Virtual reality bronchoscopy simulation: a revolution in procedural training.

BACKGROUND: In the airline industry, training is costly and operator error must be avoided. Therefore, virtual reality (VR) is routinely used to learn manual and technical skills through simulation before pilots assume flight responsibilities. In the field of medicine, manual and technical skills must also be acquired to competently perform invasive procedures such as flexible fiberoptic bronchoscopy (FFB). Until recently, training in FFB and other endoscopic procedures has occurred on the job in real patients. We hypothesized that novice trainees using a VR skill center could rapidly acquire basic skills, and that results would compare favorably with those of senior trainees trained in the conventional manner. METHODS: We prospectively studied five novice bronchoscopists entering a pulmonary and critical care medicine training program. They were taught to perform inspection flexible bronchoscopy using a VR bronchoscopy skill center; dexterity, speed, and accuracy were tested using the skill center and an inanimate airway model before and after 4 h of group instruction and 4 h of individual unsupervised practice. Results were compared to those of a control group of four skilled physicians who had performed at least 200 bronchoscopies during 2 years of training. Student's t tests were used to compare mean scores of study and control groups for the inanimate model and VR bronchoscopy simulator. Before-training and after-training test scores were compared using paired t tests. For comparisons between after-training novice and skilled physician scores, unpaired two-sample t tests were used. RESULTS: Novices significantly improved their dexterity and accuracy in both models. They missed fewer segments after training than before training, and had fewer contacts with the bronchial wall. There was no statistically significant improvement in speed or total time spent not visualizing airway anatomy. After training, novice performance equaled or surpassed that of the skilled physicians. Novices performed more thorough examinations and missed significantly fewer segments in both the inanimate and virtual simulation models. CONCLUSION: A short, focused course of instruction and unsupervised practice using a virtual bronchoscopy simulator enabled novice trainees to attain a level of manual and technical skill at performing diagnostic bronchoscopic inspection similar to those of colleagues with several years of experience. These skills were readily reproducible in a conventional inanimate airway-training model, suggesting they would also be translatable to direct patient care.

Nd-YAG laser damage to metal and silicone endobronchial stents: delineation of margins of safety using an in vitro experimental model.

STUDY OBJECTIVE: To identify margins of safety within which bronchoscopic Nd-YAG laser resection can be performed without damaging indwelling tracheobronchial stents. DESIGN: Experimental in vitro study simulating a patient-care environment. METHODS: Uncovered and covered metal Wallstent (Schneider; Zurich, Switzerland) and Dumon (Bryan Corporation; Woburn, MA) silicone stents were deployed in the tracheobronchial tree of a ventilated and oxygenated (fraction of inspired oxygen, 40%) heart-lung block of a dead canine. Rigid bronchoscopic Nd-YAG (1,064 nm) laser procedures were performed in order to deliver laser energy using fiber-to-target distances of 10 mm and 20 mm, and noncontact, continuous-mode, 1-s pulses at power settings of 10 W, 30 W, and 40 W. The major outcome measure was laser-induced stent damage, defined as discoloration, ignition, or breakage. This was assessed using six power densities: 75 W/cm(2), 172 W/cm(2), 225 W/cm(2), 300 W/cm(2), 518 W/cm(2), and 690 W/cm(2). RESULTS: The uncovered Wallstent and the silicone stent remained intact at power densities of 75 W/cm(2) (10 W, 20 mm) and 172 W/cm(2) (10 W, 10 mm), but were damaged at power densities > 225 W/cm(2) (30 W, 20 mm). The covered Wallstent was damaged at all power densities tested. CONCLUSION: Uncovered Wallstent and silicone stents are not damaged when Nd-YAG laser energy is delivered using power densities < or = 72 W/cm(2) (10 W, 10 mm). Covered Wallstents, however, had a high likelihood of ignition at all power densities studied.

Development of an experimental paradigm in which to examine human learning using two computer-based formats.

Computer-based self-instructional programs are frequently promoted as means to augment or replace the traditional anatomy curricula taught in medical schools. These programs may range from static slide shows to fully immersive virtual environments. However, the impact of these learning technologies on knowledge acquisition, and their comparative cost/benefit to education remain unclear. As a consequence, we are embarking on a series of experiments to compare knowledge acquisition and the meaningful use of information among students who are learning anatomy using one of two different computer-based self-instructional formats. These studies will be based on a specially developed learning module on basic lung anatomy; they will utilize a variety of assessment tools to measure factual knowledge, conceptual understanding of spatial-anatomic relationships, and the ability to apply newly acquired knowledge of anatomy to clinical problem-solving scenarios. The primary object of this paper is to describe the design and development of the underlying test module and to outline the two computer-based formats that will be evaluated. The virtual reality (VR) environment, UCSD's Anatomic VisualizeR, provides dynamic access to 3-dimensional polygonal models of the lesson content and supports student-centered exploration and learning. The multimedia environment, Microsoft PowerPoint, provides a structured presentation of the lesson content and illustrates important anatomic structures through the use of 2-dimensional images derived by screen captures of models available in the VR learning module. This paper also provides an overview of the first experiment in the series, a pilot study using first-year medical students without previous participation in a medical school anatomy curriculum. For this study, students will be prospectively randomized into two groups, each group learning the lung anatomy lesson using one of the computer-based formats described. Immediate knowledge retention will be measured by asking students to complete the assessment instrument immediately after completing their learning module. The results of the pilot study will be used to refine and improve the design of the remainder of studies planned in this experimental series.

Hospital charges attributable to bronchoscopy-related complications in outpatients.

BACKGROUND: Despite literature pertaining to algorithms of care, operating room charges and other financial management issues in medicine, there is a paucity of data pertaining to the fiscal consequences of bronchoscopic practice. OBJECTIVE: To identify hospital charges directly attributable to bronchoscopy-related complications in outpatients. METHODS: A prospective analysis of outpatient bronchoscopy-related complications, clinical outcomes and hospital charges resulting directly from procedure-related adverse events in 660 consecutive outpatients undergoing flexible fiberoptic bronchoscopy (FFB) during a period of 30 consecutive months at the University of California, San Diego Medical Center, was performed. RESULTS: Altogether, 1,009 consecutive outpatient FFBs were performed on 660 patients (mean age 58 years, range 16-91 years). Fifty adverse events (5% of all procedures) occurred in 44 patients. These were bronchospasm (31 cases), hemoptysis (5 cases), pneumothorax (3 cases), nausea/vomiting (3 cases), hypoxemia (2 cases), seizure (2 cases), laryngeal spasm (2 cases), chills/fever (1 case) and a vasovagal episode (1 case). Prolonged length of stay in the postprocedure recovery area on 22 occasions (2.2% of all procedures) resulted in USD 6,996 in additional hospital charges. Hospitalization was necessary in only 5 instances (0.5% of all procedures), but resulted in USD 34,500 in additional charges (range for the 5 patients, USD 2,000-11,000) that were directly attributable to a procedure-related complication. CONCLUSION: Hospital charges directly attributable to outpatient flexible bronchoscopy-related complications are minimal, but escalate considerably if hospitalization becomes necessary.

Evidence against routine scheduling of surveillance bronchoscopy after stent insertion.

STUDY OBJECTIVES: To determine whether routine scheduling of surveillance flexible fiberoptic bronchoscopy is warranted within 2 to 3 months after silicone stent insertion for central airway obstruction. DESIGN: Retrospective cohort study. SETTING: University medical center. PATIENTS: All patients with silicone stents placed for benign or malignant tracheobronchial obstruction during a 3-year period. METHODS: Incidence of stent-related complications, new respiratory symptoms, and need for therapeutic bronchoscopic intervention were noted in patients undergoing surveillance bronchoscopy (SFFB) and emergency bronchoscopy (EFFB), defined as flexible fiberoptic bronchoscopy prompted by onset of new symptoms before the date of scheduled SFFB. RESULTS: One hundred one silicone stents were inserted in 88 patients (47 with cancer, 41 with benign disease). Eighteen patients died within 2 months and had no bronchoscopy. Seventy patients underwent either SFFB or EFFB. Stent-related complications were detected in 9 of 31 asymptomatic patients (29%) undergoing SFFB; all had received tumor-specific therapy after stent insertion (in 7 of 8 patients [88%] reporting new respiratory symptoms at the time of SFFB, and in 26 of 31 patients [84%] undergoing EFFB). Overall, stent-related complications were detected in nine asymptomatic patients (10% of total), of which only four patients (5% of total, but 13% of all asymptomatic patients) required therapeutic interventions. CONCLUSION: Routine SFFB within 2 to 3 months after stent insertion did not detect a high incidence of stent-related complications among patients without new respiratory symptoms.

Novel flexible bronchoscope and single-use disposable-sheath endoscope system. A preliminary technology evaluation.

OBJECTIVE: To measure image clarity, ease of use, and handling performance of a flexible fiberoptic bronchoscope (B-F 100; Vision Sciences; Natick, MA) and sterile single-use disposable-sheath endoscope system (BS-F21 EndoSheath; Vision Sciences). DESIGN: Prospective, multicenter diagnostic technology evaluation of a medical device newly approved by the US Food and Drug Administration. SETTING: Three tertiary care referral centers with busy bronchoscopy practices. PATIENTS: Twenty-four patients undergoing bronchoscopy with a flexible fiberoptic bronchoscope and disposable sheath endoscope system. METHODS: Flexible bronchoscopy was performed through a transnasal or transoral route after topical upper airway anesthesia using standard techniques. After each procedure, the bronchoscopist rated the performance of the medical device under study using a linear scale of 1 (poor) to 5 (excellent and equal to that of a conventional flexible fiberoptic bronchoscope). RESULTS: Mean performance ratings were > 4.0 (range, 4.17 to 4.63) for image clarity, illumination, lack of fogging, distal tip angulation, and ease of transnasal passage. All other ratings were > 3.0 (range, 3.54 to 3.87), the lowest of which was handling comfort. CONCLUSION: The flexible fiberoptic bronchoscope with sterile single-use disposable-sheath endoscope system has the potential to reduce scope downtime by eliminating the need for high-level disinfection between procedures. Illumination, image clarity, and ease of insertion are very good, justifying future prospective studies comparing this device to conventional flexible fiberoptic bronchoscopes.

Predicting survival in patients with recurrent symptomatic malignant pleural effusions: an assessment of the prognostic values of physiologic, morphologic, and quality of life measures of extent of disease.

PURPOSE: To determine the prognostic value of pleural fluid pH, pleural fluid glucose, extent of pleural carcinomatosis (EPC) score, and Karnofsky Performance Scale (KPS) score in patients with recurrent symptomatic malignant pleural effusions. DESIGN: Prospective 53-month study. SETTING: Referral center for interventional pulmonology. PATIENTS: Eighty-five consecutive patients (42 men and 43 women) with recurrent symptomatic malignant pleural effusions who were referred to the interventional pulmonary service for thoracoscopic pleurodesis. MEASUREMENTS: Pleural fluid pH, pleural fluid glucose, EPC score, and KPS score. RESULTS: The KPS score was the only statistically significant predictor variable. Patients with a KPS score >/= 70 had a median survival of 395 days, as opposed to a median survival of only 34 days for patients with a KPS score /= 70, it may be very reasonable to proceed with thoracoscopic talc pleurodesis for management of their malignant pleural effusions.

Thoracoscopy: window to the pleural space.

Thoracoscopy has provided chest physicians and surgeons with an opportunity to rethink their approach to patients with pleural and pulmonary disease. In this brief review, several methods pertaining to videothoracoscopic procedures are described, followed by a summary of the major indications for this procedure. The question of whether a thoracoscopic approach to diagnosis or treatment could replace more conventional approaches is addressed for several disease processes. Finally, a few thoughts about future directions of this emerging technology are shared.

CT-guided catheter drainage of loculated thoracic air collections in mechanically ventilated patients with acute respiratory distress syndrome.

OBJECTIVE: We report our experience with CT-guided percutaneous catheter drainage of loculated thoracic air collections in mechanically ventilated patients with acute lung injury or acute respiratory distress syndrome. MATERIALS AND METHODS: Nine critically ill patients had 17 air collections (13 pneumothoraces, three pneumatoceles, one tension pneumomediastinum) that either developed despite the presence of standard surgical chest tubes or were in loculated sites that were difficult to access. All nine patients were ventilated mechanically for a clinical diagnosis of acute respiratory distress syndrome. Catheter size ranged from 7- to 28-French. Response was measured by imaging follow-up, ventilatory parameters, and clinical outcome. RESULTS: On follow-up imaging studies, all 17 air collections were shown to have been evacuated successfully. Catheters remained in place for a mean of 11 days (range, 4-28 days). No major complications occurred. Sixteen air collections were treated successfully with CT-guided catheter placement alone; the remaining air collection, a pneumothorax, was treated with subsequent placement of a chest tube by the surgeon at the patient's bedside. No surgery was undertaken for the air collections. Improvement in gas exchange was documented by increase in the hypoxemia ratio (arterial oxygen pressure divided by the inspired fraction of oxygen) in seven of 12 drainages; the other drainages were accompanied either by no improvement or by deterioration. Eight (89%) of the nine patients eventually were extubated and discharged from the hospital. The ninth patient died. CONCLUSION: CT-guided percutaneous catheter drainage provided effective treatment for loculated thoracic air collections and obviated surgical intervention in these critically ill, high-surgical-risk patients.

Effect of music on state anxiety scores in patients undergoing fiberoptic bronchoscopy.

OBJECTIVE: To study the effect of music on state anxiety levels in patients undergoing flexible fiberoptic bronchoscopy (FFB). DESIGN: Randomized clinical trial using pretests, posttests, and two groups. SETTING: Pulmonary special-procedures unit of a tertiary-care referral center. PATIENTS: Sixty adult patients: 30 patients received music during bronchoscopy and 30 control subjects received no music. RESULTS: The study population had baseline state anxiety levels similar to those previously reported in surgical patients (42.6 +/- 13 vs 42.7 +/- 14; p value, not significant [NS]) and higher than those reported in normal working adults (42.6 +/- 13 vs 34.4 +/- 10; p < 0.001). Experimental and control groups were similar in patient and procedure-related characteristics and baseline pre-FFB state and trait anxiety scores. Although trait anxiety scores decreased significantly after the procedure (pooled post-FFB scores of 32.6 +/- 10 vs pre-FFB scores of 35.5 +/- 11; p < 0.001), no reductions were noted in state anxiety (pooled post-FFB scores of 42.8 +/- 13 vs pre-FFB scores of 42.6 +/- 13; p value, NS). More importantly, playing music through headphones during FFB did not result in a statistically or clinically significant reduction in either state or trait anxiety when compared to control subjects. CONCLUSION: Relaxation music administered through headphones to patients during flexible bronchoscopy does not decrease procedure-related state anxiety.

Evaluation of patient-related and procedure-related factors contributing to pneumothorax following thoracentesis.

OBJECTIVE: To evaluate patient-related and procedure-related risk factors for thoracentesis-related pneumothorax. DESIGN: Prospective, nonrandomized cohort study. SETTING: Pulmonary Special Procedures Unit of a university medical center. METHODS: Thoracentesis using either a 22-gauge, a Boutin, or a Cope needle (depending on availability and operator preference) was performed by the pulmonary faculty or by pulmonary physicians-in-training under faculty supervision. In order to control for effusion size and the presence of loculations, chest radiography and pleural ultrasonography were performed prior to each thoracentesis. Potential patient-related and procedure-related risk factors for pneumothorax were analyzed at the procedure level using the presence or absence of pneumothorax on the postprocedure chest radiograph as the sole outcome variable. RESULTS: Two hundred fifty-five thoracenteses were performed in 205 adult patients (113 men and 92 women; mean age, 58.8+/-18 years) over a 3(1/2)-year period. One hundred fifty procedures were performed for diagnostic purposes, 28 procedures were performed for therapeutic purposes, and 77 procedures were performed for both diagnostic and therapeutic purposes. Based on the radiographic criteria, 152 effusions (60%) were small. Loculations were present in 76 patients (30%). Pneumothoraces occurred in 14 instances (5.4%), and chest tube drainage was required in 2 instances (0.78%). Hospitalization status, critical illness, effusion size or type, presence of loculations, operator, needle type, amount of fluid withdrawn, occurrence of dry tap, and type of thoracentesis were not associated with an increased frequency of pneumothorax. The only predictor variable demonstrating statistical significance was repeated thoracentesis. CONCLUSION: The results of a bivariate analysis suggest that pneumothorax following thoracentesis is a rare event that is not easily predictable when the procedure is performed by experienced operators in a controlled setting.

Therapeutic thoracoscopy.

Thoracoscopy provides a minimally invasive window to the pleural space, lung, and mediastinum. Further advances prompted by improvements of specifically designed endoscopic instruments and procedural techniques are expected. There is no doubt that thoracoscopy has a place among therapeutic procedures in the chest. The time-proven principles of thoracic surgical intervention, particularly in regard to patients with cancer, however, must not be neglected. A beckoning window always offers new opportunities, but the open door of classic surgical techniques should not be ignored.

Multicentric endobronchial smooth muscle tumors associated with the Epstein-Barr virus in an adult patient with the acquired immunodeficiency syndrome: a case report.

BACKGROUND: The incidence of benign and malignant smooth-muscle tumors (leiomyomas and leiomyosarcomas) is increased in children with the acquired immunodeficiency syndrome (AIDS). Epstein-Barr virus (EBV) infection has been implicated in the pathogenesis of these tumors. Smooth muscle tumors in adults with AIDS are extremely rare, with only six cases involving extrapulmonary sites reported in the literature. METHODS: Multifocal smooth walled endobronchial tumors were removed from a 35-year-old man with AIDS using rigid bronchoscopic laser resection. The tumor tissues were processed for routine histology, immunohistochemical stainings, and EBV in situ hybridization using an EBV-encoded RNA- 1 RNA oligonucleotide probe. RESULTS: Histologic features and immunohistochemical profiles were characteristic of smooth muscle tumors. EBV gene expression was detected in > 90% of tumor cell nuclei. Although overt histopathologic evidence of malignancy was lacking, some of the histopathologic findings, along with multifocality of the tumors and the rapid appearance of new tumors, suggested an unfavorable prognosis in this case. CONCLUSIONS: To the authors' knowledge, this is the first reported case of multicentric smooth muscle tumors involving the bronchi and lungs of an adult patient with AIDS. Diffuse EBV gene expression in the tumor tissue supports the hypothesis that EBV infection contributes to the pathogenesis of tumors of smooth muscle origin in immunocompromised hosts.

Therapeutic rigid bronchoscopy allows level of care changes in patients with acute respiratory failure from central airways obstruction.

OBJECTIVE: To determine whether emergency rigid bronchoscopic intervention, including Nd-YAG laser resection or stenting, immediately affected the need for continued mechanical ventilation or intensive care level of support in critically ill patients with acute respiratory failure from malignant or benign central airways obstruction. DESIGN: Retrospective review of medical records of all patients with acute respiratory failure and malignant or benign tracheobronchial obstruction necessitating intubation, mechanical ventilation, or hospitalization in the ICU prior to referral for therapeutic bronchoscopy. SETTING: University of California San Diego, a tertiary care institution specialized in airway management. PATIENTS: Medical records of 32 patients with malignant or benign central airways obstruction requiring admission to the ICU prior to rigid bronchoscopic intervention between January 1994 and April 1996. INTERVENTIONS: Emergent rigid bronchoscopy with dilatation, Nd-YAG laser resection, or silicone stent insertion performed in the operating room under general anesthesia. RESULTS: Thirty-two patients with central airways obstruction requiring emergent hospitalization in the ICU were referred for therapeutic rigid bronchoscopy. Airway strictures were caused by benign disease in 18 patients, and by primary bronchogenic lung cancer in 14. Of the 19 patients who were mechanically ventilated, bronchoscopic intervention allowed immediate discontinuation of mechanical ventilation in 10 (52.6%). Twenty-five patients had indwelling artificial airways (12 endotracheal tubes, 13 tracheotomy tubes). Two, however, were considered tracheotomy-dependent because of neuromuscular disease. Of the remaining 23 patients, immediate extubation or decannulation was possible in seven (30.4%). Of seven patients with no indwelling airway, five (71.4%) were immediately transferred to a lower level of care after intervention. Of the 32 total patients, 20 (62.5%) were immediately transferred to a lower level of care immediately after intervention. CONCLUSIONS: Emergency laser resection or stent insertion can favorably affect health-care utilization in patients with acute respiratory distress from central airways obstruction. Treatment may be lifesaving and allows successful withdrawal from mechanical ventilation, hospitalization in a lower level of care environment, relief of symptoms, and extended survival in critically ill patients. In patients with regionally advanced cancer, the palliative nature of this procedure postpones death by respiratory distress and may prompt consideration for institution of conservative comfort measures to reduce patient suffering.

Analysis of chronic obstructive pulmonary disease referrals for lung volume reduction surgery. The University of California San Diego Emphysema Treatment Group.

BACKGROUND: Preliminary results of lung volume reduction surgery (LVRS) for patients with severe emphysema are promising, although many issues regarding the selection process for LVRS are still unaddressed. For example, it is unclear which patients should be referred for pulmonary rehabilitation, lung transplantation, or LVRS, and whether health-care providers are optimizing conservative treatment options before referral for surgical intervention. The purpose of this analysis is to describe preliminary results of the evaluation process for LVRS implemented as part of an integrated, programmatic approach to the evaluation, treatment, and rehabilitation of patients with advanced emphysema. METHODS: The records of 105 consecutive patients with chronic obstructive pulmonary disease (COPD) referred for consideration for LVRS at the University of California San Diego Medical Center were reviewed. Results of prospective data collection pertaining to patient demographic, baseline dyspnea scores, and history of prior treatment, including pulmonary rehabilitation, were extracted. Patient disposition after the evaluation was noted. RESULTS: One hundred five patients (mean age 65 years, range 40 to 84 years) completed evaluation. Fifty-eight had never before participated in pulmonary rehabilitation, and 47 of these patients were eventually referred to a rehabilitation program. Fourteen patients were referred for consideration of lung transplantation, 25 were considered eligible for LVRS, 13 were still undergoing rehabilitation and surgical eligibility had not yet been determined, and 53 were ineligible for LVRS because patients had other illnesses (n = 34), did not meet radiological or physiologic criteria (n = 5), were considered too ill (n = 5), or were too healthy (n = 9) after rehabilitation to warrant surgical intervention. CONCLUSIONS: Lung volume reduction surgery is a surgical option to be considered within the framework of an integrated medical evaluation program that includes pulmonary rehabilitation. Pulmonary rehabilitation remains an often underused therapeutic alternative in patients with severe COPD. It has become the central component of our comprehensive management program for patients with severe dyspnea and deteriorating quality of life.

A comparison of thoracoscopic talc insufflation, slurry, and mechanical abrasion pleurodesis.

The purpose of this study was to compare the anatomic and histopathologic results of four different methods of pleurodesis in 10 dogs. Each animal was randomly assigned to receive two of the following methods of pleurodesis: thoracoscopic talc insufflation (poudrage), talc slurry administration, focal gauze abrasion by limited thoracotomy, and mechanical abrasion by thoracoscopy using a commercially available pleural abrader. Animals were killed 30 days after pleurodesis. At autopsy, the efficacy of pleurodesis was graded by evaluating the gross appearance of each pleural cavity and lung (pleurodesis score), and by determining the extent of adhesion formation (obliteration grade). Pleural and lung biopsy specimens were obtained from the areas most representative of adhesion formation for histopathologic evaluation. Pleurodesis scores (on a scale of 0 to 4) were 3.0 +/- 0.7 for talc poudrage (p < 0.05 when compared with talc slurry), 2.2 +/- 1.7 for thoracotomy, and 1.6 +/- 1.1 for talc slurry. Adhesions produced by gauze abrasion during thoracotomy were mostly peri-incisional. Thoracoscopic pleural abrasion using the pleural abrader was uniformly unsatisfactory. Granulation tissue formation was greatest in both talc models. The degree of parietal pleural thickening was greatest in the talc slurry model, but fibrosis and inflammation occurred mostly in gravity-dependent areas within the pleural cavity. Although differences were not statistically significant, thoracoscopic talc insufflation consistently produced the most widespread, firm fibrotic adhesions as evidenced by higher obliteration grades.

Thoracoscopy: nursing implications for optimal patient outcomes.

Many patients who once were considered for open chest procedures now benefit from examination and treatment of pleural disease via thoracoscopy. The thoracoscopist enters the chest cavity through small incisions through the chest wall. Procedures are performed through a video assisted thoracoscope (much like a bronchoscope or endoscope). Wound care, maintenance of the chest drainage system, pain management and vigilant assessment of the cardiorespiratory system following the procedure are integral nursing interventions when caring for these patients.

Laser bronchoscopy.

Laser bronchoscopy allows reestablishment of patent airways in patients with exophytic intraluminal tracheobronchial obstruction from malignancy. Patients with benign strictures can also be treated, thereby avoiding open surgical repair in selected instances. Because of laser-tissue interactions, and because patients often have terminal illness or severe underlying medical problems, these are potentially high-risk procedures. Proper resection techniques, experience, and repetitive performance are necessary to ensure satisfactory patient safety and outcome.