What would be the recommended induction of anesthesia for a male patient undergoing PPV/Vitrectomy with a planned regimen of Sevoflurane, Target-Controlled Infusion (TCI) remifentanil, and Atracurium?

Induction Protocol for PPV/Vitrectomy with Sevoflurane-TCI Remifentanil-Atracurium

For a hemodialysis patient undergoing vitrectomy with your planned regimen, induce with sevoflurane 8% via vital capacity technique OR propofol 2 mg/kg IV, followed immediately by remifentanil 1 mcg/kg over 30-60 seconds, then atracurium 0.5 mg/kg once loss of consciousness is achieved. 1, 2

Specific Induction Sequence

Pre-Induction Preparation

• Establish two large-bore IV lines before induction, as vascular access may be challenging in HD patients 3
• Set up invasive arterial blood pressure monitoring before induction when feasible, with transducer at tragus level 2, 4
• Have vasopressors immediately available (ephedrine 5-10 mg or metaraminol 0.5-1 mg boluses) as propofol causes dose-dependent cardiovascular depression 2, 4
• Apply BIS or entropy monitoring targeting 40-60 to prevent awareness 2, 4

Induction Options

Option 1: Sevoflurane Vital Capacity Induction (Preferred for hemodynamic stability)

• Administer 8% sevoflurane in 75% N₂O/O₂ from a primed circuit via vital capacity technique 5
• Loss of consciousness occurs in 39 seconds (59% in one breath) 5
• Once unresponsive, give remifentanil 1 mcg/kg IV over 30-60 seconds 1
• After 2-3 minutes, administer atracurium 0.5 mg/kg IV 3
• Intubate after 3-4 minutes total 6

Option 2: Propofol IV Induction

• Administer propofol 2 mg/kg IV bolus (reduce dose by 25-30% in elderly or hemodynamically unstable patients) 1, 2
• Simultaneously or immediately after, give remifentanil 1 mcg/kg over 30-60 seconds 1
• Once loss of consciousness confirmed, give atracurium 0.5 mg/kg IV 3
• Intubate after 3-4 minutes 6

Critical Dosing Considerations

Remifentanil Dosing Strategy

• The 1 mcg/kg dose provides acceptable intubation conditions with 10% incidence of respiratory depression 7
• Avoid higher doses (2-4 mcg/kg) as they cause significant hypotension and prolonged apnea 7
• If intubation occurs >8 minutes after starting remifentanil, use infusion at 0.5-1 mcg/kg/min instead of bolus 1

Atracurium Selection Rationale

• Atracurium is ideal for HD patients as metabolism is independent of kidney function (Hofmann elimination and ester hydrolysis) 3
• Dose: 0.5 mg/kg IV for intubation 3
• Avoid rocuronium or vecuronium in HD patients due to renal elimination concerns

Sevoflurane Considerations

• MAC for sevoflurane is 2.1% at age 40, decreases with age 8
• Use 8% for induction, then reduce to 1.7% for maintenance 9, 10
• Provides faster induction than propofol (39 vs 252 seconds to loss of consciousness) 5
• Better hemodynamic stability during induction compared to propofol 6, 11

Maintenance Transition

Once intubated, immediately transition to:

• Sevoflurane 1.7% end-tidal concentration 10
• Remifentanil TCI at effect-site concentration 1-3 ng/mL (start at 0.05-0.3 mcg/kg/min infusion) 2, 7
• Do NOT give additional atracurium boluses - single intubating dose only, as neuromuscular blockade interferes with depth monitoring 4
• Maintain BIS 40-60 throughout 2, 4

Critical Pitfalls to Avoid

• Never use propofol boluses during maintenance - causes hemodynamic instability; use continuous infusion only if switching from sevoflurane 2
• Never give remifentanil as bolus during maintenance - causes respiratory depression; use continuous TCI infusion only 2, 7
• Avoid rocuronium in HD patients - renal elimination makes it unsuitable 3
• Do not assume adequate depth without monitoring - use BIS/entropy to prevent awareness, especially important as sevoflurane-remifentanil has lower awareness risk than TIVA alone 3, 2
• Have rescue hydrocortisone 100 mg IV available - unexplained intraoperative hypotension in any patient may indicate adrenal crisis 3

Hemodynamic Management

• Target mean arterial pressure >65 mmHg 4
• Treat hypotension with vasopressors (ephedrine or metaraminol) rather than excessive fluids 4
• Expect heart rate to remain stable or slightly elevated with sevoflurane (more so than propofol) 6, 11
• Blood pressure typically decreases 10-20% after induction with either technique 6, 5

Special Considerations for HD Patients

• HD patients are considered "frail" with increased complication risk 3
• Assume some degree of volume status abnormality - have vasopressors ready but avoid excessive fluid administration 4
• Monitor for electrolyte abnormalities (especially potassium) that may affect cardiac stability 3
• Consider reduced propofol dose if using IV induction due to altered pharmacokinetics 2