Tracheobronchomalacia (TBM) is a condition where the walls of the trachea (windpipe) and the bronchi (the two large airways branching into the lungs) are abnormally soft and floppy, causing them to collapse during breathing. The collapse is most pronounced when you exhale, cough, or do anything that increases pressure outside the airway. A diagnosis is made when the airway narrows by more than 50% during exhalation, and it can range from barely noticeable to nearly complete obstruction.
How the Airway Collapses
Your trachea and bronchi are held open by C-shaped rings of cartilage. The back wall of the airway, which sits against the esophagus, is made of softer tissue and muscle. In TBM, the cartilage rings are either too soft from birth or have been weakened by disease, so they can’t resist the natural pressure changes that occur during breathing. When you exhale or cough, pressure outside the airway briefly exceeds pressure inside it. In a healthy airway, stiff cartilage prevents any significant change in shape. In TBM, the walls buckle inward, partially or almost completely blocking airflow.
This collapse is dynamic, meaning the airway opens back up on the next breath in. That’s a key distinction from conditions like tumors or scar tissue, which create a fixed blockage that doesn’t change with breathing.
Congenital and Acquired Causes
TBM falls into two broad categories. The congenital form is present from birth, either as an isolated defect or alongside other developmental conditions. Because the trachea and esophagus develop from the same embryonic tissue, TBM is especially common in children born with esophageal abnormalities like esophageal atresia (where the esophagus doesn’t connect properly to the stomach). It also appears alongside cystic fibrosis, bronchopulmonary dysplasia in premature infants, and other airway conditions like laryngomalacia, which involves similar softening higher up in the throat.
The acquired form develops later in life. Blood vessel abnormalities can press on the airway from the outside, gradually reshaping and weakening the cartilage. Prolonged intubation (having a breathing tube in place for an extended period), chronic infections, and inflammatory conditions can all damage the airway wall over time. In adults, TBM frequently coexists with COPD and severe asthma, with prevalence rising sharply alongside disease severity. One study found TBM in about 1.6% of adults without any airway obstruction, compared to over 18% of those with severe asthma.
What It Feels and Sounds Like
The hallmark symptom is a persistent cough that often has a distinctive barking quality, sometimes described as sounding like a seal. This cough doesn’t respond to typical cough medications. Breathing tends to be noisy, with high-pitched wheezing or a rattling sound, particularly during exhalation or physical effort. Children may have trouble getting enough air during crying, feeding, or playing. Adults often notice worsening shortness of breath during exercise that seems out of proportion to their fitness level.
Clearing mucus from the airways becomes difficult because the collapsing walls interfere with the normal mechanism of coughing, which relies on a rush of air through an open airway. This leads to recurrent respiratory infections as mucus pools in the lungs. Some people also experience choking episodes during eating, since swallowing can put additional pressure on the already-floppy airway.
Why TBM Is Often Misdiagnosed
The symptoms of TBM, particularly wheezing and shortness of breath, overlap heavily with asthma and COPD. Many patients spend years being treated for asthma before TBM is identified. In one published case, a patient was diagnosed with asthma at age one and treated with standard asthma medications for years with no improvement. A case series of 17 patients with confirmed TBM found that all of them had originally been diagnosed with either reactive airway disease or acid reflux.
The biggest red flag is failure to respond to bronchodilators, the inhaler medications that open airways in asthma. In TBM, these drugs can actually make symptoms worse because they relax the smooth muscle in the airway wall, making it even more prone to collapse. If you or your child has been treated for asthma with no improvement, or if bronchodilators seem to make breathing harder, TBM should be considered.
How TBM Is Diagnosed
Standard imaging like a regular chest X-ray or CT scan taken at one moment in time will often look normal because the airway may be fully open when the patient isn’t actively exhaling or coughing. The condition only reveals itself during the dynamic phases of breathing.
Dynamic CT scanning captures the airway in real time as the patient breathes in and out, allowing doctors to measure exactly how much the airway narrows during exhalation. This is a noninvasive option that can produce two-dimensional and three-dimensional reconstructions of the airway. Severity is graded based on how much the airway’s cross-sectional area shrinks during exhalation: 50 to 75% narrowing is considered mild, 75 to 90% is moderate, and 90% or greater is severe.
Flexible bronchoscopy, where a thin camera is guided into the airways while the patient breathes, remains the gold standard. It lets doctors directly observe the collapse in real time and assess exactly which portions of the airway are affected. This is particularly important for surgical planning.
Non-Surgical Treatment
For mild cases, particularly in young children, the condition may improve on its own as the cartilage stiffens with growth. Management during this period focuses on controlling respiratory infections promptly, using airway clearance techniques to manage mucus buildup, and avoiding triggers that worsen collapse.
When symptoms are more significant, continuous positive airway pressure (CPAP) or similar machines can act as a “pneumatic stent,” delivering enough air pressure to keep the floppy walls from collapsing. This approach has been used since the early 1980s and can improve both quality of life and lung function test results. Pressure settings are sometimes fine-tuned during a bronchoscopy so doctors can see exactly how much pressure is needed to keep the airway open. CPAP is typically used at night and intermittently during the day, and in cases that don’t respond to other treatments, it often serves as a bridge to surgery.
Surgical Options
The primary surgical procedure for TBM is called tracheobronchoplasty. The surgeon reshapes the airway back into its normal D-shaped cross-section and reinforces the floppy back wall with a piece of polypropylene mesh, essentially giving the airway an internal splint. The mesh extends from the top of the chest down through both main bronchi. This can be done through a traditional open incision on the right side of the chest or through a minimally invasive robotic approach.
Before committing to surgery, many centers will place a temporary airway stent for about a week to see whether keeping the airway open actually improves the patient’s symptoms. If it does, they proceed with surgery. Quality-of-life scores improve substantially after the procedure. In one group of 35 patients, a widely used respiratory quality-of-life score dropped from 74 to 46 (lower is better), representing a major reduction in symptom burden. A smaller group undergoing robotic surgery saw similar improvements.
Airway Stents as a Standalone Option
For patients who aren’t candidates for surgery, airway stents can hold the airway open on their own. These come in several types: silicone (straight tubes or Y-shaped), metallic, and hybrid designs combining both materials. However, long-term stenting carries significant risks. In one study, more than two-thirds of all stents placed developed at least one complication during follow-up, including the stent shifting out of position, becoming blocked by mucus or tissue growth, or fracturing. Nearly one in five stents showed complications within just five days of placement.
Metallic stents pose a particular challenge because the airway tissue grows into and around the metal within three to six weeks, making removal increasingly difficult and dangerous the longer they stay in place. Hybrid stents were most prone to migration and mucus obstruction. Because of these complications, stents generally require regular monitoring with bronchoscopy, especially during the first year, and are most often used as a temporary measure rather than a permanent solution.