Potential harm to the skin from unfiltered krypton chloride 'far-ultraviolet-C' lamps, even below an occupational exposure limit.

Ultraviolet-C (UVC) radiation can effectively inactivate pathogens on surfaces and in the air. Due to the potential for harm to skin and eyes, human exposure to UVC should be limited within the guideline exposure limits produced by the International Commission on Non-Ionising Radiation Protection (ICNIRP) or the American Conference of Governmental Industrial Hygienists (ACGIHs). Both organisations state an effective spectrally weighted limit of 3 mJ cm-2, although the spectral weighting factors of the two organisations diverged following a revision of the ACGIH guidelines in 2022. Using existing published human exposure data, the effective spectrally weighted radiant exposure was calculated for both unfiltered and filtered (to reduce UV emissions above 230 nm) krypton chloride (KrCl*) excimer lamps. The effective radiant exposure of the filtered KrCl* lamp was greater than 3 mJ cm-2when applying ICNIRP or either of the revised ACGIH spectral weightings. This indicates that both guidelines are appropriately conservative for this specific lamp. However, the effective radiant exposure of the unfiltered KrCl* lamp was as low as 1 mJ cm-2with the revised ACGIH weighting function that can be applied to the skin if the eyes are protected. Erythema has therefore been directly observed in a clinical study at an exposure within the revised ACGIH guideline limits. Extrapolating this information means that a mild sunburn could be induced in Fitzpatrick skin types I and II if that particular ACGIH weighting function were applied and an individual received an effective exposure of 3 mJ cm-2. Whilst it is improbable that such an effect would be seen in current deployment of KrCl* lamp technology, it does highlight the need for further research into skin sensitivity and irradiance-time reciprocity for UVC wavelengths.

Development of a Predictive Monte Carlo Radiative Transfer Model for Ablative Fractional Skin Lasers.

It is possible to enhance topical drug delivery by pretreatment of the skin with ablative fractional lasers (AFLs). However, the parameters to use for a given AFL to achieve the desired depth of ablation or the desired therapeutic or cosmetic outcome are hard to predict. This leaves open the real possibility of overapplication or underapplication of laser energy to the skin. In this study, we developed a numerical model consisting of a Monte Carlo radiative transfer (MCRT) code coupled to a heat transfer and tissue damage algorithm. The simulation is designed to predict the depth effects of AFL on the skin, verified with in vitro experiments in porcine skin via optical coherence tomography (OCT) imaging. Ex vivo porcine skin is irradiated with increasing energies (50-400 mJ/pixel) from a CO2 AFL. The depth of microscopic treatment zones is measured and compared with our numerical model. The data from the OCT images and MCRT model complement each other well. Nonablative thermal effects on surrounding tissue are also discussed. This model, therefore, provides an initial step toward a predictive determination of the effects of AFL on the skin. Lasers Surg. Med. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.

Surgeon Annual and Cumulative Volumes Predict Early Postoperative Outcomes after Rectal Cancer Resection.

OBJECTIVE: To determine if 5-year surgeon cumulative and annual volumes predict improved early postoperative outcomes in patients with rectal cancer. BACKGROUND: Operative experience has been shown to effect surgical outcomes. The differential role of cumulative versus annual volume has not yet been explored for rectal surgery. METHODS: The Statewide Planning and Research Cooperative System database was used to capture patients undergoing surgery in New York State from 2000 to 2013. A population-based sample of patients undergoing major rectal or rectosigmoid resection as their principal procedure during hospitalization between 2000 and 2013 were identified using International Classification of Diseases, Ninth Revision, Clinical Modification procedure codes. Surgeons were identified using a unique physician number from 1995 to 2013. RESULTS: The percentage of surgeries performed by high cumulative/high annual (HC/HA) surgeons increased from 38.3% to 58.4% (P < 0.01) with a simultaneous decrease in that performed by low cumulative/low annual (LC/LA) surgeons (52.5% to 29.8%, P < 0.01). HC/HA volume surgeons had a significantly lower rate of surgical complications (odd ratio = 0.71, 95% confidence interval = 0.60-0.83, P < 0.05) as compared with LC/LA volume surgeons. There was no significant difference in rates of anastomotic leak, nonroutine discharges or readmission among all four groups. CONCLUSIONS: The best early postoperative surgical outcomes are achieved in centers where there are high cumulative and high annual volume surgeons caring for these patients. This suggests the need for specialized designation of rectal cancer centers to support ongoing regionalization of care.

Dynamic Article: Full-Thickness Excision for Benign Colon Polyps Using Combined Endoscopic Laparoscopic Surgery.

BACKGROUND: Benign colon polyps are commonly encountered but may not always be amenable to endoscopic excision because of their size, shape, location, or scarring from previous attempts. The addition of laparoscopy allows a greater degree of bowel manipulation, but the current technique is still limited when encountering a polyp with inadequate lifting attributed to polyp morphology or scarring. We describe an extension to the existing combined endoscopic laparoscopic surgery technique using a full-thickness approach to increase polyp maneuverability and local excision of difficult but benign polyps. OBJECTIVE: The purpose of this study was to report the technical details and preliminary results of a new approach for full-thickness excision of difficult colon polyps, combined endoscopic laparoscopic surgery full-thickness excision. DESIGN: This study is a retrospective review of our experience from December 2013 to May 2015. SETTINGS: The study was conducted at a single academic institution. PATIENTS: All of the patients had previous incomplete colonoscopic polypectomy performed at other institutions. Patients were selected for our technique if the polyp had a benign appearance but was unable to be resected by traditional endoscopic or combined endoscopic laparoscopic surgery methods because of polyp morphology or scarring from previous biopsies. MAIN OUTCOME MEASURES: The safety and feasibility of this procedure were measured. RESULTS: Three patients underwent combined endoscopic laparoscopic surgery-full-thickness excision for difficult colon polyps. There were no intraoperative or postoperative complications. The length of stay was 1 day for all of the patients. All 3 of the patients had benign final pathology. LIMITATIONS: This study was limited by the small number of patients in a single institution. CONCLUSIONS: Full-thickness excision for benign colon polyps using combined endoscopic laparoscopic surgery is safe and feasible. Using this technique, difficult polyps not amenable to traditional endoscopic approaches can be removed and colectomy may be avoided.

Surgical oncology outcomes in the aging US population.

BACKGROUND: As the population ages, an increasing number of older patients are undergoing major surgery. We examined the impact of advanced age on outcomes following major gastrointestinal cancer surgery in an era of improved surgical outcomes. MATERIALS AND METHODS: This was a population-based, retrospective cohort study using the American College of Surgeons National Surgical Quality Improvement Program database. We evaluated patients undergoing major abdominal gastrointestinal cancer surgery from 2005-2012. Multivariable logistic regression was performed to determine the independent effect of advanced age on outcomes. Our primary outcome was 30-d mortality, and our secondary outcomes were 30-d major postoperative adverse events, discharge disposition, length of stay, reoperation, and readmission. RESULTS: Elderly (≥65 y) patients were twice as likely to have multiple comorbidities as those <65 y but prevalence of comorbidities was similar across all older age groups. Mortality increased with age across all procedures (P < 0.05). The risk of advanced age on mortality was highest in hepatectomy (odds ratio = 5.17, 95% confidence interval = 2.19-12.20) and that for major postoperative adverse events was highest in proctectomy (odds ratio = 2.32, 95% confidence interval = 1.53-3.52). Patients were more likely to be discharged to an institutional care facility as age increased across all procedures (P < 0.01). CONCLUSIONS: Despite being highly selected for surgery, elderly patients undergoing major gastrointestinal cancer surgery have substantially worse postoperative outcomes than younger patients (<65 y). The risk of age on postoperative outcomes was present across all operations but had its highest association with liver and rectal cancer resections.

Driving Surgical Quality Using Operative Video.

Recent evidence suggests surgical quality may be demonstrated and evaluated using video capture during surgery. Operative video documentation may also aid in quality improvement initiatives. We discuss how operative video has the potential to help improve patient outcomes and increase professional accountability, patient safety, and surgical quality.

Adenocarcinoma of the ileal pouch mucosa: case report and literature review.

PURPOSE: Cancers developing near the site of the ileoanal pouch anastomosis (IPAA) have been reported, but uncommonly in the ileal pouch mucosa itself. We present a recently encountered case of ileal pouch cancer and review the literature to examine the prevalence, risk factors, and natural history of ileal pouch adenocarcinoma as well as pouch surveillance. METHODS: A chart review of the case from our institution was conducted, and a PubMed search was undertaken for articles describing adenocarcinoma arising from the ileal pouch mucosa. RESULTS: Twenty articles containing 26 cases were reviewed in addition to our described case. More than half were reported in the last decade. Only three cases were definitively stage 1. All seven patients who underwent regular surveillance were diagnosed with stage 1 or 2 disease. Seventeen patients had neoplasia in their original proctocolectomy specimen and six did not. The mean time from pouch creation to adenocarcinoma was 8.9 years. CONCLUSIONS: The risk of developing ileal pouch mucosa adenocarcinoma appears low. However, increasing reports of these cancers are concerning as most patients present with advanced disease after many years. Patients with a previous history of dysplasia/cancer may be at increased risk. We believe surveillance after IPAA should include the anal transition zone and the ileal pouch mucosa. The establishment of expert consensus guidelines on pouch surveillance should be considered in the near future.

222 nm Far-UVC from filtered Krypton-Chloride excimer lamps does not cause eye irritation when deployed in a simulated office environment.

Far-UVC, from filtered Krypton-Chloride lamps, is promising for reducing airborne transmission of disease. While significant research has been undertaken to investigate skin safety of these lamps, less work has been undertaken on eye safety. There is limited data on human eye safety or discomfort from the deployment of this germicidal technology. In this pilot study, immediate and delayed eye discomfort were assessed in a simulated office environment with deployment of Krypton-Chloride lamps, located on the ceiling and directed downwards into the occupied room. Discomfort was assessed immediately postexposure and several days after exposure using validated, Standard Patient Evaluation Eye Dryness (SPEED) and Ocular Surface Disease Index (OSDI) questionnaires. Our results show no significant eye discomfort or adverse effects from the deployment of Far-UVC in this simulated office environment, even when lamps were operated continuously with participants receiving head exposures of up to 50 mJ cm-2 . In addition, a statistically significant reduction in bacteria and fungi of 52% was observed. Far-UVC in this simulated office environment did not cause any clinically significant eye discomfort and was effective at reducing pathogens in the room. These results contribute an important step to further investigation of the interaction of Far-UVC with the human eye.

Far-UVC: The impact of optical filters on real-world deployment.

In 2015, a study showed that Krypton-Chloride (KrCl) excimer lamps could induce erythema and basal layer DNA damage in human skin. Later studies found that filtering out longer wavelength emissions from these lamps resulted in no acute skin effects. However, there is a limited understanding of how much to reduce unwanted emissions and which wavelengths are important. Accurate spectral irradiance data is therefore crucial for safety, as variance in optical filtering significantly affects the weighted irradiance of a lamp. To simplify the risk assessment process for Far-UVC lamps, we highlight the usefulness of the lamp exposure limit (HLEL) and present this in the context of spectral emission data for 14 commercially available Far-UVC lamps. Our results demonstrate that relying solely on a radiometric measurement and a single-wavelength exposure limit at 222 nm could lead to over-exposure. The HLEL is a practical metric which can be utilized to determine the exposure time before reaching the exposure limit. It can also be used in the determination of the minimum ceiling height for compliance with standards like UL 8802. Manufacturers are urged to provide HLEL for their products; installers should adhere to HLEL; and standards and regulatory bodies should insist on this information in new guidance.

Low-dose daylight exposure induces nitric oxide release and maintains cell viability in vitro.

Any potential positive effects conferred via sunlight exposure have to be carefully balanced against carcinogenic effects. Here we provide evidence UK sunlight exposure upregulates the cardio protectant nitric oxide (NO) within in vitro skin cell lines with negligible increases in DNA damage and cell death at 1 SED, when compared against unexposed samples. The whole of the ultraviolet A (UV-A) spectrum appears to be responsible for NO release, with efficiency higher at exposures closer to shorter UV-A wavelengths and decreasing with wavelength increases. These results support further in vivo work, which could be of benefit for demographics such as the elderly (that exhibit a natural decline in NO bioavailability).

Assessing the safety of new germicidal far-UVC technologies.

The COVID-19 pandemic underscored the crucial importance of enhanced indoor air quality control measures to mitigate the spread of respiratory pathogens. Far-UVC is a type of germicidal ultraviolet technology, with wavelengths between 200 and 235 nm, that has emerged as a highly promising approach for indoor air disinfection. Due to its enhanced safety compared to conventional 254 nm upper-room germicidal systems, far-UVC allows for whole-room direct exposure of occupied spaces, potentially offering greater efficacy, since the total room air is constantly treated. While current evidence supports using far-UVC systems within existing guidelines, understanding the upper safety limit is critical to maximizing its effectiveness, particularly for the acute phase of a pandemic or epidemic when greater protection may be needed. This review article summarizes the substantial present knowledge on far-UVC safety regarding skin and eye exposure and highlights research priorities to discern the maximum exposure levels that avoid adverse effects. We advocate for comprehensive safety studies that explore potential mechanisms of harm, generate action spectra for crucial biological effects and conduct high-dose, long-term exposure trials. Such rigorous scientific investigation will be key to determining safe and effective levels for far-UVC deployment in indoor environments, contributing significantly to future pandemic preparedness and response.

Far-UVC (222 nm) efficiently inactivates an airborne pathogen in a room-sized chamber.

Many infectious diseases, including COVID-19, are transmitted by airborne pathogens. There is a need for effective environmental control measures which, ideally, are not reliant on human behaviour. One potential solution is Krypton Chloride (KrCl) excimer lamps (often referred to as Far-UVC), which can efficiently inactivate pathogens, such as coronaviruses and influenza, in air. Research demonstrates that when KrCl lamps are filtered to remove longer-wavelength ultraviolet emissions they do not induce acute reactions in the skin or eyes, nor delayed effects such as skin cancer. While there is laboratory evidence for Far-UVC efficacy, there is limited evidence in full-sized rooms. For the first time, we show that Far-UVC deployed in a room-sized chamber effectively inactivates aerosolised Staphylococcus aureus. At a room ventilation rate of 3 air-changes-per-hour (ACH), with 5 filtered-sources the steady-state pathogen load was reduced by 98.4% providing an additional 184 equivalent air changes (eACH). This reduction was achieved using Far-UVC irradiances consistent with current American Conference of Governmental Industrial Hygienists threshold limit values for skin for a continuous 8-h exposure. Our data indicate that Far-UVC is likely to be more effective against common airborne viruses, including SARS-CoV-2, than bacteria and should thus be an effective and "hands-off" technology to reduce airborne disease transmission. The findings provide room-scale data to support the design and development of effective Far-UVC systems.

Global verification of a model for determining daylight photodynamic therapy dose.

Daylight photodynamic therapy is an effective treatment for actinic keratoses and relies on a minimum PpIX-effective light exposure dose being delivered during treatment. As such, daylight dosimetry is an important aspect of this treatment. Relatively simple measurements of illuminance may be converted to PpIX-effective irradiance, and subsequently exposure dose, via a conversion model (the O'Mahoney model). This model has been verified against spectral irradiance data from the UK, however the accuracy of the model has not been determined outside the UK. In this work, we test the O'Mahoney model against spectral irradiance measurements from several global locations to within bounds of a median deviation of ±10 %. The median percentage deviations are shown to be independent of location latitude and longitude. The model can be used confidently to determine PpIX-effective irradiance from illuminance measurements irrespective of location and can be widely implemented as an effective and low-cost means of accurately measuring effective light exposure for this important treatment.

Computer Modeling Indicates Dramatically Less DNA Damage from Far-UVC Krypton Chloride Lamps (222 nm) than from Sunlight Exposure.

This study aims to investigate, with computer modeling, the DNA damage (assessed by cyclobutane pyrimidine dimer (CPD) formation) from far-ultraviolet C (far-UVC) in comparison with sunlight exposure in both a temperate (Harwell, England) and Mediterranean (Thessaloniki, Greece) climate. The research utilizes the published results from Barnard et al. [Barnard, I.R.M (2020) Photodermatol. Photoimmunol. Photomed. 36, 476-477] to determine the relative CPD yield of unfiltered and filtered far-UVC and sunlight exposure. Under current American Conference of Governmental Industrial Hygienists (ACGIH) exposure limits, 10 min of sunlight at an ultraviolet (UV) Index of 4-typical throughout the day in a temperate climate from Spring to Autumn-produces equivalent numbers of CPD as 700 h of unfiltered far-UVC or more than 30 000 h of filtered far-UVC at the basal layer. At the top of the epidermis, these values are reduced to 30 and 300 h, respectively. In terms of DNA damage induction, as assessed by CPD formation, the risk from sunlight exposure greatly exceeds the risk from far-UVC. However, the photochemistry that will occur in the stratum corneum from absorption of the vast majority of the high-energy far-UVC photons is unknown, as are the consequences.

Bring the Sunshine Indoors: Easy Dosimetry for Indoor Daylight Photodynamic Therapy.

Daylight photodynamic therapy (DPDT) is an effective and patient preferred treatment for the management of field change actinic keratosis. An important factor in DPDT is light dosimetry, to ensure that patients receive sufficient daylight for effective treatment, and this is the focus of the contribution to this issue by (La Rochelle et al. [2019] Photochem. Photobiol., https://doi.org/10.1111/php.13170). In this work, the authors present an easy-to-use method for obtaining real-time information about patient received light dose during treatment and for determining indoor locations best suited to DPDT.

Research Techniques Made Simple: Experimental UVR Exposure.

UVR exposure is a widely applied technique in clinical and preclinical studies. Such experimental conditions provide crucial information on the biological responses of skin and cell models, which may then be extrapolated and interpreted, for example, in the context of equivalent daylight exposures. It is therefore important to fully understand the characteristics of UVR and the principles behind correct and appropriate UVR exposure in experimental settings. In this Research Techniques Made Simple article, we discuss the relevant background information and the best practices for accurate, transparent, and reproducible experimentation and reporting of UVR exposure.

Measuring Daylight: A Review of Dosimetry in Daylight Photodynamic Therapy.

Successful daylight photodynamic therapy (DPDT) relies on the interaction of light, photosensitisers and oxygen. Therefore, the 'dose' of light that a patient receives during treatment is a clinically relevant quantity, with a minimum dose for effective treatment recommended in the literature. However, there are many different light measurement methods used in the published literature, which may lead to confusion surrounding reliable and traceable dose measurement in DPDT, and what the most appropriate method of light measurement in DPDT might be. Furthermore, for the majority of practitioners who do not carry out any formal dosimetry and for the patients receiving DPDT, building confidence in the evidence supporting this important treatment option is of key importance. This review seeks to clarify the methodology of DPDT and discusses the literature relating to DPDT dosimetry.

Ultraviolet radiation exposure during daylight Photodynamic Therapy.

BACKGROUND: Daylight photodynamic therapy (dPDT) is an effective treatment for field-change actinic keratoses (AK), with similar efficacy to conventional PDT but lower patient pain scores. Whilst AK occur consequent to chronic solar ultraviolet (UV) exposure, paradoxically solar visible radiation is used during PDT. OBJECTIVES: To investigate the nature and levels of UV exposure, both erythemal UV and UVA, occurring during dPDT. METHODS: Four years of solar erythemally effective UV (UVE) irradiance, UVA irradiance and illuminance data were obtained from Pubic Health England for 12 locations. For a standard 2 h treatment period, the data were converted into standard erythemal doses (SEDs), UVA dose and protoporphyrin-IX (PpIX)-weighted dose from UVE irradiance, UVA irradiance and illuminance respectively. These three parameters were compared ascertaining the UV exposure received during dPDT. RESULTS: Analysis of UV exposure during dPDT showed a UK maximum average UVE exposure of 8.2 SED at Camborne (PpIX dose 23.4 J cm-2). Treatment earlier in the day reduces average UV exposure (Camborne 5.2 SED, PpIX dose 18.2 J cm-2), whilst PpIX dose achieves threshold during winter months (Camborne, November, 0.8 SED, PpIX dose 7.1 J cm-2). Cyprus and Gibraltar (with high UV exposure during dPDT) experience a maximum of 14.3 SED and 12.9 SED, with respective PpIX doses of 36.1 J cm-2 and 35.1 J cm-2, in June. UVA exposure is also presented for comparison. CONCLUSION: Therapeutically effective dPDT doses can be achieved at times of the day and year when UV exposure is minimal.