What are the anesthesia considerations for a 55-year-old woman, weighing 55kg, with hypertension managed by Losartan (losartan) and neuropathic pain managed by Pregabalin (pregabalin), undergoing a transpedicular C-arm (Computed Tomography) guided biopsy at T9-T10 under general anesthesia?

Anesthesia Considerations for Transpedicular T9-T10 Biopsy

For this 55-year-old woman on losartan and pregabalin undergoing transpedicular biopsy under general anesthesia, continue both medications perioperatively, anticipate enhanced hypotensive responses to anesthetic agents due to losartan, and expect reduced anesthetic requirements with potential for increased sedation from pregabalin.

Preoperative Medication Management

Losartan Continuation

• Continue losartan through the morning of surgery 1, 2, 3
• Losartan provides 24-hour blood pressure control and abrupt discontinuation risks rebound hypertension 2, 3
• The drug is well-tolerated with minimal first-dose hypotension risk, making perioperative continuation safe 2, 3
• No dosage adjustment needed for this procedure as losartan preserves renal function and has excellent tolerability 2, 3

Pregabalin Continuation

• Continue pregabalin on the day of surgery 4, 5
• Abrupt discontinuation risks withdrawal symptoms and should be avoided 6
• Pregabalin is rapidly absorbed with high oral bioavailability (>90%) and will maintain therapeutic levels perioperatively 5

Intraoperative Hemodynamic Considerations

Blood Pressure Management

• Anticipate exaggerated hypotensive responses to induction agents and volatile anesthetics 1
• Losartan blocks angiotensin II-mediated vasoconstriction, reducing compensatory mechanisms during anesthesia 2, 3
• Have vasopressors immediately available (phenylephrine, ephedrine) for rapid correction of hypotension 1
• Consider reduced doses of induction agents (propofol, etomidate) by 20-30% initially 1

Orthostatic Hypotension Risk

• Position changes must be performed slowly and deliberately 1
• The combination of losartan and pregabalin increases orthostatic hypotension risk 1, 6
• Monitor blood pressure closely during transition from supine to prone positioning for the transpedicular approach 1

Anesthetic Drug Interactions

Reduced Anesthetic Requirements

• Pregabalin reduces anesthetic requirements through calcium channel modulation 7, 8
• Pregabalin binds to α2δ-1 subunits of voltage-gated calcium channels, producing sedative effects that are additive with general anesthetics 7, 8
• Consider reducing volatile anesthetic concentrations by 10-20% and titrate to effect 1, 4

Enhanced Sedation Risk

• Expect prolonged emergence and increased postoperative sedation 1, 6
• Common pregabalin side effects include somnolence (14.6%), dizziness (23.1%), and mental clouding 1, 5
• These effects are dose-dependent and additive with anesthetic agents 1, 4, 5

Postoperative Management

Pain Control Strategy

• Pregabalin provides baseline neuropathic pain coverage; supplement with multimodal analgesia 1, 4
• Continue scheduled pregabalin postoperatively to maintain therapeutic levels 4, 5
• Use acetaminophen (maximum 3g/day due to hypertension concerns) and local anesthetics as first-line adjuncts 1
• Avoid NSAIDs entirely due to cardiovascular toxicity, renal impairment risk, and sodium/water retention that could exacerbate hypertension 1

Opioid Considerations

• If opioids are required, use lowest effective doses as pregabalin potentiates opioid effects 1, 6
• Monitor closely for additive sedation and respiratory depression 1, 6
• Consider tramadol (weak opioid with SNRI properties) if moderate pain control needed, as it has favorable interaction profile with pregabalin 6

Critical Monitoring Parameters

Hemodynamic Surveillance

• Continuous blood pressure monitoring is essential given losartan's effects on compensatory mechanisms 1, 2
• Monitor for both supine and orthostatic hypotension throughout the perioperative period 1
• Maintain adequate intravascular volume with crystalloid preloading before induction 1

Neurological Assessment

• Extended PACU monitoring for delayed emergence and excessive sedation 1, 6, 4
• Assess for dizziness, confusion, and balance disorders before discharge 6, 5
• Fall risk is significantly elevated with pregabalin, especially when combined with residual anesthetic effects 1, 6

Specific Procedural Considerations

Prone Positioning

• Ensure adequate padding and positioning to prevent pressure injuries, as pregabalin-induced peripheral edema (10.4% incidence) may increase tissue vulnerability 5
• Verify hemodynamic stability in prone position before proceeding, as this position combined with losartan may cause significant hypotension 1

Renal Function

• Both losartan and pregabalin are renally excreted (losartan metabolites and pregabalin 98%) 2, 5
• Verify baseline renal function preoperatively; if creatinine clearance is reduced, pregabalin effects may be prolonged 1, 6
• Maintain adequate intraoperative perfusion pressure to preserve renal function 2

Common Pitfalls to Avoid

• Do not discontinue losartan preoperatively - this increases rebound hypertension risk without reducing hypotension risk under anesthesia 2, 3
• Do not use standard anesthetic dosing - both medications reduce requirements and increase sensitivity 1, 4
• Do not combine pregabalin with gabapentin postoperatively - creates unacceptable sedative burden 6
• Do not prescribe NSAIDs for postoperative pain - contraindicated with cardiovascular disease and hypertension 1
• Do not discharge without extended observation - pregabalin's sedative effects may be prolonged and increase fall risk 6, 5