Intramuscular pressure and fluid absorption during arthroscopic acromioplasty

Area of Science:

• Orthopedic Surgery
• Sports Medicine
• Biomedical Engineering

Background:

• Arthroscopic acromioplasty requires high irrigation fluid pressure for optimal visualization.
• Elevated intra-articular pressure may affect shoulder muscle blood circulation.
• Understanding the impact of bursal pressure on intramuscular pressure (IMP) is crucial for patient safety.

Purpose of the Study:

• To evaluate the influence of subacromial bursa pressure on shoulder muscle blood circulation.
• To measure intramuscular pressure (IMP) in the supraspinatus and deltoid muscles during arthroscopic acromioplasty.
• To assess the volume of irrigation fluid absorbed into the circulatory system at different pressures.

Main Methods:

• Microcapillary infusion technique used to measure IMP in supraspinatus and deltoid muscles.
• Subacromial bursa pressures of 100 mm Hg and 150 mm Hg were tested in separate patient groups.
• Ethanol dilution method employed to quantify irrigation fluid absorption into the circulatory system.

Main Results:

• Intramuscular pressure (IMP) varied considerably, with a notable increase (>15 mm Hg) in 50% of cases when moving the arthroscope.
• Mean IMP remained below 60 mm Hg during most of the procedure, irrespective of bursal pressure.
• Fluid absorption was 100 mL (0-229 mL) at 100 mm Hg and 37 mL (0-180 mL) at 150 mm Hg, both well below the hyperhydration risk threshold.

Conclusions:

• Subacromial bursa pressures of 100 or 150 mm Hg during arthroscopic acromioplasty result in comparable IMP levels.
• The measured IMP is generally below the threshold that compromises muscle blood circulation.
• Irrigation fluid absorption is minimal and poses no significant risk of hyperhydration syndrome.