Critical Care, Critical Care Alert, Sepsis, COVID-19, Airway

Critical Care Alert: Ketamine-Only Intubation Method in the ED

Critical Care Alert

ARTICLE
Driver, BE. Prekker, ME. Reardon, RF. Sandefur, BJ. April MD. Walls RM, Brown CA. Success and Complications of the Ketamine-Only Intubation Method in the Emergency Department. J Emerg Med. 2021; 60(3): 265-272.

OBJECTIVE
To compare first attempt intubation success and adverse events for patients who underwent intubation using ketamine-only or topical anesthesia vs traditional RSI. 

BACKGROUND
ED intubations are typically carried out using rapid sequence intubation (RSI), utilizing both a sedative agent and neuromuscular blocking agent. However, in certain patients, when masked ventilation or intubation is suspected to be difficult (including angioedema, airway obstruction, complicated anatomy, or inability to tolerate supine positioning), alternatives to RSI have been considered.  One option is to utilize topical anesthesia of the upper airway and glottis, with minimal parenteral sedation.  A more recent consideration is ketamine-only intubation, which theoretically allows for mild-moderate dissociative sedation, without impairing spontaneous ventilation. In this study, the investigators looked into the success of first pass intubation success and complications of ketamine-only intubations vs topical anesthesia and traditional RSI.

DESIGN
Multicenter observational cohort study using data from the National Emergency Airway Registry (NEAR).                                                          

Population
Inclusion Criteria

  • NEAR entries from 01/01/2016 - 12/31/2018
  • ≥ 14 years old
  • Orally or nasally intubated using RSI (sedative + NBMA), ketamine (without NBMA) or topical anesthesia (either alone or in conjunction with sedative)

Exclusion Criteria

  • Entries missing data for primary outcome (first pass success)

Primary Outcome
Successful intubation on first attempt, defined as a single insertion of the laryngoscope blade into the mouth for orotracheal intubation, and a single passage of a flexible endoscope with intent to intubate the trachea. 

Secondary Outcomes

  • Successful intubation on the first attempt for patients with ≥ 1 difficult airway characteristics
    • Reduced neck mobility
    • Mallampati score >1
    • Reduced mouth opening
    • Airway obstruction
    • Facial trauma
    • Blood/vomit in airway
  • Successful intubation on the first attempt without any adverse events
  • Cormack-Lehane grade 1 or 2 on first attempt
  • Adverse events during first attempt, or at any point during course of intubation such as cardiac arrest, dental trauma, hypoxemia among numerous others

Key Results
A total of 12,511 eligible intubations were analyzed

  • 102 ketamine-only
  • 80 topical anesthesia
  • 12,329 RSI

First-pass intubation success was achieved in 61% in ketamine-only group, 85% in topical anesthesia group and 90% in RSI group (Absolute difference between ketamine-only and topical anesthesia -24% with 95% CI -37% to -12%).

A larger percentage of patients in the ketamine-only and topical anesthesia groups were assessed to have ≥ 1 difficult airway characteristics (72% and 80%, respectively), compared to the RSI group (50%). First attempt for these "difficult airway" patients:

  • 51% in ketamine-only group
  • 86% in topical anesthesia group
  • 87% in rapid-sequence intubation group

 

Successful intubation on the first attempt without any adverse events:

  • 55% in ketamine-only group
  • 78% in topical anesthesia group
  • 83% in rapid-sequence intubation group.

One or more adverse events occurred in 32% of ketamine-only intubations compared with 19% of intubations using topical anesthesia (absolute difference 13% [95% CI 0–25%]) and 14% of RSI intubations. After a failed first attempt, a NMBA was administered more frequently in the ketamine-only group in 23 of 40 patients (58%) and in 5 of 12 (42%) in the topical anesthesia group.                   

Hypoxemia was the most common adverse event:

  • 16 % of first-attempt ketamine-only intubations
  • 13% of topical anesthesia intubations
  • 8% of rapid-sequence intubations

Of note, the median dose of IV ketamine in the ketamine-only group was 1.3 mg/kg (interquartile range 0.8 to 1.9 mg/kg). In the topical anesthesia group, 34 of 80 patients received IV ketamine as well, with a median dose of 0.6 mg/kg (interquartile range 0.3 to 1.3 mg/kg) and 7 received etomidate or midazolam.                     

Strengths

  • One of the largest multicenter analyses of ketamine-only intubations to date

Limitations

  • Limited sample size of ketamine-only and topical anesthesia intubations, making it difficult to adjust for confounders of the relationship between pharmacologic choice and intubation outcome. 
  • Different providers with unique airway strategies, possibly leading to inconsistencies with medication dosing or procedural steps.
  • A large proportion of patients (43%) in the topical anesthesia groups received a sedative medication (most commonly ketamine) as well. Though obviously challenging with a limited number of patients, it might be useful to compare purely ketamine-only and purely topical anesthesia-only.
  • Possible that patients who received ketamine-only may have been poor candidates for topical anesthesia (large oral secretions, unable to cooperate, etc.) so comparisons of these groups may be limited.
  • Differences in the ketamine-only and topical anesthesia groups may be confounded by intubation technique (oral vs nasal approach, use of fiber optic assistance, VL blade geometry, bougie, etc.)
  • Various levels of training (EM residents, EM attendings, and non-EM physicians) were included in the study, so it is possible that intubating experience was inconsistent.
  • Do first pass success and adverse events with ketamine-only intubations tell the whole story? Situations that require alternative intubation methods

EM Take-Aways
Though limited by small sample sizes, ketamine-only intubations were found to have a lower first attempt success rate and more adverse events when compared with an approach facilitated by topical anesthesia or traditional RSI. However, the ideal patient population and procedural logistics for ketamine-only intubation have not yet been clearly accepted. More controlled research is needed in this area to make more concrete determinations in this challenging patient population who are at risk of a can't intubate/can't oxygenate scenario.

Related Articles

MedWAR: Are You Up for the Challenge?

MedWAR: Are You Up for the Challenge? You are in a canoe with two friends crossing a lake when suddenly one of them loses consciousness and falls overboard, tipping the canoe and all of its contents

Top 5 Charting Pitfalls

Top 5 Charting Pitfalls In general, residents receive very little education in billing and coding. But there's value in being able to quickly and efficiently churn out patient notes while achieving t