Central airway obstruction (CAO) is caused by a variety of malignant and nonmalignant diseases. It is unusual for most pulmonologists or thoracic surgeons to manage a significant volume of these patients. This inexperience and the apparent simplicity in treating central airway disorders may have led to complications and poor outcomes. In July 2005, the Food and Drug Administration (FDA) took notice and published a product advisory.1 The advisory was clearly focused on the inappropriate deployment of metallic stents in nonmalignant airway disease, and an inability to control the complications of this therapy. The American College of Chest Physicians' Interventional Chest and Diagnostic Procedures steering committee recently published an editorial, echoing the importance of the FDA recommendations.2 The frequency of complications mandates an ability to manage the stents after their placement.3,4–6 Known complications of stent placement, that can be seen in up to 35% of patients, include migration, mucus impaction, tumor in-growth or overgrowth, stent fracture, and exuberant granulation tissue.7–14 These complications were directly cited by the FDA. The advisory called for appropriate selection of patients and recommended “trained or experienced” physicians perform the procedures. The FDA further urged bronchoscopist's “to be aware of the guidelines from professional organizations regarding recommended provider skills and competency for these procedures.” (Table 1).
The recommendations of FDA are critically important, yet the guidance provided is only modestly helpful. The published guidelines for Interventional Pulmonary training, to which the advisory refers, are consensus statements from the ATS/ERS and the ACCP.15,16 While a good first step, they are not evidence-based and the thresholds for training are not derived from any validated metric. The training paradigm for basic bronchoscopy has never changed. The “see one, do one, teach one” philosophy has prevailed. All pulmonologists are initiated in roughly the same manner. The ACGME requires 50 supervised bronchoscopies for certification of fellows.17 Is this paradigm appropriate? Is 50 supervised procedures the appropriate threshold? In an on-going multicenter study of pulmonary fellows, the learning curve is still very steep for routine diagnostic bronchoscopies after 4 times that number.18 This clearly suggests an inadequacy of our current benchmark. Establishing competency based on an arbitrary number of bronchoscopies is fraught with complications. The ABIM has seen the difficulty in arbitrary quotas, but has not made any move to help establish the competence of their board-certified practitioners.19 There is a significant variation in the instruction of basic bronchoscopy.20 Furthermore, it has been shown that there is little correlation between bronchoscopy experience, extent of training, technical skill, and knowledge of bronchoscopic theory.21 We need a standardized and evidence-based curriculum. This curriculum should be based on validated, metrics for routine bronchoscopy. Dr Prakash22 has written that the focus in assessing specialty training is now “on quality of training rather than merely the quantity.” We agree! Unfortunately, definitive data are not yet present to define how we establish the appropriate quality of the training experience in standard diagnostic bronchoscopy.
Interventional bronchoscopy is significantly more complex in the planning, execution and subsequent management than routine diagnostic bronchoscopy. A full review of all the etiologies of CAO and potential therapeutics is well beyond the scope of this editorial. Generally, malignant CAO can be separated into endoluminal disease versus extrinsic compression and primary airway tumors versus metastatic disease. Patients with a primary neoplasm should always be considered for resection and their treatment should include a surgical consultation. Although airway stent placement can be used alone, the management of malignant CAO commonly involves the integration of multiple techniques, including rigid bronchoscopy for coring out tumor, laser photoablation, photodynamic therapy, and cryotherapy. Physicians who perform stent placement procedures must be competent in multiple techniques to avoid poor results and life-threatening complications.
Nonmalignant CAO represent more of a diagnostic and therapeutic dilemma, because many of the etiologies remain a mystery. Nonmalignant CAO may involve a small segment of the airway or the entire tracheobronchial tree. Like malignant CAO, management usually involves the use of other therapeutic airway techniques in combination with stent placement. However, unlike patients with malignant CAO these patients may have relatively normal life expectancy and therefore their treatment should involve methods with low risks of long-term complications. Therefore, stent placement of intrinsic disease should be avoided at all cost in these patients.14 Therapeutic strategies for nonmalignant CAO generally require concurrent evaluation with an experienced airway surgeon. Other types of nonmalignant CAO, such as anastomotic strictures after lung transplantation or tracheal resection are best dealt with at institutions that are used to dealing with these types of patients.23
Just as there are multiple indications for airway stent placement, there are also multiple types of airway stents. Silicone stents require rigid bronchoscopy for placement but they are considered relatively easy to remove and may have a lower incidence of granulation tissue formation than other stents. Self-expanding metallic stents (SEMS) do not require rigid bronchoscopy for insertion and this has created a growing popularity for SEMS because of the apparent, “simplicity” of their deployment. Unfortunately, the ease of deploying SEMS has created a pervasive belief that stent placement is easy and thus, able to be offered by any bronchoscopist. For most of the nonmalignant CAO, thoracic surgery remains the gold standard of care. Proper use of endobronchial therapy is best decided during multidisciplinary evaluation.
Although the advisory did not focus on interventional bronchoscopy, the FDA has recommended that only trained and experienced physicians place airway stents. They advised that when required, removal of an endothelialized stent should be performed only by an experienced interventional pulmonologist or airway surgeon. Most interventionalists find this to be a difficult procedure, which can be extremely hazardous to the patient.24,25 Serious complications are likely and include major bleeding, mucosal tears, tracheal perforations, pneumothorax, and permanent incorporation of stent fragments. What defines a “trained and experienced” bronchoscopist? Who and what determine expertise? The Cambridge handbook of Expertise and Expert Performance states: “We now have some evidence that surgical expertise is acquired and highly local. The ability to perform one task derives from one specific practice with that task and does not generalize to other, even apparently similar, surgical tasks.”26 This suggests that expertise in diagnostic bronchoscopy alone will not provide expertise in therapeutic bronchoscopy. In the evaluation of training for interventional procedures, it was determined that less than 30% of training programs offering interventional procedural therapies met published competency recommendations!27 Most “formally trained” interventional pulmonologists have dedicated an additional year of training under direct mentorship. The additional year provides sufficient volume to meet published recommendations.15,16 Just as importantly, this experience allows the trainee to see and manage difficult airways and complications of therapy, including complications of metallic stents. The development of expertise relies upon experience. “The interplay between formal knowledge of medicine and experiential knowledge has emerged as a central issue in understanding medical expertise.”26 If we want to provide the highest level of care to the patients at the highest risk of airway complications, we must understand what is required to develop both the cognitive and technical expertise and create pathways that fulfill the didactic, decision-making, and experiential needs required in training interventional pulmonologists. To say a pulmonologist is trained in bronchoscopy and therefore can perform any procedure through a bronchoscope is not supported by data available in the fields of cognitive task analysis and expertise evaluation. Transfer of skills between procedural tasks is difficult because of the high specificity of process learning.26 Single weekend or week long training courses are not likely to be the most effective method to train pulmonologists to perform therapeutic bronchoscopy. In a randomized controlled trial of surgical skills training, residents were assigned to a single training program or a distributed weekly program over 4 weeks.28 Surgical residents demonstrated better retention and transfer of skills when attending distributed sessions. The learning benefits of sequential and repetitive tasks have long been known. The benefits of the repetitive use of simulators over time was demonstrated with a prospective evaluation of GI fellows using simulation laboratory training over 7 months compared with solely clinical training for interventional endoscopy.29 Expertise has been found to be most related to repeated practice under a carefully controlled training program.26
The cognitive training required for a solid foundation, upon which technical training builds, is as important as procedural skill. Teaching cognitive skills has been demonstrated to improve technical ability.30 We must better understand what defines expertise in bronchoscopy and determine what decision making is critical to procedural success. The ACCP, the ACGME, and the AAB should demand and support further study to delineate procedural metrics, define competency, and subsequently mandate evidence based cognitive and technical training.
The FDA's advisory is singularly more about bronchoscopists than about the stents. As a profession, we must understand what defines the expert and create a program to improve the cognitive and technical skill of the physician, providing both diagnostic and therapeutic bronchoscopy. Just as the science of stent placement in the tracheobronchial tree must continue to advance, so too must our understanding of procedural competence. It is only with this evidence that we, as a profession, can elucidate the most appropriate curriculum and determine the suitable metrics to define competency. Until these metrics are established, the published guidelines of the ACCP15 and the ATS/ERS16 regarding recommended provider training requirements, clinical experience, and competency must be followed. It is important that all bronchoscopists' heed the FDA's advisory and practice restraint in airway stent placement. Broad recommendations to clinicians interested in stent placement should include:
- Patient selection is critical and benign disease should only be managed with a stent as a last resort and probably be referred to a center with expertise in this area.
- Physicians placing airway stents should follow best practice, understand the indications and be able to manage the complications should they arise. Further, it is recommended that they should have access to expertise in rigid bronchoscopy or airway surgery.
- Physicians with experience in stent placement can manage malignant CAO. If problems arise referral to a center with expertise in airway management is warranted.
- It is also the responsibility of every pulmonologist or surgeon performing interventional bronchoscopy to report all adverse outcomes from stent placement to the FDA, and to review these complications in regularly scheduled morbidity and mortality conferences.
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