Validity of aerosolization detection with an air quality indicator in noncontact tonometry using corneal phantoms.

Précis: Using a controlled experimental design with corneal phantoms, this study provides evidence of the lack of validity of a static air quality indicator, previously used to characterize aerosolization during dynamic noncontact tonometry. Purpose: To evaluate the accuracy of aerosol concentrations reported by an air quality indicator (AQI) following an air puff from a noncontact tonometer using non-aerosolizing corneal phantoms. Methods: Three rubber corneal phantoms of different stiffnesses were used to represent varying intraocular pressure (IOP) values. No liquid components and therefore no aerosol-generating potential was present. Reported concentrations of particulate matter (PM) having diameter less than 2.5 and 10µm, respectively PM2.5 and PM10, were recorded using an AQI before and during an air puff generated using noncontact tonometry. The effects of covariates IOP and sensor location on changes to air quality measurements from the baseline were evaluated using analysis of variance. Monte Carlo simulations were used to determine the likelihood of observing published trends by chance. The statistical significance threshold was p<0.05. Results: No correlations were found between PM2.5 and IOP or location. Reported concentrations of PM10 depended significantly on both IOP (p=0.0241) and location (p=0.0167). Monte Carlo simulations suggest the likelihood of finding a spurious positive correlation between IOP and PM at the upper same location are 53% and 92% for PM2.5 and PM10, respectively, indicating the AQI has systematic bias resulting from non-aerosol sources. Conclusions: We were able to reproduce the published correlation between reported aerosol concentration and IOP in non-contact tonometry using dry rubber phantoms in place of living corneas with tear films. In this study, we demonstrated that published correlations linking NCT to tear film aerosolization were artifacts of the measurement technique.

Safety and efficacy of band ligation and auto-amputation as adjunct to EMR of colonic large laterally spreading tumors, and polyps not amenable to routine polypectomy.

INTRODUCTION: The safety and efficacy of colonic band ligation and auto-amputation (1) as adjunct to endoscopic mucosal resection of large laterally spreading tumors and (2) for polyps not amenable to routine polypectomy due to polyp burden or difficult location remain unknown. METHODS: An institutional review board-approved retrospective single-institution study was undertaken of patients undergoing colonic band ligation and auto-amputation from 2014 to date. Patients with indications of 'endoscopic mucosal resection for laterally spreading tumors' and 'polyp not amenable to snare polypectomy' were included in the study. Data were collected on patient demographics, colonoscopy details (laterally spreading tumors/polyp characteristics, therapies applied, complications), pathology results, and follow-up (polyp eradication based on endoscopic appearance and biopsy results). RESULTS: Patients undergoing endoscopic mucosal resection for laterally spreading tumors: Thirty-two patients (31 males, aged 68 ±â€„9.17 years) underwent endoscopic mucosal resection-band ligation and auto-amputation of 34 laterally spreading tumors (40 ±â€„10.9 mm). A median of 2 ±â€„1.09 bands were placed. Follow-up colonoscopy and biopsy results confirmed complete eradication in 21 laterally spreading tumors (70%). Nine (30%) laterally spreading tumors required additional endoscopic therapy to achieve complete eradication. Four (13%) patients underwent surgery for cancer, and two of them had resection specimens negative for cancer or residual adenoma. One patient suffered post-polypectomy syndrome. Patients undergoing band ligation and auto-amputation for polyps not amenable to snare polypectomy: Seven patients underwent band ligation and auto-amputation due to serrated polyposis syndrome (one patient) and innumerable polyps, or polyps in difficult locations (extension into diverticula: two patients; terminal ileum: two patients; appendiceal orifice: one patient; anal canal: one patient). The patient with serrated polyposis syndrome achieved dramatic decrease in polyp burden, but not eradication. Follow-up in five of the six remaining patients documented polyp eradication. The patient with serrated polyposis syndrome suffered from rectal pain and tenesmus following placement of 18 bands. CONCLUSIONS: Band ligation and auto-amputation in the colon may be a safe and effective adjunct to current endoscopic mucosal resection and polypectomy methods and warrants further study. PLAIN LANGUAGE SUMMARY: Colonoscopy with rubber band placement to aid in complete removal of large polyps and polyps in technically challenging locationsColonoscopy is a commonly performed procedure for the early detection of colon and rectal cancer, and prevention through polyp removal.During colonoscopy, sometimes situations are encountered making polyp removal difficult. These can include the presence of larger polyps or the location of a polyp in an area that makes removal technically challenging or high risk.A particularly challenging situation arises when after extensive effort there is still polyp tissue remaining that cannot be removed using routine techniques. We are interested in exploring a technique which involves the placement of a rubber band after sucking a small area of the colon lining into a cap loaded onto the tip of the colonoscope. With time the rubber band strangulates the tissue and falls off along with captured tissue and passes out of the colon naturally.To assess the effectives of this technique we studied patients that have undergone this procedure at our GI unit. We identified 32 patients with 34 large polyps between 4cm to 6cm that we placed rubber bands on polyp tissue after we were unable to completely remove the polyp. On their follow up colonoscopy, complete polyp removal was successful in 21 polyps. We were also able to achieve complete polyp removal in 9 of the remaining large polyps after additional treatment. Four patients underwent surgery because cancer was found in analysis of polyp tissue.In 5 of 6 patients with polyps in difficult locations (e.g. partly within the lumen of the appendix), placement of a rubber band led to complete removal of polyp tissue.Two patients in our study population had mild adverse events that were managed with simple measures.We believe our results show promise for our described technique and this technique should be tested in larger studies.

Acute physiologic effects of N95 respirator use on gastroenterologists performing simulated colonoscopy.

BACKGROUND AND AIMS: During the severe acute respiratory syndrome coronavirus 2 pandemic, N95 filtering facepiece respirator (FFR) use was required while performing aerosol-generating procedures. We studied the physiologic effects of N95 FFR use in a cohort of gastroenterologists performing simulated colonoscopies. METHODS: Data collection and comparisons included (1) symptoms and change in vital signs in 12 gastroenterologists performing simulated colonoscopy for 60 minutes while wearing a surgical mask (SM) and faceshield (FS); N95 FFR, SM, and FS; and powered air-purifying respirator (PAPR) and (2) respiratory belt plethysmography and continuous electrocardiographic frequency-based heart rate (HR) variability indices including very low frequency power (measures intracardiac sympathetic tone) and low frequency to high frequency ratios (intracardiac sympathetic to vagal ratio) in 11 gastroenterologists performing simulated colonoscopy while wearing an SM (15 minutes), N95 FFR and SM (60 minutes), and SM (15 minutes) in rapid sequence. RESULTS: Ten of 12 gastroenterologists (83%) reported symptoms with N95 FFR use, most commonly breathing difficulty, frustration, fatigue, and headache. Nine of these gastroenterologists (75%) had associated significant HR elevation. Respiratory peak to trough measurement showed a significant increase (F(2) = 7.543, P = .004) during the N95 FFR stage, which resolved after removal of the N95 FFR. Although not statistically different, all gastroenterologists showed a decrease in sympathetic to vagal ratios and an increase in intracardiac sympathetic effects in the N95 FFR stage. PAPR use was better tolerated but was associated with headache and elevated HR in 4 gastroenterologists (33%). CONCLUSIONS: N95 FFR use by gastroenterologists is associated with development of acute physiologic changes and symptoms.