What is the appropriate starting concentration of desflurane for intraoperative use?

Appropriate Starting Concentration of Desflurane for Intraoperative Use

For intraoperative maintenance of anesthesia, desflurane should be started at 2.5-3% concentration in adults, and titrated based on patient factors and surgical stimulation requirements. 1, 2

Initial Dosing Recommendations

• For adults after IV induction with agents like propofol or thiopental, start desflurane at approximately 0.5-1 MAC (minimum alveolar concentration), which corresponds to approximately 3% concentration 1
• Initial concentration can be increased in 0.5-1.0% increments every 2-3 breaths to achieve surgical anesthesia 1
• For maintenance of anesthesia in adults, concentrations of 2.5-8.5% are typically required, with the specific concentration depending on patient factors and surgical stimulation 1
• In pediatric patients, higher concentrations (5.2-10%) are often needed for maintenance of anesthesia 1

Patient-Specific Factors Affecting Dosing

• Age significantly impacts MAC requirements for desflurane:
  • Younger patients require higher concentrations (MAC of 7.3% in 25-year-olds) 1, 3
  • Older patients require lower concentrations (MAC of 5.2% in 70-year-olds) 1, 3
• Concomitant use of nitrous oxide reduces desflurane requirements by approximately 50% (e.g., MAC decreases from 7.3% to 4.0% in 25-year-olds when using 60% N₂O) 1
• Benzodiazepines and opioids decrease the MAC of desflurane, requiring dose adjustments 1

Surgical Stimulation Considerations

• During surgical stimulation, higher concentrations of desflurane are required to maintain the same depth of anesthesia 4
• In unstimulated patients, approximately 2.2% desflurane may achieve a BIS of 50, while during surgery, 6.8% may be required for the same BIS level 4
• For abdominal surgery with remifentanil co-administration, median end-tidal desflurane concentrations of approximately 2.5% are typically effective 5

Monitoring and Titration

• Titrate desflurane concentration based on clinical signs, hemodynamic parameters, and depth of anesthesia monitoring 2
• BIS monitoring or other processed EEG can help guide appropriate dosing, especially in elderly patients 2
• Desflurane concentration should be reduced if excessive decreases in blood pressure occur 1
• Unlike other anesthetics, increased heart rate with desflurane may not reliably indicate inadequate anesthesia 1

Special Considerations

• Desflurane is a mild airway irritant and should not be used as the sole agent for induction 1, 3
• In patients with coronary artery disease, rapid increases in desflurane concentration should be avoided due to associated increases in heart rate, blood pressure, and catecholamine levels 1
• In obese patients (BMI ≥30 kg/m²), desflurane may offer faster wake-up times compared to sevoflurane or isoflurane 2
• Desflurane may cause hypertension and tachycardia, unlike sevoflurane which has bronchodilator effects 2

Fresh Gas Flow Considerations

• During maintenance with inflow rates of 2 L/min or more, the alveolar concentration of desflurane will usually be within 10% of the inspired concentration 1
• Low-flow anesthesia (0.5-1.0 L/min) can be used effectively with desflurane, with more rapid wash-in compared to sevoflurane 6
• At fixed vaporizer settings, desflurane reaches 1 MAC faster than sevoflurane (3.7 min vs. 6.2 min at 1 L/min flow) 6

Recovery Profile

• Desflurane's low blood and tissue solubility allows for rapid emergence from anesthesia 7
• Emergence and extubation times are typically faster with desflurane compared to sevoflurane (approximately 5 min vs. 8 min) 7
• The median time from discontinuation of desflurane to appropriate response to commands is approximately 5.25 minutes 3

Remember that while these guidelines provide a framework, the concentration should be adjusted based on the individual patient's response, surgical requirements, and monitoring parameters.