Many guidelines suggest that when a difficult airway is anticipated, an awake intubation should be performed to reduce the risk of complications associated with airway manipulation under general anesthesia [6,7,8]. However, in our case, the decision to perform intubation after general anesthesia induction rather than awake intubation was influenced by the patient’s complex cardiovascular condition, including severe mitral and tricuspid regurgitation, rapid atrial fibrillation, and moderate pulmonary hypertension. During the process of awake intubation, a patient’s level of anxiety, inadequate surface anesthesia quantity, or mispositioning of the endotracheal tube can induce coughing that frequently leads to hemodynamic changes, such as hypertension and tachycardia. These hemodynamic shifts are particularly detrimental in patients with MR [9, 10]. Hypertension can increase total peripheral vascular resistance, obstructing left ventricular outflow and exacerbating MR, which in turn increases left atrial pressure. The subsequent rise in left atrial pressure can lead to pulmonary congestion and, in severe cases, left heart failure. Although tachycardia can partially mitigate the impact of MR by preventing left ventricular dilation and aggravating regurgitation, in this patient, rapid atrial fibrillation with a high ventricular rate can cause an ineffective atrial filling, reducing left ventricular filling and cardiac output. This scenario can result in heart failure or cardiogenic shock [11]. Furthermore, during spontaneous respiration, the reduction in pleural pressure can promote venous return, increasing right ventricular preload and stroke volume [12, 13]. However, under positive pressure ventilation similar to its use in general anesthesia, airway pressure increases pleural pressure, impedes venous return and reduces right ventricular preload, which can further compromise right-ventricular function [12, 13]. These considerations make awake intubation challenging, especially when managing the patient’s hemodynamic stability. Another critical factor is that the use of sedatives to improve patient comfort during awake intubation can lead to respiratory depression, with a reported incidence of up to 21% [14]. Respiratory depression can result in hypoxia, carbon dioxide retention, and pulmonary vasoconstriction, all of which worsen pulmonary hypertension. Additionally, severe coughing or airway manipulation during awake intubation can trigger bronchospasm, further increasing pulmonary vascular resistance and possibly leading to a pulmonary hypertensive crisis, which can escalate to right heart failure [15]. Given these risks, intubation after general anesthesia induction was favoured to ensure the patient’s comfort and hemodynamic stability. The use of general anesthesia allowed a controlled ventilation environment, with the ability to manage airway pressure, heart rate, and blood pressure that reduces the risks associated with airway manipulation. Additionally, general anesthesia ensured the patient was completely relaxed, reducing the likelihood of coughing and airway reflexes that could induce detrimental hemodynamic fluctuations.

The release of the “2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway”, emphasizes the importance of developing a difficult airway management strategy, whilst also updating the recommended equipment for managing both standard and advanced difficult airway procedures. The guidelines also advocate for the administration of supplemental oxygen before and during the process of difficult airway management, including the extubation period. Furthermore, the 2022 ASA guidelines provide non-invasive and invasive alternatives for difficult airway management and emphasise the importance of time restraints, as well as limiting the number of attempts using different devices and techniques. Notably, the guidelines offer more robust recommendations for extubation in difficult airway cases and present new algorithms and infographics for managing both adult and paediatric difficult airway cases. These updates significantly enhance the practical applicability and ease of implementation of the guidelines in clinical settings. New recommendations have also been made regarding the strategy for managing anticipated difficult intubation [5]. It is suggested to first rule out whether the patient has concurrent face mask or supraglottic airway difficulties, whether there is a high risk of aspiration, whether the patient is able to tolerate short periods of respiratory arrest and hypoxia, and whether it is anticipated that establishing an emergency invasive airway will be difficult; if any of the above situations exist, awake intubation should be implemented. If all are denied, for cooperative patients, although intubation after general anesthesia induction is not recommended, when the benefits of intubation after general anesthesia induction are comprehensively assessed to outweigh the risks, intubation after general anesthesia induction can be considered, but the number of attempts with any technique class should be limited to 3 by the provider managing the airway, with 1 additional attempt by secondary airway provider. It is also recommended to choose familiar airway handling methods. In addition, given the challenge of managing hemodynamics and myocardial oxygenation while concomitantly managing a difficult airway, Patel et al. suggest that in patients with an anticipated difficult airway, two anesthesia providers are to be available to allow for each assigned provider to be solely responsible for either (a) managing preinduction hemodynamics or (b) airway management. If the provider managing the airway fails to successfully intubate the trachea, they may either postpone the case or intubation until additional resources are available. If mask ventilation is not adequate (cannot intubate, cannot ventilate scenario), an emergency invasive airway access should be prepared. Meanwhile, providers may attempt alternate approaches as those preparations are being made [5]. Figure 3 summarizes the key steps of difficult intubation management in cardiac surgery. The format presented is a combined representation of the 2022 Difficult Airway Consensus [5] guideline and our intuitional experience as a high-volume cardiac surgical center.

Anticipated difficult airway infographic: cardiac surgical patient example

During the anaesthetic induction and when formulating the intubation strategy for this patient, consideration of the patient not having the aforementioned situations of being awake intubated, the hemodynamic changes caused by intubation was weighed, and the benefits and risks to the patient was considered. Thus, the decision to use fiberoptic bronchoscopy-guided intubation after general anesthesia induction was chosen. Fibreoptic bronchoscopy allows for superior airway visualization, especially in patients with difficult airways and/or anatomical distortions. This method provides flexibility and precise manipulation of the endotracheal tube, minimizing trauma to the airway structures and reducing the risk of adverse hemodynamic responses [16]. The success rate of fibreoptic bronchoscopy intubation varies with the number of attempts and studies indicating a first-attempt success rate of 85–95% in anticipated difficult airways [17, 18]. Unlike video-assisted laryngoscopy, which is excellent for visualizing the glottis, may be less effective in patients with limited neck mobility or anatomical obstructions, while fibreoptic bronchoscopy offers greater flexibility in navigating around airway distortions. Additionally, techniques such as direct laryngoscopy, which can cause significant cardiovascular stress, were considered but was deemed unsuitable for this patient. The ability to perform fiberoptic bronchoscopy with precise control and minimal hemodynamic disturbance made it the most suitable technique for securing the airway in this case. Propofol, sufentanil, and rocuronium were used as anaesthetic induction drugs. The effects of propofol and sufentanil can be easily controlled. Due to the lack of data on catecholamine levels, although the increase in heart rate after intubation was limited, there is no definitive evidence of suppressed sympathetic activity. In addition, we chose rocuronium, a muscle relaxant known for its rapid onset and quick reversibility. The reason for choosing an effective muscle relaxant was so it can provide better exposure conditions for the glottis. Additionally, esmolol, ephedrine, and epinephrine was prepared to manage potential circulatory collapse during intubation, taking into account the patient’s complex cardiovascular status. Esmolol had been chosen for its rapid onset and short half-life to control heart rate and reduce sympathetic activation, particularly in response to the stress of intubation [19, 20]. Ephedrine was available to support blood pressure in case of hypotension, as it acts as a potent vasopressor by increasing systemic vascular resistance [21]. Epinephrine was on hand to manage severe bradycardia or cardiovascular collapse, providing both inotropic and vasopressor support when needed [22]. Meanwhile, single intubation technique may be difficult considering the size of the patient’s tongue. We adopted a combination technique (video laryngoscopy combined with bronchoscopy), and past observational studies have shown that the success rate of combination technique intubation with expected difficult airways can reach 80–90% [23]. In the operation, there were two anesthesiologists each being responsible for the patient’s (a) anesthetic induction and manage the hemodynamic, and (b) intubation. Although oral intubation is the preferred intubation route, for patients with a relatively large tongue, nasal intubation is also an alternative which was why nasal preparation was also performed in advance. In addition, limiting the number of attempts at tracheal intubation or supraglottic airway placement helps to avoid potential injury and complications [5]. A reasonable approach may be to limit attempts with airway techniques (i.e., face mask, supraglottic airway, tracheal tube) to three, with one additional attempt by a consultant [5]. Thus, an antagonist was prepared once the number of intubation attempts exceeded 3 + 1 to restore spontaneous breathing and performed awake intubation, adhering to the principle of “oxygenation first.”

It is worth mentioning that successful intubation does not mean that the patient’s “difficult airway” has come to an end. Close attention is often only given to patients with difficult airways during intubation, and lessons on how to avoid catastrophic events during extubation is often overlooked and underemphasized. Extubation failure rates have been reported to be between 0.1% and 0.45% in adults in operating rooms and between 2 and 25% for adults in the intensive care unit, and major airway complications after extubation, such as intubation failure, account for approximately 1/3 of reported anesthesia-related cases [24]. Therefore, to minimize the occurrence of peri-extubation period complications, a plan should be mapped in advance. To this end, the 2022 Difficult Airway Guidelines also propose that a plan for difficult airway extubation and subsequent airway management strategies be made in advance before extubation, and whether the patient meets the conditions for extubation should be assessed to ensure that experienced personnel are able to assist with extubation, and that a decision for choosing an appropriate time and place for extubation can be evaluated. Furthermore, the assigned anaesthetist should have the ability to assess the risks and benefits of tracheostomy, to assess the risks and benefits of awake extubation and extubation before awakening from anesthesia, to assess the clinical factors that may lead to insufficient ventilation after the patient’s extubation, and to assess the feasibility of using an airway exchange catheter or supraglottic tool for a short period as provision for guiding reintubation and to provide oxygen to the patient throughout the extubation process [5]. On top of this, neuromuscular blocking drugs should be fully reversed, with verification using a nerve stimulator before extubation. Respiratory depressant medications, such as opioids, should be administered judiciously. That’s why, in this particular case, after sufficient assessment with Glasgow Coma Scale score, spontaneous breathing trial, Rapid Shallow Breathing Index and voluntary cough peak flow (which was recommend by the guideline consensus) [5, 25] by anesthesiologists, intensive care providers, and respiratory therapists, an airway exchange catheter was used through the tube under the guidance of fibreoptic bronchoscopy and the tracheal tube was removed. The patient continued to inhale oxygen throughout the operation.

In summary, managing a difficult airway in cardiac patients requires a multifaceted approach, prioritizing both the safety of establishing the airway and the potential hemodynamic impact of intubation. In cases where the patient does not have an increased risk of aspiration or cannot tolerate even brief periods of respiratory arrest, and when emergency invasive airway rescue might be challenging, the decision to perform intubation after general anesthesia induction should be made carefully. The benefits and risks of intubation in these patients must be weighed, with a preference for using well-established and familiar techniques. When it is determined that the benefits outweigh the risks, intubation after general anesthesia induction can be considered appropriate. Additionally, regardless of whether awake intubation or intubation after anesthesia induction is chosen, it is critical to adhere to the principle of using familiar techniques to limit complications. The number of attempts should be restricted to a maximum of three attempts, with an additional attempt reserved for emergency alternatives. This highlights the importance of having alternative intubation strategies at-the-ready, including supraglottic airway management, should the initial attempts fail. These strategies and principles create a greater implication for the training of clinicians in difficult airway management, particularly for those looking after cardiac patients. Emphasizes on mastering familiar and safe techniques should be highly focused when conducting training programs, with an aim for trainees to recognize the hemodynamic implications of airway management, and the ability to prepare for difficult or failed intubation scenarios, including identification of emergency alternatives on conclusion of the program. In future cases, these lessons learned can improve patient safety and outcome, ensuring that clinicians are well-prepared for the unique challenges posed by difficult airways in cardiac patients.