Dubito ergo sum. From philosophy towards prevention of unrecognised oesophageal intubation

Cogito ergo sum Renee Descartes (La Dioptrique. 1637) The quote from Descartes, is probably among those most cited by philosophers, scientists and tattoo addicts. It someway represents the essence of mankind: thoughts are generated because we are alive, and at same time they make the ‘thinking subject’ aware of its own existence (’Ego cogito, ergo sum, sive existo’ – I think, thus I am, hence I exist).1 Given the limitations of our senses, any inbound information may betray us: the information may be false, or we perceive correct information inappropriately, biasing the thought. Hence, the importance of doubts, on which Karl Popper based his theory of falsification,2 echoing what Saint Augustine (354 to 430 ac) meant thousands of years earlier with his Dubito, ergo sum: I doubt, hence I am. Now, centuries later, I think and I doubt should be read as synonyms, representing the core of any research method: should any hypothesis resist the test of doubting, it becomes thesis. All this applies to the prevention of unrecognised oesophageal intubation, with evidence and awareness of cognitive biases in medicine mandating the need to think more, or to doubt more, to avoid such a catastrophic event. The figures for unrecognised oesophageal intubation We have been aware for some time that oesophageal intubation, whilst ineffective at delivering oxygen, is not in itself fatal; it is failing to recognise the inadvertent oesophageal intubation that causes catastrophic harm.3 Recent data indicate that oesophageal intubation was reported as 1 in 18 (∼5.5%) in critically ill patients,4 a bit lower in elective cases in the operating room,5 but up to 17% in out-of-hospital intubation.6 Considering the near misses and unrecognised events, this seems just the tip of an iceberg. Oesophageal intubation is associated with severe respiratory and haemodynamic consequences such as hypoxaemia, aspiration, acidosis, cardiovascular collapse,7 making prevention and early recognition remain of paramount importance for airway management. Nevertheless, despite guidelines8 and awareness campaigns,9,10 oesophageal intubation still occurs independently of the difficulty of laryngoscopy, the expertise of the operator, or the setting of the intubation, all of which make it particularly insidious and dangerous. Technology and the human brain Unfortunately, despite the availability of technology to measure end-expiratory CO211 and to assess endotracheal tube position,12 and an awareness of their pitfalls and limitations, both methods are often underestimated, misinterpreted or unconsciously ignored. The ASA closed claims13 analysis showed that from all cases associated with a delayed detection of oesophageal intubation, the number of claims where end-expiratory CO2 was not used almost equalled the number of cases where it was either misinterpreted as bronchospasm or when an alert was miscommunicated to or not received by the team. Technology improves the performance of complex systems, but increasing technical complexity turns out to be limited by the human factor.14,15 Therefore, a modern approach to prevention of unrecognised oesophageal intubation cannot underestimate the impact of non-technical skills (especially in teamwork dynamics) and should aim at the human factor as the primary target. The very first guideline for prevention of unrecognised oesophageal intubation In August 2022, the Project for Universal Management of Airways (PUMA),16 with the unanimous endorsement of international societies, released a consensus guideline for prevention of unrecognised oesophageal intubation intended for ‘use by all airway practitioners independent of geography, clinical location, discipline or patient type’.17 The guideline was developed as a consensus, with evidence from the literature, data from coronial reports, statements from the ongoing PUMA guideline, and international feedback from advisors and scientific societies. A feature of the guideline is the emphasis on the human factor, recognising that cognitive biases (e.g. fixation error, confirmation bias, anchoring bias, pareidolia, communication, monitors ergonomics, etc.) are equally as important as the ‘traditional’ technical factors like airway and equipment difficulties or blind intubation, in the aetiology of unrecognised oesophageal intubation. A catastrophic scenario may be due to either the causes of, and failure to recognise oesophageal intubation. In this perspective, the use of a videolaryngoscope is ‘recommended whenever feasible’,17 based on the evidence that videolaryngoscopy provides a better view of the patient's airway and improves first-pass success rate.18 Promoting the use of these devices is intended to allow the airway team a shared view of anatomical structures, allowing the switch from a single-person intubation to a team-intubation, with emphasis on verbalisation, doubt sharing and effective communication independent of hierarchy.19 Visible confirmation of the correct anatomical tube placement (direct laryngoscopy, videolaryngoscopy, or flexible endoscopy) and the presence of normal, repeated and reliable sustained exhaled carbon dioxide on continuous waveform capnography remain the cornerstone of correct tracheal intubation. The unambiguous defining of sustained exhaled carbon dioxide in the guideline should reduce the risks of undetected oesophageal intubation in ‘fatal cases’ in which confusion may occur, including confounding scenarios such as bronchospasm and cardiac arrest. An approach clearly aimed to fill the gaps in classical clinical and monitoring techniques to confirm endotracheal intubation, which are nevertheless discussed and graded according to evidence-basis in the guideline. Visually-friendly infographics are also provided as quick-access cognitive supports with the aim of fostering implementation of the guideline into local clinical practice: the modus of these dichotomous infographics is not so different from Saint Augustine's postulate. A failure to satisfy the criteria of sustained exhaled CO2 should exclude any further stepwise yes/no alternatives and lead to a clear decision to remove the tube. The innovative point of view of this guideline changes the picture: the goal is not to confirm tracheal intubation but to rule out oesophageal intubation. Though conceptually similar, the profoundly different phrasing leverages on psychology and human factors: instead of searching for confirming the ‘correct’ (which may be prone for confirmation bias, anchoring bias, or fixation error), the guideline intends to exclude the ‘wrong’. The guideline turns the loss aversion bias (one of the strongest demonstrable biases in human decision making, i.e. the preference to behave differently depending on whether the decision is viewed as a gain or a loss)20 in favour of error-proof reasoning and patient safety. In some cases, this may result in removal of correctly placed tracheal tubes (a minimal percentage); when facing the unacceptable risk of unrecognised oesophageal intubation, this seems a price worth paying. Hence, it would be appropriate to say that the PUMA guideline for the prevention of unrecognised oesophageal intubation has an invisible and subtle subtitle stating dubito, ergo sum, or in the vocabulary of modern anaesthesia: if in doubt – take it out.21 Conclusions The etymological roots of ‘cogito’ and ‘cognitive bias’ are the same, but neither Descartes nor Saint Augustine identified them as the devil's hand in the genesis of accidents. The ‘learning from errors’ approach, which has served human kind for millennia, is not ethically acceptable with unrecognised oesophageal intubation. Instead, it is time for anticipation. The PUMA guideline is thus a powerful tool developed to identify pitfalls, to anticipate dangerous situations, and to support thoughtful actions avoiding cognitive biases. The future challenge is to promote a ‘preventing unrecognised oesophageal intubation culture’, and to support guideline implementation, teaching, and adherence. To achieve these aims, there is a need for a substantial call to action for the wiser use of compulsory error-prevention tools (CO2 detectors), the skilful handling of airway devices, and an awareness of human factors. The latter requires the need for a change in our mindset so as to promote error-proof pathways to increase our patients’ safety by using what the philosophers from the past taught us about the importance of doubt. Doubt should be the devil's advocate of any of our decisions, especially in airway management, and particularly in difficult airway management. Doubting in such a setting may double the benefit: dubito ergo sumus (’I doubt, thus we exist’): I exist and patient too.