Double lumen endobronchial tube intubation: lessons learned from anatomy.

BACKGROUND: Double lumen endobronchial tubes (DLTs) are frequently used to employ single lung ventilation strategies during thoracic surgical procedures. Placement of these tubes can be challenging even for experienced clinicians. We hypothesized that airway anatomy, particularly of the glottis and proximal trachea, significantly impacts the ease or difficulty in placement of these tubes. METHODS: Images from 24 randomly selected Positron Emission Tomography - Computed Tomography (PET-CT) scans were evaluated for several anatomic aspects of the upper airway, including size and angulation of the glottis and proximal tracheal using calibrated CT measurements and an online digital protractor. The anatomic issues identified were confirmed in cadaveric anatomic models. RESULTS: Proximal tracheal diameter measurements in PET-CT scans demonstrated a mean ± standard deviation of 20.4 ± 2.5 mm in 12 males and 15.5 ± 0.98 mm in 12 females (p < 0.001), and both were large enough to accommodate 39 French and 37 French DLTs in males and females, respectively. Subsequent measurements of the posterior angulation of the proximal trachea revealed a mean angle of 40.8 ± 5.7 degrees with no sex differences. By combining the 24 individual posterior tracheal angles with the 16 angled distal tip measurements DLTs (mean angle 24.9 ± 2.1 degrees), we created a series of 384 patient intubation angle scenarios. This data clearly showed that DLT rotation to a full 180 degrees decreased the mean intubation angle between the DLT and the proximal trachea from a mean of 66.6 ± 5.9 to only 15.8 ± 5.9 degrees. CONCLUSIONS: Rotation of DLTs a full 180 instead of the recommended 90 degrees facilitates DLT intubations.

Three-dimensional assessment of upper airway changes associated with mandibular positional deviations following fibula free flap reconstruction.

OBJECTIVES: Fibula free flaps (FFF) are the standard approach to mandibular reconstruction after partial resection, with the goal of restoring aesthetics and masticatory function. The graft position affects both and must be carefully selected. Correlations between sagittal positioning and upper airway anatomy are known from orthognathic surgery. This study aims to evaluate changes in mandibular position and upper airway anatomy after reconstructive surgery with FFF and corresponding correlations. MATERIALS AND METHODS: Mandibular position after reconstruction was evaluated using three-dimensional datasets of pre- and postoperative computed tomography scans of patients treated between 2020 and 2022. Three-dimensional measurements were performed on both condyles and the symphyseal region. Changes in upper airway volume and minimum cross-sectional area (minCSA) were analysed. Intra-rater reliability was assessed. Correlations between changes in upper airway anatomy and sagittal mandibular position were tested. RESULTS: The analysis included 35 patients. Intra-rater reliability was good to excellent. Condylar deviations and rotations were mostly rated as small. Changes in symphyseal position were considerably greater. Median airway volume decreased in the oropharynx and hypopharynx. Posterior deviation of the symphysis was associated with a decreasing minCSA in the hypopharynx and vice versa. CONCLUSIONS: The overall accuracy of mandibular reconstructions with FFF is high, but there is room for optimization. The focus of research should be extended from masticatory to respiratory rehabilitation. CLINICAL RELEVANCE: Effects on respiratory function should be considered prior to graft positioning. The clinical relevance of upper airway changes within the complex rehabilitation of reconstructive surgery patients needs to be further investigated.

Hypoglossal nerve stimulation over-titration.

This case report reviews worsening obstructive sleep apnea (OSA) events in a patient over-titrated with a hypoglossal nerve stimulator. A healthy 57-year-old man underwent hypoglossal nerve stimulator implantation for moderate OSA. During an in-laboratory hypoglossal nerve stimulator titration the patient had improvement of his OSA at 2.1 V. However, a further increase of voltage resulted in worsening of obstructive events. The pathophysiology behind this finding is unknown but may result from unfavorable changes in the upper anatomy due to higher energy delivered to the hypoglossal nerve and surrounding structures. This high energy may also lead to genioglossus muscle fatigue. This finding highlights the importance of hypoglossal nerve stimulation titration with a dedicated sleep study. CITATION: Chang M, Moore V, Eng K, Ryden A, Zeidler M. Hypoglossal nerve stimulation over-titration. J Clin Sleep Med. 2024;20(6):999-1001.

The Association of Upper Airway Anatomy with Brain Structure: The Multi-Ethnic Study of Atherosclerosis.

Sleep apnea, affecting an estimated 1 in 4 American adults, has been reported to be associated with both brain structural abnormality and impaired cognitive function. Obstructive sleep apnea is known to be affected by upper airway anatomy. To better understand the contribution of upper airway anatomy to pathways linking sleep apnea with impaired cognitive function, we investigated the association of upper airway anatomy with structural brain abnormalities. Based in the Multi-Ethnic Study of Atherosclerosis, a longitudinal cohort study of community-dwelling adults, a comprehensive sleep study and an MRI of the upper airway and brain were performed on 578 participants. Machine learning models were used to select from 74 upper airway measures those measures most associated with selected regional brain volumes and white matter hyperintensity volume. Linear regression assessed associations between the selected upper airway measures, sleep measures, and brain structure. Maxillary divergence was positively associated with hippocampus volume, and mandible length was negatively associated with total white and gray matter volume. Both coefficients were small (coefficients per standard deviation 0.063 mL, p = 0.04, and - 7.0 mL, p < 0.001 respectively), and not affected by adjustment for sleep study measures. Self-reported snoring >2 times per week was associated with larger hippocampus volume (coefficient 0.164 mL, p = 0.007), and higher percentage of time in the N3 sleep stage was associated with larger total white and gray matter volume (4.8 mL, p = 0.004). Despite associations of two upper airway anatomy measures with brain volume, the evidence did not suggest that these upper airway and brain structure associations were acting primarily through the pathway of sleep disturbance.

The association of upper airway anatomy with cognitive test performance: the Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Numerous upper airway anatomy characteristics are risk factors for sleep apnea, which affects 26% of older Americans, and more severe sleep apnea is associated with cognitive impairment. This study explores the pathophysiology and links between upper airway anatomy, sleep, and cognition. METHODS: Participants in the Multi-Ethnic Study of Atherosclerosis underwent an upper airway MRI, polysomnography to assess sleep measures including the apnea-hypopnea index (AHI) and completed the Cognitive Abilities Screening Instrument (CASI). Two model selection techniques selected from among 67 upper airway measures those that are most strongly associated with CASI score. The associations of selected upper airway measures with AHI, AHI with CASI score, and selected upper airway anatomy measures with CASI score, both alone and after adjustment for AHI, were assessed using linear regression. RESULTS: Soft palate volume, maxillary divergence, and upper facial height were significantly positively associated with higher CASI score, indicating better cognition. The coefficients were small, with a 1 standard deviation (SD) increase in these variables being associated with a 0.83, 0.75, and 0.70 point higher CASI score, respectively. Additional adjustment for AHI very slightly attenuated these associations. Larger soft palate volume was significantly associated with higher AHI (15% higher AHI (95% CI 2%,28%) per SD). Higher AHI was marginally associated with higher CASI score (0.43 (95% CI 0.01,0.85) per AHI doubling). CONCLUSIONS: Three upper airway measures were weakly but significantly associated with higher global cognitive test performance. Sleep apnea did not appear to be the mechanism through which these upper airway and cognition associations were acting. Further research on the selected upper airway measures is recommended.

Methodical control of the difficult pediatric airway: two case reports.

BACKGROUND: Management of children who present with a history of impossible mask ventilation or difficult tracheal intubation is fraught with challenges. Despite this, the "airway stress test" of an inhalational induction is frequently employed risking airway obstruction, breath holding, apnea, and laryngospasm. CASE PRESENTATIONS: We present two cases of children with anticipated difficult airway management. The first child (14-year-old African American boy) had severe mucopolysaccharidosis with a history of failed anesthetic induction and failed airway management. The second child (3-year-old African American girl) had progressive lymphatic infiltration of the tongue, resulting in severe macroglossia. We describe a technique that forgoes inhalational induction, incorporates recent pediatric airway guidelines, and provides a greater margin of safety. The technique encompasses the use of drugs that facilitate sedation for intravenous access, without respiratory depression or airway obstruction, titrated use of medications to achieve anesthetic depth while preserving ventilatory drive and airway tone, and the continuous provision of directed oxygen flow during airway manipulation. Propofol and volatile gases were avoided to preserve airway tone and respiratory drive. CONCLUSIONS: We emphasize that an intravenous induction technique utilizing medications that preserve airway tone and ventilatory drive, and the use of  continuous oxygen flow throughout airway manipulation, allows for successful management of children with a difficult airway. The common practice of volatile inhalational induction should be avoided in anticipated difficult pediatric airways.

Obstructive Sleep Apnoea: Focus on Pathophysiology.

Obstructive sleep apnoea (OSA) is characterized by recurring episodes of upper airway obstruction during sleep and the fundamental abnormality reflects the inability of the upper airway dilating muscles to withstand the negative forces generated within the upper airway during inspiration. Factors that result in narrowing of the oropharynx such as abnormal craniofacial anatomy, soft tissue accumulation in the neck, and rostral fluid shift in the recumbent position increase the collapsing forces within the airway. The counteracting forces of upper airway dilating muscles, especially the genioglossus, are negatively influenced by sleep onset, inadequacy of the genioglossus responsiveness, ventilatory instability, especially post arousal, and loop gain. Recent reports indicate that multiple endotypes reflecting OSA pathophysiology are present in individual patients. A detailed understanding of the complex pathophysiology of OSA encourages the development of therapies targeted at these pathophysiological endotypes and facilitates a move towards precision medicine as a potential alternative to continuous positive airway pressure therapy in selected patients.

Near total intrathoracic airway obstruction managed with a Tritube® and flow-controlled ventilation.

We describe the management of a case of near total airway obstruction in a 79-year-old man who presented with a 2-week history of increasing shortness of breath and stridor. Computed tomography imaging revealed a mid-tracheal mass of unknown aetiology with critical airway obstruction. We secured the patient's airway using a TriTube® (Ventinova, Eindhoven, the Netherlands). While this facilitated a secure airway past the lesion, various issues were encountered which complicated the safe conduct of anaesthesia. We conclude that while the TriTube and Evone® flow-controlled ventilation (Ventinova) are useful for critical airway obstruction, they can be problematic and thorough planning is essential.

Application of mixed reality technology in clinical teaching of airway anatomy under bronchoscopy / 中华医学教育探索杂志

Objective:To explore the effect of introducing mixed reality technology into traditional atlas teaching to teach airway anatomy under bronchoscopy.Methods:A total of 30 Batch 2017 fifth-year clinical medicine students from Shanghai Jiao Tong University School of Medicine were randomly divided into control group and test group by RAND function in Excel, with 15 students in each group. The control group was taught with the traditional bronchoscopic atlas teaching, and the test group was combined with mixed reality technology. The two groups had the same class time. After teaching, the teaching effect was evaluated by examination and evaluation questionnaire. SPSS 25.0 software was conducted for t test and Mann-Whitney U test. Results:The average score after teaching of test group was (61.67±20.15), and that of control group was (36.67±13.32), with statistically significant differences ( t=4.01, P<0.001). According to the questionnaire results, the scores of the test group on course understanding, course concentration, participation, mastery and satisfaction were better than those of the control group, and the differences were statistically significant ( P<0.05). Conclusion:Using mixed reality technology to assist the clinical teaching of airway anatomy under bronchoscopy can improve the quality of students' study and enhance their understanding of the teaching content and students' participation passion, achieving better teaching effect.

How Does Tube Size Affect Patients' Experiences of Postoperative Sore Throat and Hoarseness? A Randomised Controlled Blinded Study.

Sore throat (POST) and hoarseness (PH) are common complaints after endotracheal intubation (EI). The aim of this study was to investigate whether tube size impacts the experiences of POST and PH after EI in patients undergoing elective surgery, as well as to document a possible role of gender. This randomised, controlled, blinded study was conducted at Aalborg University Hospital, Thisted, Denmark or North Denmark Regional Hospital, Denmark. A total of 236 patients (53.4% female, mean age 50.9 years (SD 14.0)) were enrolled from the departments of gynaecology, parenchyma and orthopaedics. The patients were randomised to a tube size of 8.0 or 7.0 for males and 7.0 or 6.0 for females. Tube sizes were known to the anaesthesia staff but blinded for patients, researchers and staff at the postoperative care unit. POST and/or PH was reported 30-60 min before anaesthesia, at 30 min and at 2, 5, 12, 24, 48, 72 and 96 h after anaesthesia. Both female and male patients experienced significantly lower levels of POST and PH after intubation with the smallest tube size. This study demonstrates that a smaller size of tube results in a reduction in POST and PH after EI for both male and female patients.

Rapid upper airway obstruction after arteriovenous malformation rupture in a patient with neurofibromatosis.

Neurofibromatosis type 1 is rarely associated with arteriovenous malformation rupture. We present a case of a rapidly compromised upper airway due to extrinsic compression as a consequence of the rupture of an arteriovenous malformation fed by the inferior thyroid artery which required emergency cricothyroidotomy following failed attempts at orotracheal intubation. While the patient had a good overall outcome, our reflection on the management of this case highlights several important learning points. These include the importance of clear communication between different medical specialties to promote shared situation awareness, the importance of training anaesthetists in the limitations of standard difficult airway management algorithms, and the implications of the skillset mix of doctors responding to airway emergencies in district general hospitals.

Infrared flashing light through the cricothyroid membrane to guide flexible bronchoscopic tracheal intubation.

Flexible bronchoscopic tracheal intubation is a fundamental technique in the management of the difficult airway but requires specific skills which may be both difficult to achieve and maintain. Therefore, techniques to improve its success should be developed. We present two cases, one where the ear, nose and throat surgeon could not view the glottis due to laryngeal pathology, and one where pathology in the oropharynx obscured access to the trachea during attempts at flexible bronchoscopic and videolaryngoscopic tracheal intubation. In both cases, tracheal intubation was subsequently successful due to the use of the Infrared Red Intubation System. This is an infrared light source that is secured to the anterior neck. It emits a flashing infrared light that is captured by the flexible bronchoscope, thus guiding the way to the trachea. These are the first reports of this technology being used for flexible bronchoscopic tracheal intubation in patients with severe airway pathology where conventional approaches had failed. Both cases emphasise that this technique can be of benefit in avoiding a surgical airway.

Pediatric flexible bronchoscopy: A single-center report.

INTRODUCTION: Pediatric flexible laryngotracheal bronchoscopy (FB) is an integral part of diagnostics and treatment at tertiary pediatric respiratory centers. AIM: FBs performed between 2013 and 2018 at our Pediatric Allergy and Respiratory Medicine Unit of the Department of Women's and Children's Health at Padua University were examined in terms of the indications, findings, and adverse events. MATERIALS AND METHODS: The electronic medical records of pediatric patients who underwent FB at least once between 1 January 2013 and 31 December 2018 were considered. Patients' clinical data, indications for FB, anatomical findings, information derived from bronchoalveolar lavage (BAL) and bronchial brushing, and possible adverse events were analyzed. RESULTS: There were 447 pediatric FBs performed in 428 patients (aged from 1 month to 18 years) for diagnostic purposes (92.4%), to clear secretions (3.6%), or to monitor a known condition (4.0%). The main indications were recurrent lower respiratory tract infections (LRTI, 32.2%) and chronic wet cough (9.4%). Lower airway malacia was the most common abnormal finding in these two groups (36.1% and 28.6%, respectively). BAL bacterial culture was positive in 55 children (39.6%) with recurrent LRTI and in 25 (59.5%) with chronic wet cough, being Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis the microorganisms most commonly isolated. FB proved a safe procedure and was well tolerated. CONCLUSIONS: Pediatric FB is an essential tool at our tertiary pediatric respiratory center. It helps establish the anatomical conditions underlying several chronic respiratory conditions and any correlated microbiological findings, with a significant impact on further patient management.

Laryngectomy with a Tritube® and flow-controlled ventilation.

We describe the novel use of the TriTube® and Evone® ventilator (Ventinova, Eindhoven, Netherlands) to facilitate curative resection of a transglottic squamous cell carcinoma. A 43-year-old man presented with acute laryngeal and subglottic airway obstruction secondary to a stage 4 transglottic squamous cell carcinoma. The patient underwent magnetic resonance imaging followed by a diagnostic panendoscopy. It was decided that tumour resection was appropriate and a management plan was established by a multi disciplinary team. A total laryngectomy was performed. It was determined that failure of translaryngeal tracheal intubation could be rescued with emergency surgical front-of-neck airway. General anaesthesia was induced using a total intravenous anaesthesia technique, oxygenation was achieved with high-flow nasal oxygen and the airway was secured using the TriTube and flow-controlled ventilation was delivered throughout the procedure using the Evone ventilator. This avoided an awake or emergency tracheostomy, with the associated theoretical risk of tumour seeding, allowed for excellent gas exchange throughout and permitted the surgeons to maintain a closed system during much of the procedure, including during fashioning of the stoma. When traditional laryngectomy tubes are used, this process ordinarily involves multiple extubations and apnoeic periods. Furthermore, the small subglottic tube allowed intra-operative assessment of the extent of the subglottic tumour, facilitating curative en bloc resection.

Awake tracheal intubation with the ProVu™ video stylet: a case series.

Management of the difficult airway is integral to peri-operative practice. The development of devices to simplify airway handling are changing our approach to tracheal intubation. We report a case series of three patients who underwent awake tracheal intubation with the ProVu™ video stylet (Flexicare Medical Ltd, Mountain Ash, UK). All three patients had predicted difficult airways, including: limited mouth opening secondary to radiotherapy; previous exenteration, hemi-maxillectomy and scapular free flap formation; and cervical fixation. Awake tracheal intubation was performed successfully in all three cases, with no complications reported. This is the first reported case series of the ProVu™ video stylet as an awake tracheal intubation device. The benefits and limitations of this video stylet are discussed.

Obstructive sleep apnea risk factors and symptoms in children with a known parental obstructive sleep apnea diagnosis.

OBJECTIVE: To document symptoms and risk factors of obstructive sleep apnea (OSA) in children who have a parent diagnosed with OSA and compare them to an age and sex matched sample where parents are low risk for OSA. METHODS: We recruited 25 children with a parent diagnosed with OSA (P-OSA) and 29 age and gender matched children from the community whose parents scored low risk for OSA (P-NOSA). Comparisons were made using the OSA-18 questionnaire, anthropometric measurements, and mallampati score. Statistical analysis included t-tests for OSA-18 score and BMI measures and non parametric analysis for mallampati score. OSA-18 domain scores were analysed using T-test and Bonferroni correction for multiple comparisons. RESULTS: Fifty-six percent of the P-OSA group had a mallampati score of III/IV compared to 11% in the P-NOSA sample (p = 0.005). There was a significant difference in BMI between the P-OSA sample (mean ± SD 19.5 ± 5.7 kg/m2) and the P-NOSA sample (16.95 ± 2.08 kg/m2, p = 0.002). Forty-four percent of P-OSA children were found to be either overweight or obese (BMI z-score). None of the P-NOSA children fell into this category. No significant difference was found between the P-OSA and P-NOSA samples on the OSA-18 score (P-OSA 36.5 ± 8.1, P-NOSA 29.2 ± 9.1, p = 0.07). Five children in the P-OSA sample scored >60 but no P-NOSA children scored >60. CONCLUSIONS: This study suggests that children with a parent diagnosed with OSA are more likely to have risk factors of pediatric OSA compared to age and sex matched children of parents without OSA but do not have more symptoms.

Combined use of a videolaryngoscope and a flexible bronchoscope for awake tracheal intubation when front-of-neck airway is not an option.

We report a case of successful tracheal intubation with the combined use of a videolaryngoscope and flexible bronchoscope in a patient with difficult airway when both techniques had individually failed. A 35-year-old man presented with airway obstruction due to massive neck swelling causing hypoxia, stridor and respiratory distress. He had a history of oral cancer which had been resected with bilateral neck dissection and free flap reconstruction 2 months previously. Due to extensive anterior neck swelling, we judged that front-of-neck airway would not be a suitable approach. After unsuccessful attempts at awake tracheal intubation with videolaryngoscopy and flexible bronchoscopy separately, we combined both techniques with a successful outcome. By using a combined technique to address the specific problems presented by this case, a life-threatening emergency was resolved. This case highlights why it is useful for anaesthetists to be familiar with multiple techniques to awake tracheal intubation, both individually and in combination.