Today, I review, link to, and embed Success and Complications of the Ketamine-Only Intubation Method in the Emergency Department. [PubMed Abstract] [Full-Text PDF]. J Emerg Med. 2021 Mar;60(3):265-272. doi: 10.1016/j.jemermed.2020.10.042. Epub 2020 Dec 9.
All that follows is from the above resource.
Abstract
Background: Rapid sequence intubation (RSI), defined as near-simultaneous administration of a sedative and neuromuscular blocking agent, is the most common and successful method of tracheal intubation in the emergency department. However, RSI is sometimes avoided when the physician believes there is a risk of a can’t intubate/can’t oxygenate scenario or critical hypoxemia because of distorted anatomy or apnea intolerance. Traditionally, topical anesthesia alone or in combination with low-dose sedation are used when physicians deem RSI too risky. Recently, a ketamine-only strategy has been suggested as an alternative approach.
Objective: We compared first attempt success and complications between ketamine-only, topical anesthesia alone or with low-dose sedation, and RSI approaches.
Methods: We analyzed registry data from the National Emergency Airway Registry, comprising emergency department intubation data from 25 centers from January 2016 to December 2018. We excluded pediatric patients (<14 years of age), those in cardiac and respiratory arrest, or those with an alternate pharmacologic approach (i.e., neuromuscular blocking agent only or nonketamine sedative alone). We analyzed first attempt intubation success and adverse events across the 3 intubation approaches. We calculated differences in outcomes between the ketamine-only and topical anesthesia groups.
Results: During the study period, 12,511 of 19,071 intubation encounters met inclusion criteria, including 102 (0.8%) intubated with ketamine alone, 80 (0.6%) who had intubation facilitated by topical anesthesia, and 12,329 (98.5%) who underwent RSI. Unadjusted first attempt success was 61%, 85%, and 90% for the 3 groups, respectively. Hypoxemia (defined as oxygen saturation <90%) occurred in 16%, 13%, and 8% of patients during the first attempt, respectively. At least 1 adverse event occurred in 32%, 19%, and 14% of the courses of intubation for the 3 groups, respectively. In comparing the ketamine-only and topical anesthesia groups, the difference in first pass success was -24% (95% confidence interval -37% to -12%), and the difference in number of cases with ≥1 adverse event was 13% (95% confidence interval 0-25%), both favoring the topical anesthesia group.
Conclusion: Although sometimes advocated, the ketamine-only intubation approach is uncommon and is associated with lower success and higher complications compared with topical anesthesia and RSI approaches.
Keywords: difficult airway; emergency intubation; ketamine; rapid sequence intubation; topical anesthesia.
DISCUSSION
In this registry analysis, we found that when the
ketamine-only method was used to facilitate intubation,
success was lower and adverse events were higher
when compared with an approach facilitated primarily
by topical anesthesia. While we could not control for
important differences in groups because few ED patients
underwent either technique, the success of the ketamine
only approach was quite low (61%) compared with traditional ED intubation success (12).The ketamine-only technique is ostensibly used for patients with anticipated difficult intubation. For those with
$1 difficult airway characteristic, however, success with
ketamine only (51%) was far lower than with topical
anesthesia (86%) or RSI (87%) in this population.
Furthermore, first attempt success with ketamine only
(51%) in the NEAR registry was lower than success rates
reported in other studies for patients with difficult airway
characteristics, which range from 78% to 90% (12,15).
This is despite the fact that patients intubated with topical
anesthesia facilitation had higher rates of anatomic distortion than those intubated with ketamine only. Patient selection may explain much of the difference between ketamine-only and topical anesthesia success; patients receiving ketamine only may have been unsuitable for topical anesthesia techniques because of excessive oral secretions or bleeding, inadequate cooperation, lack of equipment, or lack of experience with topical anesthesia application and endoscopic intubation.It is unclear if the theoretical benefits of a ketamineonly approach outweigh the risks observed in the current
study and how this approach compares with RSI when using a modern extraglottic device and cricothyrotomy as
backup approaches. We do not know how patients would
have fared if RSI was used instead, which provides full
control of the patient, and has been shown in several
studies and a systematic review to result in in better glottic views, higher success, and fewer complications
compared with intubation with a sedative alone (4–
7,16,17). In the current study, administration of a
NMBA was the most common change for ketamineonly patients after the first attempt was unsuccessful.Although RSI has been shown, in general, to be superior to withholding a NMBA, it is possible that the ketamine-only approach is the best approach in select circumstances, possibly including scenarios when NMBAs must absolutely be avoided and the physician does not have access to an endoscope or the skill to use it. However, the ideal circumstances for ketamine-only are speculative and not currently supported by empirical data. It may be prudent for emergency physicians to use widely
accepted emergency airway management algorithms until data support the success and safety of the ketamineonly approach (2).While ketamine usually preserves spontaneous breathing, there are case reports of apnea in critically ill patients
and it frequently results in at least subclinical respiratory
depression (18–20). This is an important consideration in
patients with a severe metabolic acidosis because the goal
is usually to preserve the compensatory high minute
ventilation. It may be preferable to induce full muscle
relaxation and apnea with neuromuscular blockade,
facilitating a best attempt at intubation, rather than risk
a longer, ketamine-facilitated intubation attempt with
relative hypoventilation and lesser chance of success. In
the ED, sedation-only intubation approaches can lead to
a dangerous circumstance: respiratory depression without
enough muscle relaxation to facilitate tube passage.
Sedation-only approaches may have fallen out of favor
in the era of RSI because they seem to lack the primary
benefits of both the awake approach (optimal ability of
patient to breath and protect their own airway) and RSI
(optimal preoxygenation and laryngoscopy conditions).
Vomiting, seen in 7% of patients with ketamine-only intubations, is another known complication of ketamine. Although vomiting related to ketamine use in procedural sedation usually occurs late in the recovery phase when patients can clear their own airway, any vomiting caused by an intubation technique could lead to large-volume aspiration, a feared complication of emergency airway management (21).CONCLUSION
Although the ketamine-only technique is sometimes
advocated, it was rarely used in this large ED registry,
and had lower success and a higher rate of adverse events
than other airway management strategies.Acknowledgments—Presented at the Annual Meeting for the Society of Academic Emergency Medicine, Denver, CO, May
2020.
