a b s t r a c t

Background: Cricothyrotomy is a critical technique for rescue of the failed airway in the emergency department (ED). Since the adoption of video laryngoscopy, the incidence of rescue Surgical airways (those performed after at least one unsuccessful orotracheal or Nasotracheal intubation attempt), and the circumstances where they are attempted, has not been characterized.

Objective: We report the incidence and indications for rescue surgical airways using a multicenter observational registry.

Methods: We performed a retrospective analysis of rescue surgical airways in subjects >=14 years of age. We describe patient, clinician, airway management, and outcome variables.

Results: Of 19,071 subjects in NEAR, 17,720 (92.9%) were >=14 years old with at least one initial orotracheal or nasotracheal intubation attempt, 49 received a rescue surgical airway attempt, an incidence of 2.8 cases per 1000 (0.28% [95% confidence interval 0.21 to 0.37]). The median number of airway attempts prior to rescue surgical airways was 2 (interquartile range 1, 2). Twenty-five were in Trauma victims (51.0% [36.5 to 65.4]), with Neck trauma being the most common traumatic indication (n = 7, 14.3% [6.4 to 27.9]).

Conclusion: Rescue surgical airways occurred infrequently in the ED (0.28% [0.21 to 0.37]), with approximately half performed due to a trauma indication. These results may have implications for surgical airway skill acquisi- tion, maintenance, and experience.

(C) 2023

1. Introduction

The “can’t intubate, can’t ventilate” airway is a Rare occurrence during airway management in which a patient cannot be intubated by conventional methods (i.e., orotracheal intubation with video laryngos- copy) and oxygen saturations cannot be maintained. The surgical air- way has historically been the primary rescue route for this scenario and may refer to several procedures including surgical and percutane- ous cricothyrotomies [1]. Therefore, the rescue surgical airway is an essential component of Emergency airway management training and competency.

* Corresponding author at: 545 1st Ave., New York, NY 10016, United States of America

E-mail address: [email protected] (J. Offenbacher).

The current incidence of surgical airways in the ED is unknown. Prior work has demonstrated that rescue surgical airways occur in 0.3-1.1% of general ED intubations, with a significant percentage of these cases (55-100%) occurring in the setting of trauma [2-6]. How- ever, these estimates may be dated, and not reflect current practice. With the widespread availability and adoption of video laryngoscopy (VL), which is associated with reduced peri-intubation adverse events in ED patients, the incidence of rescue surgical airways may have changed [7-9].

• 1. Study objective

We describe the incidence of rescue surgical airways in the ED and characterize the indications for the intervention using the most current iteration of the National Emergency Airway Registry .

https://doi.org/10.1016/j.ajem.2023.02.020

0735-6757/(C) 2023

1. Materials and methods
   1. Study design and setting

We performed a retrospective analysis using NEAR, a 25-center ob- servational intubation registry of both academic and community EDs [10]. Each site obtained local institutional review board approval to participate. Our results are reported according to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement [11].

• 1. Data collection

Data collection processes have been described previously [12]. How- ever, in brief, intubating clinicians record data from each ED intubation into an online form (StudyTRAX, version 3.47.0011, ScienceTRAX), accessed through www.nearstudy.net. Sites submitted compliance re- ports to the coordinating center showing that >90% of intubations were entered into the registry. Centers that could not maintain 90% reporting were considered non-compliant and had their data removed from the final dataset.

• 1. Study population

We analyzed data from subjects >=14 years old from January 1, 2016 to December 31, 2018 who had a surgical airway performed after at least one orotracheal or nasotracheal intubation attempt.

• 1. Outcome measures

The primary outcome was the incidence of rescue surgical airways. Our secondary outcome was surgical airway success, the successful placement of a surgical airway, via a surgical technique. We also report patient demographics, indications for intubation, number of attempts prior to surgical rescue, survival to ED disposition and peri-intubation adverse events. For the purposes of this study, we defined “peri-intuba- tion” and “peri-surgical airway” as occurring during or immediately after an orotracheal or surgical airway attempt.

• 1. Measures

We examined patient, clinician, and airway management variables among subjects who received a rescue surgical airway attempt. Patient variables included age, sex, and body habitus. Age was stratified by 75 years and body habitus was dichotomized to obese / morbidly obese as these factors have been associated with Peri-intubation cardiac arrest in critically ill patients, where patients experience cardiac arrest during, or immediately after, an intubation attempt [13]. Clinician vari- ables included Medical specialty and level of training. Airway manage- ment variables included indication, inability to preoxygenate prior to initial intubation, active cardiac arrest prior to first orotracheal intuba- tion attempt, Apneic oxygenation, hypoxemia (defined as, <90% prior to first orotracheal intubation attempt), blood pressure prior to first orotracheal intubation attempt (including, hypertensive [defined as systolic blood pressure > 139 mmHg] and hypotensive [defined as sys- tolic blood pressure < 100 mmHg]), clinician perceived difficult airway, objective difficult airway attributes [i.e., high Mallampati (score of 3 or 4), reduced mouth opening (1-2 fingers), reduced neck mobility, re- duced thyromental distance (<3 fingers), any head/neck/face trauma, any airway obstruction including blood in the airway], intubation method (i.e., no medications, sedation and paralysis, paralysis only, se- dation only, topical with sedation), devices used prior to rescue surgical airway attempt (i.e. laryngoscope [direct vs. video], bougie, extraglottic device), number of orotracheal intubation attempts prior to rescue sur- gical airway, surgical airway type (i.e., surgical cricothyrotomy), and bougie use during surgical airway. Oxygen saturation prior to initial

intubation attempt was dichotomized at 90% as this cutoff has been as- sociated with peri-intuabtion cardiac arrest [14]. Rescue surgical airway success was assessed in prespecified subgroups, including active cardiac arrest, airway obstruction, bougie use, facial trauma, head/neck/face trauma, obese / morbidly obese, and medical vs. trauma indication. Sim- ilarly, the proportion of peri-surgical airway cardiac arrest cases was ex- amined by number of total airway attempts. Variable coding for collection and analysis are detailed in the Technical Appendix (Variable Coding). In many cases, due to the low incidence, subgroup categories were considered on an exploratory basis, considering those variables thought to be of high importance but with the knowledge of limitations due to their low occurrence.

• 1. Analysis

We determined percentages and percent differences with confi- dence intervals (CI) using the 1-sample proportions test with continuity correction and the 2-sample test for equality of proportions with conti- nuity correction, respectively. Since all variables were categorical, miss- ing observations were coded as ‘Missing’ for all variables. One subject who underwent a rescue surgical airway had missing success data. Therefore, Random forest multiple imputation was used to impute the missing successful on the first surgical attempt outcome for that case prior to performing subgroup analyses (Supplemental Table 1). We de- termined significance of trend by the chi-squared test for trend in pro- portions. We used R version 4.2.1 (2022-06-23 ucrt)) (R Foundation for Statistical Computing, Vienna, Austria) to conduct the analysis (packages and versions are in the technical appendix).

1. Results
   1. Population and incidence

Of 19,071 subjects in NEAR, 17,720 (92.9%) were >=14 years old with at least one initial orotracheal intubation attempt, and 49 received a res- cue surgical airway attempt (Fig. 1). Therefore, overall, rescue surgical airways occurred in 2.8 cases per 1000 (0.28% [95% CI 0.21 to 0.37]) ini- tial orotracheal intubation attempts in the ED. However, rescue surgical airways occurred in 6.0 cases per 1000 (0.60% [0.40 to 0.90]) among

trauma indications and 1.8 cases per 1000 (0.18% [0.12 to 0.27]) among non-trauma indications.

Fig. 1. Displays the study flow diagram with subject exclusions.

Table 1

Patient, Clinician, and Airway Management Characteristics.

Variable	N	% (95% CI)
Subjects	49	-
Age
<=75 years old	46	93.9 (82.1 to 98.4)
>75 years old	3	6.1 (1.6 to 17.9)
Female: Yes	10	20.4 (10.7 to 34.8)
Body Habitus
Obese / Morbidly Obese	21	42.9 (29.1 to 57.7)
Clinician Specialty Emergency Medicine	38	77.6 (63.0 to 87.8)
Anesthesia	6	12.2 (5.1 to 25.5)
General Surgery	5	10.2 (3.8 to 23.0)
Clinician Level of Training
Post-Graduate Year 2	8	16.3 (7.8 to 30.2)
Post-Graduate Year 3	18	36.7 (23.8 to 51.7)
Post-Graduate Year 4	3	6.1 (1.6 to 17.9)
Post-Graduate Year >=5 or Fellow	2	4.1 (0.7 to 15.1)
Attending	18	36.7 (23.8 to 51.7)
Indication for Initial Intubation?? Medical	24	49 (34.6 to 63.5)
Trauma (Blunt)	11	22.4 (12.2 to 37.0)
Trauma (Penetrating)	14	28.6 (17.0 to 43.5)
Five Most Common Initial Intubation Indications Neck Trauma	7	14.3 (6.4 to 27.9)
Polytrauma	7	14.3 (6.4 to 27.9)
Cardiac Arrest	6	12.2 (5.1 to 25.5)
Traumatic Arrest	5	10.2 (3.8 to 23.0)
Pneumonia	4	8.2 (2.6 to 20.5)
Unable to Preoxygenate prior to Initial Intubation	30	61.2 (46.2 to 74.5)
Active Cardiac Arrest at Initial Intubation	14	28.6 (17.0 to 43.5)
Apneic Oxygenation
Yes	8	16.3 (7.8 to 30.2)
Missing	35	71.4 (56.5 to 83)
Oxygen Saturation Prior to Initial Intubation Attempt >=90%	26	53.1 (38.4 to 67.2)
Missing	5	10.2 (3.8 to 23)
Systolic Blood Pressure Prior to Initial Intubation Attempt Hypertensive, >139 mmHg	9	18.4 (9.2 to 32.5)
Hypotensive, <100 mmHg	8	16.3 (7.8 to 30.2)
Missing	14	28.6 (17.0 to 43.5)
Clinician Perceived Difficult Airway	42	85.7 (72.1 to 93.6)
Mallampati
High, 3 or 4	6	12.2 (5.1 to 25.5)
Not Assessed	38	77.6 (63.0 to 87.8)
Mouth Opening
Reduced, 1-2 Fingers	10	20.4 (10.7 to 34.8)
Not Assessed	32	65.3 (50.3 to 77.9)
Reduced Neck Mobility	20	40.8 (27.3 to 55.7)
Thyromental Distance
Reduced, <3 Fingers	9	18.4 (9.2 to 32.5)
Not Assessed	37	75.5 (60.8 to 86.2)
Any Head Neck Face Trauma	12	24.5 (13.8 to 39.2)
Any Airway Obstruction	23	46.9 (32.8 to 61.6)
Blood in the Airway	35	71.4 (56.5 to 83)
Intubation Method
Sedation and Paralysis	28	57.1 (42.3 to 70.9)
No Meds	16	32.7 (20.4 to 47.7)
Paralysis Only	2	4.1 (0.7 to 15.1)
Sedation Only	2	4.1 (0.7 to 15.1)
Topical with Sedation	1	2.0 (0.1 to 12.2)
First Attempt Route Oral	46	93.9 (82.1 to 98.4)
Nasal	3	6.1 (1.6 to 17.9)
Bougie-assisted intubation prior to surgical airway attempt	19	38.8 (25.5 to 53.8)
Surgical Airway Occurring on Total Airway Attempt #?
2	18	36.7 (23.8 to 51.7)
3	19	38.8 (25.5 to 53.8)
4	12	24.5 (13.8 to 39.2)
Surgical Airway Type Surgical Cricothyrotomy	41	83.7 (69.8 to 92.2)
Missing	8	16.3 (7.8 to 30.2)
Bougie-assisted surgical airway	20	40.8 (27.3 to 55.7)

CI, confidence interval.

* Limited to the first surgical attempt. There were only 50 recorded total surgical airway attempts on 49 subjects.

?? Overall, 51.0% (36.5 to 65.4) of total cases had trauma indications for the initial intubation.

Table 2

Devices Used Prior to First Rescue Surgical Airway Attempt.

1st Attempt

2nd Attempt

3rd Attempt

• 1. Indications

Twenty-five cases were performed on subjects with trauma indica- tions for the initial intubation attempt (51.0% [36.5 to 65.4]), with the

Total, n 49 31 12

Video Laryngoscopy, n (%) 24 (49) 16 (51.6) 7 (58.3)

Direct Laryngoscopy, n (%) 22 (44.9) 12 (38.7) 4 (33.3)

Intubating Laryngeal Mask Airway, n (%)? 0 (0) 2 (6.5) 0 (0)

Bronchoscopy-Assisted Intubation, n (%) 3 (6.1) 1 (3.2) 1 (8.3)

* There were no cases of extraglottic device use for preoxygenation or as a non- intubating rescue technique for unsuccessful orotracheal or nasotracheal intubation prior to rescue surgical airway.

• 1. Patient and clinician characteristics

Of the patients who underwent an ED rescue surgical airway, the median age was 41 (interquartile range 34, 60) and forty-six were <=75-years-old (93.9% [95% CI 82.1 to 98.4]). In addition, 21 sub- jects were obese / morbidly obese (42.9% [29.1 to 57.7]). Lastly, EM cli- nicians performed the rescue surgical airway in 38 cases (77.6% [63.0 to 87.8]) (Table 1).

Table 3

Surgical Airway Outcomes.

Variable	N	% (95% CI)
Subjects Successful First Surgical Attempt? Yes	49 44	89.8 (77.0 to 96.2)
Missing	1	2.0 (0.1 to 12.2)

Survived to ED Disposition 36 73.5 (58.7 to 84.6) Surgical First Attempt Adverse Events

Peri-Surgical Airway Cardiac Arrest 6 12.2 (5.1 to 25.5)

Iatrogenic Bleeding 3 6.1 (1.6 to 17.9)

Main Stem Intubation 2 4.1 (0.7 to 15.1)

CI, confidence interval; ED, emergency department.

* After multiple imputation, 45 were successful on first surgical attempt (91.8% [95% CI 79.5 to 97.4]).

most common indication being neck trauma (n = 7, 14.3% [6.4 to 27.9]) (Table 1). In addition, 14 cases were in active cardiac arrest at the time of the initial orotracheal intubation attempt (28.6% [17.0 to 43.5]) with 8 of those cases being in traumatic arrest (Table 1and Supplemental Table).

• 1. Airway management and outcomes

Rescue surgical airways occurred after the first, second, and third total airway attempts, with an incidence number of 18 (36.7% [23.8 to 51.7]), 19 (38.8% [25.5 to 53.8]), and 12 (24.5 [13.8 to 39.2]), respec-

tively. Therefore, the median number of airway attempts prior to rescue surgical airways was 2 (interquartile range 1, 2). Most cases received a surgical cricothyrotomy (n = 41, 83.7% [69.8 to 92.2]); however, surgical airway type (e.g., surgical vs. percutaneous vs. needle cricothyrotomy) was not reported in 8 cases (Table 1). Bougie-assisted intubation was attempted in 19 cases prior to the rescue surgical airway (38.8% [25.5 to 53.8]), and it was used in 20 cases during the rescue sur- gical airway (40.8% [27.3 to 55.7]) (Table 1). Direct and video laryngos- copy were commonly used before rescue surgical airways (Table 2). Overall, 36 cases survived to hospital admission or transfer (73.5% [58.7 to 84.6]); however, 31 of the 35 cases not in active cardiac arrest at first airway attempt survived to hospital admission or transfer (88.6% [72.3 to 96.3]). Lastly, 44 rescue surgical airway cases were suc- cessful on the first surgical attempt (89.8% [77.0 to 96.2]) (Table 3).

• 1. Subgroups

As previously describes, these analyses were exploratory in nature due to low incidence. Rescue surgical airway success on the first surgical attempt appeared similar across multiple subgroups, but CIs were wide due to procedural infrequency (Fig. 2 and Supplemental Table 1). Addi- tionally, the proportion of cases with peri-procedure cardiac arrest dur- ing or immediately after the rescue surgical airway was stratified by

Fig. 2. Displays a dumbbell plot of surgical airway success by subgroup. Random forest multiple imputation was used to impute the success variable for the one subject missing the out- come.

Fig. 3. Proportion of surgical airways complicated by peri-surgical cardiac arrest (during or immediately after a surgical attempt) stratified by total airway attempt. Significance in trend determined by the Chi-squared Test for Trend in Proportions.

total airway attempt number, and the trend was insignificant (p trend = 0.163) (Fig. 3 and Supplemental Table 2).

1. Discussion

In this large cohort of subjects >=14 years old who received at least one orotracheal intubation attempt in the ED, rescue surgical airways were performed infrequently, occurring in approximately 2.8 per 1000 cases (0.28% [0.21 to 0.37]). In addition, only 25 of 49 (51.0% [36.5 to 65.4]) had a trauma indication. These findings help inform training and preparedness efforts if the demographic of patients requiring res- cue surgical airways has changed.

We observed an incidence of rescue surgical airways and proportion of associated trauma indications at the lower end of previously pub- lished estimates. Earlier work has estimated the overall incidence of ED surgical airways as around 0.3 to 1.1% of general ED intubations with 73-100% of surgical airways being performed after unsuccessful orotracheal intubation [15-18]. Although academic sites may be over- represented in NEAR and implementation of an EM residency has been associated with a reduced rate of cricothyrotomy, widespread use of VL may explain a decreased need for rescue surgical airway [19- 22]. In addition, prior work found trauma indications in about 55-100% of surgical airways in the ED [23-25]. Along with VL, deemphasis on surgical airways for patients with suspected Cervical spine injuries may explain this change in the proportion of trauma indi- cations [26]. Additionally, an increasing incidence of obesity may also contribute to the relative rise in surgical airways in non-trauma patients [27].

The infrequency of rescue surgical airways performed during the

study period impedes drawing definitive conclusions. However, we found several results to be informative. For example, bougie was used in only 19 cases prior to a rescue surgical airway attempt (38.8% [25.5 to 53.8]) (Table 1). The bougie is a simple adjunct that may help to facil- itate the intubation of Difficult airways [28]. However, there is equipoise regarding the benefit of bougie use on first intubation attempts in acute care settings [29,30]. Since 85.7% (72.1 to 93.6) of subjects had a clinician-perceived difficult airway (Table 1), bougie may have been underutilized in this cohort. Additionally, although 2 cases received a rescue intubation attempt with an intubating laryngeal mask airway be- fore the rescue surgical airway attempt (4.1% [0.7 to 15.1]) (Table 2), no Extraglottic devices were used before a rescue surgical airway for preoxygenation or as a primary rescue technique (i.e., without the in- tention of intubating). This observation suggests that extraglottic air- ways might be underutilized in this cohort given their high success rate [31-33]. Lastly, only 73.5% (58.7 to 84.6) of subjects who had a res- cue surgical airway survived to ED disposition (Table 3), and the

proportion of those with a peri-surgical airway arrest was numerically greater at each total airway attempt, though insignificantly (Fig. 2). Therefore, since multiple airway attempts have been associated with peri-intubation cardiac arrest and the proportion of rescue surgical air- ways that were successful on the first attempt is high (89.8% [77.0 to 96.2] and 91.8% [79.5 to 97.4] after multiple imputation) (Table 3), it is reasonable to conclude that that an earlier surgical airway might con- tribute to a better outcomes [34]. These findings support the notion that recognition of a failed airway and the timely decision for surgical rescue are important, because a delay in surgical rescue may contribute to patient morbidity and mortality.

Our results have several implications for emergency airway manage- ment training. Despite occurring infrequently, rescue surgical airways are a highly successful rescue technique for emergency airway manage- ment. Therefore, ED clinicians should continue to train to perform the procedure. In addition, given the high incidence of PEri-surgical airway cardiac arrest, which appears to increase with each overall airway at- tempt (Fig. 3), ED clinicians should have sufficient training to confi- dently perform a surgical airway early and without delay. Similarly, depending on the clinical circumstances, clinicians might consider in- terventions that facilitate timely placement of a surgical airway, such as a double set up [35]. Lastly, bougie-assisted intubation was per- formed infrequently prior to surgical airway attempts (38.8% [25.5 to 53.8]); therefore, emergency airway management training should continue to emphasize bougie use for difficult airways and as a rescue technique.

1. Limitations

We acknowledge several limitations of our registry-based analysis. Our study was retrospective, and data were recorded by intubating cli- nicians. Although reporting compliance is monitored, all intubations re- quiring surgical intervention may not have been captured. Our results may be affected by several factors. These may include confounding by indication and unmeasured confounders, as well as hindsight and self- report bias. Timings of airway interventions were not recorded; there- fore, our results may be confounded by resuscitation time bias. These data are predominantly from academic emergency departments, which may limit generalizability to other practice environments. Lastly, the infrequency of rescue surgical airways in the data set limits the pre- cision of our observations.

1. Conclusion

In this cohort of subjects >14 years old, rescue surgical airways oc- curred in only 0.28% (95% CI 0.21 to 0.37) of cases, lower than previously reported, and occurred equally in medical and trauma patients.

Presentations

None.

Financial support

No funding was obtained for this study.

Conflicts of interest disclosure

All listed authors report no conflicts of interest.

CRediT authorship contribution statement

Joseph Offenbacher: Writing - review & editing, Writing - original draft, Project administration, Methodology, Investigation, Data curation, Conceptualization. Dhimitri A. Nikolla: Writing - review & editing, Writing - original draft, Project administration, Methodology,

Investigation, Formal analysis, Data curation, Conceptualization. Jestin

N. Carlson: Writing - review & editing, Writing - original draft, Meth- odology, Formal analysis, Conceptualization. Silas W. Smith: Writing - review & editing, Writing - original draft, Project administration, Meth- odology, Investigation, Formal analysis, Conceptualization. Nicholas Genes: Writing - review & editing, Writing - original draft, Methodol- ogy, Investigation, Formal analysis, Conceptualization. Dowin H. Boatright: Writing - review & editing, Writing - original draft, Formal analysis. Calvin A. Brown: Writing - review & editing, Writing - original draft, Methodology, Investigation, Formal analysis, Data curation, Con- ceptualization.

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi. org/10.1016/j.ajem.2023.02.020.

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