Airway management in CHARGE syndrome, devising a well tolerated approach

Managing airways in patients undergoing surgery for craniofacial malformations presents a challenge for anaesthesiologists.1 Biomedical models have been extensively utilised in orthopaedics and maxillofacial surgery to fabricate customised prostheses, plates and cutting guides.2,3 The development of new technologies applied to medicine improves the presurgical preparation of these complex cases. We present an example of this process where surgery was made possible by utilising a customised 3D printed model and a modified nasotracheal tube. Although 3D printed biomedical models have been previously reported in literature, none have specifically addressed craniofacial malformations.4–6 CHARGE syndrome is a genetic condition characterised by a range of congenital malformations affecting various organ systems. The acronym ‘CHARGE’ represents the common features of the syndrome: Coloboma, Heart defects, Atresia of the choanae, Retardation of growth and development, Genital anomalies and Ear abnormalities. The incidence of CHARGE syndrome is estimated to be 1 in 8000 to 10 000 live births, and it often presents significant challenges in both medical management and surgical interventions. One of the most critical issues faced in patients with CHARGE syndrome is managing the airway, which can be further complicated by craniofacial abnormalities and other comorbidities. We present the case of a 24-year-old female patient weighing 55 kg, diagnosed with CHARGE syndrome. In addition to the characteristic features of the syndrome, the patient had a history of Ebstein's anomaly, coloboma, microtia, hearing impairment, and congenital choanal atresia. These conditions, combined with the patient's difficult airway characteristics, presented unique challenges for airway management during the planned jaw surgery. 7–10 The patient has given consent for the publication of the data. The case occurred in January 2024. The patient's pre-operative assessment revealed significant facial bone underdevelopment, including micrognathia, retrognathia and a short neck. The thyromental distance was less than 3 cm, Mallampati score was 4, and mouth opening was restricted to less than 2 cm. Notably, the congenital choanal atresia had been partially corrected surgically during childhood, but it remained a concern for the planned nasal intubation. The pre-operative echocardiogram showed a severely dilated right ventricle and atrium, severe tricuspid regurgitation with severe pulmonary hypertension and slightly depressed cardiac systolic function. In this report, we present a case with an in-house patient customised 3D printed model of a modified airway generated from computed tomography (CT) scan that was used to rehearse and refine the tracheal intubation procedure. Although length and diameter estimations can be made using the CT scan, transferring this to a customised model allowed us to perform a simulation with the fibre bronchoscope, facilitating the subsequent real-life intubation in our patient. Airway management and 3D model creation Upon reviewing the patient's CT scan (Fig. 1), it became evident that conventional intubation methods would be challenging due to the narrow nasal passages and other anatomical restrictions. The CT scan helped us to identify the dimensions of the choana and highlighted the need for initial oral or submental intubation rather than nasal intubation for this particular case. (1) Creating the 3D model: On the basis of the CT scan, a customised 3D printed model of the patient's airway was created (Fig. 2). This allowed us to simulate the intubation procedure using a fibreoptic bronchoscope to better visualise the airway anatomy and refine our approach. The 3D model played a crucial role in identifying potential issues before the procedure, such as the limited space for nasal intubation and the need for alternative airway management strategies (Fig. 3). (2) Model insights: The model revealed the complete obstruction of the right nostril and limited capacity in the left nostril, which could only accommodate a 5-mm flexometalic tube. However, the length of the tube was deemed inadequate for the duration of the surgery, which led to the decision to use oral intubation with videolaryngoscopy with planning for potential submental intubation if necessary (Fig. 3). Fig. 1: The measurements and computed tomography scan.Fig. 2: The 3D model.Fig. 3: The 3D model with the bougie passing through the nasal space.Creating the 3D model Image segmentation A pre-operative cone beam CT scan of the patient was used to obtain initial airway images; the open-source software 3D Slicer (v. 5.2.1, https://www.slicer.org/, Accessed 6 October 2023) was used (Fig. 1). Modelling The exported model was then processed using the modelling software Meshmixer (v 3.5, Autodesk Inc., California, USA). The mesh was prepared for 3D printing by a mesh cleaning process, which included remeshing, editing mesh defects and smoothing. The final model was exported in STL format for the 3D printing stage. 3D printing It was printed in the 3D Lab of Hospital Universitario La Paz, in a stereolithography 3D printer (Form 2, Formlabs, Massachusetts, USA) with Flexible 80 A resin at a 0.1 mm printing resolution. The process took approximately 12 h and 160 ml of material. After printing, the model was removed from the build platform and was washed for 10 min in a Form Wash (Formlabs) filled with 99% isopropyl alcohol to clean the part and remove the liquid resin. External support structures were removed, and then, the model was washed for another 10 min. As some internal support structures could still be present, no curing process was performed. Airway management plan and options Given the complexity of the patient's anatomy, we devised a comprehensive plan for airway management: (1) Plan A: Perform oral intubation with videolaryngoscopy, using an intubation guide, to minimise the risk of nasal bleeding, which could complicate nasal intubation. After securing the airway with the oral tube, proceed to nasal intubation using a fibreoptic bronchoscope, advancing to the vocal cords and subsequently exchanging the tube. (2) Plan B: If nasal intubation failed, preparations for submental intubation were made as an alternative. (3) Plan C: As a final contingency, tracheostomy equipment was made available and ready for immediate use in case of a critical airway emergency. In accordance with the patient's clinical history and condition, we used noninvasive haemodynamic monitoring (Starling Device (Starling Fluid Management Monitoring System). Baxter International.), pulse oximetry, noninvasive blood pressure measurement, ECG and anaesthetic depth with BIS (Bisespectral index)®. Aspect Medical Systems. Before induction of anaesthesia, face mask ventilation was assessed, while monitoring the patient. Upon observing capnography in spontaneous ventilation, we then proceeded with induction, making a judgement that the airway could be maintained after neuromuscular relaxation had been achieved. High-flow nasal oxygen delivered via nasal prongs were used to avoid hypoxia and hypercarbia during induction. As a rescue plan, we prepared for urgent administration of sugammadex. Supraglottic devices and a fibreoptic bronchoscope and tracheostomy equipment were also immediately available. Fentanyl 250 μg, rocuronium 50 mg and an etomidate/propofol mixture (70 mg/10 mg) were administered during induction to minimise hypotension. After verifying haemodynamic stability, maintenance was achieved with propofol TCI (Schnider Ce 2.5 to 3 μg/ml), rocuronium and fentanyl boluses. The patient's mean arterial pressure remained above 60 mmHg during the procedure. We opted to secure the airway using an oral tube assisted by videolaryngoscopy and an intubation guide (Flexitip. IES Medical). This decision aimed to proactively address the potential risk of nasal bleeding, which could have occurred had we attempted nasal intubation initially. Due to the limited oral opening, the oral intubation was initially performed using a hyper-angulated videolaryngoscope (McGrath™ MAC Video Laryngoscope, Medtronic). As nasotracheal intubation was essential for the surgery, a fibreoptic bronchoscope was utilised. Although the narrow nasal passages posed difficulties, the airway was successfully secured. The problem previously highlighted with respect to tube length was solved by removing the flexometallic tube connection and inserting a spliced nonflexometallic orotracheal tube inside it (Fig. 4). This allowed the surgery to be completed satisfactorily. At no time during the surgery was it necessary to make changes to the tube and the airway pressure remained stable. However, as a precaution, the fibreoptic bronchoscope remained prepared and ready for use throughout the procedure.Fig. 4: The final arrangement of ‘tube within tube’.The surgery lasted approximately 9 h. The patient maintained stable haemodynamics, with mean arterial pressures kept above 60 mmHg throughout the procedure. After the nasal intubation had been achieved, the surgical site was prepared, and the procedure proceeded smoothly without any airway-related complications. At the end of the surgery, after reversing the neuromuscular block, the patient was successfully extubated. No complications were observed, and the patient remained stable. The equipment for performing a tracheostomy was kept ready throughout the procedure, in case it was urgently needed due to any issues during intubation or extubation. The meticulous planning of airway management is crucial for the success of surgery in patients with such conditions.11 In our case, the patient's unique anatomy posed a challenge that prompted us to innovate with available resources. The 3D model played a vital role in visualising the complexities of nasal intubation, guiding our strategic planning. Nasal intubation avoiding the mouth is necessary for this particular surgery, but the length of the flexometallic tube that can pass through the narrow choana is too short. Therefore, we designed a ’tube-over-tube’ manoeuvre that allowed us to complete the surgery without complications Discussion It is essential when addressing a case of craniofacial malformation to have airway management plans in place, as well as an anticipation of the materials that will be needed. Our experience emphasises the value of advanced imaging techniques and 3D modelling in improving pre-operative planning and enhancing patient safety during complex surgeries. By simulating the intubation process with the model, we were able to refine our approach, reducing the likelihood of intra-operative complications.5,6 In addition, the unavailability of a suitable small-calibre preformed nasal tube was resolved through the tube-over-tube approach.6,11 In future cases, we would consider further integrating the use of novel airway devices that may be more suited to the unique anatomical challenges posed by CHARGE syndrome. In addition, earlier implementation of fibreoptic bronchoscopy and a multidisciplinary approach can assist optimisation of well tolerated airway management. Key learning points for anaesthesia in CHARGE syndrome patients are listed below: (1) Pre-operative imaging and modelling: Comprehensive pre-operative imaging, including 3D modelling, is important for planning airway management in patients with complex craniofacial anomalies such as those with CHARGE syndrome. (2) Flexibility in airway management plans: Always prepare multiple airway management strategies (Plans A, B and C) to address unexpected complications. (3) Multidisciplinary collaboration: Ensure close collaboration with specialists (e.g. ENT surgeons, cardiac specialists) to manage the diverse health challenges in CHARGE syndrome patients effectively.