Airway Occlusion Research Articles

Bronchial valve treatment for pulmonary air leak after anatomical lung resection for cancer

A persistent post-operative pulmonary expiratory air leak after an anatomical pulmonary resection is usually managed conservatively, but can be associated with significant morbidity and increased costs. The use of bronchial valves is a minimally invasive method that may be an effective and safe treatment in this setting. In a prospective study, the clinical efficacy of intrabronchial valve treatment in patients with a prolonged persistent pulmonary air leak after anatomical surgical resection for cancer was investigated. 10 out of 277 patients with anatomical pulmonary resection for cancer were included, and 90% were scheduled for valve treatment. We demonstrated an air leak cessation at a median of 2 days after valve placement, which resulted in chest tube removal at a median of 4 days after valve placement. Elective removal of the intrabronchial valves could be safely planned 3 weeks after valve implantation. Lung function alteration associated with airway occlusion by valves was limited. Intrabronchial valve treatment with the aid of a digital thoracic drainage system is an effective and safe therapy for patients with a prolonged pulmonary air leak after anatomical lung resection for cancer.

Elective use of an uncuffed small-bore cricothyrotomy tube with balloon occlusion of the subglottic airway

To conduct a qualitative observational study on positive pressure ventilation through a percutaneous uncuffed small-bore cricothyrotomy tube with balloon occlusion of the subglottic airway to minimize supraglottic leak. Ten consecutive procedures were performed in the nine men enrolled in this study. The demographics of the participants were: aged 50-73 yr, weight 48-87 kg, American Society of Anesthesiologists class I-II, and scheduled for endoscopic submucosal dissection via flexible endoscopy for en bloc resection of superficial meso- and hypopharyngeal cancer. The airway was initially secured with a supraglottic airway (SGA) under sevoflurane-based anesthesia, and a cricothyrotomy was then performed using a Portex(®) Minitrach II uncuffed cricothyrotomy tube (4-mm internal diameter). Following SGA removal, a Coopdech(®) bronchial blocker was orally or nasally inserted, and the balloon was inflated to occlude the trachea immediately beneath the glottis. The ventilator setting was initially based on observation of chest motion and end-tidal carbon dioxide tension and then readjusted according to arterial blood gas levels. All procedures were completed within a median time of 149 min. Effective ventilation was achieved in all patients despite mild hypercapnia (PaCO2 of 58 mmHg at maximum) in some patients. SpO2 levels were maintained at ≥ 98%. This technique provides effective intraoperative ventilation and easy endoscopic access, and it countermeasures against the likely complication of postoperative laryngeal edema. Moreover, there is no need for conventional tracheostomy or prolonged intubation. This approach establishes a curative and less invasive pharyngeal cancer therapy. Certain adverse outcomes can be avoided, including impaired speech and swallowing, possible delayed closure of the stoma, or a compromised cosmetic outcome.

Respiratory CO2 response in acute cervical spinal cord injury (CO2 response in spinal cord injury)

Retrospective study. The objective of this study was to compare the CO₂ response of acute tetraplegic cervical spinal cord injury (SCI) patients undergoing mechanical ventilation with a control group of critically ill patients ready for weaning of mechanical ventilation and successfully extubated. This study was conducted at the intensive care unit of a University Hospital in Mallorca, Spain. CO₂ response was studied in 12 acute tetraplegic cervical SCI patients at the C4-C7 level and 22 control patients. The control group patients were consecutively selected from a database of patients with mechanical ventilation and who were successfully extubated after a CO₂ response test. To increase the CO₂ , we used the method of re-inhalation of expired air, and we evaluated the hypercapnic ventilatory response, the change in minute ventilation induced by the increase of partial pressure of arterial carbon dioxide (PaCO₂ ), which measures the whole respiratory system (metabolic control, neuromuscular or ventilatory apparatus), and the hypercapnic drive response, the change in the airway occlusion pressure at 100 ms induced by the increase in PaCO2, which measures the chemosensitivity of the respiratory center. Cervical SCI patients were younger than the control group patients (26±7 and 62±12 years, respectively; P<0.001). Mean values of the hypercapnic ventilatory response in cervical SCI and control groups were 0.52±0.31 and 0.64±0.33 l min(-1) per mm Hg (P=0.40), respectively, and the hypercapnic drive response was 0.24±0.16 and 0.48±0.23 cm H₂O per mm Hg (P=0.001), respectively. Acute tetraplegic cervical SCI patients had reduced hypercapnic drive response that may contribute to the difficult weaning, without reduction in hypercapnic ventilatory response.

Cardiovascular risk and mortality in end-stage renal disease patients undergoing dialysis: sleep study, pulmonary function, respiratory mechanics, upper airway collapsibility, autonomic nervous activity, depression, anxiety, stress and quality of life: a prospective, double blind, randomized controlled clinical trial

BackgroundChronic kidney disease (CKD) is one of the most serious public health problems. The increasing prevalence of CKD in developed and developing countries has led to a global epidemic. The hypothesis proposed is that patients undergoing dialysis would experience a marked negative influence on physiological variables of sleep and autonomic nervous system activity, compromising quality of life.Methods/DesignA prospective, consecutive, double blind, randomized controlled clinical trial is proposed to address the effect of dialysis on sleep, pulmonary function, respiratory mechanics, upper airway collapsibility, autonomic nervous activity, depression, anxiety, stress and quality of life in patients with CKD. The measurement protocol will include body weight (kg); height (cm); body mass index calculated as weight/height2; circumferences (cm) of the neck, waist, and hip; heart and respiratory rates; blood pressures; Mallampati index; tonsil index; heart rate variability; maximum ventilatory pressures; negative expiratory pressure test, and polysomnography (sleep study), as well as the administration of specific questionnaires addressing sleep apnea, excessive daytime sleepiness, depression, anxiety, stress, and quality of life.DiscussionCKD is a major public health problem worldwide, and its incidence has increased in part by the increased life expectancy and increasing number of cases of diabetes mellitus and hypertension. Sleep disorders are common in patients with renal insufficiency. Our hypothesis is that the weather weight gain due to volume overload observed during interdialytic period will influence the degree of collapsibility of the upper airway due to narrowing and predispose to upper airway occlusion during sleep, and to investigate the negative influences of haemodialysis in the physiological variables of sleep, and autonomic nervous system, and respiratory mechanics and thereby compromise the quality of life of patients.Trial registrationThe protocol for this study is registered with the Brazilian Registry of Clinical Trials (ReBEC RBR-7yhr4w and World Health Organization under Universal Trial Number UTN: U1111-1127-9390 [http://www.ensaiosclinicos.gov.br/rg/RBR-7yhr4w/]).

Frequency of the Preoperative Flaws and Commonly Required Maneuvers to Correct Them

The purpose of this study was to identify the most common deformities seen preoperatively in secondary rhinoplasty patients and the required surgical maneuvers to correct them. A retrospective chart review of 100 consecutive secondary rhinoplasty patients was performed. Preoperative variables included demographics, prior rhinoplasty data, main aesthetic/functional concerns, and the senior author's physical examination of the nose. Details of the operative maneuvers were reviewed. The average patient age was 39.2 years. All patients had previous rhinoplasties performed by other surgeons. The most common preoperative complaints were airway occlusion (65 percent), dorsum asymmetry (33 percent), nostril asymmetry (18 percent), and tip asymmetry (14 percent). The most common preoperative nasal deformities seen by the senior author (B.G.) were dorsal asymmetry (65 percent), wide dorsum (47 percent), nostril asymmetry (41 percent), wide alar base (38 percent), and dorsal hump (30 percent). The senior author saw significantly more nasal deformities than the patients themselves, especially in the following areas: dorsal asymmetry (65 percent versus 33 percent; p = 0.0002), wide dorsum (47 percent versus 13 percent; p < 0.0001), nostril asymmetry (41 percent versus 18 percent; p = 0.0003), wide alar base (38 percent versus 6 percent; p < 0.0001), dorsal hump (30 percent versus 9 percent; p < 0.0001), and columella protrusion (25 percent versus 6 percent; p = 0.0002). The most common revision rhinoplasty surgical maneuvers were septoplasty (71 percent), alar rim graft (67 percent), dorsal graft (63 percent), osteotomy (60 percent), and dorsal hump removal (46 percent). The high incidence of airway concerns among secondary rhinoplasty patients is alarming and emphasizes the urgent need to pay attention to the airway during primary rhinoplasty. There is often a disparity between what the patient sees and what the surgeon observes.

A novel airway device with tactile sensing capabilities for verifying correct endotracheal tube placement

We present a new device for verifying endotracheal tube (ETT) position that uses specialized sensors intended to distinguish anatomical features of the trachea and esophagus. This device has the potential to increase the safety of resuscitation, surgery, and mechanical ventilation and decrease the morbidity, mortality, and health care costs associated with esophageal intubation and unintended extubation by potentially improving the process and maintenance of endotracheal intubation. The device consists of a tactile sensor connected to the airway occlusion cuff of an ETT. It is intended to detect the presence or absence of tracheal rings immediately upon inflation of the airway occlusion cuff. The initial study detailed here verifies that a prototype device can detect contours similar to tracheal rings in a tracheal model.

Does weight loss affect the apnea/hypopnea index?

Does weight loss affect the apnea/hypopnea index?

Simulation of upper airway occlusion without and with mandibular advancement in obstructive sleep apnea using fluid-structure interaction

Obstructive Sleep Apnea (OSA) is a common sleep disorder characterized by repetitive collapse of the upper airway (UA). One treatment option is a mandibular advancement splint (MAS) which protrudes the lower jaw, stabilizing the airway. However not all patients respond to MAS therapy and individual effects are not well understood. Simulations of airway behavior may represent a non-invasive means to understand OSA and individual treatment responses. Our aims were (1) to analyze UA occlusion and flow dynamics in OSA using the fluid structure interaction (FSI) method, and (2) to observe changes with MAS. Magnetic resonance imaging (MRI) scans were obtained at baseline and with MAS in a known treatment responder. Computational models of the patients' UA geometry were reconstructed for both conditions. The FSI model demonstrated full collapse of the UA (maximum 5.83mm) pre-treatment (without MAS). The UA collapse was located at the oropharynx with low oropharyngeal pressure (−51.18Pa to −39.08Pa) induced by velopharyngeal jet flow (maximum 10.0m/s). By comparison, simulation results from the UA with MAS, showed smaller deformation (maximum 2.03mm), matching the known clinical response. Our FSI modeling method was validated by physical experiment on a 1:1 flexible UA model fabricated using 3D steriolithography. This is the first study of airflow dynamics in a deformable UA structure and inspiratory flow. These results expand on previous UA models using computational fluid dynamics (CFD), and lay a platform for application of computational models to study biomechanical properties of the UA in the pathogenesis and treatment of OSA.

Intraoperative airway occlusion during endovascular aortic repair for ruptured ductal arteriosus aneurysm: rescue by jet ventilation

a Department of Anesthesia and Analgesia, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Chia-Yi, Taiwan b Division of Thoracic and Cardiovascular Surgery, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Chia-Yi, Taiwan c Department of Radiology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Chia-Yi, Taiwan d Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan

Justification for Chest Physiotherapy during Ultra‐Protective Lung Ventilation and Extra‐Corporeal Membrane Oxygenation: A Case Study

This case report describes the chest physiotherapy (CPT) intervention provided to a 32-year old man with severe respiratory failure undergoing extra-corporeal membrane oxygenation (ECMO) support and ultra-protective ventilatory strategy. Low tidal volume ventilation when used in patients with extremely low dynamic respiratory compliance may predispose the patient to secretion retention, and the role of CPT in this setting is unclear. The method used is a single subject case report. Written consent obtained from patient's representative. Secretion clearance in this patient was initially limited to suctioning; however, after developing major airway occlusion secondary to impacted secretions, he received intensive CPT consisting of positioning, ventilator hyperinflation, expiratory chest wall shaking and suctioning. After 13 days of two to three times daily CPT, the patient weaned from ECMO support. Regular CPT may have facilitated secretion clearance and lung recovery in this patient. Future research should investigate the optimal CPT techniques for patients with sub-dead space tidal ventilation and extremely low dynamic respiratory compliance during ECMO with ultra-protective ventilatory strategy (UPVS).

Real‐time 3D magnetic resonance imaging of the pharyngeal airway in sleep apnea

To investigate the feasibility of real-time 3D magnetic resonance imaging (MRI) with simultaneous recording of physiological signals for identifying sites of airway obstruction during natural sleep in pediatric patients with sleep-disordered breathing. Experiments were performed using a three-dimensional Fourier transformation (3DFT) gradient echo sequence with prospective undersampling based on golden-angle radial spokes, and L1-norm regularized iterative self-consistent parallel imaging (L1-SPIRiT) reconstruction. This technique was demonstrated in three healthy adult volunteers and five pediatric patients with sleep-disordered breathing. External airway occlusion was used to induce partial collapse of the upper airway on inspiration and test the effectiveness of the proposed imaging method. Apneic events were identified using information available from synchronized recording of mask pressure and respiratory effort. Acceptable image quality was obtained in seven of eight subjects. Temporary airway collapse induced via inspiratory loading was successfully imaged in all three volunteers, with average airway volume reductions of 63.3%, 52.5%, and 33.7%. Central apneic events and associated airway narrowing/closure were identified in two pediatric patients. During central apneic events, airway obstruction was observed in the retropalatal region in one pediatric patient. Real-time 3D MRI of the pharyngeal airway with synchronized recording of physiological signals is feasible and may provide valuable information about the sites and nature of airway narrowing/collapse during natural sleep.

Ultrashort‐TE MRI longitudinal study and characterization of a chronic model of asthma in mice: inflammation and bronchial remodeling assessment

Asthma is a chronic disease characterized by bronchial hyperresponsiveness (BHR), bronchial inflammation and remodeling. The great improvements in (1)H MRI ultrashort-TE (UTE) sequences in the last decade have allowed lung images with high-resolution and good signal-to-noise ratio to be obtained in parenchymal tissues. In this article, we present a UTE (1)H MRI high-resolution study of a chronic model of asthma in mice with the aim to longitudinally assess the main features of asthma using a fully noninvasive approach. Balb/c mice (n = 6) were sensitized with ovalbumin over a period of 75 days. The control group (n = 3) received normal saline on the same days. MRI acquisitions were performed on days 0, 38 and 78 to study the inflammatory volumes and bronchial remodeling (peribronchial signal intensity index, PBSI). Plethysmographic studies were performed on days 0, 39 and 79 to assess BHR to methacholine using the enhanced pause (Penh) ratio. The average inflammatory volume measured by MRI in the ovalbumin group (15.6 ± 2.4 μL) was increased significantly relative to control mice (-0.3 ± 0.7 μL) on day 38. The inflammatory volume was larger (34.2 ± 3.1 μL) on day 78 in the ovalbumin group. PBSI was significantly higher in the ovalbumin group on day 78 (1.53 ± 0.08) relative to the control group (1.16 ± 0.10), but not on day 38. After sensitization, asthmatic mice presented BHR to methacholine on days 39 and 79. Penh ratios correlated significantly with the inflammatory volume on day 39 and with the PBSI on day 79. This study shows, for the first time, that high-resolution UTE (1)H MRI of the lungs may allow the noninvasive quantification of peribronchial eosinophilic inflammation with airways occlusion by mucus and of bronchial remodeling in a murine asthma model that correlates with functional parameters.

Reliability of Airway Occlusion Pressure as an Index of Respiratory Motor Output

Airway occlusion pressure 0.1 s after the start of inspiratory flow (P0.1) is used as an index of respiratory motor output; however, the reliability of P0.1 in this capacity has not been sufficiently investigated. Therefore, the aim of our study was to examine the reliability of P0.1. Eleven healthy subjects (7 men and 4 women) participated in our study. Subjects were placed in a supine position, and P0.1 was measured every 30 s for 5 min, following a 1-min period during which ventilation and breathing frequency were measured. A total of 10 P0.1 values were obtained, and the intraclass correlation coefficient (ICC) was used to analyze reliability. ICC values from ICC (1, 2) to ICC (1, 10) were calculated following a number of measurements (k), where ICC (1, k) was increased sequentially from 2 to 10. The ICC (1, 2) through ICC (1, 10) values were found to be between 0.877 and 0.960 (95% CI 0.565-0.966 and 0.912-0.987, respectively). When the target coefficient was set at 0.9, the ICC (1, 1) from 10 measurements was calculated a minimum of 4 times. Although a single measurement of P0.1 was somewhat reliable, the 95% CIs indicated that it is necessary to determine the average value of 3 or more measurements. The minimum of 4 repeat measurements were required to obtain valid results, indicating that the current method of determining P0.1 by averaging the values from at least 4 repeated measurements is valid.

Transdiaphragmatic pressure measurements reveal age‐related diaphragm muscle dysfunction during non‐ventilatory behaviors

The diaphragm muscle (DIAm) is responsible for breathing and must provide sufficient force to accomplish both ventilatory and non‐ventilatory behaviors. Age‐related changes to the DIAm, especially sarcopenia, may limit the ability to accomplish expulsive, non‐ventilatory behaviors essential for airway clearance, and thus contribute to respiratory complications. Age‐related changes in load (as a result of chest wall stiffening or lung compliance) may impact DIAm function. Adult male mice (6 and 24 months old) underwent measurements of respiratory system compliance and transdiaphragmatic pressure (Pdi) during: eupnea, hypoxia (10% O2) –hypercapnia (5% CO2), spontaneously occurring deep breaths, airway occlusion, and bilateral phrenic nerve stimulation. Overall respiratory system compliance decreased with age (increased load), while Pdi required for ventilatory behaviors did not change, consistent with the reserve capacity of the DIAm. The Pdi generated during deep breaths and airway occlusion were reduced 30–45% with age. These results indicate that DIAm dysfunction during aging is associated with reduced force to perform expulsive, non‐ventilatory behaviors. Reduced reserve capacity in old age may underlie increased susceptibility to lung infections and augment respiratory compromise associated with other age‐related diseases. Supported by T32‐HL‐105355 and the Mayo Clinic.

New Insights in Bronchiolitis Obliterans Syndrome after Lung Transplantation Using (micro-)CT

Purpose Bronchiolitis Obliterans Syndrome (BOS) is a major cause of mortality after lung transplantation. Although the mechanism remains elusive the introduction of μCT has made it possible to locate lesions within the bronchiolar tree. Methods and Materials Unused donor (n=5) and explanted lungs (n=6) from patients with BOS, collected at re-transplantation, were rapidly frozen near TLC and Multi detector volumetric computed tomography (MDCT) scans were performed on the intact specimen, which was then cut into 2cm thick slices and cores of tissue removed from each slice were fixed, dried and examined by μCT. Results The MDCT demonstrated a normal number of airways (BOS vs. control) at each generation when all the branching pathways were examined, but, starting from generation 5, airways Conclusions The airway occlusion associated with BOS is located in preterminal bronchioles, re-opening into normal appearing airways before the terminal bronchioles are reached. [ figure 1 ]

Mesenchymal stem cells reprogram host macrophages to attenuate obliterative bronchiolitis in murine orthotopic tracheal transplantation

After lung transplantation, obliterative bronchiolitis (OB) is one of the major limitations for the long-term survival of allografts. At present, effective treatment to prevent this phenomenon remains elusive. Mesenchymal stem cells (MSCs) are capable of modulating the immune system through the interaction with a wide range of immune cells. Here, we found that treatment of mice with bone marrow derived MSCs prevents the development of airway occlusion and increased IL-10 levels in trachea grafts, which was eliminated by the depletion of macrophages. Mechanistically, MSCs-derived PGE2, through the receptors EP2 and EP4, promoted the release of IL-10 and inhibited the production of IL-6 and TNF-α by macrophages. These results suggest that MSCs can both decrease the innate inflammatory responses and prevent allograft rejection by down-regulating the levels of IL-6 and TNF-α and increasing IL-10 production respectively. For easy availability and immune privilege, MSC-based treatment of OB provides an effective strategy for regulation of immune responses in lung transplantation.

Rattus model utilizing selective pulmonary ischemia induces bronchiolitis obliterans organizing pneumonia.

Bronchiolitis obliterans organizing pneumonia (BOOP), a morbid condition when associated with lung transplant and chronic lung disease, is believed to be a complication of ischemia. Our goal was to develop a simple and reliable model of lung ischemia in the Sprague-Dawley rat that would produce BOOP. Unilateral ischemia without airway occlusion was produced by an occlusive slipknot placed around the left main pulmonary artery. Studies were performed 7 days later. Relative pulmonary and systemic flow to each lung was measured by injection of technetium Tc 99m macroaggregated albumin. Histological sections were examined for structure and necrosis and scored for BOOP. Apoptosis was detected by immunohistochemistry with an antibody against cleaved caspase 3. Pulmonary artery blood flow to left lungs was less than 0.1% of the cardiac output, and bronchial artery circulation was ∼2% of aortic artery flow. Histological sections from ischemic left lungs consistently showed Masson bodies, inflammation, and young fibroblasts filling the distal airways and alveoli, consistent with BOOP. In quantitative evaluation of BOOP using epithelial changes, inflammation and fibrosis were higher in ischemic left lungs than right or sham-operated left lungs. Apoptosis was increased in areas exhibiting histological BOOP, but there was no histological evidence of necrosis. Toll-like receptor 4 expression was increased in ischemic left lungs over right. An occlusive slipknot around the main left pulmonary artery in rats produces BOOP, providing direct evidence that ischemia without immunomodulation or coinfection is sufficient to initiate this injury. It also affords an excellent model to study signaling and genetic mechanisms underlying BOOP.

Central Respiratory Drive in Patients With Neuromuscular Diseases

The contribution of the central respiratory drive in the hypercapnic respiratory failure of neuromuscular diseases (NMD) is controversial. To compare the CO2 response and the duration of weaning of mechanical ventilation between a group of NMD patients and a group of quadriplegic patients due to ICU-acquired weakness (ICU-AW). We prospectively studied 16 subjects with NMD and 26 subjects with ICU-AW ready for weaning, using the method of the re-inhalation of expired air. We measured the hypercapnic drive response, defined as the ratio of change in airway occlusion pressure 0.1 second after the start of inspiration (ΔP0.1) to the change in Paco2 (ΔPaco2), and the hypercapnic ventilatory response, defined as the ratio of the change in minute ventilation (ΔVe) to ΔPaco2. We considered a value of ≤ 0.19 cm H2O/mm Hg as reduced hypercapnic drive response. Hypercapnic drive response (ΔP0.1/ΔPaco2 = 0.14 ± 0.08 cm H2O/mm Hg vs 0.37 ± 0.27 cm H2O/mm Hg, P = .002) and hypercapnic ventilatory response (ΔVe/ΔPaco2 = 0.21 ± 0.19 L/min/mm Hg vs 0.44 ± 0.40 L/min/mm Hg, P = .02) were lower in the NMD than in the ICU-AW subjects. Duration of weaning values, according to the Kaplan-Meier curves, were similar in both groups (Log-rank = 0.03, P = .96). Eleven NMD (69%) and 9 ICU-AW (35%) subjects had hypercapnic drive response ≤ 0.19 cm H2O/mm Hg. The duration of weaning was longer in subjects with hypercapnic drive response ≤ 0.19 cm H2O/mm Hg (log-rank = 15.4, P < .001). Subjects with acute hypercapnic respiratory failure due to NMD had reduced hypercapnic drive response, compared to ICU-AW subjects. The duration of weaning was longer in subjects with reduced hypercapnic drive response.

Ferret Lung Transplant: An Orthotopic Model of Obliterative Bronchiolitis

Obliterative bronchiolitis (OB) is the primary cause of late morbidity and mortality following lung transplantation. Current animal models do not reliably develop OB pathology. Given the similarities between ferret and human lung biology, we hypothesized an orthotopic ferret lung allograft would develop OB. Orthotopic left lower lobe transplants were successfully performed in 22 outbred domestic ferrets in the absence of immunosuppression (IS; n = 5) and presence of varying IS protocols (n = 17). CT scans were performed to evaluate the allografts. At intervals between 3-6 months the allografts were examined histologically for evidence of acute/chronic rejection. IS protects allografts from acute rejection and early graft loss. Reduction of IS dosage by 50% allowed development of controlled rejection. Allografts developed infiltrates on CT and classic histologic acute rejection and lymphocytic bronchiolitis. Cycling of IS, to induce repeated episodes of controlled rejection, promoted classic histologic hallmarks of OB including fibrosis-associated occlusion of the bronchiolar airways in all allografts of long-term survivors. In conclusion, we have developed an orthotopic lung transplant model in the ferret with documented long-term functional allograft survival. Allografts develop acute rejection and lymphocytic bronchiolitis, similar to humans. Long-term survivors develop histologic changes in the allografts that are hallmarks of OB.

Airway Occlusion Caused by Tumor Necrosis After Chemotherapy with Bevacizumab

Airway Occlusion Caused by Tumor Necrosis After Chemotherapy with Bevacizumab