Delayed Sequence Intubation

A strategy of time separation between the administration of a dissociative induction agent and the neuromuscular blocker to allow preintubation optimization.

INTRODUCTION

Delayed sequence intubation (DSI) differs from rapid sequence intubation (RSI), in that it separates the induction and paralysis to allow preintubation procedures such as preoxygenation in patients who are noncompliant (e.g. delirious) (FIGURE 3.1). It can be thought of as procedural sedation where the procedure is preoxygenation. In indicated situations requiring further preoxygenation, DSI is an alternative to precipitous intubation without full paralytic effect or bag-mask ventilation in the sedated and paralyzed patient. Respectively, these two traditional options increase the risk of first-pass failure or the risk of gastric insufflation and passive regurgitation in sick, nonfasted patients. Both options ensure an abbreviated period before critical levels of hypoxemia.

CLASSIC INDICATIONS

Preoxygenation prior to intubation in a delirious or otherwise uncooperative hypoxemic and/or hypercapnic patient

Adequate oxygenation but need for further denitrogenation of the lungs and bloodstream in order to prolong the safe apnea period in a delirious or otherwise uncooperative patient

EXTENDED INDICATIONS

Need for an additional procedure or further optimization of physiologic parameters prior to intubation in a delirious or otherwise uncooperative patient

Nasogastric tube placement for a patient with upper gastrointestinal bleed and stomach filled with blood

Need to optimize patient’s blood pressure secondary to hypotension

Need to optimize patient’s respiratory and metabolic status secondary to metabolic acidosis

FIGURE 3.1 Delayed sequence intubation algorithm.

CONTRAINDICATIONS

Need for a “crash” airway

Patient unable to breathe spontaneously

Patient unable to protect his/her own airway

Relative contraindications—situations in which ketamine would be less than favorable and absence of alternative agents e.g.dexmedetomidate or droperidol

Elderly patients with coronary artery disease

Patients with elevated blood pressure or tachycardia

EQUIPMENT

Equipment for preoxygenation

Nasal cannula (NC)

Nonrebreather (NRB) mask

Consider methods for positive-pressure ventilation if the patient is exhibiting physiologic shunt

Ventilator and noninvasive ventilation (NIV) mask

Bag-valve mask (BVM) with adjustable positive end-expiratory pressure (PEEP) valve

Induction medication that maintains ventilatory drive and airway reflexes

That is ketamine (1–2 mg/kg) given over approximately 30 seconds

Standard equipment and medications for airway management

STANDARD TECHNIQUE

Administration of induction agents that do not blunt spontaneous ventilations or airway reflexes

Give a dissociative dose of ketamine (1–2 mg/kg) over approximately 30 seconds

Alternative agents

Dexmedetomidine 1 μg/kg over 10 minutes

Droperidol 5 to 10 mg

After intubation, check electrocardiogram (ECG) to determine whether any QT prolongation

For these two latter agents, a separate induction agent should be administered just prior to neuromuscular blocker administration

Preoxygenation and denitrogenation in standard manner with oxygen saturation >95% for 2 to 3 minutes or at least eight vital capacity (VC) breaths (note: patients who have received a DSI agent cannot take VC breaths)

NRB

Alternatives in patient exhibiting shunt physiology (saturation not improving with increased FIO₂)

BVM with PEEP valve

NIV—PEEP/Continuous positive airway pressure (CPAP)

PEEP levels between 5 and 15 cm H₂O

Follow with apneic oxygenation

Concurrent preparation for definitive airway management in standard manner

EXAMPLE OF PROCEDURE

Delirious hypoxic patient not tolerating an NRB for preoxygenation

Ketamine 1 to 2 mg/kg by slow intravenous push

Preoxygenation and denitrogenation with NRB/NC or NIPPV (Non-Invasive Positive Pressure Ventilation) for 2 to 3 minutes

Administer NMB (Neuromuscular blockade)

45 to 60 seconds of apnea with apneic oxygenation

Intubate

COMPLICATIONS

Complications from DSI are no different from complications inherent in attempts to intubate hypoxic/hypercapnic, delirious and/or otherwise unstable patients, with the exception being the establishment of a prolonged safe apnea period:

Aspiration

Gastric distention

Emesis with ketamine—occurs after emergence and is a concern if the patient is allowed to emerge from the dissociated state prior to endotracheal intubation

SAFETY/QUALITY TIPS

Procedural

Administering ketamine as a quick bolus will often cause 15 to 30 seconds of apnea; this can be avoided by pushing ketamine more slowly (over 30 seconds)

Application of a NC at high flow, in addition to either a face mask or NIV oxygenation, will optimize oxygenation and facilitate apneic oxygenation after the paralytic is given

Avoid very high positive pressure (>15 cm H₂0) when using NIV

Cognitive

The intubating provider should be at bedside during the entire DSI procedure, prepared to abort DSI at any point and commence with RSI (by giving the paralytic)

Although the goal of DSI is to optimize intubating conditions, in some cases, the underlying insult can be adequately addressed during the dissociated period, and intubation avoided. We recommend that a full intubation setup be prepared for every DSI case, however.