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Address reprint requests and correspondence: Wayne Pearce, MB, BCh, Department of Anesthesiology and Perioperative Medicine, The Pennsylvania State University, Colllege of Medicine, 500 University Drive, H187, Hershey, PA 17033-0850.
Department of Surgery, Division of Otolaryngology – Head and Neck Surgery, The Pennsylvania State University, Colllege of Medicine, Hershey, Pennsylvania
Department of Surgery, Division of Otolaryngology – Head and Neck Surgery, The Pennsylvania State University, Colllege of Medicine, Hershey, Pennsylvania
Department of Surgery, Division of Otolaryngology – Head and Neck Surgery, The Pennsylvania State University, Colllege of Medicine, Hershey, Pennsylvania
In airway management, a ``Cannot Intubate, Cannot oxygenate” emergency, or simply ``CICO” (IPA: kaɪkəʊ), is an inability to restore alveolar oxygenation by means of any non-surgical lifeline (facemask, endotracheal tube, or supraglottic airway device). With ``CICO,” hypoxic brain damage and death will result unless there is rapid resolution. The ability of an airway team member to swiftly establish an emergency Front of Neck Airway as a CICO rescue is currently deemed to be an essential skill for everyone that performs tracheal intubations. This paper presents the context, components, justification, and human factors-related ramifications of a simple rescue cricothyroidotomy technique currently favored in many institutions and commended in guidelines internationally, particularly in the context of a cognitive tool, the Vortex Approach to airway management.
Background: CICO, NAP4, and the DAS 2015 guidelines
Elaine Bromiley, a healthy 37-year-old mother of 2, was admitted to an outpatient surgery facility on 29 March 2005 for elective functional sinus surgery and rhinoplasty. Her death, a result of prolonged oxygenation failure after induction of anesthesia, became 1 of 2
high-profile airway deaths that would have a substantial effect on subsequent national recommendations and guidelines for the management of the difficult airway. Elaine's husband, Martin, an airline pilot with a background in human factors and system safety, insisted that an independent investigator review the events that led to her death.
The response of the anesthetic community to the resulting report turned out to be the most potent factor that inspired the development of a fourth United Kingdom National Audit Project (NAP4) of the Royal College of Anaesthetists.
and in partnership with the Difficult Airway Society (DAS) over the span of a year. The audit project drew on approximately 3 million general anesthetics. The report of its findings and recommendations published in 2011 influenced airway management worldwide. It is the largest audit of serious airway complications in world literature,
that, moreover, was a source of extremely valuable qualitative data. The details of each reported case allowed for thematic analysis that allowed for new insights into potential causations and associations, potential preventive strategies and early signs of complications.
With Elaine, following induction of anesthesia a laryngeal mask airway could not be sited due to the provider's inability to open her mouth properly. Further deepening of anesthesia, and eventual paralysis with suxamethonium, also did not allow any further successful airway intervention. Since she was not preoxygenated before the induction of anesthesia, her oxygen saturation plummeted. A Cannot Intubate, Cannot oxygenate (CICO; phonetically: kaɪkəʊ) situation, the ultimate difficult airway, developed. This feared complication has an overall incidence of only 0.0019%,
Yet, over the course of the next 20-25 minutes 2 anesthesiologists and the otolaryngologist continuously attempted to intubate the trachea using a variety of techniques and instruments. Although the nurses present realized that an emergency Front of Neck Airway (eFONA) was called for, they were not assertive enough to speak up. Eventually after at least 20 minutes of oxygen saturation readings of around 40% during these attempts, an intubating laryngeal mask was sited, and spontaneous respirations returned after the remifentanil infusion was stopped. The fit of the laryngeal mask allowed for alveolar oxygen delivery, but oxygen saturation readings never exceeded 90%. The decision was made to allow Elaine to wake up spontaneously, but she never recovered consciousness and died 17 days later from hypoxic brain damage.
The chance of encountering an airway management scenario requiring an eFONA as an Ear, Nose, and Throat (ENT) surgeon or anesthesiologist is realistic. A general anesthesiologist can expect to encounter it at least once in their career. Despite all recent advancements, NAP4 found that the incidence of CICO has remained unchanged even though the authors acknowledged the possibility of underreporting. Of the 58 out of 2 million anesthetics that required eFONA, 74% were head and neck patients. The Danish Airway Database recently reported results of eFONAs from a cohort of 452 461 general anesthetics over a 7-year period,
and eFONA occurred in 1 in 1,700 anesthetics. One-third of cases were not predicted to be difficult tracheal intubations. Approximately half of the cases occurred during ENT surgery, with an almost threefold incidence (1:625). Anesthesiologists performed only a very small number of eFONAs, but failed in half of those they attempted. Remarkably, despite shortcomings, no patient died or developed brain damage as a result of an airway event.
The much larger NAP4 registry-based study noted recurring recognizable events and pitfalls in fatal airway cases (Figure 1).
NAP4 thematic analysis of cases revealed that the management of critical, life-threatening airway challenges tend to involve multiple repeat attempts at upper airway lifeline placement without recognizing the need for a change of approach, and not using awake techniques where it was indicated. Another striking recurring feature was the failure to plan for failure. In situations where airway management became unexpectedly difficult the response was unstructured and the outcome generally poor. Head and neck surgery cases feature frequently in cases reported. Unhurried establishment of FONA with local anesthesia appeared to be rarely considered and was encouraged by the NAP4 investigators. They also remarked that the risk of adverse outcomes is high in head and neck surgery when any part of the process of careful assessment and coordinated planning fails. In cases where CICO developed, transition to eFONA was often delayed due to practical and psychological barriers to implementation, or failed due to inexpert attempts. It also noted a high failure rate of emergency narrow caliber cannula cricothyroidotomy (about 60%). In contrast, surgical eFONA was almost universally successful. It concluded that anesthesiologists should be skilled and regularly train in performing a surgical crictothyrotomy.
Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: Anaesthesia.
All society - and independently - produced difficult airway management guidelines end in a final common ``emergency” pathway that culminate in a rescue surgical airway.
guidelines replaced its 2004 final pathway (Plan D), rescue techniques for CICO by Laryngeal Mask Airway, cannula cricothyroidotomy, or surgical airway,
and removed percutaneous narrow-bore infraglottic rescue from its recommendations. The equipment for narrow-bore (less than an internal diameter [ID] of 4 mm) cannula cricothyroidotomy requiring a high-pressure ventilation source in adults, is not universally available in all airway management locations. Also, most anesthesiologists do not use them regularly. The technique is more likely to result in breath stacking, barotrauma, catheter kinking, or dislodgement, and does not provide airway protection with a cuff. Of all the available options, it is associated with the highest complication and failure rates, and resulting obscuring surgical emphysema from displacement may render scalpel eFONA difficult or impossible.
CICO is a type of emergency that does not allow for indecision. The speed of re-oxygenation is of critical importance to outcome. Delay produced by performing a needle cricothyroidotomy and then having to convert to a SBACT may be the difference between a good outcome and severe disability or death.
Narrow-bore cannulas should only be inserted after frequent training, familiarity with the procedure's limitations due to prior elective use, the presence of standardized equipment, and the use of devices that ensure full expiration of tidal volume (such as the Cook ENK modulator, Ventrain, or Meditech rapid O2). Wide-bore cannula over guidewire insertion techniques were also deemed in the DAS guidelines to be less suited for CICO rescue since they require fine motor control that degrades in stressful situations.
Following the influence of the US ENT surgeon, Chevalier Jackson, tracheostomy was established as a standard rescue technique in CICO situations since cricothyroidotomy was seen as unacceptably hazardous for fear of later tracheal stenosis, particularly after a landmark 1,921 paper of his. Cricothyroidotomy was seen as a “high tracheostomy” (above the thyroid gland) that was performed as an elective or emergency surgical airway in the 1920s. He, therefore, argued that high tracheostomy “should never be taught or done.” When it is done it should be converted to a “low tracheostomy” as soon as possible. The teaching was transmitted through generations of surgeons relatively unchallenged.
He, therefore, advocated a rapid 2-step emergency tracheostomy. The skin of the anterior neck was widely opened, and then a finger was used to palpate a suitable gap between the tracheal rings “in the pool of blood that fills the wound.” Later evidence suggested that the risk of tracheal stenosis related largely to inflammatory airway obstructions, or to transection of the cricoid ring.
This injunction was motivated by the desire to promote standardized training, but also because of the fact that performing an SBACT uses equipment readily available in all locations where an anesthetic is performed or where emergency airway management occurs. Further, a cuffed wide-bore endotracheal has several advantages: protection against aspiration, ventilation with a low-pressure standard breathing circuit, complete expiration of tidal volume, the application of positive end-expiratory pressure, and monitoring of exhaled carbon dioxide.
However, the correct equipment should be immediately accessible: a scalpel with a broad number 10 or 20 blade (same width as the tracheal tube), a bougie with a coudé (angled) tip, and a cuffed endotracheal tube. Micro-laryngeal tubes (MLTs) with an ID of 5.0 and 6.0 mm are ideal for SBACT, since the cuff diameter of these tubes averages 31 mm, similar to that of the cuff diameter of a standard ID 8.0 mm tube. The disparity between inflated cuff diameter and trachea found with ``standard” tracheal tubes with an ID of 5.0 or 6.0 mm can potentially generate a leak. This would not only interfere with oxygenation but would thwart the above mentioned advantages of surgical tracheal tube insertion.
The sniffing position used for routine airway management does not provide optimal conditions for SBACT. Rather, neck extension is required. In an emergency this can be achieved in one of two ways: either by pushing a pillow under the shoulders and allowing the head of the patient to drop back, or by pulling the patient up so that the head hangs over the top of the operating table or litter.
The initial incision depends on whether the cricothyroid membrane is palpable or not. After that, the sequence is the same (https://das.uk.com/content/video/fona): ``stab, twist, bougie, tube.”
If the cricothyroid membrane is palpable, 100% oxygen is supplied from the upper airway throughout (in order of preference) through a supraglottic airway device, tightly fitting face mask or nasal insufflation. A laryngeal handshake is performed with the nondominant hand – the operator stands on the left of the patient if right handed (Figure 2A, Figure 3).
Using this hand, the middle finger and thumb palpate the top of the larynx and roll it side to side, before sliding down the thyroid laminae. The index finger is used to palpate the cricothyroid membrane and this hand is then used to stabilize the larynx. Using the dominant hand, a horizontal stab incision is made with the number 10 scalpel piercing the cricothyroid membrane (Figure 2B) with the blade facing the operator. With the blade in the incision it is turned 90° caudally, with the sharp edge toward the patient's feet (Figure 2C). At this point hands are switched, with the nondominant hand holding the blade while pulling it laterally towards the operator taking care to maintain the vertical position of the blade. If the blade is not held at a vertical position, difficulty inserting the bougie would result. The coudé tip of the bougie is inserted into the trachea while holding the bougie in such a way that its opposite end points away from the operator with most of its length dangling parallel to the floor. The tip of the bougie is then rotated to point down the trachea and it is advanced 10-15 cm into the trachea (Figure 2D). ``Hold up” at 5 cm would suggest that the bougie is pretracheal.
It is important not to withdraw the bougie with the scalpel still in the wound. That could result in lacerations of the bougie surface. Such incisions can cause ``bougie trapping” where the tracheal tube can be railroaded into the trachea, but the bougie cannot be removed from the tracheal tube. Forcible removal peels back the bougie surface and risks loss of the bougie tip in the airway. That would then necessitate the removal of the tracheal tube and bougie.
For this reason, some advocate the insertion of finger rather than the scalpel, and, if required, followed by insertion of the bougie. The blade is removed and with the nondominant hand stabilizing the larynx, an assistant railroads a lubricated endotracheal tube with gentle twisting motion into the trachea over the bougie. Oxygenation is confirmed with waveform capnography.
2 anesthesiologist-retrieval specialists registered over a combined 40 years of practice the performance of 24 eFONAs (all successful), using the operator's little finger as a ``sensate” dilator that confirms that the incision has penetrated into the laryngeal lumen, and that the incision is of sufficient size to allow passage of the endotracheal tube. They also found that the fingertip was sufficiently sensitive to identify intralaryngeal pathology by palpation, particularly mucosal edema, that might hinder the passage of the endotracheal tube. They employed a bougie in only 5 of their 24 eFONAs: once without clinical need, on 1 occasion due to difficulty railroading the endotracheal tube because the initial incision was too small, and in 3 other instances because the larynx was excessively swollen owing either to injury or infection. In 1 case the swelling was evident at first glance, in others it was detectable by the absence of a palpable laryngeal lumen.
In the patient with an impalpable cricothyroid membrane, or if the SBACT technique is unsuccessful, a scalpel-finger-bougie technique is used. With this, the DAS guideline makes a recommendation that a vertical incision 80-100 mm in length be performed. To ensure that the cricothyroid membrane is contained in the incision a recent observational study
recommends a 90 mm incision with a commencement point 20 mm above the suprasternal notch, regardless of sex or neck position. Then the blade is put down and with fingers of both hands the larynx and cricothyroid membrane is located using blunt dissection, after which the laryngeal handshake is performed and SBACT is performed as outlined above.
Failed emergency SBACT is a desperate clinical situation.
eFONA can be attempted more distally by an experienced operator, with the alternative being emergency surgical or percutaneous tracheostomy or tracheal access.
A year after the appearance of the 2015 DAS guidelines an editorial appeared in Clinical Otolaryngology
It asks a question - where does the DAS guidelines’ recommendation for SBACT leave a surgeon (with considerable experience in the practice of tracheostomy) when confronted with a patient who is rapidly becoming hypoxic and whom an anesthesiologist is unable to intubate or oxygenate? Its answer lies in the disclaimer of the DAS guidelines. The technique employed remains at the discretion of the person who has been charged with the provision of the surgical airway. For the surgeon experienced in performing tracheostomies, the procedure can be performed in under 5 minutes. Yet in the setting of critical hypoxia and a periarrest event, even a 5 minute tracheostomy may be too long. For most anesthesiologists, many surgical trainees, and the majority of nonhead and neck surgeons, it may be more expeditious to carry out an SBACT when confronted with most patients in CICO.
Even for experienced airway surgeons in a periarrest situation, this may also be the case. Unfortunately, little training has been devoted to the performance of SBACT beyond emergency airway training courses for anesthesiologists – where the recommendation is for a trainee to perform the SBACT sequence in under 40 seconds. It is, however, important that all specialties involved in airway emergencies invest in training to ensure adequate expertise is widely available. The airway team needs to be coordinated and declare CICO – surgeons arriving at a failed airway event need to understand clearly what this means and a request for eFONA, a surgical airway or just ``help” is going to require an immediate SBACT in the vast majority of situations. The time to first discuss and decide the most appropriate eFONA technique is not when confronted with a profoundly hypoxic patient.
on eFONA by ENT surgeons and residents found that there is inconsistency between advised technique, technique of preference and technique actually performed by ENT surgeons. Of all reported eFONAs (N = 30), 80% were managed by tracheotomy. In future eFONAs, 74% stated cricothyroidotomy would be their technique of preference. At the Radboud University Nijmegen Medical Center from where the survey was conducted, ENT and anesthesiology residents train together and are taught to choose a tracheotomy in an urgent scenario (where the patient's vitals are stable), and a cricothyroidotomy in an emergency scenario (CICO, no time to waste). Both a cuffed percutaneous technique and SBACT are taught.
The recommendations that resulted from this national survey have considerable overlap with those of NAP4. A local multidisciplinary team responsible for all advanced airway management, and particularly of invasive airway management, should be established by institutions. This team would note current concepts, technique, and existing guidelines from relevant specialties, make conscious decisions on what cricothyroidotomy technique to use, decide who should be competent, train and assess these people on a regular basis, and create local work plans.
Manikin training in the simulation laboratory seems to be superior to porcine models,
The ENT surgeon has a role to play in this not only as a trainee but as a trainer, as well as a facilitator of institutional airway safety. Familiarization with a standardized technique is vital.
Elaine Bromiley's widower, Martin, founded the Clinical Human Factors Group 2 years after her death. A couple of years later a video was released combining a reconstruction of the case with commentary.
Nicholas Chrimes, an anesthesiologist in Australia, drawing from this video, devised a cognitive tool along in consultation with Peter Fritz, an emergency physician and retrieval specialist. Chrimes named it the Vortex Approach to airway management,
It relies on ``conceptual imprinting” of a ``graphic metaphor” with a particular shape (a vortex) and colors (blue and green). It is similar to the spiral management path proposed by 2 Italian airway authorities
whose image was a spiraling maelstrom resembling a hurricane viewed from above. These cognitive aids rely on the fact that visual memory is better preserved than the ability to recall algorithms in times of cognitive overload during high-stress, high-stakes emergencies such as CICO. It renders decision-making in a rapidly evolving life-threatening emergency faster and more focused.
The latest DAS guidelines for the management of tracheal intubation in critically ill adults formally commend and recognize the vortex approach by incorporating elements of it. The guidelines article also contains a very succinct description of the Vortex Approach (refer to Figure 4): “. . . the Vortex approach defines a ``green zone” as a place of effective oxygenation and relative safety, and [entering] the Vortex as the converse. While in the Vortex, attempts at intubation, SGA [=SAD] placement, and facemask ventilation form an alternating continuum, culminating in [either] success (movement into a green zone) or in cumulative failure (spiralling further into the Vortex), necessitating transition to FONA.” Therefore, a team engaged in airway rescue would find itself either sucked into a ``vortex” of progressive failure culminating in eFONA, or land in one of the tiers of green zones. The implementation tool, designed to be displayed in the Operating Room and other locations of airway intervention (see Figure 5 – note the associated CICO rescue kit). A particularly powerful simulation laboratory reenactment of the Elaine Bromiley case was produced by Chrimes,
The implementation tool poster also contains a number of icons to the right of the vortex. These are categories of structured optimization prompts (manipulations of the head and neck, of the larynx, of the device, adjuncts, suction, and oxygen flow, etc.) called out in real time by a coordinator during the airway emergency. An important prompt is for the confirmation of optimal muscle tone for a best effort at placing a lifeline. This icon indicates that with a challenging airway, an attempt at entering the green zone without neuromuscular blockade cannot be considered a ``best attempt.” This is contrary to traditional teaching but entirely evidence based.
Administering a neuromuscular blocker facilitates all airway maneuvers: mask ventilation, supraglottic airway device placement, tracheal intubation, eFONA and may abolish laryngospasm that may be responsible for CICO.
If 1 ``best attempt” at entry into the green zone techniques by means of each of the lifelines has occurred, further attempts are not mandated. Incremental risk must be assumed with each failed attempt, and excessive instrumentation can make a ``can oxygenate” situation insidiously deteriorate to a ``cannot oxygenate” one. The vortex allows a maximum of 3 attempts at each technique while in the green zone between attempts, but rapid transition to eFONA while ``stuck” in the vortex, or after 3 attempts at each technique. It is evident from the sigmoid shape of the oxyhemoglobin dissociation curve that after the inflexion point where the arterial oxygen saturation descends through 90%, the rate of desaturation accelerates. That means that as descent into the vortex accelerates, a corresponding escalating state of readiness for eFONA is required. It is only with the confirmation of alveolar oxygen delivery by the presence of an end-tidal CO2 waveform, a rising oxygen saturation reading, or both, that the green zone has been entered.
The green zone is a space in which to optimize the patient's oxygenation and hemodynamics, to assemble resources and to formulate a strategy.
The remaining options become more restricted the lower the ``tier” of the green zone that is entered. It is important to note that the green zone is the only place where ``waking” the patient is a permissible exit strategy. When in the funnel of the vortex, the only exit strategy is either the successful placement of an airway lifeline, or entering a green zone by an eFONA. ``Waking” is never an option in the funnel.
The green zone equivalent in the DAS 2018 guidelines is a new ``stop, think, communicate” step following successful rescue oxygenation after intubation failure. eFONA is still recommended by means of SBACT, but other eFONA techniques for ``trained experts only” appear on the flow chart: nonscalpel cricothyroidotomy, percutaneous tracheostomy, and surgical tracheostomy.
An important dimension of these new guidelines is the integration of an adapted version of the CICO status tool of the Vortex Approach (Figure 6). The shift in focus from attempts to enter the Green Zone via the upper airway lifelines, to that of achieving entry into the green zone via infraglottic CICO Rescue, is a process of stepwise increasing readiness with each lifeline failure, rather than a (sudden, desperate) pivot.
With the unsuccessful attempt with the first lifeline, CICO status is set to ``ready” (call for help, allocate proceduralist, bring kit to bedside), with the unsuccessful attempt at entry into the green zone with a second lifeline, CICO status is set to ``set” (open kit and prepare equipment, identify anatomy, get poised for CICO rescue), and, finally, to ``go” (optimize position, initiate CICO rescue) with failure at the third lifeline and declaration of CICO. In the language of the DAS 2018 guidelines these 3 escalations of CICO status become: (i) ``getting the eFONA set” to the bedside (or ensuring it is there) after 1 failed intubation attempt; (ii) ``opening the eFONA set” after 1 failed attempt at facemask and supraglottic airway device oxygenation; and (iii) immediately using the eFONA set at CICO declaration. This formalized transition using defined triggers is referred to as ``priming for eFONA.” Priming will occur more often than actual CICO declaration requiring rescue by eFONA, but will facilitate psychological and operational preparation to act, that will, in turn, expedite eFONA performance.
The DAS guidelines also refer to post-eFONA care and follow-up. Fiberoptic inspection or X-ray is required to rule out endobronchial placement. Once stabilized, the airway will need conversion to tracheal tube or tracheostomy. Pharyngeal or esophageal injury with potential of mediastinal infection may have occurred and may require further investigation.
Conclusion
At the time of writing a newly formed American Society of Anesthesiologists’ Task Force has recently been set up for the development of an (overdue) update of its 2013 guidelines for the management of the difficult airway. This update will take form not untouched by the current intellectual and didactic climate in international airway management circles regarding CICO rescue by means of eFONA. The utilization of a standardized simple technique, regularly taught, and rehearsed by multidisciplinary teams, employing readily available equipment, and incorporated into a cognitive tool such as the Vortex Approach will generate a shared mental model, provide focus during cognitive overload in CICO situations, and prevent fixation errors and perseveration in time-wasting airway maneuvers, as well as inexpert attempts at, eFONA. The skill of establishing a timely eFONA that transpires from the interaction of a coordinated team is the patient safety equivalent of airbag technology in motorcars.
Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: Anaesthesia.
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