level. The fluid absorption was 100 mL (0 to 229 mL) in the 100 mm Hg group and 37 mL (0 to 180 mL) in the 150 mm Hg group. All values were well below the 1000 mL absorption lim it regarding the risk of development of a hyperhydration syndrome. In arthr oscopic acromioplasty a bursal pressure of 100 or 150 mm Hg will result in similar IMP levels, in most cases below the threshold for muscle blood circ ulation. The amount of fluid absorbed to he circulatory system will be harm less.