Journal: Anesth Analg 105(5):1214 1218, 2007. 31 References
Reprint: Dept of General Anesthesiology and Intensive Care (B), Vienna Medical University, Wahringer Gurtel 18-20, 1090 Vienna, Austria (SA Kozek-Langenecker, MD)
Faculty Disclosure: Abstracted by S. Ouellette, who has nothing to disclose.
Garlic is among the most commonly used medicinal plants in presurgical patients. Caring for patients perioperatively taking mostly self-administered herbal supplements is an evolving challenge. Various bioactive constituents of garlic inhibit platelet aggregation. Interference with the biosynthesis of prostaglandins via inhibiting cyclooxygenase 1 and direct interaction with the fibrinogen receptors have been reported as the target mechanisms for garlic-induced platelet inhibition. In vivo, extracts of garlic inhibited platelet aggregation, adhesion to fibrinogen, and thromboxane B2 secretion. Garlic increased the risk for postoperative bleeding and spinal hematoma. Current trends in anesthesia practice suggest avoiding any garlic consumption 7 days before surgery if postoperative bleeding is a concern.
The extent to which dietary doses of garlic influence platelet aggregation is unknown. Making dietary rules that preclude ingestion before surgery may be unnecessary. To clarify this issue, investigators tested the effect of raw garlic at a dose of 4.2 g prepared in Greek tsatsiki on platelet function using point-of-care monitoring devices sensitive to cyclooxygenase 1-inhibition and platelet adhesive capacity.
Whole blood from 18 healthy volunteers was investigated before and 5 hours after ingestion of the study medication consisting of Greek tsatsiki with 4.2 g raw garlic, or Greek tsatsiki without garlic (placebo), in a randomized, crossover, observer-blinded, placebo¬controlled study. The potential effects of garlic were investigated in 5 volunteers after daily ingestion of 4.2 g of raw garlic over 1 week. Platelet function was assessed with the Platelet Function Analyzer, impedance aggregometry, and thrombelastographic Platelet Mapping™. In vitro experiments were performed to prove the sensitivity of the assays to garlic-induced platelet inhibition.
Baseline values for platelet function were within normal range in all volunteers. Platelet function was not improved by single and repeated oral consumption of Greek tsatsiki containing raw garlic in any point-of-care monitoring test used. Dishes containing socially acceptable doses of raw garlic are unlikely to increase the risk of perioperative bleeding. Further studies are needed to determine the potential additive effects of platelet-inhibiting drugs combined with garlic and other herbs. |
