use of endobronchial ultrasound scope (ebus) transducer to identify pneumothorax-a feasibility study

Conditions: Pneumothorax

Summary: endobronchial ultrasound (ebus) is a technique that uses ultrasound along with bronchoscope to visualize airway wall and structures adjacent to it. pneumothorax is a known complication from ebus procedure. to rule out a pneumothorax after the procedure, a chest -x-ray is usually done. point-of-care sonography has emerged as an invaluable tool in the assessment of patients with both traumatic and non-traumatic dyspnea. multiple studies involving bedside ultrasound has shown that a pneumothorax can easily be ruled out if pleural sliding sign or b lines are visualized on lung ultrasonography; the accuracy of lung ultrasound in ruling out pneumothorax approach computed tomography and exceed plain radiography. preforming a lung ultrasound using the ebus bronchoscope tip as a way to rule out pneumothorax has never been described previously. if this is possible it will obviate the need of getting a chest -x-ray and decrease the dose of radiation that the patient is exposed to. in this study we will demonstrate that the feasibility of using the transducer of the ebus bronchoscope to perform bedside lung ultrasound to rule out pneumothorax.

the use of ultrasound in diagnosis and treatment of patients has been well-established for many decades. the use of thoracic ultrasonography is a fairly new and rapidly evolving field. the interface between the ultrasound probe and chest wall can produce artifacts that can be useful in diagnosing a pneumothorax. in one prospective study the utility of ultrasound was compared to chest x-ray and ct-scan by trauma surgeon (1). their results demonstrate that ultrasound was more sensitive than chest x-ray to identify early pneumothorax. the study also demonstrated that 63% of pneumothoraxes diagnosed were occult and would have been later diagnosed on ct chest. in these critical situations where is subtle pneumothorax can be missed, a bedside ultrasound has been proven to accelerate the diagnosis and thus treatment. similarly another prospective study noted that up to 76% of all traumatic pneumothoraxes were missed by standard ap chest x-ray, when interpreted by trauma team (2). this number was significantly higher than a retrospective study in which 55% of pneumothoraxes were missed on ap chest films reviewed by radiologist (3). the sensitivity of ultrasound in detecting pneumothorax has been demonstrated in multiple studies to be similar to ct-scan, which is considered to be gold standard for the detection of pneumothorax (4, 5). visualization of normal pleural lung sliding is itself sufficient to exclude pneumothorax , if lung sliding is not present the finding of b lines( vertical lines), which usually originate from the lung parenchyma will also exclude the possibility of pneumothorax at the interspace in question, since the lung parenchyma cannot be visualized if there is air interposed between the pleura and the lung. endobronchial ultrasound (ebus) is considered an integral component of diagnosis of indeterminate mediastinal lymph nodes, masses and peripheral pulmonary nodules. ebus is minimally invasive, safe and highly accurate (6). according to current estimates that incidence if complications associated with ebus is between 1-1.5% (6, 7). major complications are associated with needle aspirations. the incidence of pneumothorax was found to be 3.3% in one retrospective analysis (8), with 31% of patients requiring chest tube eventually for treatment of pneumothorax. post-procedure chest-x-rays are commonly performed to rule out pneumothorax. based on current data chest-x-rays are considered suboptimal for diagnosis of pneumothorax and can also expose patients to undue radiation. the ebus probe contains a small ultrasound through which ultrasound images of various structure i.e. lymph nodes, ventricles, pulmonary vasculature can be visualized. ruling out pneumothorax via lung ultrasound using ebus probe has never been described. if this is possible, it avoids the need of obtaining post-procedure chest-x-rays thus decreasing the dose of radiation exposure and prevent time delays for the arrival of chest-x-rays. in this study we will demonstrate the feasibility of using the transducer of the ebus bronchoscope to perform bedside lung ultrasound to rule out pneumothorax.

Eligibility criteria:
inclusion criteria: 1. all patients presenting for bronchoscopy (these patient are expected to have normal pleural sliding sign identified by ultrasound) 2. patients with pneumothorax requiring chest tube(this group of patient is expected to have residual pneumothorax for identification of absence of lung sliding, b lines and lung point) 3. patients with respiratory failure on mechanical ventilation(this group of patient is expected to have alveolo-interstitial findings such as b lines) exclusion criteria: -absence of informed consent