Indoor Air Quality Implications of Germicidal 222 nm Light.

One strategy for mitigating the indoor transmission of airborne pathogens, including the SARS-CoV-2 virus, is irradiation by germicidal UV light (GUV). A particularly promising approach is 222 nm light from KrCl excimer lamps (GUV222); this inactivates airborne pathogens and is thought to be relatively safe for human skin and eye exposure. However, the impact of GUV222 on the composition of indoor air has received little experimental study. Here, we conduct laboratory experiments in a 150 L Teflon chamber to examine the formation of secondary species by GUV222. We show that GUV222 generates ozone (O3) and hydroxyl radicals (OH), both of which can react with volatile organic compounds to form oxidized volatile organic compounds and secondary organic aerosol particles. Results are consistent with a box model based on the known photochemistry. We use this model to simulate GUV222 irradiation under more realistic indoor air scenarios and demonstrate that under some conditions, GUV222 irradiation can lead to levels of O3, OH, and secondary organic products that are substantially elevated relative to normal indoor conditions. The results suggest that GUV222 should be used at low intensities and in concert with ventilation, decreasing levels of airborne pathogens while mitigating the formation of air pollutants.

Our evolution in the treatment of hepatic artery and portal vein thrombosis in pediatric liver transplantation: Success with catheter-directed therapies.

BACKGROUND: In pediatric liver transplant recipients, hepatic artery thrombosis and portal vein thrombosis are major causes of acute graft failure and mortality within 30 days of transplantation. There is, however, a strong possibility of graft salvage if flow can be re-established to reduce ischemic injury. The current standard treatment is surgical revascularization, and if unsuccessful, retransplantation. Due to our success in treating these complications with catheter-directed therapies, we sought to summarize and publish the outcomes of all patients who experienced hepatic artery thrombosis or portal vein thrombosis within 30 days of liver transplantation. METHODS: We conducted a retrospective cohort analysis of 27 pediatric liver transplant recipients who experienced hepatic artery thrombosis (n = 13), portal vein thrombosis (n = 9), or both (n = 5) between September 2012 and March 2021. We collected and tabulated data on the patients and therapies performed to treat them, including success rates, primary and secondary patency, and clinical outcomes. RESULTS: Among these patients, 6 were managed with anticoagulation and relisting for transplant and 21 had a primary revascularization attempt. Surgical recanalization was attempted in 7 patients of which 3 had successful recanalization (43%) and catheter-directed recanalization was attempted in 14 patients with 100% success in re-establishing blood flow to the graft. Additionally, patency was increased, and mortality was decreased in patients treated with catheter-directed recanalization compared to surgical revascularization or anticoagulation alone. CONCLUSION: This data illustrates the need to further investigate catheter-directed thrombolysis as a potential first-line treatment for postoperative HAT and PVT in pediatric liver transplant recipients.

A new chapter in an evolving pandemic: Successful pediatric liver transplantation with SARS-CoV-2+ donors.

BACKGROUND: Amid a viral pandemic with poorly understood transmissibility and pathogenicity in the pediatric patient, we report the first pediatric liver transplants utilizing allografts from SARS-CoV-2+ donors. METHODS: We describe the outcomes of two pediatric liver transplant recipients who received organs from SARS-CoV-2 nucleic acid test-positive (NAT+) donors. Data were obtained through the respective electronic medical record system and UNet DonorNet platform. RESULTS: The first donor was a 3-year-old boy succumbing to head trauma. One of four nasopharyngeal (NP) swabs and 1 of 3 bronchoalveolar lavage (BAL) NAT tests demonstrated SARS-CoV-2 infection before organ procurement. The second donor was a 16-month-old boy with cardiopulmonary arrest of unknown etiology. Three NAT tests (2 NP swab/1 BAL) prior to procurement failed to detect SARS-CoV-2. The diagnosis was made when the medical examiner repeated 2 NP swab NATs and an archive plasma NAT, all positive for SARS-CoV-2. Both 2-year-old recipients continue to do well 8 months post-transplant, with excellent graft function and no evidence of SARS-CoV-2 transmission. CONCLUSIONS: This is the first report to describe successful pediatric liver transplantation from SARS-CoV-2+ donors. These data reinforce the adult transplant experience and support the judicious use of SARS-CoV-2+ donors for liver transplantation in children. With SARS-CoV-2 becoming endemic, the concern for donor-derived viral transmission must now be weighed against the realized benefit of life-saving transplantation in the pediatric population as we continue to work toward donor pool maximization.

Survey of public attitudes towards imminent death donation in the United States.

Imminent death donation (IDD) is described as living organ donation prior to a planned withdrawal of life-sustaining care in an imminently dying patient. Although IDD was ethically justified by United Network for Organ Sharing, the concept remains controversial due to presumed lack of public support. The aim of this study was to evaluate the public's attitudes towards IDD. A cross-sectional survey was conducted of US adults age >18 years (n = 2644). The survey included a case scenario of a patient with a devastating brain injury. Responses were assessed on a 5-point Likert scale. Results showed that 68% - 74% of participants agreed or strongly agreed with IDD when posed as a general question and in relation to the case scenario. Participants were concerned about "recovery after a devastating brain injury" (34%), and that "doctors would not try as hard to save a patient's life" (33%). Only 9% of participants would be less likely to trust the organ donation process. In conclusion, our study demonstrates strong public support for IDD in the case of a patient with a devastating brain injury. Notably, participants were not largely concerned with losing trust in the organ donation process. These results justify policy change towards imminent death donation.

Liver transplant in a recently COVID-19 positive child with hepatoblastoma.

We describe the successful pediatric liver transplant for unresectable hepatoblastoma in a 4-year-old male with COVID-19 prior to transplant. The first negative NP swab was documented 1 month after initial diagnosis, when SARS-CoV-2 antibodies were also detected. The patient was actively listed for liver transplant after completing four blocks of a SIOPEL-4 based regimen due to his PRETEXT IV disease which remained unresectable. Following three additional negative NP swabs and resolution of symptoms for 4 weeks, he underwent a whole-organ pediatric liver transplant. COVID-19 positivity determined via NP swab SARS-CoV-2 real-time RT-PCR (Hologic Aptima SARS-CoV-2 RT-PCR assay). IgG and IgM total SARS- CoV-2 antibodies detected by Ortho Clinical Diagnostics VITROS® Immunodiagnostics Products Anti-SARS-CoV-2 Test. Patient received standard prednisone and tacrolimus-based immunosuppression without induction therapy following transplant. Post-transplant course was remarkable for neutropenia and thrombocytopenia, with discharge home on post-transplant day #11. Surveillance tests have remained negative with persistent SARS-CoV-2 IgG antibodies at 6 weeks after transplant. We describe one of the earliest, if not the first case of liver transplant following recent recovery from COVID-19 in a pediatric patient with a lethal malignant liver tumor. A better understanding of how to balance the risk profile of transplant in the setting of COVID-19 with disease progression if transplant is not performed is needed. We followed existing ASTS guidelines to document clearance of the viral infection and resolution of symptoms before transplant. This case highlights that pediatric liver transplantation can be safely performed upon clearance of COVID-19.

The pediatric solid organ transplant experience with COVID-19: An initial multi-center, multi-organ case series.

The clinical course of COVID-19 in pediatric solid organ transplant recipients remains ambiguous. Though preliminary experiences with adult transplant recipients have been published, literature centered on the pediatric population is limited. We herein report a multi-center, multi-organ cohort analysis of COVID-19-positive transplant recipients ≤ 18 years at time of transplant. Data were collected via institutions' respective electronic medical record systems. Local review boards approved this cross-institutional study. Among 5 transplant centers, 26 patients (62% male) were reviewed with a median age of 8 years. Six were heart recipients, 8 kidney, 10 liver, and 2 lung. Presenting symptoms included cough (n = 12 (46%)), fever (n = 9 (35%)), dry/sore throat (n = 3 (12%)), rhinorrhea (n = 3 (12%)), anosmia (n = 2 (8%)), chest pain (n = 2 (8%)), diarrhea (n = 2 (8%)), dyspnea (n = 1 (4%)), and headache (n = 1 (4%)). Six patients (23%) were asymptomatic. No patient required supplemental oxygen, intubation, or ECMO. Eight patients (31%) were hospitalized at time of diagnosis, 3 of whom were already admitted for unrelated problems. Post-transplant immunosuppression was reduced for only 2 patients (8%). All symptomatic patients recovered within 7 days. Our multi-institutional experience suggests the prognoses of pediatric transplant recipients infected with COVID-19 may mirror those of immunocompetent children, with infrequent hospitalization and minimal treatment, if any, required.

Successful kidney transplantation in a small child with end-stage renal disease due to angiotensin receptor blocker fetopathy and atretic inferior vena cava.

Kidney transplantation is the treatment of choice in pediatric patients with end-stage renal disease. This population presents technical challenges particularly in those less than 20 kg due to anomalous anatomy, vascular access issues prior to transplantation, and a generally small size for age. Standard allograft outflow is usually achieved utilizing the iliac veins or IVC. When use of the iliocaval system is not feasible, alternative anastomosis must be considered. Herein, we report a case of a pediatric kidney transplantation where successful allograft outflow was achieved using the SMV when he was found to have an atretic IVC intraoperatively. In this setting, use of the portal system was required to achieve adequate allograft outflow. We created a donor iliac graft for added length to anastomose the renal vein with the SMV. In the setting of IVC occlusion with poor drainage, we utilized a patent vessel with larger caliber for outflow to reduce the risk of high venous pressures, allograft failure, venous rotation, and thrombosis. We conclude that the SMV may serve as an alternative outflow tract in the small pediatric patient and provides the vessel caliber needed to reduce the risks of complications.

Trends in pediatric liver transplant donors and deceased donor circumstance of death in the United States, 2002-2015.

While much of the discussion regarding expanding the donor pool for pediatric liver transplantation has surrounded the use of technical variant grafts, little attention has been directed toward changes in the deceased donor population. The aim of this study was to investigate trends in the circumstance of the death of deceased donors used for pediatric liver transplantation. All pediatric liver transplant recipients transplanted between 2002 and 2015 were identified in the UNOS database and were categorized based on the donor circumstance of death. There was no significant correlation between year of transplantation and number of pediatric liver transplants performed, pediatric donors, split livers, or living donors. There was a significant downward trend in donors from motor vehicle fatalities and an upward trend in suicide, non-MVA, and death due to natural causes. There was also an upward trend in drowning, one of the most common mechanisms of death among non-MVA in 2015. While the number of donors who died in MVA has fallen, the number of deceased donors who died from suicide, natural causes, and non-MVA, especially drowning, has increased, maintaining the overall number of pediatric deceased donor livers transplanted.

Chamber studies of OH + dimethyl sulfoxide and dimethyl disulfide: insights into the dimethyl sulfide oxidation mechanism.

The oxidation of dimethyl sulfide (DMS) in the marine atmosphere represents an important natural source of non-sea-salt sulfate aerosol, but the chemical mechanisms underlying this process remain uncertain. While recent studies have focused on the role of the peroxy radical isomerization channel in DMS oxidation, this work revisits the impact of the other channels (OH addition and OH abstraction followed by bimolecular RO2 reaction) on aerosol formation from DMS. Due to the presence of common intermediate species, the oxidation of dimethyl sulfoxide (DMSO) and dimethyl disulfide (DMDS) can shed light on these two DMS reaction channels; they are also both atmospherically relevant species in their own right. This work examines the OH oxidation of DMSO and DMDS, using chamber experiments monitored by chemical ionization mass spectrometry and aerosol mass spectrometry to study the full range of sulfur-containing products across a range of NO concentrations. The oxidation of both compounds is found to lead to rapid aerosol formation (which does not involve the intermediate formation of SO2), with a substantial fraction (14%-47 % S yield for DMSO and 5 %-21 % for DMDS) of reacted sulfur ending up in the particle phase and the highest yields observed under elevated NO conditions. Aerosol is observed to consist mainly of sulfate, methanesulfonic acid, and methanesulfinic acid. In the gas phase, the NOx dependence of several products, including SO2 and S2-containing organosulfur species, suggest reaction pathways not included in current mechanisms. Based on the commonalities with the DMS oxidation mechanism, DMSO and DMDS results are used to reconstruct DMS aerosol yields; these reconstructions roughly match DMS aerosol yield measurements from the literature but differ in composition, underscoring remaining uncertainties in sulfur chemistry. This work indicates that both the abstraction and addition channels contribute to rapid aerosol formation from DMS and highlights the need for more study into the fate of small sulfur radical intermediates (e.g., CH3S, CH3SO2, and CH3SO3) that are thought to play central roles in the DMS oxidation mechanism.

Hippocampal-sparing whole brain volumetric modulated arc therapy (VMAT) planning in Monaco: a "How-to" not pull your hair out.

NRG-CC001 recently reported positive results on hippocampal-sparing IMRT (HS-IMRT) in conjunction with memantine for the reduction in cognitive decline compared to conventional whole brain radiation therapy. Herein, we report our experience in planning volumetric modulated arc therapy (VMAT) cases in Monaco® with the anticipation of increased utilization of the planning technique for delivery on Elekta linear accelerators. Twelve patients previously treated with whole brain radiation therapy who would have been eligible for NRG-CC001 were replanned with VMAT HS-IMRT for to a dose of 30Gy/10fx using constraints from the trial. All 12 patients were able to be planned with VMAT and achieve NRG-CC001 dose constraints. Median maximum and D100% to the right and left hippocampi were: 13.37Gy and 13.43Gy, respectively and 8.76Gy and 8.86Gy, respectively. Median coverage of the brain minus the hippocampi with 30Gy was 96.53%. All cases passed quality assurance testing with 3%/3 mm and 2%/2 mm criterion. Hippocampal-sparing IMRT whole brain radiation therapy can be feasibly planned with VMAT technique in Monaco® and delivered on Elekta linear accelerators.

Single Fraction Frameless Stereotactic Radiosurgery on the Gamma Knife Icon for Patients With Brain Metastases: Time to Abandon the Frame?

PURPOSE: The latest version of the Gamma Knife, the Icon, allows for immobilization with a mask in lieu of the traditional frame during stereotactic radiosurgery. There have been some concerns regarding extent of immobilization during single fraction frameless treatment and potential effect on outcomes. As such, we reviewed outcomes in patients with brain metastases treated in a single fraction using either a frame or mask on the Gamma Knife Icon at our institution. METHODS AND MATERIALS: We reviewed the records of 95 patients with a total of 374 metastases treated between May 2019 and January 2021. Thirty-nine patients (41%) were treated using the Leksell frame with the remainder being immobilized with a mask. The median number of metastatic lesions was 2 (1-20). The median prescription dose was 20 Gy (11.5-24 Gy). Odds ratios were generated to identify predictors of mask use. Kaplan-Meier analysis was used to calculate survival, local failure, and distant failure rates. Cox regression was used to identify predictors of survival. Propensity matching was used to account for indication bias. RESULTS: Of the 95 patients treated, 88 (93%) had follow-up with a median duration of 5 months (1-18). Frame utilization was more likely with 6 to 10 brain metastases. Median overall survival was not reached and was 70% and 60% at 6 and 12 months for the entire cohort, respectively. There was no significant difference in survival by immobilization method (P = .12). Six patients had local failure in 10 total lesions (3 patients in each group). After propensity matching the 12 month tumor local control was 96% and 85% for framed and frameless cases, respectively (P = .07). CONCLUSIONS: Frameless mask-based stereotactic radiosurgery using the Gamma Knife Icon is feasible and maintains the excellent local control seen with the use of the headframe.

Management of Acute Portal Vein Thrombosis With Serial Mechanical Thrombectomy and tPA in a Pediatric Liver Transplant Recipient: A Case Report.

BACKGROUND: Acute portal vein thrombosis is a major cause of fulminant allograft failure in pediatric liver transplantation. Timely intervention is critical to save the graft and patient. Serial interventional radiologic management of this condition is scarcely reported in the literature. CASE SUMMARY: A recently transplanted 17-year-old male presented to the emergency department with abdominal pain. Rising liver enzymes prompted discovery of a diffuse portal thrombus, which precipitated fulminant liver failure. The adolescent developed respiratory failure, vasodilatory shock, acute kidney injury, and hepatic encephalopathy, complicating treatment. Multiple interventions attempted to clear the thrombus, including interventional radiologic and medical therapies. Uniquely, a continuous infusion catheter was placed at the thrombosis, delivering local tissue plasminogen activator during a 5-day period. Upon thrombus clearance, the patient made a full recovery with no complications during 12 months of follow-up. CONCLUSIONS: When used as a component of multidisciplinary management, continuous locally directed tissue plasminogen activator may be a useful tool for clearance of persistent portal vein thrombosis.

Splenic Artery Transposition for Liver Transplantation: An Underutilized Technique?

BACKGROUND: Successful liver transplantation is dependent on restoration of hepatic arterial (HA) flow. Although uncommon, some native recipient HAs are not suitable or inadequate for anastomosis, thereby necessitating extra-anatomic HA reconstruction. Splenic artery transposition (SAT) is 1 method of HA reconstruction, in which the recipient splenic artery is transposed to reestablish perfusion of the donor liver. Due to the rarity of the technique, literature describing outcomes is limited. In the current report, we describe 3 patients (2 adults, 1 pediatric) who underwent complex upper abdominal surgery before whole-organ deceased donor liver transplantation with SAT. METHODS: The demographic and patient care information was collected prospectively and subsequently reviewed retrospectively. Given the de-identified nature of the data included, this study was exempt from approval from an ethics board. RESULTS: Recipient splenic arteries were dissected from their origin at the celiac trunk, for approximately 3-5 cm to ensure a gentle anterior-cranial curve toward the right upper quadrant, allowing anastomosis to the donor celiac trunk in an end-to-end fashion. Postoperatively, all 3 patients had rapid normalization of liver function tests and brisk HA flow demonstrated by Doppler ultrasound. Longer-term follow-up, ranging from 1 to 3 years, reveals continued patency of the reconstructed HAs and liver function tests within normal limits. CONCLUSIONS: Our experience points to SAT as a safe and effective technique for extra-anatomic HA reconstruction.

A simple field-based biodegradation test shows pH to be an inadequately controlled parameter in laboratory biodegradation testing.

Biodegradation tests are essential for characterizing the behavior of organic micropollutants in the environment, but they are carried out almost exclusively in the laboratory. Test parameters such as temperature and test chemical concentration are often applied in ways that affect observed biodegradation, and laboratory testing requires sophisticated temperature-controlled facilities. We developed a field-based test based on OECD 309 which minimizes the need for laboratory resources such as temperature-controlled facilities by using bottles incubated in the natural water body. The test also utilized contaminant residues present in unspiked natural water to increase the relevance of the results to the local system. A test in a local river and a matching lab-based test were conducted in parallel. We quantified 26 of 40 targeted micropollutants and observed dissipation for 13. Significant differences in half-life (up to a factor of 3.5) between lab and field bottles were observed for 7 compounds, with 6 of 7 degrading more slowly in field bottles. For 4 of these, dissipation was positively correlated to the neutral fraction of the chemical. Differences in the neutral fraction arose due to a higher pH in the lab bottles induced by outgassing of CO2 from the oversaturated river water. We conclude that pH is an important parameter to control in biodegradation testing and that field-based tests may be more environmentally relevant.

Predictors of Treatment Interruption During Frameless Gamma Knife Icon Stereotactic Radiosurgery.

PURPOSE: The Gamma Knife (GK) Icon allows for the delivery of stereotactic radiosurgery using a thermoplastic mask in combination with intrafraction motion monitoring using high definition motion management. The system pauses treatment if the magnitude of motion in all directions exceeds 1 to 1.5 mm, causing a break in treatment and prolongation of the session. We reviewed the records of patients treated in a frameless manner on our GK Icon system to determine predictors for treatment interruption. METHODS AND MATERIALS: We reviewed the records of patients treated between May 2019 and May 2020 on the GK Icon using a frameless technique for brain metastases, gliomas, schwannomas, and meningiomas. We recorded treatment time as noted in the plan document, actual treatment delivery time, and any pauses in treatment. We tabulated baseline characteristics including age, gender, diagnosis, performance status, and shifts at time of treatment. We used a receiver operating curve analysis to determine a timepoint corresponding with treatment interruption. We then conducted a logistic regression analysis to generate odds ratios for likelihood of treatment. RESULTS: We identified 150 patients meeting inclusion criteria. The majority (82%) were patients with brain metastases. The median age was 63 and the median dose was 27 Gy (16-30 Gy) in 3 fractions (1-5 fractions). The median treatment time was 23 minutes (4-108 minutes). Sixty-nine patients (46%) had at least 1 pause in treatment (range, 1-7). Receiver operating curve analysis revealed treatment time >19 minutes and rotation >0.47 degrees to be associated with interruption. Multivariable logistic regression revealed rotation >0.47 degrees and treatment time >19 minutes as predictive of interruption. CONCLUSIONS: For patients with rotations exceeding 0.47 degrees or an extended treatment time, physicians should expect treatment interruptions, consider fractionation to lessen table time, or use a frame-based approach.

Adaptation of a Gamma Knife Icon stereotactic radiosurgery program in the face of the COVID-19 pandemic.

Objective: The COVID-19 pandemic necessitated drastic and rapid changes throughout the field of radiation oncology, some of which were unique to the discipline of radiosurgery. Guidelines called for reduced frame use and reducing the number of fractions. Our institution implemented these guidelines, and herein we show the resultant effect on patient treatments on our Gamma Knife Icon program. Methods: In early March 2020 we rapidly implemented suggested changes according to ASTRO and other consensus guidelines as they relate to stereotactic radiosurgery in the COVID-19 era. We reviewed the GK Icon schedule at our institution between January 01 and April 30, 2020. We documented age, condition treated, technique (frame vs. mask), and number of fractions. We then tabulated and graphed the number of patients, framed cases, and fractions delivered. Results: Seventy-seven patients were treated on the GK Icon over that period, for a total of 231 fractions. The number of unique patients varied from 18 (April) to 22 (January). Of the 77 patients only 5 were treated using a frame. The number of fractions per month decreased significantly over time, from 70 in January to 36 in April. Likewise, the percentage of single fraction cases increased from 4.5% per month in January to 67% in April. Conclusions: The results presented here show that it is possible to quickly and efficiently change work flows to allow for reduced fractionation and frame use in the time of a global pandemic. Multidisciplinary cooperation and ongoing communication are integral to the success of such programs.