Airway Axis Research Articles

Comparison of Efficacy of Intubation with HugeMed Non-channelled Video Laryngoscope, McCoy and Macintosh Laryngoscope in Simulated Difficult Laryngoscopy Using Rigid Cervical Collar: A Prospective Randomized Trial.

In cervical spine injuries, there is an impairment in positioning of the patient to maintain the airway axis during endotracheal intubation (ETI). Literature shows video laryngoscope (VLS) facilitating the intubation in these patients with cervical immobilization. VL3 VLS (HugeMed Medical Technical Development, Shenzhen, China) is a newer VLS with limited studies. The primary aim of this study is to compare the efficacy of ETI using VL3 VLS with Macintosh and McCoy (MC) blades for simulated difficult airway with rigid cervical collar (RCC). The secondary aim was to compare the oral insertion of laryngoscope and intraoral bleeding. One hundred and fifty patients were randomly divided into three groups depending on laryngoscope used for ETI. Group M, Group V, and Group MC used Macintosh, VL3, and MC laryngoscopic blades, respectively, for ETI. During ETI, the Intubation Difficulty Scale (IDS), intubation time (IT), ease of laryngoscope insertion, and any bleeding intraorally were noted. The data collected were further analyzed. IDS was statistically significantly least (0.9 ± 1.5) with VL3 VLS compared to direct laryngoscopy with Macintosh and MC blades. There was significantly no difference in IT among the three groups. Insertion of blade of VL3 was significantly more difficult than Macintosh or MC. Intraoral bleeding was present in 8% of patients with VL3. VL3 VLS can be used for ETI during cervical immobilization using RCC. More studies are needed to define its efficacy in different difficult airway situations compared with different VLS.

Microwave Ablation for Malignant Central Airway Obstruction: A Pilot Study

Background: Malignant central airway obstruction (CAO) is a debilitating complication of primary lung cancer and pulmonary metastases. Therapeutic bronchoscopy is used to palliate symptoms and/or bridge to further therapy. Microwave ablation (MWA) heats tissue by creating an electromagnetic field around an ablation device. We present a pilot study utilizing endobronchial MWA via flexible bronchoscopy as a novel modality for the management of malignant CAO. Methods: Therapeutic bronchoscopy with a flexible MWA probe was performed in 8 cases. We reviewed tumor size, previous ablative techniques, number of applications, ablation time, amount of energy delivered, rate of successful recanalization, complications, and 30-day follow-up. Results: Successful airway recanalization was achieved in all cases. No complications were noted. In 1 case, tumor in-growth within a silicone stent was ablated with no damage to the stent. Discussion: Endobronchial MWA is a novel technique for tumor destruction while maintaining an airway axis. The oven effect and air gap around a tumor allow for safe and effective tissue devitalization and hemostasis without a thermal effect on structures surrounding the airway.

A prospective observational study on predicting the risk of obstructive sleep apnea and difficult intubation in patients posted for elective surgery

Introduction: The present study compared video laryngoscope with Macintosh laryngoscope in terms of laryngoscopic time, total intubation time, Cormack and lehane scale and stress response while intubating. Materials and methods: After a standardized technique of induction of anesthesia, Group MCL (53 cases) intubated with Macintosh laryngoscope and Group VVL (53cases) intubated with Vividtrac Video laryngoscope. We compared laryngoscopic time, total intubation time, Cormack and lehane scale and stress response while intubating in these two groups. Results: The heart rate and blood pressure was above immediately after post intubation and started declining to reach post induction value at about three to five minutes in both groups (p values > 0.05).The mean tracheal intubation time was 11.05 seconds in MCL group and 18.05 seconds in VVL group (p-0.001). All cases in VVL group were intubated in first attempt, but one patient in MCL group required two attempts for success (p->0.05). Visualisation of glottis and non-alignment of the airway axis was better with VVL (p-0.001). There is no desaturation noted in all of the 106 cases. Conclusion: Vivid trac Laryngoscope has a comparable similar safety profile with Macintosh laryngoscope with respect to deleterious haemodynamic response produced by rigid manipulation of airway. Vivid trac Video Laryngoscope, a rigid channeled indirect laryngoscope provides always the better view of the laryngeal inlet than the Macintosh direct laryngoscope. Intubation time in Vividtrac video laryngoscopy was more than conventional laryngoscopy.

Comparison of Haemodynamic Response to Intubation with KingVision and C-MAC Videolaryngoscope in Adults

Background: Videolaryngoscopes are now being advocated as the universal device for airway management due to their ability to provide an improved glottic visualisation. Due to their ability to see around the corners, they obviate the need to align the airway axes and thus may lead to less airway stimulation. This may result in less haemodynamic response during laryngoscopy and intubation. The present study was designed to compare the haemodynamic response to intubation with King Vision and C-MAC videolaryngoscopes. Methods: After obtaining informed consent, adults with unanticipated difficult intubation, scheduled to undergo surgery under general anaesthesia were randomised to be intubated with either King Vision (Group K) or C-MAC (Group C) videolaryngoscope. Following a standardised general anaesthesia induction protocol all subjects were intubated with the allocated videolaryngoscope and haemodynamic parameters (heart rate, systolic pressure, diastolic pressure and mean arterial pressure) were recorded at specific time points. Statistical analysis was done using the SPSS Software (version 18.0). Results: The changes in the heart rate, systolic pressure, diastolic pressure and mean arterial pressure following laryngoscopy and intubation with the allocated videolaryngoscope were statistically similar between the two groups at all time points. Conclusion: Haemodynamic responses to laryngoscopy and intubation with King Vision and C-MAC videolaryngoscopes were similar.

Changes in airway diameter and mucus plugs in patients with asthma exacerbation.

Airway obstruction due to decreased airway diameter and increased incidence of mucus plugs has not been directly observed in asthma exacerbation. We studied the changes in the inner diameter of the airway (Din) and the frequency of mucus plugs by airway generation in patients with asthma exacerbation. We compared these patients to those in a stable phase using high-resolution computed tomography (HRCT). Thirteen patients with asthma were studied by HRCT during asthma exacerbation and in a stable period. The HRCT study was performed on patients who could safely hold their breath for a short while in a supine position 1 hour after initial treatment for asthma exacerbation. Using a curved multiplanar reconstruction (MPR) software, we reconstructed the longitudinal airway images and the images exactly perpendicular to the airway axis to measure the Din and mucus plugs from the second- (segmental) to sixth-generation bronchi in all segments of the lungs.The ratios of Din (exacerbation/stable) were 0.91(P = 0.016), 0.88 (P = 0.002), 0.83 (P = 0.001), 0.80 (P = 0.001), and 0.87 (NS) in the second-, third-, fourth-, fifth-, and sixth-generation bronchi, respectively. The percentages of airway obstruction due to mucus plugs were notably higher in the fourth- and fifth-generation bronchi (17.9%/18.1% in stable phase and 43.2%/45.9% in the exacerbation phase, respectively) than in the other generations of bronchi. Among the bronchi examined, the fourth- and fifth-generation bronchi were significantly obstructed during asthma exacerbation compared with the stable phase in terms of a decreased airway diameter and mucus plugs.

Noncanonical Wnt planar cell polarity signaling in lung development and disease.

The planar cell polarity (PCP) signaling pathway is a potent developmental regulator of directional cell behaviors such as migration, asymmetric division and morphological polarization that are critical for shaping the body axis and the complex three-dimensional architecture of tissues and organs. PCP is considered a noncanonical Wnt pathway due to the involvement of Wnt ligands and Frizzled family receptors in the absence of the beta-catenin driven gene expression observed in the canonical Wnt cascade. At the heart of the PCP mechanism are protein complexes capable of generating molecular asymmetries within cells along a tissue-wide axis that are translated into polarized actin and microtubule cytoskeletal dynamics. PCP has emerged as an important regulator of developmental, homeostatic and disease processes in the respiratory system. It acts along other signaling pathways to create the elaborately branched structure of the lung by controlling the directional protrusive movements of cells during branching morphogenesis. PCP operates in the airway epithelium to establish and maintain the orientation of respiratory cilia along the airway axis for anatomically directed mucociliary clearance. It also regulates the establishment of the pulmonary vasculature. In adult tissues, PCP dysfunction has been linked to a variety of chronic lung diseases such as cystic fibrosis, chronic obstructive pulmonary disease, and idiopathic pulmonary arterial hypertension, stemming chiefly from the breakdown of proper tissue structure and function and aberrant cell migration during regenerative wound healing. A better understanding of these (impaired) PCP mechanisms is needed to fully harness the therapeutic opportunities of targeting PCP in chronic lung diseases.

Managing the airway of acid burn contracture of the neck in a 12-year-old girl

Managing the airway of patient with postburn contracture at the neck is often challenging for otolaryngologists and anesthesiologists. It affects the oro-pharyngo-laryngeal airway axes because of anatomical and functional deformities because of the long-standing contracture in the face and neck region. We present a case of extensive neck postburn contractures distorting anatomy, whose airway was assessed and managed using a video fiberoptic bronchoscope (FOB) (Ambu® aScope™). Our experience of the utility of FOB mirrors the experience and literature in the management of difficult airway.

Effect of cuff inflation technique in video laryngoscopic assisted nasal intubation in oral cancer surgeries

Introduction: TA scope is an indirect optical video laryngoscope (VL) which provides a better glottic view without manipulating all three airway axis. Cuff inflation in nasal tube (NT) makes tube midline and good alignment with glottic opening. Aim: This study aims to evaluate the success rate of nasal intubation with cuff inflation technique through VL. Methods: A total of 50 patients posted for oral cancer surgery were included. After general anesthesia induction, NT passed up to oropharynx; with VL NT cuff inflation with 15 ml of air done in Group I and no cuff inflation in Group D. NT was advanced to vocal cords, cuff was deflated; the NT was then advanced into the trachea, and then cuff was reinflated (M0). If this failed, cuff inflation was further inflated 5 cc more (M1) or counterclockwise 180° rotation (M3) or help of Magill's forceps (M3) was used. Results: NT tip locations were midline in 88% after cuff inflation. The duration of intubation was earlier in inflated group (32 ± 18 s vs. 44 ± 20 s). Additional maneuvers such as more 5 cc air or Magill forceps were more in Group D (52% vs. 22% P = 0.25). First trail intubation success without any maneuvers was 48% in Group I and 12% Group D (P = 0.006). Counterclockwise 180° endotracheal tube rotation (M2) was useful to pass NT to VC in 32%, 48% Group I and D, respectively (P = 0.25). Air required for cuff inflation was 16.57 ± 2.65 ml in Group I. Conclusion: Cuff inflation technique has a good success rate with minimum additional assistance in video laryngoscopic nasal intubation.

Perioperative airway management for aortic valve replacement in an adult with mucopolysaccharidosis type II (Hunter syndrome)

We herein report anesthetic management during aortic valve replacement for aortic valve regurgitation in a patient with adult mucopolysaccharidosis type II (MPS type 2) (Hunter syndrome). This disorder is rare and related to the accumulation of a mucopolysaccharide in lysosomes. It affects various organs, including the airways, heart, and central nerves. In children with MPS type 2, the risk of airway obstruction during anesthesia/sedation is high, and the degree of difficulty increases with aging. The patient described herein was a 33-year-old male without mental retardation. Before surgery, trismus, megaloglossia, and the disturbance of cervical vertebral excursion were noted, suggesting difficulties with ventilation/intubation. Anesthesia was induced under sedation/spontaneous respiration. A laryngeal deployment was conducted using a video laryngoscope; however, the Cormack grade was III. Nasotracheal fiber intubation was performed, and airway obstruction occurred. A muscle relaxant was administered, facilitating ventilation. However, subglottic stenosis, which was not detected before the surgery, made the tracheal tube insertion difficult. Aortic valve replacement was performed without complications. A detailed postoperative examination of the airways revealed oropharyngeal soft tissue outgrowth, narrowing of the upper airway, subglottic stenosis, and displacement/circumflex of the airway axis. Either awake intubation or rapid induction can be selected for this patient; however, either way have risks of airway obstruction. It is important that strategies under light anesthesia or incomplete neuromuscular blockade should be avoided for such our patient as suggested in the JSA airway management guidelines. A preoperative multidisciplinary airway assessment and simulation are important.

Reference Values for Central Airway Dimensions on CT Images of Children and Adolescents.

The purpose of this study was to acquire normative data on central airway dimensions on chest CT scans in the pediatric population. Chest CT findings reported as normal by a radiologist were collected retrospectively at 10 international centers. An experienced and independent thoracic radiologist reevaluated all CT scans for image quality and for normal findings. Semiautomated image analysis was performed to measure dimensions of the trachea and right and left main bronchi at inspiration. Intrathoracic tracheal length was measured from carina to thorax inlet. Cross-sectional area and short and long axes were measured perpendicular to the longitudinal airway axis starting from the carina every centimeter upward for the trachea and every 0.5 cm downward for the main bronchi. The effects on airway diameters of age, sex, intrathoracic tracheal length, and distance from the carina were investigated by use of mixed-effects models analysis. Among 1160 CT scans collected, 388 were evaluated as normal by the independent radiologist with sufficient image quality and adequate inspiratory volume level. Central airways were successfully semiautomatically analyzed in 294 of 388 CT studies. Age, sex, intrathoracic tracheal length, and distance from carina were all significant predictors in the models for tracheal and right and left main bronchial diameters (p < 0.001). The central airway dimensions increased with age up to 20 years, and dimensions were larger in male than in female adolescents. Normative data were determined for the central airways of children and adolescents. Central airway dimensions depended on distance from the carina and on intrathoracic tracheal length.

Quantitative assessment of airway dimensions in young children with cystic fibrosis lung disease using chest computed tomography

To evaluate lung disease progression using airway and artery (AA) dimensions on chest CT over 2-year interval in young CF patients longitudinally and compare to disease controls cross-sectionally. Retrospective analysis of pressure controlled end-inspiratory CTs, 12 routine baseline (CT1 ) and follow up (CT2 ) from AREST CF cohort; 12 disease controls with normal CT. All visible AA-pairs were measured perpendicular to the airway axis. Inner and outer airway diameters and wall (outer-inner radius) thickness were divided by adjacent arteries to compute Ain A-, Aout A-, and AWT A-ratios, respectively. Differences between CF and control data were assessed using mixed effects models predicting AA-ratios per segmental generation (SG). Power calculations were performed with 80% power and ɑ = 0.05. CF, median age CT1 2 years; CT2 3.9 years, 5 males. Controls, median age 2.9 years, 10 males. Total of 4798 AA-pairs measured. Cross-sectionally: Ain A-ratio showed no difference between controls and CF CT1 or CT2 . Aout A-ratio was significantly higher in CF CT1 (SG 2-4) and CT2 (SG 2-5) compared to controls. AWT A-ratio was increased for CF CT1 (SG 1-5) and CT2 (SG 2-6) compared to controls. CF longitudinally: Ain A-ratio was significantly higher at CT2 compared to CT1 . Increase in Aout A-ratio at CT2 compared to CT1 was visible in SG ≥4. Sample sizes of 21 and 58 would be necessary for 50% and 30% Aout A-ratio reductions, respectively, between CF CT2 and controls. AA-ratio differences were present in young CF patients relative to disease controls. Aout A-ratio as an objective parameter for bronchiectasis could reduce sample sizes for clinical trials.

Diagnosis of bronchiectasis and airway wall thickening in children with cystic fibrosis: Objective airway-artery quantification

ObjectivesTo quantify airway and artery (AA)-dimensions in cystic fibrosis (CF) and control patients for objective CT diagnosis of bronchiectasis and airway wall thickness (AWT).MethodsSpirometer-guided inspiratory and expiratory CTs of 11 CF and 12 control patients were collected retrospectively. Airway pathways were annotated semi-automatically to reconstruct three-dimensional bronchial trees. All visible AA-pairs were measured perpendicular to the airway axis. Inner, outer and AWT (outer−inner) diameter were divided by the adjacent artery diameter to compute AinA-, AoutA- and AWTA-ratios. AA-ratios were predicted using mixed-effects models including disease status, lung volume, gender, height and age as covariates.ResultsDemographics did not differ significantly between cohorts. Mean AA-pairs CF: 299 inspiratory; 82 expiratory. Controls: 131 inspiratory; 58 expiratory. All ratios were significantly larger in inspiratory compared to expiratory CTs for both groups (p<0.001). AoutA- and AWTA-ratios were larger in CF than in controls, independent of lung volume (p<0.01). Difference of AoutA- and AWTA-ratios between patients with CF and controls increased significantly for every following airway generation (p<0.001).ConclusionDiagnosis of bronchiectasis is highly dependent on lung volume and more reliably diagnosed using outer airway diameter. Difference in bronchiectasis and AWT severity between the two cohorts increased with each airway generation.Key points• More peripheral airways are visible in CF patients compared to controls.• Structural lung changes in CF patients are greater with each airway generation.• Number of airways visualized on CT could quantify CF lung disease.• For objective airway disease quantification on CT, lung volume standardization is required.

A pillow of 8 cm height did not improve laryngeal view and alignment of airway axes but increased anesthesiologist discomfort compared to a pillow of 4 cm height during tracheal intubation in adult patients.

BackgroundNeck flexion by head elevation using an 8 to 10 cm thick pillow and head extension has been suggested to align the laryngeal, pharyngeal and oral axis and facilitate tracheal intubation. Presently, the laryngeal view and discomfort for tracheal intubation were evaluated according to two different degrees of head elevation in adult patients.MethodsThis prospective randomized, controlled study included 50 adult patients aged 18 to 90 years. After induction of anesthesia, the Cormack Lehane grade was evaluated in 25 patients using a direct laryngoscope while the patient's head was elevated with a 4 cm pillow (4 cm group) and then an 8 cm pillow (8 cm group). In the other 25 patients, the grades were evaluated in the opposite sequence and tracheal intubation was performed. The success rate and anesthesiologist's discomfort score for tracheal intubation, and laryngeal, pharyngeal and oral axes were assessed.ResultsThere were no differences in the laryngeal view and success rate for tracheal intubation between the two groups. The discomfort score during tracheal intubation was higher in the 8 cm group when the patient's head was elevated 4 cm first and then 8 cm. The alignment of laryngeal, pharyngeal and oral axes were not different between the two degrees of head elevation.ConclusionsA pillow of 8 cm height did not improve laryngeal view and alignment of airway axes but increased the anesthesiologist discomfort, compared to a pillow of 4 cm height, during tracheal intubation in adult patients.

Lobe-based computed tomography assessment of airway diameter, airway or vessel number, and emphysema extent in relation to the clinical outcomes of COPD

ObjectiveThe aim of this study was to evaluate the relationship between computed tomography assessed lobe-based lung parameters and the clinical outcomes of patients with chronic obstructive pulmonary disease (COPD), including the frequency of exacerbation and annual change in forced expiratory volume in 1 second (FEV1).Patients and methodsWe studied 65 patients with COPD. We reconstructed computed tomography images to trace the bronchial tree from right B1 to B10 and created 3 cm circle images around the airways exactly perpendicular to the airway axis in the central, middle, and peripheral zones of the bronchi. The number of airways and vessels, airway inner diameter and area of emphysema in the circles were calculated for each segment. Then, we analyzed the relationships between the lobe-based image parameters and the frequency of exacerbation and annual decline in the FEV1. In addition, we assessed the effects of proximal airway lumen-obliterated emphysema (ALOE) on these clinical features.ResultsThe airway diameter was not associated with the frequency of exacerbation or annual decline in FEV1. Among the structural parameters, lower lobe emphysema was most associated with the frequency of exacerbation. The reductions in the number of airways and vessels in total lobe were associated with the annual decline in FEV1. The subgroup of patients with ALOE demonstrated lower FEV1 and more frequent exacerbation than those without ALOE.ConclusionLower lobe emphysema predicts frequent COPD exacerbation, whereas the annual decline in FEV1 is associated with the number of airways and vessels in total lobe.

A Comparative Study of Tracheal Intubation Characteristics Using Macintosh and Airtraq Laryngoscope

Background: Direct laryngoscopy for endotracheal intubation with the Macintosh blade is most commonly used for establishing a patent airway. Airtraq Tm Optical Laryngoscope, does not require the alignment of the 3 airway axes for glottic visualization. Objective: We aim to compare these two laryngoscopes in view of laryngoscopic grading, ease of tracheal intubation and hemodynamic changes associated with laryngoscopy and intubation. Materials and Methods: 50 ASA I and II patients were randomly divided into Macintosh (M) group and Airtraq (A) group. Cormack Lehane grading, ease of intubation, laryngeal intubation time in secs and incidence of sore throat was noted. HR&BP was recorded at 0, 1, 3, 5&10 minutes following intubation. Unpaired 't' test compared inter-group data, while paired 't' test compared within group cardiovascular data. (p<0.05 statistically significant). Results: The demographic data of both groups were comparable. Cormack-Lehane grading was better in group A than in group M [grade I group A(84%) and group M(60%)]. The mean time for laryngeal intubation (Mean ± SD) for group A (8.3 ± 4.6 secs) and group M (20.46 ± 6.6 secs) (t = 7.6, p< 0.01). Ease of intubation was better in group A than group M. The rise in blood pressure and heart rate was significantly less in Group A as compared to Group M. Conclusion: Airtraq laryngoscope was superior to Macintosh laryngoscope as it provided better laryngoscopic views, shorter laryngoscopy and intubation time, easier intubation and the rise in heart rate and systolic blood pressure was significantly less.

Coregistered autofluorescence-optical coherence tomography imaging of human lung sections

Autofluorescence (AF) imaging can provide valuable information about the structural and metabolic state of tissue that can be useful for elucidating physiological and pathological processes. Optical coherence tomography (OCT) provides high resolution detailed information about tissue morphology. We present coregistered AF-OCT imaging of human lung sections. Adjacent hematoxylin and eosin stained histological sections are used to identify tissue structures observed in the OCT images. Segmentation of these structures in the OCT images allowed determination of relative AF intensities of human lung components. Since the AF imaging was performed on tissue sections perpendicular to the airway axis, the results show the AF signal originating from the airway wall components free from the effects of scattering and absorption by overlying layers as is the case during endoscopic imaging. Cartilage and dense connective tissue (DCT) are found to be the dominant fluorescing components with the average cartilage AF intensity about four times greater than that of DCT. The epithelium, lamina propria, and loose connective tissue near basement membrane generate an order of magnitude smaller AF signal than the cartilage fluorescence.

Changes in the airway lumen and surrounding parenchyma in chronic obstructive pulmonary disease

BackgroundThe purpose of this study was to examine changes in the airway lumen and parenchyma in relation to lung function in patients with chronic obstructive pulmonary disease (COPD) compared with controls.MethodsWe studied 70 patients with COPD and 15 normal subjects. Using reconstructed computed tomography (CT) images, we traced the bronchial trees and reconstructed 3 cm circle images around the airways exactly perpendicular to the airway axis at the peripheral, middle, and central zones of the bronchi. We measured the number of airways and vessels, the airway inner diameter, and the area of emphysema in the circles, and analyzed the relationship of these image parameters to lung function.ResultsReduced airway numbers and increased upper lobe emphysema were observed even in early spirometric stages in patients with COPD compared with controls. Other findings included decreased airway inner diameter in advanced spirometric stages. The numbers of peripheral zone bronchi, the extent of the middle zone emphysematous area, and the mean airway inner diameter of the airways were the best predictors of spirometric parameters. A portion of the airways in patients with COPD showed a loss of airway patency at middle or central zone bronchi predominantly in the late spirometric stages. Lumen-obliterated bronchial trees could be traced into emphysematous areas showing air trapping.ConclusionCompared with controls, our CT observations in patients with COPD showed that airway lumen and lung parenchyma changes along airways differed by spirometric stage, and these changes were associated with decreased lung function. A portion of CT-identified emphysema in patients with COPD appeared to be due to lumen-obliterated airways in the bronchial tree.

Treatment of Complex Airway Lesions After Lung Transplantation With Self-Expandable Nitinol Stents: Early Experience

Airway complications (AC) are considered a serious cause of morbidity after lung transplantation (LT). Mechanical dilatation, laser vaporization, and silicone stent placement usually solve it. However, the use of self-expandable metallic stents (SENS) may be indicated in selected cases. Ten lung transplant recipients with AC were treated with SENS. Six patients underwent LT for cystic fibrosis, 2 for idiopathic pulmonary fibrosis, 1 for bronchiectasis, and 1 for emphysema. All patients received at least 1 treatment attempt with dilatation and silicone stent placement. The indications for SENS placement were the presence of a tortuous airway axis with stenosis and malacia of the right main bronchus in 5 patients; a long stenosis of the main and intermediate right bronchus involving the upper lobe orifice in 3 patients; or malacia that could not be stabilized with silicone stents in 3 cases. In 1 patient the procedure was bilateral. Functional improvement was immediate with a mean forced expiratory volume at 1 second (FEV 1) gain of 35%. No stent dislocation was observed. Symptoms did not occur again in 5 patients with previous recurrent episodes of pneumonia. One stenosis, which was due to the ingrowth of granulation tissue occurred at 6 months after the procedure, was successfully treated with mechanical dilatation and laser vaporization. The deployment of SENS in a selected group of patients with AC after LT was easy, safe, and effective.

MDCT assessment of airway wall thickness in COPD patients using a new method: correlations with pulmonary function tests

Quantitative assessment of airway-wall dimensions by computed tomography (CT) has proven to be a marker of airway-wall remodelling in chronic obstructive pulmonary disease (COPD) patients. The objective was to correlate the wall thickness of large and small airways with functional parameters of airflow obstruction in COPD patients on multi-detector (MD) CT images using a new quantification procedure from a three-dimensional (3D) approach of the bronchial tree. In 31 patients (smokers/COPD, non-smokers/controls), we quantitatively assessed contiguous MDCT cross-sections reconstructed orthogonally along the airway axis, taking the point-spread function into account to circumvent over-estimation. Wall thickness and wall percentage were measured and the per-patient mean/median correlated with FEV1 and FEV1%. A median of 619 orthogonal airway locations was assessed per patient. Mean wall percentage/mean wall thickness/median wall thickness in non-smokers (29.6%/0.69 mm/0.37 mm) was significantly different from the COPD group (38.9%/0.83 mm/0.54 mm). Correlation coefficients (r) between FEV1 or FEV1% predicted and intra-individual means of the wall percentage were -0.569 and -0.560, respectively, with p < 0.001. Depending on the parameter, they were increased for airways of 4 mm and smaller in total diameter, being -0.621 (FEV1) and -0.537 (FEV1%) with p < 0.002. The wall thickness was significantly higher in smokers than in non-smokers. In COPD patients, the wall thickness measured as a mean for a given patient correlated with the values of FEV1 and FEV1% predicted. Correlation with FEV1 was higher when only small airways were considered.

In vivo lung morphometry with hyperpolarized 3He diffusion MRI: Theoretical background

MRI-based study of 3He gas diffusion in lungs may provide important information on lung microstructure. Lung acinar airways can be described in terms of cylinders covered with alveolar sleeve [Haefeli-Bleuer, Weibel, Anat. Rec. 220 (1988) 401]. For relatively short diffusion times (on the order of a few ms) this geometry allows description of the 3He diffusion attenuated MR signal in lungs in terms of two diffusion coefficients—longitudinal ( D L ) and transverse ( D T ) with respect to the individual acinar airway axis [Yablonskiy et al., PNAS 99 (2002) 3111]. In this paper, empirical relationships between D L and D T and the geometrical parameters of airways and alveoli are found by means of computer Monte Carlo simulations. The effects of non-Gaussian signal behavior (dependence of D L and D T on b-value) are also taken into account. The results obtained are quantitatively valid in the physiologically important range of airway parameters characteristic of healthy lungs and lungs with mild emphysema. In lungs with advanced emphysema, the results provide only “apparent” characteristics but still could potentially be used to evaluate emphysema progression. This creates a basis for in vivo lung morphometry—evaluation of the geometrical parameters of acinar airways from hyperpolarized 3He diffusion MRI, despite the airways being too small to be resolved by direct imaging. These results also predict a rather substantial dependence of 3He ADC on the experimentally-controllable diffusion time, Δ . If Δ is decreased from 3 ms to 1 ms, the ADC in normal human lungs may increase by almost 50%. This effect should be taken into account when comparing experimental data obtained with different pulse sequences.