Platelet Activation by Crushed and Uncrushed Muscle Patch: Flow Cytometry Analysis

Introduction: Muscle patches are considered the current gold standard for hemorrhage control in major vessel hemorrhage in the skull base, with many case reports of its use in situations such as cavernous carotid injury during pituitary surgery. This is thought to be due to the formation of a platelet plug seal at the site of the vessel defect, however the ability of a muscle patch to activate platelets is yet to be investigated in vitro.

Aims: This study aims to determine the percentage of platelets activated by supernatants of crushed and uncrushed muscle in control patients on no antiplatelet medications and on those taking aspirin and clopidogrel.

Method: Whole blood was collected from 30 patients. Of the patients recruited, 10 were taking aspirin, 10 were taking clopidogrel and 10 controls were on no antiplatelet agent. Whole blood was exposed to crushed and uncrushed muscle supernatant and platelet activation was analyzed by flow cytometry.

Results: In control patients, crushed muscle exposure resulted in a 5.18 times increase in platelet activation compared with uncrushed (6.63% versus 0.99% p = 0.002). In patients taking aspirin the ratio increased to 6.53 (31.38% versus 5.84% p < 0.0001) when comparing crushed muscle to uncrushed and in patients taking clopidogrel the ratio increased to 9.40 (26.08% versus 4.67% p < 0.0001).

Discussion: This study provides evidence not only that muscle patches cause platelet activation, but that this occurs to a significantly greater degree when the muscle is crushed. The higher levels of platelet activation in patients taking aspirin as well as patients taking clopidogrel may reflect an innate propensity of these patients to thrombosis and suggests the muscle patch may still be efficacious in activating platelets in these patients in situations such as pituitary apoplexy where the surgeon is operating relatively urgently without waiting for platelet replenishment therapies.