Phenotypes of Velopharyngeal Tube Law in Obstructive Sleep Apnea.

OBJECTIVE: The biomechanics of upper airway collapse in obstructive sleep apnea (OSA) remains poorly understood. The goal of this study is to compare the area-pressure relationship (tube law) of the velopharynx at peak inspiration and peak expiration. STUDY DESIGN: Cross-sectional. SETTING: Academic tertiary medical center. METHODS: The velopharyngeal tube law was quantified in a convenience sample of 20 OSA patients via step reductions in nasal mask pressure during drug induced sleep endoscopy (DISE). The velopharyngeal airspace cross-sectional area was estimated from endoscopy while luminal pressure was recorded with a catheter. The tube law was quantified for nasal mask pressures from 14 to 0 cmH2O at peak inspiration and at peak expiration in all patients. The tube law was also quantified during the breathing cycle at a constant nasal mask pressure of 4 cmH2O in 3 patients representing different phenotypes. RESULTS: Velopharyngeal compliance (the slope of the tube law) was not statistically different in the peak inspiration versus peak expiration tube laws. Three phenotypes were observed, namely inspiratory collapse (phenotype 1), expiratory collapse (phenotype 2 = palatal prolapse), and a mostly stable airway during inspiration and expiration that collapsed as CPAP was reduced (phenotype 3). CONCLUSION: Velopharyngeal compliance is not significantly different at peak inspiration and peak expiration, which suggests that muscle tone is low when luminal pressure is above the closing pressure. Additional studies are needed to investigate how different phenotypes of velopharyngeal collapse may affect therapeutic outcomes.

Motor control of the palatoglossus and genioglossus during changes in breathing route.

High activity of upper airway dilator muscles is thought to be critical in preventing sleep-related upper airway collapse. To date, most of the research regarding upper airway dilator muscles has focused on the genioglossus muscle, which protrudes the tongue and opens the retroglossal airway. However, collapse commonly occurs in the retropalatal region. We therefore aimed to examine the motor control of the palatoglossus muscle as well as investigate breathing route-related changes in genioglossus and palatoglossus motor units. Single motor unit recordings of the genioglossus and palatoglossus were made simultaneously in healthy individuals during wakefulness while breathing through the nose with the mouth closed (NMC), nose with mouth open (NMO) or orally (OMO). The palatoglossus was found to have all 5 motor unit firing patterns that have been observed in other upper airway dilator muscles, but during nasal breathing had a higher proportion of tonically active but inspiratory modulated motor units as compared to the genioglossus (67% vs 30%). When still breathing nasally but with the mouth open, the units with an expiratory firing pattern in genioglossus, and all firing patterns in palatoglossal, increased their firing rates compared to nasal breathing with the mouth closed (GG: 17.8±4.9 vs 23.1±4.8 Hz, PG: 17.0±4.0 vs 19.3±4.0 Hz). Finally, oral breathing resulted in dramatic reductions in the number of palatoglossal motor units that were firing (35 units vs 92 during nasal breathing). Palatoglossus activity may contribute importantly to airway collapsibility and may provide an alternate pathway for preventing sleep-related airway collapse.

Breath on the Brink: Navigating Anaesthesia Management in a Case With a Mediastinal Mass.

Mediastinal teratomas are rare, often asymptomatic, but clinically significant neoplasms that can manifest with a spectrum of symptoms, frequently attributed to the compression of surrounding critical anatomical structures. Here, we present the case of a 19-year-old male with respiratory distress and chest pain attributed to a large anterior mediastinal mass, ultimately diagnosed as a benign mature teratoma of the thymus. Radiological imaging revealed a large, partially cystic mass compressing the pulmonary arteries, aortic arch, and left main bronchus. Surgical excision was deemed necessary due to symptomatic presentation. Anaesthesia management during mediastinal mass excision posed significant challenges, with prompt sternotomy due to ventilation difficulties after induction. Immediate decompression of the mass improved ventilation and saturation. Despite postoperative complications, including pulmonary leaks necessitating tracheostomy, the patient achieved significant recovery. Anaesthesia strategy was to prioritise avoiding muscle relaxants and maintaining spontaneous ventilation to mitigate airway collapse and hemodynamic instability during induction. Collaboration between anaesthesia, surgical, and intensive care teams is vital for comprehensive preoperative assessment, intraoperative readiness, and postoperative care. This case underscores the importance of interdisciplinary collaboration and meticulous planning to optimise outcomes in patients undergoing surgery for mediastinal teratomas.

Unexpected Airway Collapse: A Rare Case of Spontaneous Postoperative Tracheobronchomalacia in the Absence of Identifiable Risk Factors.

We report the case of a 53-year-old female who developed tracheobronchomalacia immediately following an uncomplicated robotic hysterectomy with bilateral salpingo-oophorectomy to treat postmenopausal bleeding. Induction of anesthesia was notable for moderately difficult intubation, managed with applied cricothyroid pressure and a small 6.5 endotracheal tube placement via GlideScope. The surgical course was uneventful. The patient remained intubated in the post-anesthesia care unit but was not providing end-tidal volumes. Attempts to replace the endotracheal tube with a larger tube were unsuccessful and the patient was temporarily unable to ventilate. Rapid troubleshooting discovered that a laryngeal mask airway (LMA) could sufficiently ventilate the patient. An otolaryngologist was able to perform direct bronchoscopy, which revealed more than 50% dynamic anterior-posterior collapse of the trachea and bronchi. The patient was subsequently awakened from anesthesia and monitored in the intensive care unit, ventilating with an LMA. After a couple of hours, it was determined that the patient's airway was protected, and the LMA was removed.

Long-term pneumatic stenting with positive expiratory pressure therapy for severe expiratory central airway collapse.

Expiratory central airway collapse (ECAC) comprising excessive central airway collapse (EDAC) and tracheobronchomalacia. Treatment is challenging for severe cases that are not candidates for surgical management. We report a case of severe ECAC successfully managed with continuous positive airway pressure (CPAP) therapy. A 75-year-old female patient status post right pneumonectomy, presented with chronic cough. Dynamic bronchoscopy evaluation showed severe EDAC which improved with intraprocedural noninvasive positive pressure (NIPPV) therapy. Due to patients' comorbidities, she was not a candidate to surgical tracheobronchoplasty. Therefore, we attempted pneumatic stenting with long-term CPAP therapy resulting in improvement of symptoms and functional capacity. The long-term efficacy of pneumatic stenting has not been clearly established yet. Literature review of management of ECAC with NIPPV consist primarily of case reports and there is only one clinical trial being conducted to assess the efficacy of CPAP therapy in ECAC. While NIPPV arises as a sufficient alternative for management of severe ECAC, larger scale studies are needed to prove the real efficacy of NIPPV in this setting.

Tracheobronchomalacia following allogeneic haematopoietic stem cell transplantation.

Tracheobronchomalacia (TBM) occurs due to the weakening of cartilaginous part of the trachea, resulting in compromised airway function and leading to symptoms such as dyspnea, cough, and inability to clear secretions. Bronchiolitis obliterans syndrome (BOS) is the most prevalent late noninfectious pulmonary complication in patients who underwent allogeneic haematopoietic stem cell transplantation (HSCT). Therefore, patients experiencing progressive dyspnea and chronic cough after allogenic HSCT, with new obstructive pattern on pulmonary function test, are typically diagnosed with post-transplant BOS. However, it is important to note that TBM can also manifest as an obstructive defect pattern on pulmonary function test. Tracheomalacia has been reported as a rare complication of allogenic stem cell transplantation. We present two patients who developed TBM following allogeneic HSCT and were initially treated for post-transplant BOS but did not experience symptom improvement. However, after treatment with continuous positive airway pressure, their symptom subsided.

Association Between Soft Tissue Measures From Computed Tomography and Upper Airway Collapsibility on Drug-Induced Sleep Endoscopy.

OBJECTIVE: Positive airway pressure (PAP) titration during drug-induced sleep endoscopy (DISE) provides objective measures of upper airway collapsibility. While skeletal measurements relate to collapsibility measures on DISE, the influence of soft tissue dimensions on upper airway collapsibility is not known. We analyzed the relationship of measures of upper airway soft tissue volumes, specifically soft palate, pharyngeal lateral walls, and tongue, with metrics of collapsibility. STUDY DESIGN: Cross-sectional analysis from a prospective cohort. SETTING: Academic medical center. METHODS: Patients seeking PAP alternative therapies for obstructive sleep apnea (OSA) underwent standardized supine computed tomography (CT) acquisition and DISE protocols. The CT analysis primarily focused on soft tissue volumes and, secondarily, on airway and skeletal volumetric measures. DISE with PAP administration (DISE-PAP) enabled the determination of the pressure at which inspiratory airflow first commenced (pharyngeal critical pressure, PcritA) and the pressure at which inspiratory flow limitation was abolished (pharyngeal opening pressure, PhOP). Both unadjusted and adjusted correlation analyses were performed to understand the relationship between upper airway anatomy and either PcritA or PhOP. RESULTS: One hundred thirty-nine subjects completed both CT and DISE-PAP. On average, patients were male (70.5%), white (84.2%), middle-aged (56.6 ± 13.5 years), and overweight (29.6 ± 4.7 kg/m2), with moderate-severe apnea-hypopnea index (29.7 ± 21.3 events/h). Adjusted for age, sex, body mass index, and skeletal volumes, soft palate, and lateral pharyngeal wall volumes were not associated with PhOP or PcritA, but a larger tongue was associated with more positive PhOP (⍴ = 0.20, P = .02), and more positive PcritA (⍴ = 0.16, P = .07). Exploratory analyses revealed smaller minimum cross-sectional retropalatal area and intramandibular volume were also associated with increased collapsibility measures. CONCLUSION: After controlling for clinical factors and skeletal volume, greater tongue volume was associated with more severe collapsibility during DISE. These results, in concert with previous work, suggest that greater tongue volume in a smaller skeletal dimensions contribute to the severity of airway collapsibility, a key driver of OSA pathogenesis.

Comparison of airway collapsibility following single induction dose ketamine with propofol versus propofol sedation in children undergoing magnetic resonance imaging: A randomised controlled study.

Background and Aims: Adequate sedation is essential for children undergoing magnetic resonance imaging (MRI) console. Propofol is commonly used for sedation, but it has the drawback of upper airway collapse at higher doses, which may be overcome by ketamine. This study was designed to evaluate the beneficial effect of ketamine on propofol in preventing airway collapse. Methods: Fifty-eight children undergoing MRI were randomised to Group P (propofol bolus dose followed by infusion or Group KP (bolus dose of ketamine and propofol followed by propofol infusion). The primary aim is to compare the upper airway cross-sectional area (CSA) and diameters (transverse diameter [TD] and anteroposterior diameter [APD]) obtained from MRI during inspiration and expiration. Results: Upper airway collapse as measured by delta CSA in mean (SD) [95% confidence interval] was statistically more significant between the two groups [at the soft palate level, 16.9 mm2 (19.8) [9.3-24.4] versus 9.0 mm2 (5.50) [6.9-11.1] (P = 0.043); at the base of the tongue level, 15.4 mm2 (11.03) [11.2-19.6] versus 7.48 mm2 (4.83) [5.64-9.32] (P < 0.001); at the epiglottis level, 23.9 (26.05) [14.0-33.8] versus 10.9 mm2 (9.47) [7.35-14.5] (P = 0.014)]. A significant difference was obtained for TD at all levels and for APD at the soft palate and base of tongue level. Conclusion: Adding a single dose of ketamine to propofol reduced the upper airway collapse significantly, as evidenced by the MRI-based measurements of upper airway dimensions, compared to propofol alone.

Therapeutic effect analysis of excessive dynamic airway collapse treated by laser(13 cases) / 中国内镜杂志

Objective To evaluate the safety and effectiveness of excessive dynamic airway collapse(EDAC)treated by laser.Methods 13 patients with EDAC confirmed by bronchoscopy from January 2018 to August 2022 were selected and divided into a simple EDAC group(6 cases)and an EDAC combined with tracheobronchomalacia(TBM)group(7 cases)based on whether they were combined with TBM.All patients underwent laser tracheobronchoplasty under bronchoscope.Symptoms,airway collapse,oxygenation index,modified version of British Medical Research Council dyspnoea scale(mMRC)and 6 min walking test before and after treatment were compared to evaluate the therapeutic effect.Results 13 patients underwent 17 times of laser tracheobronchoplasty with laser power of 8～15 W,and 4 patients underwent 2 times of laser tracheobronchoplasty.After treatment,the clinical symptoms of cough,sputum,shortness of breath and dyspnea were improved in all patients.1 week post-treatment,the EDAC group showed a significant improvement in airway lumen stenosis,with a significant statistical difference(P<0.05),1 month post-treatment,enhancements were observed in airway stenosis,oxygenation index,FEV1%,6-minute walk test,and mMRC,which remained stable over a 6 month follow-up.In the EDAC + TBM group,significant enhancements in airway stenosis,oxygenation index,and mMRC were noted 1 week post-treatment,with statistical significance(P<0.05).Between 8 d～6 months post-treatment,some patients exhibited a recurrence of airway stenosis,necessitating comprehensive interventions like balloon dilation,cryotherapy,and stent insertion.Local necrosis and granuloma occurred in some patients after laser therapy,and no serious complications associated with laser intervention were found in all patients.Conclusion Laser tracheobronchoplasty is a safe and effective technique for the treatment of EDAC.For patients with EDAC alone,the therapeutic effect is good,but for patients with EDAC combined with TBM,the long-term effect is not good.

Early-onset pharyngeal airway collapse in infants: a retrospective single-center study.

BACKGROUND: Early-onset pharyngeal airway collapse (PAC) in infants, which presents with onset within 6-months old is relatively rare. This disease has not been given enough attention in clinic. The aim of this study was to explore the clinical features, endoscopic findings and outcomes of early-onset PAC in infants. METHODS: The children of PAC with onset within 6-months old were included. A retrospective study was conducted. RESULTS: (1) Total 26 cases were included. The age of onset was neonatal period in 20 cases, 1 to 3-months old in 5 cases, and 4 to 6-months old in 1 case. (2) The main clinical manifestations were noisy breathing (26/26), suprasternal retraction (18/26), snoring (14/26) and hypoxic episode (13/26). (3) Based on the endoscopic findings, collapse at the retropalatal level was most common (24/26). (4) Twelve cases underwent pharyngolaryngeal CT examination, which revealed abnormal findings in 7 cases. (5) Fifteen cases were accompanied with the other airway malformations. (6) In the group with comorbidities of cerebral impairment or craniofacial abnormalities, 1 case was lost to follow up, 4 cases died, and 10 cases survived, in which 9 cases had neurodevelopmental disorders. In the group without comorbidities, 2 cases were lost to follow up, 9 cases survived, in which 1 case had neurodevelopmental disorders. The incidence of poor prognosis including death and neurodevelopmental disorders was significantly higher in the group with comorbidities than that without comorbidities (P<0.01). (7) An symptomatic improvement of PAC was found in the majority of the survived cases (18/19) with age. CONCLUSIONS: Early-onset PAC in infants usually exhibits varying degrees of relief with age, whereas the cases with comorbidities had a poor prognosis.

Bronchial collapse and bronchial stenting in 9 dogs.

BACKGROUND: Principal and lobar bronchial collapse is increasingly recognized as an isolated entity. OBJECTIVE: Retrospectively describe the procedure and outcomes of dogs undergoing bronchial stenting at a single referral hospital. ANIMALS: Nine client-owned dogs with variable degrees of collapse of the left principal bronchus (LPB), lobar bronchus 1 (LB1), and lobar bronchus 2 (LB2), and with clinically relevant signs of respiratory dysfunction. METHODS: Data were collected from patient records. All dogs underwent stenting of the LPB and LB2. Anatomic and functional impairment grades were assigned to each case before and 4 weeks after stenting. Data regarding response to stenting and complications were evaluated. RESULTS: Bronchial stenting was considered successful in all cases, with all dogs experiencing improved quality of life (QOL), and decreased functional impairment grade at 4 weeks post-stenting. Follow-up of >6 months was available for 6 dogs and of these, 5 were alive at 12 months, 3 were alive at 18 months, and 1 was alive at 24 months. Stent-related complications occurred in 4 dogs, and were resolvable in 3. Two dogs developed pneumothorax, 1 developed recurrent pneumonia, and 1 developed new-onset coughing. All dogs had mild and manageable coughing post-stenting. CONCLUSIONS AND CLINICAL IMPORTANCE: Stenting of the LBP and LB2 might be an effective option for dogs with advanced collapse of these bronchi and associated signs. Although all included dogs had resolution or improvement of clinical signs considered life-threatening or as affecting QOL, ongoing coughing is expected. Patient selection appears important with regard to achieving successful outcomes.

Pneumatic stenting in the surgical candidacy assessment for cough variant expiratory central airway collapse.

Expiratory Central Airway Collapse (ECAC) is a multifactorial, underdiagnosed entity that poses unique challenges. Airway stenting is used as a predictor for successful outcomes after central airway stabilization surgery via tracheobronchoplasty (TBP). This approach may pose suboptimal performance in certain ECAC variants. We hypothesize that Continuous Positive Airway Pressure (CPAP), used as a pneumatic stent, could be a non-invasive alternative to evaluate surgical candidacy in cough-predominant ECAC presentations. We report on a 67-year-old female with a history of chronic cough and confirmed ECAC. After optimization of medical therapy without significant relief and unsuccessful stent trial. We opted to perform CPAP trial during exercise, the patient exercised on a treadmill, and CPAP was applied at two levels (9 cmH2O, 11 cmH2O). The use of CPAP was associated with resolution of cough and a decrease in exercise-related perceived exertion. Applying CPAP during exercise may be a promising alternative to stent trials to determine patients' candidacy for surgical management of cough-predominant ECAC.

Thermoablative Techniques to Treat Excessive Central Airway Collapse.

Excessive central airway collapse (ECAC) is a condition characterized by the excessive narrowing of the trachea and mainstem bronchi during expiration, which can be caused by Tracheobronchomalacia (TBM) or Excessive Dynamic Airway Collapse (EDAC). The initial standard of care for central airway collapse is to address any underlying conditions such as asthma, COPD, and gastro-esophageal reflux. In severe cases, when medical treatment fails, a stent-trial is offered to determine if surgical correction is a viable option, and tracheobronchoplasty is suggested as a definitive treatment approach. Thermoablative bronchoscopic treatments, such as Argon plasma coagulation (APC) and laser techniques (potassium-titanyl-phosphate [KTP], holmium and yttrium aluminum pevroskyte [YAP]) are a promising alternative to traditional surgery. However, further research is needed to assess their safety and effectiveness in humans before being widely used.

The evolution of anesthesia management of patients with anterior mediastinal mass.

Anesthesia management of patients with mediastinal mass compressing the central airway is considered challenging. It is widely believed that general anesthesia induction in patients with mediastinal mass is associated with airway collapse, difficulty in ventilation and hemodynamic compromise. Additionally, several case reports and case series described patients demise after induction of general anesthesia. This has led to the strong recommendations to use inhalation induction, avoid the use of muscle relaxant and maintenance of spontaneous ventilation. Recent studies shed new light on our understanding of airway changes associated with mediastinal mass by directly visualizing and measuring the actual changes of the airway caliber and the variation in the peak inspiratory flow (PIF) and peak expiratory flow (PEF) in patients with mediastinal mass. These studies describe the changes in airway mechanics in different states e.g., awake and anesthetized, spontaneous and positive pressure ventilated with or without muscle relaxation. Interesting new findings in these recent publications show that general anesthesia with and without muscle relaxation does not worsen a pre-existing narrowing of the airway compressed by mediastinal mass. Moreover, it was discovered that the addition of positive pressure ventilation, positive end-expiratory pressure (PEEP) and muscle relaxation in an anesthetized patient were associated with improvement in the airway caliber and airflow in these patient's population. This new understanding of the mechanics of airway obstruction and the effects of anesthesia and mechanical ventilation on patients with mediastinal mass challenges our current anesthesia practices and leads us to consider a new approach to anesthetize and ventilate these patients. This article will review the past literature that led to the widely practiced current anesthesia techniques and how it is challenged with the new research. The author will also provide a new perspective and anesthesia technique that align with the new research findings for safe induction and maintenance of general anesthesia in patients with mediastinal mass.

Relationship of Upper Airway Collapse with Severity of Sleep Apnoea and Sleepiness.

Introduction: Obstructive sleep apnoea (OSA) is characterized by repeated episodes of upper airway collapse. A review of literature shows limited and conflicting data regarding impact of upper pharyngeal collapse on severity of OSA and degree of sleepiness. Objective: To evaluate the association of the number of levels and degree of upper airway collapse and severity of OSA. Methods: This is a retrospective study including all patients with OSA over a two-year period. Data regarding neck circumference (NC), body mass index (BMI), nasopharyngolaryngoscopy with Muller's manoeuvre, Epworth sleepiness scale (ESS) questionnaire and a full night polysomnography were collected. Correlation of the number of sites involved and degree of collapse at each site (velum, lateral pharyngeal wall- Level I, base of tongue - Level II and epiglottis - Level III) with BMI, NC, AHI and ESS were assessed. Results: Of the 144 patients, 98% had collapse at Level I. 80% of patients had multisegmental collapse with 30% having collapse at all three levels. The number of levels and the severity of collapse did not have a proportionate effect on the AHI and ESS and were not directly dependent on the BMI. However, changes in NC had a significant effect on the severity of collapse.Conclusion: Severity of OSA and degree of sleepiness were not directly dependent on the severity and the number of levels of collapse. Since majority of the patients had multi segmental collapse, the study highlights the importance of careful assessment of all levels to tailor management strategies for optimum patient management.

Comparing Diagnostic Efficacy of Imaging During Muller's Maneuver Versus Drug Induced Sleep Endoscopy in Obstructive Sleep Apnoea.

The aim of the study was to compare the diagnostic efficacy of quantitative computed tomography (CT) based upper airway analysis using the Muller's maneuver (MM) and compare the findings with drug induced sleep endoscopy (DISE). A prospective observational study was conducted on 50 adult patients with symptoms of OSA and having apnoea-hypopnea index more than 5. They further underwent CT during normal breathing and during MM; findings of which were compared with DISE. Collapse at velum had statistically significant correlation with collapse at retropalatal level in CT (in MM) (P value = 0.001; r = 0.536). Base of tongue in DISE correlates significantly with retroglossal collapse on CT (P value = 0.002; r = 0.423). Epiglottic and oropharyngeal collapse had no correlation with any CT parameter. Collapse in CT as measured during MM shows significant correlation with DISE findings at velum and tongue base but cannot solely predict all levels without the aid of DISE.

Tracheobronchoplasty: Indications and Best Approaches.

Tracheobronchomalacia (TBM) is an increasingly recognized abnormality of the central airways in patients with respiratory symptoms. Severe TBM in symptomatic patients warrants screening dynamic CT of the chest and/or awake dynamic bronchoscopy. The goal of surgical repair is to restore the C-shaped configuration of the airway lumen and splint or secure the lax posterior membrane to the mesh to ameliorate symptoms. Robotic tracheobronchoplasty is safe and associated with improvements in pulmonary function and subjective improvement in quality of life.

Transverse Maxillary Deficiency Predicts Increased Upper Airway Collapsibility during Drug-Induced Sleep Endoscopy.

OBJECTIVE: To examine the relationship between craniofacial skeletal anatomy and objective measures of pharyngeal collapse obtained during drug-induced sleep endoscopy. We hypothesized that transverse maxillary deficiency and an increased pharyngeal length will be associated with higher levels of pharyngeal collapsibility. STUDY DESIGN: Cross-sectional analysis in a prospective cohort. SETTING: University Hospital. METHODS: A cross-sectional analysis was conducted in a cohort of consecutive patients from the positive airway pressure (PAP) alternatives clinic who underwent computed tomography (CT) analysis and drug-induced sleep endoscopy for characterization of upper airway collapsibility. PAP titration was used to determine pharyngeal critical pressure (PCRIT ) and pharyngeal opening pressure (PhOP). CT metrics included: Transverse maxillary dimensions (interpremolar and intermolar distances) and pharyngeal length (posterior nasal spine to hyoid distance). RESULTS: The cohort (n = 103) of severe obstructive sleep apnea (Apnea and Hipopnea Index 32.1 ± 21.3 events/h) was predominantly male (71.8%), Caucasian (81.6%), middle-aged (54.4 ± 14.3 years), and obese (body mass index [BMI] = 30.0 ± 4.9 kg/m2 ). Reduced transverse maxillary dimensions were associated with higher PCRIT (intermolar distance: ß [95% confidence interval, CI] = -.25 [-0.14, -0.36] cmH2 O/mm; p = .03) and PhOP (Interpremolar distance: ß = -.25 [-0.14, -0.36] cmH2 O/mm; p = .02). Longer pharyngeal length was also associated with higher PCRIT (ß = .11 [0.08, 0.14] cmH2 O/mm, p = .04) and PhOP (ß [95% CI] = .06 [0.03, 0.09] cmH2 O/mm, p = .04). These associations persisted after adjustments for sex, age, height, and BMI. CONCLUSION: Our results further the concept that skeletal restriction in the transverse dimension and hyoid descent are associated with elevations in pharyngeal collapsibility during sleep, suggesting a role of transverse deficiency in the pathogenesis of airway obstruction.

Comparison of Four Mechanical Insufflation-Exsufflation Devices: Effect of Simulated Airway Collapse on Cough Peak Flow.

BACKGROUND: Mechanical insufflation-exsufflation (MI-E) devices are used to improve airway clearance in individuals with acute respiratory failure. Some MI-E devices measure cough peak flow (CPF) during MI-E to optimize pressure adjustments. The aim was to compare CPF and effective cough volume (ECV: volume expired/coughed > 3 L/s) measurements between 4 MI-E devices under simulated conditions of stable versus collapsed airway. METHODS: Four MI-E devices were tested on the bench. Each device was connected via a standard circuit to a collapsible tube placed in an airtight chamber that was attached to a lung model with adjustable compliance and resistance. Pressure was measured upstream and downstream the collapsing tube; air flow was measured between the chamber and the lung model. Each device was tested in 2 conditions: collapse condition (0 cm H2O) and no-collapse condition (-70 cm H2O). For each condition, 6 combinations of inspiratory/expiratory pressures were applied. CPF was measured at the "mouth level" by the device built-in flow meter and at the "tracheal level" by a dedicated pneumotachograph. Comparisons were performed with non-parametric tests. RESULTS: CPF values measured at the tracheal level and ECV values differed between devices for each inspiratory/expiratory pressure in the collapse and no-collapse conditions (P < .001). CPF values were significantly lower at the tracheal level in the collapse as compared with the no-collapse condition (P < .001 for each device), whereas they were higher at the mouth level (P < .05) for 3 of the 4 devices. CONCLUSIONS: CPF values differed significantly across MI-E devices, highlighting limitation(s) of using only CPF values to determine cough effectiveness. In simulated of airway collapse, CPF increased at the mouth, whereas it decreased at the tracheal level.

Nocturnal continuous positive airway pressure offers symptomatic benefit in excessive dynamic airway collapse despite normal sleep study.

Excessive dynamic airway collapse (EDAC) and tracheobronchomalacia (TBM) cause debilitating symptoms yet are often misdiagnosed as asthma or chronic obstructive pulmonary disease (COPD). EDAC/TBM should be considered in all cases of obstructive ventilatory defect refractory to medical management. Diagnosis is made with flexible bronchoscopy and/or inspiratory and expiratory phase computed tomography (CT) scans. Treatment should be individualised and "pneumatic stenting" with the use of continuous positive airway pressure (CPAP) may lead to symptomatic relief, and in some cases regardless of the degree of collapse or absence of sleep disordered breathing in overnight oximetry. The case of a 63-year-old female referred to a tertiary respiratory department for a trial of CPAP due to EDAC is presented. Over the course of a few months, she had presented frequently to hospital with cough and shortness of breath which had been attributed to asthma. As she had not responded to treatment, an inpatient flexible bronchoscopy was performed which identified EDAC of the right main bronchus and she was referred to a tertiary ventilation department. Despite a normal sleep study whilst self-ventilating, nocturnal CPAP therapy significantly improved quality and duration of sleep, daytime symptoms and therefore quality of life. She was discharged with nocturnal CPAP and remains adherent to treatment.