Clinical implications of airway obstruction with normal or low FEV1 in childhood and adolescence.

BACKGROUND: Airway obstruction is defined by spirometry as a low forced expiratory volume in 1 s (FEV1) to forced vital capacity (FVC) ratio. This impaired ratio may originate from a low FEV1 (classic) or a normal FEV1 in combination with a large FVC (dysanaptic). The clinical implications of dysanaptic obstruction during childhood and adolescence in the general population remain unclear. AIMS: To investigate the association between airway obstruction with a low or normal FEV1 in childhood and adolescence, and asthma, wheezing and bronchial hyperresponsiveness (BHR). METHODS: In the BAMSE (Barn/Child, Allergy, Milieu, Stockholm, Epidemiology; Sweden) and PIAMA (Prevention and Incidence of Asthma and Mite Allergy; the Netherlands) birth cohorts, obstruction (FEV1:FVC ratio less than the lower limit of normal, LLN) at ages 8, 12 (PIAMA only) or 16 years was classified as classic (FEV1

A pilot study to assess the effects of preventing fluid retention in the legs by wearing compression stockings on overnight airway narrowing in mild asthma.

PURPOSE: Nocturnal asthma is a sign of asthma worsening and could be partially due to more fluid drawn into the thorax during sleep by gravitational force and/or pharyngeal collapse in those with obstructive sleep apnea. Wearing compression stockings during the day reduces fluid shift from the legs to the neck overnight. However, the potential effect of wearing compression stockings to reduce fluid accumulation in the leg and to improve nocturnal small airway narrowing in patients with asthma has not been investigated. This study investigates whether reducing leg fluid volume by wearing compression stockings during the day would attenuate small airway narrowing in patients with asthma before and after sleep. METHODS: We enrolled 11 participants with asthma. All participants underwent overnight polysomnography with or without wearing compression stockings for 2 weeks. Before and after sleep, leg fluid volume (LFV) was measured by bioelectrical impedance, and airway narrowing was primarily assessed by respiratory system resistance and reactance at 5 Hz (R5 and X5 respectively) using oscillometry. RESULTS: After 2 weeks of wearing compression stockings, the LFV measured in the evening was reduced (∆ = - 192.6 ± 248.3 ml, p = 0.02), and R5 and X5 improved (∆ = - 0.7 ± 0.9 cmH2O/L/s, p = 0.03 and 0.2 ± 1.4 cmH2O/L/s, p = 0.05 respectively). No changes were observed in the morning. CONCLUSIONS: Preventing fluid retention in the legs by wearing compression stockings for 2 weeks during the day, reduced LFV and airway narrowing in the evening in all participants with asthma, but not in the morning after sleep.

Monkeys exhibit a paradoxical decrease in performance in high-stakes scenarios.

In high-stakes situations, people sometimes exhibit a frustrating phenomenon known as "choking under pressure." Usually, we perform better when the potential payoff is larger. However, once potential rewards get too high, performance paradoxically decreases-we "choke." Why do we choke under pressure? An animal model of choking would facilitate the investigation of its neural basis. However, it could be that choking is a uniquely human occurrence. To determine whether animals also choke, we trained three rhesus monkeys to perform a difficult reaching task in which they knew in advance the amount of reward to be given upon successful completion. Like humans, monkeys performed worse when potential rewards were exceptionally valuable. Failures that occurred at the highest level of reward were due to overly cautious reaching, in line with the psychological theory that explicit monitoring of behavior leads to choking. Our results demonstrate that choking under pressure is not unique to humans, and thus, its neural basis might be conserved across species.

Diagnostic utility of spirometry for children with induced laryngeal obstruction or chronic non-specific cough.

PURPOSE: To determine the diagnostic utility of spirometry in distinguishing children with Induced Laryngeal Obstruction (ILO) or chronic non-specific cough (a.k.a. tic cough) from those with mild or moderate to severe asthma. METHODS: Retrospective cross sectional design. Children diagnosed with ILO (N = 70), chronic non-specific cough (N = 70), mild asthma (N = 60), or moderate to severe asthma (N = 60) were identified from the electronic medical record of a large children's hospital. Spirometry was completed before ILO, non-specific cough, or asthma diagnoses were made by pediatric laryngologists or pulmonologists. Spirometry was performed following American Thoracic Society guidelines and was interpreted by a pediatric pulmonologist. Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 Second (FEV1), FEV1/FVC Ratio (FEV1/FVC), Forced Mid-Expiratory Flow 25--75 % (FEF25-75%), pulmonologist interpretation of flow volume loops, and overall exam findings were extracted from the medical record. RESULTS: Ninety seven percent of children with ILO or chronic non-specific cough presented with spirometry values within normative range. Patients with ILO, non-specific cough, and mild asthma presented with FVC, FEV1, FEV1/FVC, and FEF25-75% values in statistically similar range. Children with moderate to severe asthma presented with significantly reduced FVC (p < .001), FEV1 (p < .001), FEV1/FVC (p < .001), and FEF25-75% (p < .001) values when compared with patients in the other groups. Flow volume loops were predominantly normal for children with ILO and non-specific cough. CONCLUSIONS: Findings indicate that ILO and chronic non-specific cough can neither be diagnosed nor differentiated from mild asthma using spirometry alone. Spirometry should therefore be used judiciously with this population, bearing in mind the limitations of the procedure. Future research should determine the most effective and efficient ways of delineating ILO and non-specific cough from other respiratory conditions in children.

DISE with CPAP: a useful procedure to evaluate upper airway collapsibility.

PURPOSE: Drug-induced sleep endoscopy (DISE) is commonly performed in patients suffering obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) intolerance. We aimed to evaluate the effects of adding CPAP to DISE to provide understanding of the reason of its failure and better guidance in future therapeutic decisions. METHODS: A retrospective observational descriptive study was conducted on CPAP-intolerant patients with moderate-severe OSA. DISE was used to evaluate upper airway collapsibility, and CPAP was tested to better describe anatomical sites of obstruction and to measure the opening pharyngeal pressure. RESULTS: Sample size consisted of 38 patients with a mean age of 49 ± 9 years. Mean BMI was 28.4 ± 2.4 kg/m2, mean apnea-hypopnea index (AHI) was 35.4 events per hour ± 20.1, and mean saturation under 90% (TSat90) was 14.5%. In DISE we found a collapse at Velum in 92% of patients, at Oropharyngeal level in 89%, at tongue in 42%, and at epiglottis in 36%. In the subgroup of patients with clinical failure with CPAP, we observed 100% of epiglottic collapse and 50% of tongue obstruction. In this specific population, we recommended personalized surgery and myofunctional therapy. CONCLUSION: DISE-CPAP is a useful tool to select the treatment that better fits to each patient taking care all information available. It improves our ability to prescribe a multilevel treatment with an exhaustive topographic evaluation of upper airway collapsibility that complements CPAP classic titration, and it can be helpful to distinguish better candidates for surgery, myofunctional therapy or CPAP.

A novel technique for assessment of post-extubation airway obstruction can successfully replace the conventional cuff leak test: a pilot study.

BACKGROUND: Post-extubation airway obstruction is an important complication of tracheal intubation. The cuff leak test is traditionally used to estimate the risk of this complication. However, the cuff leak test parameters are not constant and may depend on the respiratory system and ventilator settings. Furthermore, deflating the cuff also be a risk factor for patient-ventilator asynchrony and ventilator-associated pneumonia. Instead of using the cuff leak test, we measured the pressure of the leak to the upper airway through the gap between the tube and glottis with a constant low flow from the lumen above the cuff without deflating the cuff and called it "pressure above the cuff." The purpose of this study was to investigate whether pressure above the cuff can be used as an alternative to the cuff leak volume. METHODS: This prospective observational study was conducted at Kumamoto University Hospital after obtaining approval from the institutional review board. The pressure above the cuff was measured using an endotracheal tube with an evacuation lumen above the cuff and an automated cuff pressure modulation device. We pumped 0.16 L per minute of air and measured the steady-state pressure using an automated cuff pressure modulation device. Then, the cuff leak test was performed, and the cuff leak volume was recorded. The cuff leak volume was defined as the difference between the expiratory tidal volume with the cuff inflated and deflated. The relationship between the pressure above the cuff and cuff leak volume was evaluated. The patient-ventilator asynchrony during each measurement was also examined. RESULTS: The pressure above the cuff was measured, and the cuff leak volume was assessed 27 times. The pressure above the cuff was significantly correlated with the cuff leak volume (r = -0.76, p < 0.001). Patient-ventilator asynchrony was detected in 37% of measurements during the cuff leak test, but not during the pressure above the cuff test. CONCLUSIONS: This study suggests that pressure above the cuff measurement may be a less complicated alternative to the conventional cuff leak test for evaluation of the risk of post-extubation airway obstruction. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry (UMIN000039987; March 30, 2020). https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000044604.

Expiratory central airway collapse during positive pressure ventilation: a case report.

BACKGROUND: Physiologic narrowing of the central airway occurs during expiration. Conditions in which this narrowing becomes excessive are referred to as expiratory central airway collapse. Expiratory central airway collapse is usually managed by applying positive pressure to the airways, which acts as a pneumatic stent. The particularity of the case reported here included the patient's left main bronchus being permeable during spontaneous breathing but collapsing during general anaesthesia, despite positive pressure ventilation and positive end-expiratory pressure. CASE PRESENTATION: We present the case of a 55-year-old man admitted for the placement of a ureteral JJ stent. Rapid desaturation occurred a few minutes after the onset of anaesthesia. After excluding the most common causes of desaturation, fibreoptic bronchoscopy was performed through the tracheal tube and revealed complete collapse of the left main bronchus. The collapse persisted despite the application of positive end-expiratory pressure and several recruitment manoeuvres. After recovery of spontaneous ventilation, the collapse was lifted, and saturation increased back to normal levels. No evidence of extrinsic compression was found on chest X-rays or computed tomography scans. CONCLUSION: Cases of unknown expiratory central airway collapse reported in the literature were usually managed with positive pressure ventilation. This approach has been unsuccessful in the case described herein. Our hypothesis is that mechanical bending of the left main bronchus occurred due to loss of the patient's natural position and thoracic muscle tone under general anaesthesia with neuromuscular blockade. When possible, spontaneous ventilation should be maintained in patients with known or suspected ECAC.

Asthma and fixed airflow obstruction: Long-term trajectories suggest distinct endotypes.

BACKGROUND: Long-term trajectories of asthma with fixed airflow obstruction (FAO) may reveal links to inflammatory endotypes. OBJECTIVE: We investigated whether measures of asthma control and airway inflammation and remodelling differed by long-term FAO status in moderate-to-severe asthma. METHODS: Adults enrolled in the Difficult Asthma Study assessed initially using serial Asthma Control Questionnaire (ACQ), exacerbation history, spirometry and sputum cytology over 12 months, as well as endoscopic bronchial biopsy with airway smooth muscle (ASM) quantification, were revaluated three or more years later with questionnaires and spirometry. FAO was defined as a persistent post-bronchodilator forced expired volume in one second (FEV1 )-to-forced vital capacity ratio below 0.70. RESULTS: Sixty-two participants (mean ± SD age 48 ± 11 years; 50% female; 75% atopic; asthma duration 24 ± 14 years) returned for follow-up assessment (median interval 7.9 years; IQR: 5.4-8.8 years). Compared to participants without FAO (n = 28), those with FAO at baseline and long-term follow-up (n = 18) had higher baseline sputum neutrophil content and ASM, and a higher exacerbation frequency that persisted at long-term follow-up. Sputum eosinophils, ACQ and long-term FEV1 decline did not differ. Participants with incident FAO at long-term follow-up (n = 16) had higher baseline exacerbation frequency, sputum eosinophil content, higher ACQ scores and greater decline in FEV1 , whereas baseline ASM was similar to those without FAO. CONCLUSION: In moderate-to-severe asthma, long-term FAO is characterized by neutrophilic sputum inflammation and airway remodelling, but FEV1 decline is similar to those without FAO. Long-term incident FAO is preceded by higher exacerbation frequency, higher sputum eosinophil content and significant FEV1 decline.

Effects of upper airway obstruction or hypoxia on gastroesophageal reflux in newborn lambs.

BACKGROUND: Although it is commonly accepted that upper airway obstruction (UAO) increases gastroesophageal reflux (GER), the link is poorly understood and insufficiently documented. In addition, while hypoxia is often encountered in infants with UAO, its consequences on GER are virtually unknown. The two aims of the present study were to characterize the effects of (1) UAO and (2) hypoxia on GER. METHODS: Seventeen lambs underwent polysomnographic and esophageal impedance/pH-metry monitoring during UAO vs. a control condition (6 h, ten lambs) or 10% hypoxia vs. normoxic condition (3 h, seven other lambs). RESULTS: Moderate-to-severe UAO was maintained throughout monitoring (inspiratory tracheal pressure of -13 (-15, -12) cm H2O vs. -1 (-1, -1) cm H2O in control condition, p = 0.005). While the number of GERs increased with UAO (2 (1, 4) vs. 0 (0, 3) in the control condition, p = 0.03), the increase was less than anticipated and inconsistent among the lambs. Also, sustained 10% hypoxia did not alter the number of GERs (2 (1, 3) vs. 0 (0, 5) in the control condition, p = 0.9). CONCLUSIONS: The presence of an UAO for 6 h mildly increased the number of GERs, whereas hypoxia for 3 h had no significant effect. IMPACT: The effect of upper airway obstruction and hypoxia on gastroesophageal reflux is poorly documented in the neonatal period. A moderate-to-severe upper airway obstruction for 6 h results in a mild, inconsistent increase in the number of gastroesophageal refluxes. Overall, a hypoxia of 10% for 3 h had no significant impact on gastroesophageal reflux. The prescription of an antireflux medication in infants with upper airway obstruction must not be systematic but rely on objective signs of a pathologic gastroesophageal reflux.

Ventilation strategies for front of neck airway rescue: an in silico study.

BACKGROUND: During induction of general anaesthesia a 'cannot intubate, cannot oxygenate' (CICO) situation can arise, leading to severe hypoxaemia. Evidence is scarce to guide ventilation strategies for small-bore emergency front of neck airways that ensure effective oxygenation without risking lung damage and cardiovascular depression. METHODS: Fifty virtual subjects were configured using a high-fidelity computational model of the cardiovascular and pulmonary systems. Each subject breathed 100% oxygen for 3 min and then became apnoeic, with an obstructed upper airway. When arterial haemoglobin oxygen saturation reached 40%, front of neck airway access was simulated with various configurations. We examined the effect of several ventilation strategies on re-oxygenation, pulmonary pressures, cardiovascular function, and oxygen delivery. RESULTS: Re-oxygenation was achieved in all ventilation strategies. Smaller airway configurations led to dynamic hyperinflation for a wide range of ventilation strategies. This effect was absent in airways with larger internal diameter (≥3 mm). Intrapulmonary pressures increased quickly to supra-physiological values with the smallest airways, resulting in pronounced cardio-circulatory depression (cardiac output <3 L min-1 and mean arterial pressure <60 mm Hg), impeding oxygen delivery (<600 ml min-1). Limiting tidal volume (≤200 ml) and ventilatory frequency (≤8 bpm) for smaller diameter cannulas reduced dynamic hyperinflation and gas trapping, preventing cardiovascular depression. CONCLUSIONS: Dynamic hyperinflation can be demonstrated for a wide range of front of neck airway cannulae when the upper airway is obstructed. When using small-bore cannulae in a CICO situation, ventilation strategies should be chosen that prevent gas trapping to prevent severe adverse events including cardio-circulatory depression.

Ventilated Patients With COVID-19 Show Airflow Obstruction.

OBJECTIVE: Many patients with coronavirus disease 2019 (COVID-19) need mechanical ventilation secondary to acute respiratory distress syndrome. Information on the respiratory system mechanical characteristics of this disease is limited. The aim of this study is to describe the respiratory system mechanical properties of ventilated COVID-19 patients. DESIGN, SETTING, AND PATIENTS: Patients consecutively admitted to the medical intensive care unit at the University of Iowa Hospitals and Clinics in Iowa City, USA, from April 19 to May 1, 2020, were prospectively studied; final date of follow-up was May 1, 2020. MEASUREMENTS: At the time of first patient contact, ventilator information was collected including mode, settings, peak airway pressure, plateau pressure, and total positive end expiratory pressure. Indices of airflow resistance and respiratory system compliance were calculated and analyzed. MAIN RESULTS: The mean age of the patients was 58 years. 6 out of 12 (50%) patients were female. Of the 21 laboratory-confirmed COVID-19 patients on invasive mechanical ventilation, 9 patients who were actively breathing on the ventilator were excluded. All the patients included were on volume-control mode. Mean [±standard deviation] ventilator indices were: resistive pressure 19 [±4] cmH2O, airway resistance 20 [±4] cmH2O/L/s, and respiratory system static compliance 39 [±16] ml/cmH2O. These values are consistent with abnormally elevated resistance to airflow and reduced respiratory system compliance. Analysis of flow waveform graphics revealed a pattern consistent with airflow obstruction in all patients. CONCLUSIONS: Severe respiratory failure due to COVID-19 is regularly associated with airflow obstruction.

Assessment of Extensive Airway Obstruction Using Point-by-Point Lateral Pressure Measurements during Bronchoscopy.

BACKGROUND: The positioning of the stent at the flow-limiting segment is crucial for patients with extensive airway obstruction to relieve dyspnea. However, CT and flow-volume curves cannot detect the area of maximal obstruction. OBJECTIVES: The aim of this study is to physiologically evaluate extensive airway obstruction during interventional bronchoscopy. METHODS: We prospectively measured point-by-point lateral airway pressure (Plat) at multiple points from the lower lobe bronchus to the upper trachea using a double-lumen catheter in 5 patients. The site of maximal obstruction was evaluated continuously to measure point-by-point Plat at multiple points when the airway catheter was withdrawn from the lower lobe bronchus to the upper trachea. RESULTS: Remarkable pressure differences occurred at the site of maximal obstruction assessed by point-by-point Plat measurements. After initial stenting in 1 case, migration of the maximal obstruction to a nonstented segment of the weakened airway was seen with extensive stenosis from the trachea to the bronchi. In the second case, in addition to radiological analysis, point-by-point Plat measurements could identify the location of the maximal obstruction which contributed to dyspnea. CONCLUSIONS: Point-by-point Plat measurement could be used to detect the site of maximal obstruction physiologically. Furthermore, Plat measurement could assess the need for additional procedures in real time in patients with extensive airway obstruction.

Long-term survival following initiation of home non-invasive ventilation: a European study.

INTRODUCTION: Although home non-invasive ventilation (NIV) is increasingly used to manage patients with chronic ventilatory failure, there are limited data on the long-term outcome of these patients. Our aim was to report on home NIV populations and the long-term outcome from two European centres. METHODS: Cohort analysis including all patients established on home NIV from two European centres between 2008 and 2014. RESULTS: Home NIV was initiated in 1746 patients to treat chronic ventilatory failure caused by (1) obesity hypoventilation syndrome±obstructive sleep apnoea (OHS±OSA) (29.5%); (2) neuromuscular disease (NMD) (22.7%); and (3) obstructive airway diseases (OAD) (19.1%). Overall cohort median survival following NIV initiation was 6.6 years. Median survival varied by underlying aetiology of respiratory failure: rapidly progressive NMD 1.1 years, OAD 2.7 years, OHS±OSA >7 years and slowly progressive NMD >7 years. Multivariate analysis demonstrated higher mortality in patients with rapidly progressive NMD (HR 4.78, 95% CI 3.38 to 6.75), COPD (HR 2.25, 95% CI 1.64 to 3.10), age >60 years at initiation of home NIV (HR 2.41, 95% CI 1.92 to 3.02) and NIV initiation following an acute admission (HR 1.38, 95% CI 1.13 to 1.68). Factors associated with lower mortality were NIV adherence >4 hours per day (HR 0.64, 95% CI 0.51 to 0.79), OSA (HR 0.51, 95% CI 0.31 to 0.84) and female gender (HR 0.79, 95% CI 0.65 to 0.96). CONCLUSION: The mortality rate following initiation of home NIV is high but varies significantly according to underlying aetiology of respiratory failure. In patients with chronic respiratory failure, initiation of home NIV following an acute admission and low levels of NIV adherence are poor prognostic features and may be amenable to intervention.

Triggers of breathlessness in inducible laryngeal obstruction and asthma.

BACKGROUND: Inducible laryngeal obstruction (ILO) is often misdiagnosed as, or may coexist with, asthma. Identifying differences in triggering factors may assist clinicians to differentiate between the two conditions and could give mechanistic insights. OBJECTIVE: To identify and compare patient-reported triggers in ILO and asthma. METHODS: This was a two-part study. Initially, we conducted a retrospective case note review of the triggers of ILO from endoscopically confirmed ILO patients to generate a Breathlessness Triggers Survey (BrTS). Triggers were categorized as scents, environmental factors, temperature, emotions, mechanical factors and daily activities. Secondly, ILO and/or asthma patients completed the BrTS prospectively, rating the likelihood of each item triggering their symptoms using a five-point Likert scale (strongly disagree to strongly agree). Chi-square testing was performed to compare responses by cohort. RESULTS: Data from 202 patients with ILO [73% female, mean (SD) age 53(16) years] were included in the case note review. For the prospective study, 38 patients with ILO only [63% females, age 57(16) years], 39 patients with asthma only [(56% female, age 53(13) years] and 12 patients with both ILO and asthma [83% female, mean age, 57 (14) years)] completed the BrTS. The triggers identified in the case note review were confirmed in the independent sample of patients with ILO and/or asthma and identified several difference in prevalence of the triggers between disease types. Mechanical factors (talking [P < .001], shouting [P = .007] and swallowing [P = .002]) were more common in the ILO cohort compared to patients with asthma. Environmental factors (pollen/flowers [P = .005] and damp air [P = .012]) were more common in asthma. There were no differences between groups in frequency of reporting scents as triggers (except for vinegar, more common in ILO, P = .019), temperature, emotions or daily activities. CONCLUSION: There were notable differences between patient-reported triggers of ILO and asthma, which may support clinician differential diagnosis.

Acute exacerbations of COPD versus IPF in patients with combined pulmonary fibrosis and emphysema.

RATIONALE: Patients with combined pulmonary fibrosis and emphysema (CPFE) may develop acute exacerbations of IPF (AE-IPF) or COPD (AE-COPD). The incidence and the characteristics of exacerbations in patients with CPFE (e.g., COPD vs IPF) have not been well described. OBJECTIVES: To compare the incidence and rate of exacerbations in patients with CPFE vs. IPF and evaluate their effect on clinical outcomes. METHODS: Comprehensive clinical data from CPFE and IPF patients were retrospectively reviewed. Baseline characteristics including lung function data, oxygen requirements, and pulmonary hemodynamics, were collected. Acute exacerbation events in both groups were defined clinically and radiographically. In the CPFE group, two patterns of exacerbations were identified. AE-COPD was defined clinically by symptoms of severe airflow obstruction causing respiratory failure and requiring hospitalization. Radiographic data were also defined based on previously published literature. AE-IPF was defined clinically as an acute hypoxic respiratory failure, requiring hospitalization and treatment with high dose corticosteroids. Radiographically, patients had to have a change in baseline imaging including presence of ground-glass opacities, interlobular septal thickening or new consolidations; that is not fully explained by other etiologies. RESULTS: Eighty-five CPFE patients were retrospectively compared to 112 IPF patients. Of 112 patients with IPF; 45 had AE-IPF preceding lung transplant (40.18%) compared to 12 patients in the CPFE group (14.1%) (p < 0.05). 10 patients in the CPFE group experienced AE-COPD (11.7%). Patients with AE-IPF had higher mortality and more likely required mechanical ventilation and extracorporeal membrane oxygenation (ECMO) compared to patients with AE-COPD, whether their underlying disease was IPF or CPFE. CONCLUSIONS: CPFE patients may experience either AE-IPF or AE-COPD. Patients with CPFE and AE-COPD had better outcomes, requiring less intensive therapy compared to patients with AE-IPF regardless if underlying CPFE or IPF was present. These data suggest that the type of acute exacerbation, AE-COPD vs AE-IPF, has important implications for the treatment and prognosis of patients with CPFE.

Compression of the left mainstem bronchus by patent ductus arteriosus in neonates under consideration for ductal stenting.

Stent angioplasty of patent ductus arteriosus has been shown to be a viable alternative to operative shunt placement in cyanotic neonates. With broader implementation of this strategy, novel complications are bound to arise. We present a series of cases evaluated for ductal stent angioplasty in which a dilated and torturous ductus arteriosus compressed the left mainstem bronchus. After reviewing our recent experience with ductal stenting and isolated Blalock-Taussig shunts, our best estimate of the incidence of bronchial compression by the dilated ductus is 4.6% (3/64, 95% confidence interval 1.0-12.9%). Awareness of the airway and other nonvascular contents of the thorax is an important consideration prior to ductal stenting.

Prevalence of Complete Airway Closure According to Body Mass Index in Acute Respiratory Distress Syndrome.

BACKGROUND: Complete airway closure during expiration may underestimate alveolar pressure. It has been reported in cases of acute respiratory distress syndrome (ARDS), as well as in morbidly obese patients with healthy lungs. The authors hypothesized that complete airway closure was highly prevalent in obese ARDS and influenced the calculation of respiratory mechanics. METHODS: In a post hoc pooled analysis of two cohorts, ARDS patients were classified according to body mass index (BMI) terciles. Low-flow inflation pressure-volume curve and partitioned respiratory mechanics using esophageal manometry were recorded. The authors' primary aim was to compare the prevalence of complete airway closure according to BMI terciles. Secondary aims were to compare (1) respiratory system mechanics considering or not considering complete airway closure in their calculation, and (2) and partitioned respiratory mechanics according to BMI. RESULTS: Among the 51 patients analyzed, BMI was less than 30 kg/m2 in 18, from 30 to less than 40 in 16, and greater than or equal to 40 in 17. Prevalence of complete airway closure was 41% overall (95% CI, 28 to 55; 21 of 51 patients), and was lower in the lowest (22% [3 to 41]; 4 of 18 patients) than in the highest BMI tercile (65% [42 to 87]; 11 of 17 patients). Driving pressure and elastances of the respiratory system and of the lung were higher when complete airway closure was not taken into account in their calculation. End-expiratory esophageal pressure (ρ = 0.69 [95% CI, 0.48 to 0.82]; P < 0.001), but not chest wall elastance, was associated with BMI, whereas elastance of the lung was negatively correlated with BMI (ρ = -0.27 [95% CI, -0.56 to -0.10]; P = 0.014). CONCLUSIONS: Prevalence of complete airway closure was high in ARDS and should be taken into account when calculating respiratory mechanics, especially in the most morbidly obese patients.

The need for physiological phenotyping to develop new drugs for airways disease.

Asthma and COPD make up the majority of obstructive airways diseases (OADs), which affects ∼11 % of the population. The main drugs used to treat OADs have not changed in the past five decades, with advancements mainly comprising variations on existing treatments. The recent biologics are beneficial to only specific subsets of patients. Part of this may lie in our inability to adequately characterise the tremendous heterogeneity in every aspect of OAD. The field is currently moving towards the concept of personalised medicine, based on a focus on treatable traits that are objective, measurable and modifiable. We propose extending this concept via the use of emerging clinical tools for comprehensive physiological phenotyping. We describe, based on published data, the evidence for the use of functional imaging, gas washout techniques and oscillometry, as well as potential future applications, to more comprehensively assess and predict treatment response in OADs. In this way, we hope to demonstrate how physiological phenotyping tools will improve the way in which drugs are prescribed, but most importantly, will facilitate development of new drugs for OADs.

A Prospective, Randomized Trial Comparing Respiratory Status During Anesthesia for Airway Stenting: Spontaneous Respiration Versus Controlled Ventilation With Muscle Relaxants.

BACKGROUND: Airway stenting is a procedure in which a stent is inserted into a stenotic site of the airway. The safest method of ventilation for airway stenting is controversial. A prospective randomized interventional study was conducted on airway stenting. We conducted this study to investigate whether controlled ventilation with muscle relaxants (MR) during airway stenting reduces the incidence of desaturation events (percutaneous oxygen saturation [SpO2] <95%) in comparison with spontaneous respiration (SP). METHODS: Sixty-four patients were enrolled at our hospital between April 2016 and August 2018, and were randomly assigned to the controlled ventilation with MR group or SP group. For anesthesia, total intravenous anesthesia with propofol target-controlled infusion and remifentanil was performed. In the SP group, SP was maintained. In the MR group, a rigid bronchoscope was inserted after the administration of MR to perform controlled ventilation. The incidence of desaturation events was analyzed by logistic regression adjusted by the preoperative respiratory state and stenotic site of the airway. RESULTS: The incidence of desaturation events in the SP and MR groups was 75.0% (24/32) and 9.7% (3/31), respectively, with an odds ratio of 0.04 (95% confidence interval, 0.01-0.16, reference = SP group; P < .001). In the SP group, the mean intraoperative pH was lower than that in the MR group (7.2 ± 0.1 vs 7.4 ± 0.1, respectively; P < .001). In this group, the mean partial pressure of arterial carbon dioxide (PaCO2) was higher (70.2 ± 17.0 mm Hg vs 40.5 ± 8.0 mm Hg, respectively; P < .001) and the mean partial pressure of oxygen in the arterial blood/fraction of the inspiratory oxygen ratio was lower (263.1 ± 64.2 mm Hg vs 396.4 ± 69.4 mm Hg, respectively; P < .001). CONCLUSIONS: Controlled ventilation with MR during airway stenting reduced the incidence of desaturation events, maintaining a favorable respiratory status.

Impact of Silicone Stent Placement in Symptomatic Airway Obstruction due to Non-Small Cell Lung Cancer - A French Multicenter Randomized Controlled Study: The SPOC Trial.

BACKGROUND: Therapeutic bronchoscopy (TB) is an accepted strategy for the symptomatic management of central airway malignant obstruction. Stent insertion is recommended in case of extrinsic compression, but its value in preventing airway re-obstruction after endobronchial treatment without extrinsic compression is unknown. OBJECTIVE: Silicone stent Placement in symptomatic airway Obstruction due to non-small cell lung Cancer (SPOC) is the first randomized controlled trial investigating the potential benefit of silicone stent insertion after successful TB in symptomatic malignant airway obstruction without extrinsic compression. METHOD: We planned an inclusion of 170 patients in each group (stent or no stent) over a period of 3 years with 1-year follow-up. The 1-year survival rate without symptomatic local recurrence was the main endpoint. Recurrence rate, survival, quality of life, and stent tolerance were secondary endpoints. During 1-year follow-up, clinical events were monitored by flexible bronchoscopies and were evaluated by an independent expert committee. RESULTS: Seventy-eight patients (mean age 65 years) were randomized into 2 arms: stents (n = 40) or no stents (n = 38) after IB. Consequently, our main endpoint could not be statistically answered. Improvement of dyspnea symptoms is noticeable in each group but lasts longer in the stent group. Stents do not change the survival curve but reduce unattended bronchoscopies. In the no stent group, 19 new TB were performed with 16 stents inserted contrasting with 10 rigid bronchoscopies and 3 stents placed in the stent group. In a subgroup analysis according to the oncologic management protocol following TB (first-line treatment and other lines or palliation), the beneficial effect of stenting on obstruction recurrence was highly significant (p < 0.002), but was not observed in the naïve group, free from first-line chemotherapy. CONCLUSION: Silicone stent placement maintains the benefit of TB after 1 year on dyspnea score, obstruction's recurrence, and the need for new TB. Stenting does not affect the quality of life and is suggested for patients after failure of first-line chemotherapy. It is not suggested in patients without previous oncologic treatment.