EXTUBATION ALGORITHM
The PUMA extubation algorithm provides a crucial link between risk evaluation and formulation of an extubation strategy.
INSTRUCTIONS FOR USING THE EXTUBATION ALGORITHM
These instructions assume familiarity with the concepts described in the PUMA guideline for tracheal extubation.
Before considering use of the extubation algorithm, first ensure respiratory, haemodynamic, neurological, metabolic, surgical, resource and trajectory preconditions for extubation have been satisfied.
Once these preconditions have been met, subsequent questions prompt consideration of three key issues that must be addressed when developing an approach to extubation:
The risk that re-intubation will be challenging
The risk of hypoxaemia during airway rescue (with a facemask or supraglottic airway)
The potential for patient, team or situation risk factors to improve
These three issues are addressed by the questions arranged under columns 1, 2 and 3 respectively. Each of these questions prompts a binary decision with yes/no responses indicated by following the green or red arrows respectively.
Risk that re-intubation will be challenging (column 1)
This issue is assessed using 3 questions, starting in the top left corner of the algorithm.
Q1: Did the initial intubation indicate that re-intubation should be rapid and reliable?. To qualify as ‘rapid’ for the purpose of this determination, the projected time to re-intubate should approximate that expected for routine performance by a skilled operator. If the answer to this question is ‘NO’ the implication is not that necessarily that encountering challenges with re-intubation is probable, simply that factors have been identified that suggest the risk of this has been significantly elevated from baseline.
Answering ‘NO’ to this question might be prompted by challenges encountered at the initial tracheal intubation such as poor view, requirement for multiple tracheal intubation attempts and/or unplanned use of specialised equipment. Conversely, answering ‘YES’ to this question does not require that no challenges have been identified with intubation, only that the operator is confident that they can be readily overcome using planned interventions (e.g., use of hyperangulated videolaryngoscopy) such that they won’t impede achieving ‘airway success’. Thus this assessment legitimately involves subjective considerations that may lead two operators separately undertaking a risk evaluation on a given patient to answer the question differently based on their own skill level, or the same operator evaluating the same patient to answer differently based on alterated team or situation factors.
Q2: Since the initial intubation, could the ability to re-intubate have been significantly compromised?
Potential changes since the initial intubation are discussed in tables 2 and Box 1 of the PUMA extubation guideline. These changes influence the risk of encountering challenges with re-intubation, even if the initial intubation was rapid and reliable.
Q3: Is there a significantly increased risk that the patient will require time critical airway management following extubation? It is important to emphasise that this question refers to significantly increased risk and time critical airway management. Any patient may require re-intubation, however a significantly increased risk of re-intubation being required should prompt a more conservative approach to extubation. If re-intubation is not time critical, then a greater scope of options (including awake techniques) to reintubate are feasible, increasing the margin of safety from hypoxaemia.
Risk of hypoxaemia during airway rescue (column 2)
This refers to the risk of hypoxaemia resulting from interruptions to ventilation due to challenges with ventilation using a facemask or supraglottic airway during the process of re-intubation or a decreased safe apnoea time. It is assessed by considering the question “Are BOTH facemask and supraglottic airway ‘at risk’?”.
Facemask and supraglottic airway should be designated ‘at risk’ if they are not expected to be ‘rapid and reliable’ or if the safe apnoea time is severely reduced. The assessment of whether facemask or supraglottic airway is anticipated to be ‘rapid and reliable’ is performed according to the principles outlined in the guideline. If both supraglottic airway and mask ventilation are considered ‘at risk’ of being unsuccessful, this decreases the margin of safety from hypoxaemia by increasing the likelihood of airway obstruction. In addition, if facemask and supraglottic airway ventilation are challenging or unsuccessful, re-intubation also becomes more likely to be challenging, due to both the potential increased urgency of re-intubation and the potential for ‘composite failure’ of lifelines, necessitating a more conservative extubation strategy.
Potential for patient, team or situation risk factors to improve (column 3)
Patient factors include airway swelling, aspiration risk, safe apnoea time, degree of patient co-operation and other physiological improvements. Team factors include the number, experience and expertise of available team members and other performance modifiers such as fatigue, stress and workload. And situation factors take into consideration the environment, equipment, monitoring, processes and time of day. The practitioner should consider whether deferring extubation will significantly decrease risk, due to an improvement in one or more of these factors.
The only answer that matters to each of these questions is what the airway operator considers to be correct for a given patient, in their hands, in a particular context. The extubation algorithm is intended to be used as an implementation tool that is referred to in real time to help a given airway operator determine the best approach to their specific patient.
Having used the algorithm, the operator must consider the appropriateness of the suggested approach based on their more nuanced understanding of the relevant patient, team and situation factors. There may be legitimate reasons to adopt a more liberal or conservative approach than the algorithm suggests, but the operator should be able to articulate the specific reasons for any deviation. In general, where there is doubt a more conservative approach is advocated.
Where the suggested approach involves proceeding with extubation, decisions regarding other considerations (e.g., patient position, use of bite block, appropriate location for and duration of post-extubation care) not dictated by the algorithm should be included in the extubation strategy.
Whenever extubation is deferred, re-evaluation of any risk factors that have potentially changed during this interval should be repeated. This updated information should then be used to determine whether it is appropriate to consider extubation and the suggested approach using the algorithm.