What is the preferred induction agent, ketamine and rocuronium or an alternative, for a patient with a history of cardiovascular or respiratory disease undergoing surgical procedures requiring general anesthesia?

Ketamine-Rocuronium for Rapid Sequence Induction

For patients with cardiovascular or respiratory disease requiring rapid sequence induction, ketamine (1-2.5 mg/kg) combined with rocuronium (0.9-1.2 mg/kg) is the preferred induction regimen, providing superior hemodynamic stability compared to propofol or thiopental-based approaches. 1

Guideline-Based Recommendations for Induction

Muscle Relaxant Selection

• Use rocuronium 0.9-1.2 mg/kg for rapid sequence induction in patients with cardiovascular or respiratory disease 1
• The European Society of Anaesthesiology and Intensive Care provides a strong recommendation (moderate evidence) for this dosing range as equivalent to succinylcholine for rapid airway control 1
• Lower doses of rocuronium (0.6-0.7 mg/kg) produce less reliable intubating conditions and should be avoided in emergency situations 1

Induction Agent Selection for Hemodynamically Compromised Patients

Ketamine is the optimal choice for patients with cardiovascular disease based on the following evidence:

• Ketamine produces sympathomimetic effects with dose-dependent increases in heart rate, blood pressure, and cardiac output, making it ideal for hemodynamically unstable patients 2
• Ketamine 2 mg/kg combined with rocuronium maintains superior hemodynamic stability during induction compared to propofol, particularly preventing the hypotension and decreased systemic vascular resistance seen with propofol 3
• Etomidate is an alternative for hemodynamically unstable patients, though it impairs steroidogenesis and has been withdrawn in some countries 1, 2, 4

Respiratory Disease Considerations

For patients with respiratory compromise:

• Ketamine causes bronchodilation, which is beneficial for patients with asthma or chronic obstructive pulmonary disease 1
• However, ketamine increases upper airway secretions—this must be managed with anticholinergics (atropine or preferably glycopyrrolate) 1
• The combination of ketamine with rocuronium avoids the histamine release associated with other agents that could worsen bronchospasm 1

Optimal Dosing Protocol

Standard Rapid Sequence Induction Protocol

Step 1: Pre-oxygenation

• Provide 100% oxygen for 3-5 minutes before induction 2

Step 2: Induction Sequence

• Administer ketamine 1-2.5 mg/kg IV (lower doses for elderly or frail patients) 1, 3, 5
• Immediately follow with rocuronium 0.9-1.2 mg/kg IV 1
• Apply cricoid pressure according to local institutional guidelines (though evidence for efficacy is limited) 1

Step 3: Intubation Timing

• Intubate at 60 seconds after rocuronium administration 6, 5
• Excellent intubating conditions are achieved in 100% of patients using ketamine-rocuronium at this timeframe 5

Enhanced Protocol for Optimal Conditions

For elective cases where time permits:

• Consider priming with rocuronium 0.04 mg/kg 3 minutes before induction 7
• Follow with ketamine 1 mg/kg + rocuronium 0.4 mg/kg for intubation at 30 seconds 7
• This achieves excellent intubating conditions with 17% twitch tension at intubation 7

Combination Strategies

Ketamine with Other Agents

Midazolam co-administration:

• Adding midazolam 2 mg IV 2 minutes before ketamine reduces psychomimetic side effects without compromising hemodynamic stability 5
• This combination is particularly useful for patients who may experience ketamine-related emergence phenomena 5

Fentanyl considerations:

• Avoid fentanyl in hemodynamically unstable patients when using ketamine, as it provides no additional benefit for intubating conditions and may cause hypotension 6
• S-ketamine 0.5 mg/kg produces superior intubating conditions compared to fentanyl 1.5 mcg/kg when combined with etomidate and rocuronium 6

Critical Safety Considerations

Monitoring Requirements

• Maintain continuous pulse oximetry and capnography throughout induction 8
• Ensure vascular access is maintained until the patient is no longer at risk for cardiorespiratory depression 8
• Practitioners must be able to rescue patients from unintended deep sedation or general anesthesia 8

Contraindications to Ketamine

Absolute contraindications:

• Uncontrolled cardiovascular disease (uncontrolled hypertension, recent MI with ongoing ischemia) 8
• Active psychosis 8
• Severe liver dysfunction 8
• Significantly elevated intracranial or intraocular pressure 8

Important caveat: Traditional concerns about ketamine increasing intracranial pressure are attenuated by controlled ventilation and subsequent anesthesia, making it acceptable in head-injured patients requiring hemodynamic stability 4

Secretion Management

• Administer glycopyrrolate or atropine before or with ketamine to prevent excessive airway secretions 1
• This is particularly critical in patients with respiratory disease where secretions could worsen airway management 1

Comparison with Alternative Regimens

Why Not Propofol-Rocuronium?

Propofol causes significant hemodynamic instability:

• Propofol 0.5 mg/kg produces significant decreases in mean arterial pressure and systemic vascular resistance within 1 minute of induction 3
• This hypotension is particularly dangerous in patients with cardiovascular disease or hypovolemia 1, 2
• While propofol provides faster recovery times, this advantage is irrelevant during the critical induction period 1

Why Not Thiopental-Rocuronium?

Thiopental provides inferior intubating conditions:

• Thiopental 5 mg/kg produces excellent/good intubating conditions in only 50% of patients at 60 seconds, compared to 100% with ketamine 2.5 mg/kg 5
• Thiopental causes more pronounced diaphragmatic response and worse vocal cord positioning 5
• Thiopental may cause severe bronchoconstriction in patients with asthma in the presence of cholinergic stimulation 1

Common Pitfalls to Avoid

1. Underdosing rocuronium: Using 0.6 mg/kg instead of 0.9-1.2 mg/kg results in suboptimal intubating conditions 1

2. Attempting intubation too early: Waiting only 30-45 seconds after standard-dose rocuronium leads to poor conditions; wait the full 60 seconds 6, 5

3. Failing to manage secretions: Not using anticholinergics with ketamine can lead to airway complications from excessive secretions 1

4. Using ketamine in truly uncontrolled hypertension: While ketamine is sympathomimetic, it should not be used in patients with severe uncontrolled hypertension or acute coronary syndrome 8

5. Combining with unnecessary adjuncts: Adding fentanyl to ketamine-rocuronium provides no benefit and may worsen hemodynamics 6