The intriguing case of an endobronchial valve migration


Lung surgery, like every other type of surgery, can have complications that sometimes require further procedures to be dealt with. Surgeons are always looking for new ways to keep these procedures as minimally invasive as possible, but they also have to ensure these are effective and safe.


Consultant surgeon Mr David Waller  and his surgical trainee Miss Michelle Lee at the Department of Thoracic Surgery in St Bartholomew’s Hospital, London, routinely deal with complex cases of lung surgery. They have recently shared an unusual case of foreign body migration of an endobronchial valve implanted in one of their patients.


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Hello and welcome to ResearchPod. Thank you for listening and joining us today.


In this episode, we’ll talk about the work of Mr David Waller, a consultant surgeon at the Department of Thoracic Surgery in St Bartholomew’s Hospital, London who routinely deals with complex cases of lung surgery, and Miss Michelle Lee, who is his surgical trainee.


Lung surgery, like every other type of surgery, can have complications that sometimes require further procedures to be dealt with. Surgeons are always looking for new ways to keep these procedures as minimally invasive as possible, but they also have to ensure these are effective and safe. Mr Waller and his surgical trainee Miss Lee have recently shared their experience with an unusual case of foreign body migration, more specifically an endobronchial valve, a small medical device implanted by doctors in one of the airway branches to treat specific breathing complications.


The lungs are two organs sitting on each side of the thorax that consist the main parts of the human gas-exchanging system, which means they supply oxygen to the body, and they dispose of the carbon dioxide waste produced by the cells. Air is pumped into the lungs by entering the nose and mouth and through the windpipe, also known as trachea, entering the lung pipe system, called bronchi. This starts with a left and right main bronchus, one for each lung. Each main bronchus branches off into smaller ducts, and they themselves into smaller ones and so on, resembling a lot the branches of a tree. The walls of the smaller ducts have a thin layer of muscle that allows them to relax or contract, affecting their width and the amount of air passing through them. The tiny final ducts, called bronchioles, have a width of half a millimetre or 1/50 of an inch. Each bronchiole ends in a tiny air sac called an alveolus. This is where the gas exchange takes place. Every lung is wrapped in a slippery two-layered tissue called pleura. The inner layer of the pleura clings to the outside of the lung, while the outer layer lines the inside of the ribcage and its muscles. Between the two layers a space called the pleural cavity is formed.


But what is an endobronchial valve? Endobronchial means the inside of the airway, and – being a valve – it’s a small device that a surgeon can implant in one of the bronchi to control the airflow in it, using a technique called bronchoscopy.


With bronchoscopy the clinician can look inside the airways using a flexible camera known as an endoscope. Endobronchial valves were initially designed to improve breathing for patients with emphysema, a disease caused by the loss of lung elasticity making the bronchi unable to contract and therefore inefficient in moving air out of the lungs during exhalation. Eventually, the trapped air leads to the over-expansion of the lungs and the breakdown of the walls of the alveoli, causing poor airflow and long-term breathing problems.


The valve, which self-expands after insertion adjusts to the width of the duct. This deals with the issue by allowing air to exit the segment of the lung supplied by the bronchus it sits in during exhalation, but preventing air entering the same segment during inhalation. This redirects air to the rest of the lung, which expands to help compensate for the dysfunctional collapsed area making breathing much easier.


Besides reducing the volume of defective lung segments, the endobronchial valves can also be used to stop a prolonged air leak. The air leak comes from an opening in both the lung tissue and the inner layer of its overlying pleura, leading to direct communication of a bronchus with the pleural cavity. This can happen spontaneously following injury or as a complication after lung surgery. The communication between the lung and the pleural cavity, also known as a fistula, can lead to problems with infections, long term drains and the need to re-operate. Using the valve has been shown to be effective in some cases of spontaneous or post-surgery air leaks. The mechanism behind this is that, by preventing further leakage the endobronchial valve gives time for the affected tissues to heal and the communication between the two areas to close.


Mr David Waller and the rest of the surgical team at the Department of Thoracic Surgery in St Bartholomew’s Hospital, London have recently encountered a very unusual case of migration of an endobronchial valve, several weeks after they used it in one of their patients.


A 62-year-old man who initially underwent surgery for a suspected small lung tumour had the upper segment of his right lung resected. Following this, he developed a surgery-related prolonged air leak requiring the long-term use of drains, and eventually a localised infection requiring further surgery to clear. During this second surgery, the team also dealt with the ongoing leak, performing a procedure to expose the inside of the lung to the outside of the body by creating an opening to the overlying skin, called cavernostomy. To achieve optimal results, they also removed the third right rib on the same side and performed a chest muscle reconstruction. Unfortunately, these drastic measures did not solve the problem. Diagnostic bronchoscopy revealed a communication between a bronchus and the pleural cavity, also known as bronchopleural fistula. They decided to use an endobronchial valve to control the airflow inside the bronchus. This was inserted during the procedure and had an immediate effect, substantially reducing the visible leak from the chest drain that was already in place. The patient recovered quickly after the procedure, allowing for the drain to be removed in two weeks time.


However, although the patient’s breathing improved the surgical wound on the chest would not heal. 11 weeks later he visited the outpatient department for a follow up and a review of his open wound. After examining him, Miss Michelle Lee and her team were surprised to find the endobronchial valve poking out of the man’s wound! It was removed and in the following weeks the wound finally healed, and the patient was discharged from the team’s care.


The endobronchial valve used by the team was a one-way valve originally designed to treat patients with a severe case of emphysema. It has recently also been used to close spontaneous or post-surgical air leaks, since blocking the airflow to the fistula allows the wound to heal and the abnormal opening to close. Although there are anchors on the valve designed to penetrate the internal surface of the bronchi preventing valve migration, this can still happen. Patients then complain of a sudden worsening of their breathing and this symptom creates an immediate need for thorough investigations via urgent x-rays and bronchoscopy. The valve is then often removed during bronchoscopy and another implanted if deemed appropriate by the surgeon. More rarely, the patients will cough the valve up.


It is not entirely clear what causes the endobronchial valves to dislodge, although a possible explanation could be the choice of the incorrect size for the respective duct width. That implies that size decision and placement of a valve should both be performed by a surgeon who is very familiar with the procedure and its risks.


From the start. Mr David Waller’s team had to deal with an unusual indication of valve placement, as this was not a straightforward case. However, since the leak eventually seized, the team believes that the fistula healed behind the valve and that the healing process gradually pushed it out of the lungs and into the skin, potentially through a false passage created by the surgery itself. Despite the team’s assumptions, the exact reason behind the valve’s migration to the skin and the actual route it followed remains unclear. According to Mr David Waller and Miss Michelle Lee, there is a lesson learned from this unusual case; that extended indications of endobronchial valve insertion should be treated with extra caution by a team of experienced and appropriately trained thoracic surgeons.


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