Alternatives to Rapid Sequence Intubation

Contemporary Airway Management With Ketamine

Andrew H. Merelman, BS; Michael C. Perlmutter, BA; Reuben J. Strayer, MD

Disclosures

Western J Emerg Med. 2019;20(3):466-471. 

In This Article

Abstract and Introduction

Abstract

Endotracheal intubation (ETI) is a high-risk procedure commonly performed in emergency medicine, critical care, and the prehospital setting. Traditional rapid sequence intubation (RSI), the simultaneous administration of an induction agent and muscle relaxant, is more likely to harm patients who do not allow appropriate preparation and preoxygenation, have concerning airway anatomy, or severe hypoxia, acidemia, or hypotension. Ketamine, a dissociative anesthetic, can be used to facilitate two alternatives to RSI to augment airway safety in these scenarios: delayed sequence intubation – the use of ketamine to allow airway preparation and preoxygenation in the agitated patient; and ketamine-only breathing intubation, in which ketamine is used without a paralytic to facilitate ETI as the patient continues to breathe spontaneously. Ketamine may also provide hemodynamic benefits during standard RSI and is a valuable agent for post-intubation analgesia and sedation. When RSI is not an optimal airway management strategy, ketamine's unique pharmacology can be harnessed to facilitate alternative approaches that may increase patient safety.

Introduction

Airway management and endotracheal intubation (ETI) are life-saving interventions frequently performed in emergency medicine (EM), critical care, and prehospital medicine. Despite its prevalence, ETI is associated with considerable patient morbidity and mortality, and is considered the riskiest commonly-performed procedure in acute care.[1,2] Rapid sequence intubation (RSI), which uses the simultaneous administration of an induction agent and paralytic, is the most common method of facilitating ETI. Traditional RSI, however, is burdened by the crucial risks of hypoxia and acidosis should ETI and assisted ventilation fail, as well as hypotension and hypoperfusion caused by the abrupt transition from negative-pressure to positive-pressure ventilation.[3]

Ketamine, a dissociative anesthetic classically used to facilitate painful procedures in non-intubated patients, has unique properties that offer patient-safety advantages over traditional RSI induction agents. These properties can be leveraged in novel ways to permit alternative pharmacologic approaches that mitigate RSI risks. Because dissociative doses of ketamine disconnect the patient from external stimuli while brainstem function remains intact, painful or distressing procedures such as ETI can be performed on the unaware, dissociated patient while cardiorespiratory tone is preserved or augmented.[4] This allows the provider to modify traditional RSI in ways that address the most important RSI risks.

Two alternatives to RSI have emerged that harness ketamine's unique pharmacology to improve airway management safety in specific clinical scenarios: delayed sequence intubation (DSI) – the use of ketamine to allow airway preparation and preoxygenation in the agitated patient; and ketamine-only breathing intubation (KOBI), which uses ketamine without a paralytic to facilitate ETI as the patient continues to breathe spontaneously. In this narrative review we discuss these techniques, neither of which at present is supported by clear evidence.

In conventional RSI, ketamine has become a preferred induction agent because of its relative hemodynamic stability (compared to propofol, midazolam, and thiopental) and long duration of action (compared to propofol and etomidate). Additionally, ketamine provides analgesia, amnesia, and sedation in a single agent, making it well-suited for post-intubation sedation.

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