Difficult Airway Algorithms and Checklists: Airway Management in Critical Care Medicine (2023)

This session covers:

The rationale for difficult airway algorithms

DAS guidelines

The Vortex Approach

Emergency intubation checklists

The reasons for using a difficult airway algorithm

The Difficult Airway Society (DAS) publishes evidence-based, peer-reviewed guidelines for unplanned failed intubations.¹These guidelines describe relatively simple airway skills, some of which are listed by CICM, ACEM and ANZCA as core competencies for trainees and all of which are covered in the CCAM course.

The Vortex Approach is a cognitive aid that moves the intubator between three general airway management strategies: oxygenation via a face mask, a supraglottic airway device (SAD), or a tracheal tube. He recommends that when an optimal attempt fails with each successive technique, emergency surgical ventilation be performed.

Both algorithms are designed to improve situational awareness (where are we now?) and facilitate decision-making (what do we do next?) That "fixation" on one method, resulting in failure to reach the next, and ultimately a surgical airway has long been recognized as a problem in the management of difficult airways.²An analysis of 2833 tracheal intubations in the ICU and ER showed that more than two laryngoscopy attempts significantly increased the incidence of several deleterious complications: hypoxemia (70% vs. 11.8%); burping of stomach contents (22% vs. 1.9%); Aspiration of gastric contents (13% vs. 0.8%); bradycardia (21% vs. 1.6%); and cardiac arrest (11% vs. 0.7%).³

The National Audit Project of the UK Royal College of Anesthetists (NAP 4) suggested that, despite the widespread use of algorithms, this phenomenon continues to cause morbidity and mortality. In the review, there were several incidents where multiple attempts at laryngoscopy in patients initially able to ventilate resulted in an "unable to intubate, no oxygenation" scenario, and several others where ventilators were initially not available when stated. .^4-6

The DAS and Vortex algorithms are relatively simple and straightforward, making them easy to remember. However, it is clear that clinicians still find it difficult to navigate these algorithms in stressful situations. This is due to a variety of factors, including implantations, but also the fact that intubation failure is a relatively rare occurrence. Consequently, there is a need to practice and rehearse the skills and behaviors needed to follow an airway algorithm to its successful completion.

Some of the practical skills involved (eg cricothyrotomy) are rarely used in daily practice and therefore several authorities have recommended teaching them on a simulator. Furthermore, acquiring simple airway skills does not require a full high-fidelity simulator: for example, there is good evidence that practicing on a simple model of the bronchial tree helps students acquire the manual dexterity needed for fiberoptic bronchoscopy in real world patients.⁷

However, technical skills are only part of the story. As medical staff, we also need to be trained in the attitudes and behaviors needed to deal with a crisis. These characteristics are referred to as “soft skills” or “human factors” and training in this area is often referred to as “crisis resource management”.

The tragic case of Elaine Bromiley provides compelling evidence for the importance of human factors and health. This 37-year-old mother died in 2005 while under anesthesia for routine surgery when Difficult Airway Society guidelines were not followed when it was difficult to intubate her trachea or ventilate her lungs. The independent review following Elaine's death concluded that the technical skills of the anesthesiologists involved, facilities and staffing levels were more than adequate, and that human factors such as low situational awareness, decision-making and communication skills, and non-compliance with a difficult airway algorithm was responsible for his responsible death.⁸Elaine Bromiley's husband, Martin, an airline pilot and human factors trainer for the airline industry, responded to this tragedy by founding the Clinical Human Factors Group, an independent organization that provides awareness and training for non-technical human factors that promote skills.www.chfg.org).

Watch Martin's video below to learn more about Elaine's case and how Martin suggests we respond.

DAS guidelines

The DAS guidelines place a high value on planning: plans B, C and D should be decided in advance so that they can be implemented quickly if plan A (the main technique) fails. The guidelines emphasize that oxygenation takes precedence over everything else during the execution of any plan and that if difficulties arise, the best available help should be sought in advance.

The DAS guidelines were originally published in 2004 but updated in 2015. The most important changes were:

- There is an algorithm that covers routine and RSI induction (as opposed to separate ones) and maintenance ventilation with a face mask is compatible with all inductions

-Video laryngoscopy is explicitly included

-Crycoid pressure should be removed if laryngoscopy or intubation is difficult and left for supraglottic airway device (SAD) insertion in plane B

- Plan B focuses on oxygenation with a SAD, with less emphasis on intubation through a SAD, although this is still an option

- Second generation SADs are preferred (e.g. Proseal LMA™, igel™, Supreme™, Aura Gain™)

-The degree of neuromuscular block should be actively assessed if intubation fails

-Focus will be placed on standardization and training for Plan D, with surgical cricothyrotomy ("scalpel, bougie, tube") as the standard technique. DAS recommends that cannulated techniques be used only by professionals trained and trained in the technique in question (i.e., specialists only).

-Emphasis is on indicating difficulties in airway management

- Emphasis on crisis resource management, teamwork, and regular team algorithm testing.

These algorithms are designed for perioperative rather than critical care use. Therefore, they are not applicable to all critically ill patients. When planning to intubate a critically ill patient, careful consideration should be given to waking the patient if the airway cannot be secured. This option is often not available in very sick or seriously injured patients, forcing staff to switch to a surgical airway when all else fails.

Notes on DAS 2015 guidelines

- Plan A: maximum of 4 attempts at direct laryngoscopy or videolaryngoscopy (as long as it is possible to maintain oxygenation between attempts). Emphasis on external laryngeal manipulation

-Plan B: no more than 4 attempts to introduce SAD. Less emphasis on SAD intubation. Blind techniques not recommended with ILMA

-Plan C: If the above fails, all efforts are directed towards oxygenation through bag-mask ventilation. Maneuvers are suggested to promote adequate oxygenation. If bag-mask ventilation is not possible, muscle relaxation should be performed (with an agent other than rocuronium or vecuronium if sugammadex has been administered to this point).

- At this point, if possible, the patient is awakened if oxygenation is successful. If oxygenation fails, CICO is declared and the CICO algorithm is used

-Plan D: Preferred surgical technique, with emphasis on identifying the anatomy ("hand grip on the throat"¹and vertical incision), then a "scalpel, bougie, tube" technique⁹

The vortex approach (cf.www.vortexapproach.org)

The Vortex Approach is a cognitive aid that supports situational awareness and decision making in managing difficult airways.^10,11The main rationale for this approach is that, in times of stress, clinicians need very simple decision rules that are goal-oriented rather than technology-oriented. Vortex facilitates decision making by encouraging progression through three broad categories of airway management; Oxygen delivery by face mask, DSS, or tracheal tube. Each technique (“lifeline”) must have a best try of up to three attempts before proceeding to the next.

optimization strategies

The authors emphasize that optimization strategies must be applied between attempts, because without changing anything, the next attempt will probably fail like the previous one. It should also be noted that the approach does not require three attempts, suggesting that if a technique clearly fails an ideal attempt, another technique should be used. The Vortex approach includes five optimization strategies that can be applied to all upper airway lifelines:

1. Manipulations:head and neck (eg, head elevation, jaw thrust); larynx (eg, bimanual laryngoscopy); and device (e.g., two-man technique, bougie left spin)
2. Attachments:(e.g., nasopharyngeal airway, laryngoscope for SAD, bougie
3. Size and type:Mask, SAD, tube or laryngoscope
4. to suck
5. Rachenmuskeltonus:Consider increasing neuromuscular blockade

resgate CICO

When optimal attempts at all three upper airway lifelines fail, an emergency coniotomy (“CICO rescue”) should be performed.

Importantly, unlike DAS guidelines, the Vortex approach advocates CICO recovery even when oxygen saturation is maintained. Unlike DAS guidelines, the vortex approach does not prescribe the techniques to be used, but the goals to be achieved (adequate face mask, SAD or tracheal tube oxygenation or CICO rescue).

Performing a CICO rescue at 100% oxygen saturation may seem counterintuitive. The authors of the Vortex approach justify this by saying that after optimal trials with all three techniques, subsequent trials are unlikely to be successful and are likely to make the situation worse. They also believe that the patient is less likely to experience dangerous hypoxia, the operator has more time to perform the procedure and is calmer while doing it.

"The Green Zone"

The final concept in the Vortex approach is the "Green Zone". This is the horizontal "safety zone" that is locatedof the vortex. You are in the "green zone" when you are providing adequate oxygen to the patient, which is defined by the presence of aexpired CO2 waveform and/or elevated O2 saturations.

It is important to note that the green zone does not have an O2 saturation value. This is because the interpretation of oxygen saturations is very context dependent. For example, a well preoxygenated patient with normal lungs but critical airway obstruction might have an SpO2 reading of 90%. This would be more concerning than a patient with chronic lung disease with a good ETCO2 recording and O2 saturation that increased to 90% with an optimization strategy. The Vortex authors suggest that rather than numerically defining adequate oxygenation, one should ask the question:

"If this SpO2 level continues for the next 15 minutes, is this patient likely to suffer hypoxic harm?"

If the answer is yes, optimizations or changes in technology must be planned.

planning in the field

Being in the green zone gives you time to think, create a plan, mobilize resources, and consider what to do if the next plan fails. See “Green Zone Planning Considerations”.

WHY ARE THERE A LOT OF GREEN AREAS OUTSIDE THE 3D VERSION OF VORTEX?

Not all Green Zones are created equal. Clearly, if after a short period of difficult mask ventilation you enter the green zone, which you resolve with a simple repositioning of the head, this is very different than if you reach the green zone after three unsuccessful intubation attempts, three attempts to insertion of SAD and a second dose of muscle relaxant. You will be more stressed, have fewer options and, by definition, will be closer to completing a CICO bailout. Instead of a green zone at the tip of the vortex, it's in a green zone near the pointy end.

In the CCAM course we teach that the DAS algorithm and the Vortex approach can and should be used together. In this approach, the DAS algorithm is used to plan the techniques to be used during airway management, which must be communicated to the team before anesthesia induction in Plan A, B, C, D format. used as a cognitive aid to help the team move from one plan to the next (after they have done their best on a given lifeline).

The combination of the DAS algorithm and the Vortex approach is particularly relevant for critically ill or injured patients, where the vortex lifelines are used in the same order as the DAS algorithm Plan A, B, C and D (endotracheal tube, tracheal tube) . ) supraglottic airways). , mask, CICO rescue). Waking critically ill patients in the event of airway management failure is usually not an option. Instead, following the combined DAS/Vortex approach takes the team through planes A, B, C, and D in a familiar sequence.

In collaboration with the developers of the Vortex algorithm, we developed the Cognitive Emergency Airway Tool, which we believe embodies the essential elements of the DAS algorithm and Vortex approach. This simple visual aid is designed to guide staff through the steps to manage a difficult airway in stressful situations:

Airway management can be a complex task, especially in critically ill or injured patients. Many studies have shown that the incidence of complications and intubation failure is higher outside the operating room. A recent study performed in the emergency room showed a 24% incidence of difficult laryngoscopy and a 16% incidence of desaturation.¹²A British analysis of 164 non-surgical intubations found a 13% incidence of desaturation, a 21% incidence of significant hypotension, and 4 deaths.¹³In an Australian intensive care unit, 18% of patients had desaturation and 22% had hypotension.¹⁴

In NAP 4, the ER and ICU had a disproportionate number of serious respiratory events that were more likely to result in long-term harm. Of the 184 major respiratory illnesses, 36 occurred in the ICU, with 50% resulting in death and another 10% in brain damage. This corresponded to a 70-fold increased risk of death compared to patients in the anesthesia cohort. Incidents are more likely to occur outside of business hours, affecting young physicians, and failure to use capnography contributed to 74% of deaths. One of the NAP 4 authors' strongest recommendations was the introduction of pre-intubation checklists so that items such as capnography are not forgotten.⁶

The effect of intubation checklists has not been extensively studied. One study showed little impact on the number of intubation attempts or vital signs, although these parameters were of little concern prior to the introduction of the checklist.¹⁵A small simulation study showed better task performance with no impact on intubation time.^sixteenPerhaps the most convincing evidence for checklists is a study from a French ICU, where implementation of a protocol of ten separate interventions resulted in a significant reduction in hypoxemia and hypotension.¹⁷

How to use an intubation checklist

Intubation checklists serve as a final check before administering induction drugs. As such, they resemble the "timeout" operating room. The checklist should begin when all team members feel ready to proceed. All team members must remain silent and listen, and the most appropriate person must respond to each challenge and answer each question. For example, the respiratory nurse would answer questions about breathing equipment; the drug manager asks questions about drugs. For the sake of speed, it is acceptable for more than one person to answer the "yes/no" questions.

As such, filling out the checklist should take less than a minute. If you have a minute (that is, if the patient is not in an extreme state), that time will be well spent.

Checklists can also be used as a reminder by individual staff members to help them prepare the patient, medication and equipment. It's a good idea to have a few copies of the checklist available to facilitate this.

Below are two examples of intubation checklists. The first is from Australia and the second from the United Kingdom (cf.www.saferintubation.com).

Also, watch the video from RPA ICU in Sydney showing the intubation checklist in action.

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