Peripheral Neuroanatomy, Human Anatomy, USMLE Step 1 - Full Vignette with Extended Explanations

Описание: A 48-year-old woman with idiopathic pulmonary fibrosis and a history of atrial fibrillation on apixaban is scheduled for ambulatory shoulder surgery. She reports chronic exertional dyspnea and frequent bruising, with recent labs showing stable pulmonary function and a measurable anticoagulant effect. Given her anticoagulation profile and pulmonary comorbidities, what critical factors should you consider when planning a safe regional anesthetic approach in line with the latest clinical guidelines?

VIDEO INFO
Category: Peripheral Neuroanatomy, Human Anatomy, USMLE Step 1
Difficulty: Expert - Expert level - For those seeking deep understanding
Question Type: Recent Changes
Case Type: Rare Presentation

Explore more ways to learn on this and other topics by going to https://endlessmedical.academy/auth?h...

QUESTION
A 48-year-old retired woman with idiopathic pulmonary fibrosis (IPF) is scheduled for ambulatory arthroscopic shoulder debridement. She reports exertional dyspnea stable for the past year and easy bruising with minor trauma; no hemoptysis, melena, or prior neuraxial procedures. She denies recent infection. She lives alone and drinks one alcoholic beverage daily. She previously smoked 1 pack/day for 20 years and quit 10 years ago....

OPTIONS
A. Delay the deep plexus/peripheral block until at least 72 hours after the last high-dose apixaban dose, or proceed earlier only if a drug-specific assay shows apixaban less than 30 ng/mL or anti-factor Xa activity =0.1 IU/mL; perform an ultrasound-guided single-shot supraclavicular block with ropivacaine 0...
B. Proceed at 48 hours post-last dose if a drug-specific assay shows anti-factor Xa activity less than 0.2 IU/mL, interpreting this as acceptable for peripheral blocks, and inject ropivacaine 0.5% 25 mL (125 mg) under ultrasound in pre-op without further delay.
C. Proceed at 48 hours guided by normal PT/INR and aPTT because routine coagulation tests are adequate for apixaban assessment, and select bupivacaine 0.5% 30 mL (150 mg) to prolong block duration in the ambulatory setting.
D. Perform the block at 24 hours using andexanet alfa reversal followed by ropivacaine 0.75% 20 mL (150 mg) with planned top-ups as needed, since reversal eliminates bleeding risk for deep plexus blocks in outpatient surgery centers.

CORRECT ANSWER
A. Delay the deep plexus/peripheral block until at least 72 hours after the last high-dose apixaban dose, or proceed earlier only if a drug-specific assay shows apixaban less than 30 ng/mL or anti-factor Xa activity =0.1 IU/mL; perform an ultrasound-guided single-shot supraclavicular block with ropivacaine 0.5% 25 mL (125 mg) in the ambulatory OR.

EXPLANATION
Delay the deep plexus/peripheral block until at least 72 hours after the last high-dose apixaban dose, or proceed earlier only if a drug-specific assay shows apixaban less than 30 ng/mL or anti-factor Xa activity =0.1 IU/mL; perform an ultrasound-guided single-shot supraclavicular block with ropivacaine 0.5% 25 mL (125 mg) in the ambulatory OR. This is correct because the patient is taking high-dose apixaban (5 mg twice daily). The 2025 ASRA Pain Medicine fifth-edition antithrombotic guidelines recommend a conservative approach for deep plexus/peripheral blocks: defer until =72 hours after the last dose or proceed sooner only if a drug-specific assay confirms minimal anticoagulant effect (apixaban less than 30 ng/mL or anti-factor Xa =0.1 IU/mL). At 48 hours, her anti-factor Xa is 0.28 IU/mL, above the threshold, so waiting or confirming lower activity is indicated....


Further reading:

Links to sources are provided for optional further reading only. The questions and explanations are independently authored and do not reproduce or adapt any specific third-party text or content.

---------------------------------------------------

Our cases and questions come from the https://EndlessMedical.Academy quiz engine - multi-model platform. Each question and explanation is forged by consensus between multiple top AI models (i.e. Open AI GPT, Claude, Grok, etc.), with automated web searches for the latest research and verified references. Calculations (e.g. eGFR, dosages) are checked via code execution to eliminate errors, and all references are reviewed by several AIs to minimize hallucinations.

Important note: This material is entirely AI-generated and has not been verified by human experts; despite stringent consensus checks, perfect accuracy cannot be guaranteed. Exercise caution - always corroborate the content with trusted references or qualified professionals, and never apply information from this content to patient care or clinical decisions without independent verification.

Clinicians already rely on AI and online tools - myself included - so treat this content as an additional focused aid, not a replacement for proper medical education. Visit https://endlessmedical.academy for more AI-supported resources and cases.

This material can not be treated as m