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Chapter 51. Neuraxial Anesthesia and Peripheral Nerve Blocks in Patients on Anticoagulants

In which subgroup of patients is the risk of neuraxial hematoma formation after neuraxial blockade the lowest?

A. Elderly patients

B. Obstetric patients

C. Patients using aspirin

D. Patients with abnormal coagulation

B is correct. Obstetric patients have the lowest risk of neuraxial hematoma formation following neuraxial blockade. Spinal hematoma is seen in 1:200,000 cases. Protective mechanisms include: hypercoagulable state of pregnancy, wider capacity of epidural space, and higher intra-epidural pressure.

A is incorrect. Elderly have increased risk of degenerative spine abnormalities, osteoporosis, and peripheral vascular disease. Risk is estimated at 1:3800.

C is incorrect. Although in most cases aspirin use is not a contraindication for neuraxial blockade, the risk is evidently higher in this subgroup when compared to overall risk of hematoma formation after neuraxial blockade (ranging from 1:2700 to 1:19,505).

D is incorrect. Patients with abnormal coagulation profiles have a high risk of hematoma formation (estimated at 1:315).

Which of the following medications exerts its anticoagulant properties by blocking the P2Y12 receptor on platelets?

A. Aspirin

B. Celecoxib

C. Ticlopidine

D. Tirofiban

C is correct. By blocking the P2Y12 receptor with ticlopidine, adenosine diphosphate (ADP) is not able to activate platelets through this receptor. Other drugs in this category are clopidogrel, prasugrel, ticagrelor, and cangrelor.

A is incorrect. Aspirin blocks platelet function by inhibiting COX-1 and subsequent TXA2 formation.

B is incorrect. Celecoxib is a selective COX-2 inhibitor, which has no antiplatelet effects.

D is incorrect. Tirofiban blocks the αIIbβ3 receptor on platelets. Platelet-to-platelet aggregation mediated by fibrinogen is hereby abolished.

Concerning the stopping of antiplatelet medication before neuraxial blockade:

A. Clopidogrel is recommended to be stopped for 3 days.

B. Prasugrel is recommended to be stopped for 5 days.

C. Ticagrelor is recommended to be stopped for 7 days.

D. Ticlopidine is recommended to be stopped for 10-14 days.

D is correct. Ticlopidine is recommended to be stopped for 10 to 14 days by several international societies. Ticlopidine exhibits delayed reactions on platelet function. Platelet function appears to be inhibited after 24 to 48 hours of ingestion. Its effect ...

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