Time to oxygenation for cannula‐ and scalpel‐based techniques for emergency front‐of‐neck access: a wet lab simulation using an ovine model

Real-time vs. static ultrasound-guided needle cricothyroidotomy: a randomized crossover simulation trial

Cricothyroidotomy is a key technique for securing airways when tracheal intubation and oxygenation are difficult to achieve. In recent years, it has become clear that ultrasonography is more accurate than palpation for identifying the cricothyroid membrane. However, it is unclear how ultrasound should be administered. We investigated whether real-time or static ultrasound techniques were more useful for needle cricothyrotomy in patients with simulated anatomical abnormalities of the neck. Three cervical simulators with anatomical abnormalities were created. After education and hands-on training in needle cricothyroidotomy, 48 participants (27 junior residents, 12 anesthesia residents, and nine anesthesiologists) performed needle cricothyroidotomy using either a real-time or static ultrasound technique (crossover study). Fisher's exact test was used to assess the success rate and accuracy of the puncture (p < 0.05 was considered statistically significant). The success rate of cricothyrotomy puncture was significantly higher with the real-time ultrasound technique than with the static ultrasound technique. The real-time ultrasound technique led to significantly higher puncture accuracy and shorter procedure time than the static ultrasound technique. Needle cricothyroidotomy using real-time ultrasonography may be more useful than that using static ultrasonography.

Randomized crossover trial comparing two open surgical cricothyrotomy techniques

Objective

Emergency cricothyrotomy is a life-saving procedure that is performed in "can't intubate can't oxygenate" scenario. A recent study comparing an open surgical technique using a bougie and endotracheal tube (ETT) with a Seldinger technique using the Cook Melker catheter showed that the open technique was quicker but suggested that the open technique could be quicker if using the Melker catheter instead of a bougie and ETT. The objective of this study was to compare the surgical technique using bougie and ETT with an open technique using the Melker catheter.

Methods

A randomized crossover trial was conducted involving emergency physicians (EPs) and trainees. Participants performed both techniques in succession on an airway model, with the technique performed first being randomized for each participant. The primary outcome was time to first insufflation of the artificial lung. Participants also indicated their comfort with each technique on a 5-point Likert scale and which technique they preferred.

Results

Seventeen EPs and 19 trainees participated. The Melker catheter technique was performed quicker with a mean time of 29.2 s versus 44.3 s for the bougie/ETT technique (difference 15.1 s, 95% confidence interval 10.8-19.4 s). The Melker catheter was most preferred by participants (61% vs. 39%). There was no significant difference in the comfort ratings between each technique. Time to model lung insufflation was not affected by training level or time since last performed a cricothyrotomy, either real or simulated.

Conclusions

The Melker catheter was quicker to perform and the most preferred by participants.

Video Versus Nonvideo in a Rabbit Training Model for Establishing an Emergency Front of Neck Airway in Children: A Prospective Trial

OBJECTIVES

Simulating a realistic "cannot intubate, cannot oxygenate" (CICO) situation to train an "emergency front of neck airway" is difficult. It further remains unclear if provision of regular technical refreshers improves performance in the setting of a real CICO situation. The purpose of this prospective study on an established surgical rabbit cadaver tracheostomy model was to evaluate the benefit of viewing training material shortly before performing "emergency front of neck airway."

METHODS

Previously trained participants were randomized into 2 groups. The control group (video) was allowed to watch an instructional video before performing a tracheotomy on the training model, while the study group (nonvideo) was not. Queried outcomes included success rate, performance time, and severe secondary airway injuries between the 2 groups.

RESULTS

In 29 tracheotomies performed by 29 participants, the overall success rate was 86% (92% video; 81% nonvideo, P = 0.4). Performance time was not different between the 2 groups (video: 80 s [IQR 25-75 : 53-86], nonvideo 64 s [IQR 25-75 : 47-102]; P = 0.93). Only in the nonvideo group, the performance time and the time between the workshops correlated positively ( P = 0.048). Severe secondary injuries were noted in 4 of 29 rabbit cadavers, 2 in each group. Watching a refresher video before performing an emergency surgical tracheostomy in an infant training model did not influence the success rate and the performance time in previously trained anesthetists.

CONCLUSIONS

These results highlight the ease of learning, memorization, and recall of this emergency surgical tracheostomy technique and may demonstrate its applicability in a real infant CICO situation.

A case series of the Royal Perth Hospital cannula-first approach in the 'can't intubate, can't oxygenate' scenario

At the Royal Perth Hospital, we have been developing and teaching a can't intubate, can't oxygenate (CICO) rescue algorithm for over 19 years, based on live animal simulation. The algorithm involves a 'cannula-first' approach, with jet oxygenation and progression to scalpel techniques if required in a stepwise fashion. There is little reported experience of this approach to the CICO scenario in humans. We present eight cases in which a cannula-first Royal Perth Hospital approach was successfully implemented during an airway crisis. We recommend that institutions teach and practice this approach; we believe it is effective, safe and minimally invasive when undertaken by clinicians who have been trained in it and have immediate access to the requisite equipment. The equipment is low cost, comprising a 14G Insyte cannula, saline, 5 ml syringe and a Rapid-O2. Training can be provided using low-fidelity manikins or part-task trainers.

Scalpel cricothyrotomy versus punctured cricothyrotomy in the context of the CICO crisis. A systematic review and Meta-analysis

IMPORTANCE

The preferential use of a scalpel (SCT) or puncture techniques (PCT) for cricothyrotomy remains a controversial topic.

OBJECTIVE

We performed a systematic review and meta-analysis comparing puncture cricothyrotomy with scalpel cricothyrotomy using overall success rate, first-time success rate, and time taken to perform the procedure as the primary outcome together with complications as a secondary outcome.

EVIDENCE REVIEW

Pubmed databases, EMBASE databases, MEDLINE, Google Scholar, and Cochrane Central Register of Controlled Trials, from 1980 to October 2022.

FINDINGS

A total of 32 studies were included in the systematic review and meta-analysis. It also showed that PCT was close to SCT in terms of overall success rate (82.2% vs. 82.6%, Odd Ratios OR = 0.91, [95%CI: 0.52-1.58], p = 0.74) as well as first-performance success rate (62.9% vs. 65.3%, OR = 0.52, [0.22-1.25], p = 0.15). PCT does not compare favorably with SCT in terms of required time for the procedure (the mean time required for PCT versus SCT incision in the intervention groups was 0.34 standard deviations higher (Mean Difference MD = 17.12, [3.37-30.87], p = 0.01) as well as complications (21.4% vs. 15.1%, Relative Risk RR = 1.49, [0.80-2.77], p = 0.21).

CONCLUSIONS AND RELEVANCE

The results show that SCT has an advantage over PCT in terms of time required for the procedure, while there is no difference in overall success rate, first-time success rate after training, and complications. The superiority of SCT may be the result of fewer and more reliable procedural steps. However, the level of evidence is low (GRADE).

Comparison of emergency surgical cricothyroidotomy and percutaneous cricothyroidotomy by experienced airway providers in an obese, in vivo porcine hemorrhage airway model

BACKGROUND

Emergency front-of-neck airway (eFONA) is a life-saving procedure in "cannot intubate, cannot oxygenate" (CICO). The fastest and most reliable method of eFONA has not been determined. We compared two of the most advocated approaches: surgical cricothyroidotomy and percutaneous cricothyroidotomy, in an obese, in vivo porcine hemorrhage model, designed to introduce real-time physiological feedback, relevant and high provider stress. The primary aim was to determine the fastest method to secure airway. Secondary aims were arterial saturation and partial pressure of oxygen, proxy survival and influence of experience.

METHODS

Twelve pigs, mean weight (standard deviation, SD) (60.3 ± 4.1) kg, were anesthetized and exposed to 25-35% total blood volume hemorrhage before extubation and randomization to Seldinger technique "percutaneous cricothyroidotomy" (n = 6) or scalpel-bougie-tube technique "surgical cricothyroidotomy" (n = 6). Specialists in anesthesia and intensive care in a tertiary referral hospital performed the eFONA, simulating an actual CICO-situation.

RESULTS

In surgical cricothyroidotomy vs. percutaneous cricothyroidotomy, the median (interquartile range, IQR) times to secure airway were 109 (IQR 71-130) s and 298 (IQR 128-360) s (P = 0.0152), arterial blood saturation (SaO₂) were 74.7 (IQR 46.6-84.2) % and 7.9 (IQR 4.1-15.6) % (P = 0.0167), pO₂ were 7.0 (IQR 4.7-7.7) kPa and 2.0 (IQR 1.1-2.9) kPa (P = 0.0667), and times of cardiac arrest (proxy survival) were 137-233 s, 190 (IQR 143-229), from CICO. All six animals survived surgical cricothyroidotomy, and two of six (33%) animals survived percutaneous cricothyroidotomy. Years in anesthesia, 13.5 (IQR 7.5-21.3), did not influence time to secure airway.

CONCLUSION

eFONA by surgical cricothyroidotomy was faster and had increased oxygenation and survival, when performed under stress by board certified anesthesiologists, and may be an indication of preferred method in situations with hemorrhage and CICO, in obese patients.

Cannula cricothyroidotomy in the impalpable neck: An observational study of simulated 'can't intubate, can't oxygenate' scenarios by teams following a cannula-first algorithm in live anaesthetised pigs

Live animal models can be used to train anaesthetists to perform emergency front-of-neck-access. Cannula cricothyroidotomy success reported in previous wet lab studies contradicts human clinical data. This prospective, observational study reports success of a cannula-first 'can't intubate, can't oxygenate' algorithm for impalpable anatomy during high fidelity team simulations using live, anaesthetised pigs.Forty-two trained anaesthesia teams were instructed to follow the Royal Perth Hospital can't intubate, can't oxygenate algorithm to re-oxygenate a desaturating pig with impalpable neck anatomy (mean (standard deviation, SD) 16.2 (3.5) kg); mean (SD) tracheal internal diameter 11 (1.4) mm. Teams were informed that failure would prompt veterinary-led euthanasia.All teams performed percutaneous cannula cricothyroidotomy as the initial technique, with a median (interquartile range, IQR (range)) start time of 42 (35-50 (24-93)) s. First-pass percutaneous cannula success was 29% to both insufflate tracheal oxygen and re-oxygenate. Insufflation success improved with repeated percutaneous attempts (up to three), but prolonged hypoxia time increasingly necessitated euthanasia (insufflation 57%; re-oxygenation 48%). First, second and third percutaneous attempts achieved insufflation at median (IQR (range)) 74 (64-91 (46-110)) s, 111 (95-136 (79-150)) s and 141 (127-159 (122-179)) s, respectively. Eighteen teams failed with percutaneous cannulae and performed scalpel techniques, predominantly dissection cannulation (n = 17) which achieved insufflation in all cases (insufflation 100%; re-oxygenation 47%). Scalpel attempts were started at median (IQR (range)) 142 (133-218 (97-293)) s and achieved insufflation at 232 (205-303 (152-344)) s.While percutaneous cannula cricothyroidotomy could rapidly re-oxygenate, the success rate was low and teams repeated attempts beyond the recommended 60 s time frame, delaying transition to the more successful dissection cannula technique. We recommend this 'cannula-first' can't intubate, can't oxygenate algorithm adopts a 'single best effort' strategy for percutaneous cannula, with failure prompting a scalpel technique.

Success and Time to Oxygen Delivery for Scalpel-Finger-Cannula and Scalpel-Finger-Bougie Front-of-Neck Access: A Randomized Crossover Study With a Simulated "Can't Intubate, Can't Oxygenate" Scenario in a Manikin Model With Impalpable Neck Anatomy

BACKGROUND

Emergency front-of-neck access (FONA) is particularly challenging with impalpable neck anatomy. We compared 2 techniques that are based on a vertical midline neck incision, followed by finger dissection and then either a cannula or scalpel puncture to the cricothyroid membrane.

METHODS

A manikin simulation scenario of impalpable neck anatomy and bleeding was created. Sixty-five anesthesiologists undergoing cricothyrotomy training performed scalpel-finger-cannula (SFC) and scalpel-finger-bougie (SFB) cricothyrotomy in random order. Primary outcomes were time to oxygen delivery and first-attempt success; data were analyzed using multilevel mixed-effects models.

RESULTS

SFC was associated with a shorter time to oxygen delivery on univariate (median time difference, -61.5 s; 95% confidence interval [CI], -84.7 to -38.3; P < .001) and multivariable (mean time difference, -62.1 s; 95% CI, -83.2 to -41.0; P < .001) analyses. Higher first-attempt success was reported with SFC than SFB (47 of 65 [72.3%] vs 18 of 65 [27.7%]). Participants also had higher odds at achieving first-attempt success with SFC than SFB (odds ratio [OR], 10.7; 95% CI, 3.3-35.0; P < .001). Successful delivery of oxygen after the "can't intubate, can't oxygenate" (CICO) declaration within 3 attempts and 180 seconds was higher (84.6% vs 63.1%) and more likely with SFC (OR, 5.59; 95% CI, 1.7-18.9; P = .006). Analyzing successful cases only, SFC achieved a shorter time to oxygen delivery (mean time difference, -24.9 s; 95% CI, -37.8 to -12.0; P < .001), but a longer time to cuffed tube insertion (mean time difference, +56.0 s; 95% CI, 39.0-73.0; P < .001). After simulation training, most participants preferred SFC in patients with impalpable neck anatomy (75.3% vs 24.6%).

CONCLUSIONS

In a manikin simulation of impalpable neck anatomy and bleeding, the SFC approach demonstrated superior performance in oxygen delivery and was also the preferred technique of the majority of study participants. Our study findings support the use of a cannula-based FONA technique for achieving oxygenation in a CICO situation, with the prerequisite that appropriate training and equipment are available.

A report on virtual 'Can't intubate, can't oxygenate' conference workshops at the 2021 Annual Scientific Meeting of the Australian and New Zealand College of Anaesthetists

The COVID-19 pandemic has had profound implications for continuing medical education. Travel restrictions, lockdowns and social distancing in an effort to curb spread have meant that medical conferences have been postponed or cancelled. When the Australian and New Zealand College of Anaesthetists made the decision to commit to a fully virtual 2021 Annual Scientific Meeting, the organising committee investigated the viability of presenting a virtual 'Can't intubate, can't oxygenate' workshop. A workshop was designed comprising a lecture, case scenario discussion and demonstration of emergency front-of-neck access techniques broadcast from a central hub before participants separated into Zoom® (Zoom Video Communications, San Jose, CA, USA) breakout rooms for hands-on practice, guided by facilitators working virtually from their own home studios. Kits containing equipment including a 3D printed larynx, cannula, scalpel and bougie were sent to workshop participants in the weeks before the meeting. Participants were asked to complete pre- and post-workshop surveys. Of 42 participants, 32 responded, with the majority rating the workshop 'better than expected'. All except two respondents felt the workshop met learning objectives. Themes of positive feedback included being impressed with the airway model, the small group size, content and delivery. Feedback focused on previously unperceived advantages of virtual technical skills workshops, including convenience, equitable access and the reusable airway model. Disadvantages noted by respondents included lack of social interaction, inability to trial more expensive airway equipment, and some limitations of the ability of facilitators to review participants' technique. Despite limitations, in our experience, virtual workshops can be planned with innovative solutions to deliver technical skills education successfully.

Emergency Front-of-Neck Airway Rescue Via the Cricothyroid Membrane: A High-Resolution Computed Tomography Study of Airway Anatomy in Adults

BACKGROUND

Emergency front-of-neck airway rescue is recommended in a can't intubate, can't oxygenate clinical scenario. Cannula cricothyroidotomy has been reported as having a high failure rate. Our primary aim was to estimate the angle of the trachea in relation to the horizontal axis in a simulated emergency front-of-neck airway rescue position. Our secondary aims were to estimate the optimal cannula angle of approach and evaluate the anatomical relationship of the cricothyroid membrane (CTM) to adjacent structures. We also assessed whether the CTM lies above or below the neck midpoint, a point equidistant from the suprasternal notch (SSN), and the chin surface landmarks. All measurements were compared between the male and female subjects.

METHODS

Subjects having elective computed tomography of their thorax were consented to have extension of the computed tomography to include their neck. A preliminary radiation dose and risk assessment deemed the additional radiation to be of very low risk (level IIa). Subjects were positioned supinely on the computed tomography table. Standard neck extension was achieved by placing a pillow under the scapulae and a rolled towel under the neck to simulate emergency front-of-neck airway rescue positioning.

RESULTS

Fifty-two subjects were included in this study: 31 men and 21 women. The mean angle of the trachea in relation to the horizontal axis was 25.5° (95% confidence interval [CI], 21.8-29.1) in men and 14.0° (95% CI, 11.5-16.5) in women. The mean minimum angles required for hypothetical cannula cricothyroidotomy for men and women were 55.2° (95% CI, 51.8-58.7) and 50.5° (95% CI, 45.4-55.6), respectively. The CTM was located lower in the neck in men compared to women. The CTM was located below the neck midpoint in 30 of 30 (100%) male subjects and 11 of 20 (55%) female subjects (P < .001).

CONCLUSIONS

The trachea angulates posteriorly in a simulated emergency front-of-neck airway rescue position in supine subjects and to a greater degree in men compared to women (P < .001). The minimum angle required for hypothetical cannula cricothyroidotomy was >45° in the majority (75%) of subjects studied. A steeper cannula angle of approach may be more reliable and warrants further clinical study. If airway anatomy is indistinct and performing a vertical scalpel cricothyroidotomy, consideration should be given to performing this incision lower in the neck in men compared to women.

The Formulation of Cognitive Aids and a Systematic Approach to Emergency Front-of-Neck Access, Following a "Can't Intubate, Can't Oxygenate" Crisis in a Patient With Ankylosing Spondylitis

A patient with ankylosing spondylitis in a "can't intubate, can't oxygenate" situation was rescued with cannula cricothyrotomy and transtracheal jet oxygenation. The case revealed clinical and systematic weaknesses, leading to standardization and reorganization of our equipment. Prepackaged cannula cricothyrotomy sets were placed in standardized locations in the operating rooms in line with our institution's "cannula first" policy. Cognitive aids specific to emergency front-of-neck access (eFONA) were created and placed strategically with the eFONA equipment to prompt and guide operators during airway emergencies. The aids have also been incorporated into our training curriculum to encourage their use.

Rabbit training model for establishing an emergency front of neck airway in children

BACKGROUND

A 'cannot intubate, cannot oxygenate' (CICO) situation is rare in paediatric anaesthesia, but can always occur in children under certain emergency situations. There is a paucity of literature on specific procedures for securing an emergency invasive airway in children younger than 6 yr. A modified emergency front of neck access (eFONA) technique using a rabbit cadaver model was developed to teach invasive airway protection in a CICO situation in children.

METHODS

After watching an instructional video of our eFONA technique (tracheotomy, intubation with Frova catheter over which a tracheal tube is inserted), 29 anaesthesiologists performed two separate attempts on rabbit cadavers. The primary outcome was the success rate and the performance time overall and in subgroups of trained and untrained participants.

RESULTS

The overall success rate across 58 tracheotomies was 95% and the median performance time was 67 s (95% confidence interval [CI], 56-76). Performance time decreased from the first to the second attempt from 72 s (95% CI, 57-81) to 61 s (95% CI, 50-81). Performance time was 59 s (95% CI, 49-79) for untrained participants and 72 s (95% CI, 62-81) for trained participants. Clinical experience and age of the participants was not correlated with performance time, whereas the length of the tracheotomy incision showed a significant correlation (P=0.006).

CONCLUSION

This eFONA training model for children facilitates rapid skill acquisition under realistic anatomical conditions to perform an emergency invasive airway in children younger than 2 yr.

Rescue oxygenation success by cannula or scalpel-bougie emergency front-of-neck access in an anaesthetised porcine model

In the obese, the evidence for the choice of the optimal emergency front-of-neck access technique is very limited and conflicting. We compared cannula and scalpel-bougie emergency front-of-neck access techniques in an anaesthetised porcine model with thick pretracheal tissue. Cannula and scalpel-bougie cricothyroidotomy techniques were performed in 11 and 12 anaesthetised pigs, respectively. Following successful tracheal access, oxygenation was commenced and continued for 5 min using Rapid-O2 device for cannula and circle breathing system for scalpel-bougie study groups. The primary outcome was a successful rescue oxygenation determined by maintenance of arterial oxygen saturation >90% 5 min after the beginning of oxygenation. Secondary outcomes included success rate of airway device placement, time to successful airway device placement, and trauma to the neck and airway. The success rate of rescue oxygenation was 18% after cannula, and 83% after scalpel-bougie technique (P = 0.003). The success rate of airway device placement was 73% with cannula and 92% with scalpel-bougie technique (P = 0.317). Median (inter-quartile-range) times to successful airway device placement were 108 (30–256) and 90 (63–188) seconds (P = 0.762) for cannula and scalpel-bougie emergency front-of-neck access, respectively. Proportion of animals with iatrogenic trauma additional to the procedure itself was 27% for cannula and 75% for scalpel-bougie technique (P = 0.039). Thus, in the porcine model of obesity, the scalpel-bougie technique was more successful in establishing and maintaining rescue oxygenation than cannula-based technique; however, it was associated with a higher risk of severe trauma.

Cricothyroidotomy needle length is associated with posterior tracheal wall injury: A randomized crossover simulation study (CONSORT)

BACKGROUND

Cricothyroidotomy is the final strategy in the "cannot intubate, cannot oxygenate" scenario, but half of needle cricothyroidotomy attempts result in failure. The most frequent complication in needle cricothyroidotomy is posterior tracheal wall injury. We hypothesized that needle length is related to posterior wall injury and compared needle cricothyroidotomy with a commercial kit to a modified shorter needle to evaluate success and posterior wall injury rates.

METHODS

The commercial kit has a needle stopper to prevent posterior wall injury, with a penetrating length of 25 mm. We made long stopper to shorten the length by 5 mm (net 20 mm penetrating length). Residents were recruited, received a lecture about cricothyroidotomy and practiced needle cricothyroidotomy using the commercial kit on a simulator. They then performed cricothyroidotomy using the commercial kit or the shorter needle on an ex-vivo porcine larynx covered with artificial skin. An intra-tracheal endoscope recorded the procedure. The video was evaluated for success/failure or posterior wall injury by independent evaluators. Larynxes with a distance from the outer surface to the inner lumen exceeding 13 mm were excluded. The distance in each larynx was measured by dissection after the study. Success and posterior wall injury rates were analyzed using Fisher exact test (P < .05 was statistically significant).

RESULTS

Forty-seven residents participated in the study. Data for two residents were excluded. There was no statistically significant difference in success rate between the commercial kit (100%, 45/45) and the shorter needle (91%, 41/45, P = .12). Failure was defined if the needle tip did not reach the lumen in four trials. Cannulated but complicated by posterior wall injury occurred in 33% (15/45) with the commercial kit and 5% (2/43) with the shorter needle (P < .01).

CONCLUSION

During needle cricothyroidotomy, force is needed for the needle to penetrate the cricothyroid ligament. The advancing needle sometimes cannot be stopped after penetrating the cricothyroid ligament. These data suggest that needle length is associated with posterior wall injury.