What are the downsides to delayed sequence intubation (DSI) in critically ill or injured patients, particularly those with chronic obstructive pulmonary disease (COPD) or other underlying respiratory diseases?

Downsides to Delayed Sequence Intubation

Delayed sequence intubation (DSI) carries specific risks including potential for aspiration during the dissociative sedation phase, risk of apnea from ketamine dosing, and critically—delay in securing a definitive airway in patients who may be deteriorating rapidly.

Primary Risks and Complications

Aspiration Risk

• The most significant concern with DSI is aspiration during the dissociative sedation phase before paralysis and intubation. While ketamine preserves airway reflexes better than other sedatives, critically ill patients with full stomachs, gastric distension, or impaired protective reflexes remain at risk 1.
• Blood, secretions, and vomitus in the airway can complicate both the preoxygenation phase and subsequent laryngoscopy 1.

Respiratory Complications

• Apnea can occur following ketamine administration, though typically self-limiting (< 15 seconds in reported cases) 2.
• Over-sedation may precipitate complete airway obstruction, particularly in patients with existing upper airway pathology or edema 1.
• Critical respiratory failure may be precipitated during the DSI process, especially in patients dependent on CPAP/PEEP 1.

Time-Critical Situations

• The fundamental problem with DSI is the inherent delay in securing a definitive airway 3.
• In moderately injured trauma patients (ISS < 20), delayed intubation (≥25 minutes) is associated with significantly higher mortality (11.8%) compared to early intubation (1.8%, p=0.045) 3.
• Patients who are initially stable but deteriorating may suffer worse outcomes when intubation is delayed 3.

Hemodynamic Concerns

Cardiovascular Instability

• Post-DSI complications include bradycardia (heart rate < 60 bpm), systolic blood pressure drops > 20 mmHg, and tachycardia 2.
• The time spent optimizing preoxygenation may allow further hemodynamic deterioration in shock states 3.
• Critically ill patients are prone to hypotension in the immediate post-intubation phase due to blunting of compensatory sympathetic response, and DSI extends the vulnerable period 4.

Technical and Practical Limitations

Patient Selection Challenges

• DSI is only appropriate for agitated patients who will not tolerate preoxygenation—it is not a routine technique 5.
• Inadequate patient cooperation or urgency usually requires standard rapid sequence intubation instead 1.
• Time-critical intubation and limited patient cooperation are practical limitations that may make DSI inappropriate 1.

Operator Experience Requirements

• DSI requires significant expertise in both procedural sedation and airway management 4.
• The technique adds complexity to an already high-risk procedure in critically ill patients 1.

Specific High-Risk Populations

Patients with Airway Obstruction

• Awake techniques including DSI may precipitate complete airway obstruction from over-sedation, topical anesthesia, laryngospasm, or bleeding 1.
• Upper airway edema, distortion from fluid resuscitation, or existing pathology increases risk 1.

Obese Patients

• Obesity doubles complication risk during intubation, with four-fold increase for BMI > 40 kg/m² 1.
• The extended time frame of DSI may be particularly problematic in obese patients with reduced functional residual capacity 1.

Patients with Severe Hypoxemia

• In patients with severe hypoxemia (PaO₂/FiO₂ < 150), even optimal preoxygenation may be inadequate, and the delay inherent to DSI may worsen outcomes 1.
• Patients already receiving NIV, CPAP, or HFNO should undergo intubation promptly when these modalities are failing; delay leads to profound hypoxemia 1.

Critical Pitfalls to Avoid

Inappropriate Use

• DSI should never be used simply for convenience or as a routine approach—it is reserved for agitated patients who absolutely cannot tolerate preoxygenation 5.
• Do not use DSI when rapid sequence intubation is more appropriate (most critically ill patients) 1.

Failure to Recognize Deterioration

• Multiple attempts at laryngoscopy and delays during intubation are associated with increased complications including cardiac arrest and death 1.
• The time spent on DSI may allow progression of airway edema, bleeding, or other complications 6.

Missing the Window

• Patients with rib fractures have greater frequency of delayed intubation and worse outcomes—recognize these patients early 3.
• Failure to transition promptly to definitive airway management when DSI is not working leads to worse outcomes 1.

When DSI May Be Contraindicated

• Active vomiting or high aspiration risk 5.
• Hemodynamic instability requiring immediate airway control 7.
• Anatomically difficult airway where delay is dangerous 1.
• Severe hypoxemia despite maximal preoxygenation attempts 1.
• Upper airway obstruction with stridor or significant edema 8, 6.