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Proteolytic enzyme levels during cardiopulmonary bypass
Advances in Shock Research
|January 1, 1982
Summary
Cardiopulmonary bypass can cause lung damage by increasing proteolytic enzymes. Blood interacting with the bypass circuit may trigger this enzyme release, contributing to postperfusion lung syndrome.
Area of Science:
- Biomedical Engineering
- Cardiovascular Surgery
- Pulmonary Medicine
Background:
- Pulmonary damage, or "shock lung," often follows cardiopulmonary bypass.
- Elevated plasma proteolytic enzymes are frequently observed in these cases.
Purpose of the Study:
- To determine if cardiopulmonary bypass itself, or factors like hemodilution and tissue damage, cause changes in plasma proteinase activity.
- Investigate the role of extracorporeal circulation in enzyme level alterations.
Main Methods:
- Three groups of dogs were studied: controls (anesthesia, heparinization, Ringer's lactate transfusion), hemodilution with sham thoracotomy, and total cardiopulmonary bypass (90 minutes).
- Serum beta-glucuronidase and acid phosphatase activity were measured using spectrophotometry at various time points.
- Enzyme levels were assessed immediately after anesthesia, during the procedure, and on postoperative days 2 and 3.
Main Results:
- Beta-glucuronidase increased by 78.2% and acid phosphatase by 46.3% during extracorporeal circulation.
- Enzyme activity increases were significantly higher in the cardiopulmonary bypass group compared to controls and sham-operated groups.
- These findings indicate that the bypass circuit itself contributes to elevated enzyme levels.
Conclusions:
- The postperfusion lung syndrome may be partly caused by proteinase release.
- Blood interacting with materials within the extracorporeal circuit is a likely trigger for this enzyme release.
- This study highlights a potential mechanism contributing to lung injury after cardiopulmonary bypass.