What moderate‑sedation protocol should be used for an adult undergoing flexible bronchoscopy to provide anxiolysis, analgesia, and maintain spontaneous ventilation with continuous monitoring?

Moderate Sedation Protocol for Adult Flexible Bronchoscopy

For adults undergoing flexible bronchoscopy, use a combination of topical lidocaine (≤8.2 mg/kg) with incremental intravenous midazolam plus an opioid (fentanyl or remifentanil), supplemented with oxygen at ≥2 L/min to maintain SpO2 ≥90%, while continuously monitoring with pulse oximetry. 1, 2

Topical Anesthesia

• Lidocaine is the preferred topical anesthetic due to its short half-life and wide safety margin 2
• Limit total lidocaine dose to 8.2 mg/kg (approximately 29 mL of 2% solution for a 70 kg patient), with extra caution in elderly patients or those with liver or cardiac impairment 1
• Use the minimum necessary amount when instilling through the bronchoscope 1
• Plasma levels above 5 mg/L increase risk of seizures and cardiac suppression 1

Critical Pitfall

• Patients with metastatic liver disease, renal failure, or congestive heart failure are at higher risk for lignocaine accumulation and toxicity 1

Sedation Regimen

The combination of benzodiazepines plus opioids is recommended due to synergistic effects on patient tolerance and the antitussive properties of opioids 2

Standard Protocol:

• Midazolam: Administer in small incremental intravenous doses until desired sedation achieved 1
• Opioid options:
  • Fentanyl (standard choice) 2
  • Remifentanil (ultrashort-acting, particularly useful for longer procedures) 1, 3

Alternative: Propofol Monotherapy

• Propofol can achieve similar sedation, amnesia, and patient tolerance compared to benzodiazepine-opioid combinations 2
• For continuous infusion: Start with loading rate of 125 mcg/kg/min, then maintenance at 75 mcg/kg/min, adjusted every 2.5 minutes 4
• Propofol is increasingly used by pulmonologists without anesthesiologist attendance, though this requires appropriate training 5

Agents NOT Recommended:

• Anticholinergic premedication does not produce clinically meaningful effects and should be avoided 2

Oxygen Supplementation

• Oxygen at ≥2 L/min via nasal cannulae is mandatory to maintain SpO2 ≥90% 1
• Expect a fall in PaO2 of approximately 2.5 kPa during the procedure 1
• Continue oxygen supplementation for 1-2 hours post-procedure, particularly in patients with impaired lung function or those receiving amnestic doses of midazolam 1, 6

Critical Pitfall:

• Patients on oxygen supplementation may have "safe" oximetry readings while developing CO2 retention—remain alert for signs of respiratory failure 1
• Consider transcutaneous CO2 monitoring in high-risk patients 1

Monitoring Requirements

Mandatory Monitoring:

• Continuous pulse oximetry throughout the procedure 1, 6
• Visual assessment of respiratory effort and patient comfort 1

Selective ECG Monitoring:

• Consider continuous ECG for patients with:
  • Abnormal baseline 12-lead ECG AND preoperative hypoxemia (PaO2 <8 kPa) 1
  • Severe cardiovascular disease or unstable angina 1, 6
• Routine cardiac monitoring is not recommended for all patients 1

Procedure-Specific Modifications

For High-Risk or Critically Ill Patients:

• Pre-oxygenate with 100% oxygen before, during, and after the procedure 1, 7
• Switch ventilator to mandatory mode (not triggered modes like pressure support) 1, 7
• Use special swivel connector with perforated diaphragm to maintain PEEP/CPAP during scope insertion 1, 7
• Deep sedation, analgesia, or muscle relaxation may be required in unstable hypoxic patients to prevent patient-ventilator dyssynchrony 1, 7

For Intubated Patients:

• Match bronchoscope size to endotracheal tube—a 5.7 mm scope occupies 40% of a 9 mm tube and 66% of a 7 mm tube 1
• Increase ventilator pressure limit to maintain adequate tidal volumes 1, 7
• Apply lubrication to facilitate passage and prevent equipment damage 1

Recovery and Post-Procedure Care

• Maintain oxygen supplementation until patient is stable and awake 1, 6
• If topical anesthetics were used, laryngeal reflexes may be depressed for up to 1 hour—patients should not drink during this period due to aspiration risk 1
• Patients should not drive, sign legal documents, or operate machinery for 24 hours after sedation 6

Key Safety Principles

• Most life-threatening adverse events involve drug overdose, inadequate monitoring, or inappropriate sedation 1
• Hypoxemia is common, particularly when the bronchoscope is in the mid-trachea, even with oxygen supplementation 1
• Drug combinations may increase the likelihood of adverse outcomes—use incremental dosing and continuous assessment 1
• Maintain spontaneous ventilation whenever possible to assess dynamic airway compression and vocal cord movement 1