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The commercial Computational Fluid Dynamics (CFD) software STAR-CCM+ was used to simulate the flow and breakup characteristics of a Liquid Jet Injected into the gaseous Crossflow (LJIC) under real engine operating conditions. The reasonable calculation domain geometry and flow boundary conditions were obtained based on a civil aviation engine performance model similar to the Leap-1B engine which was developed using the GasTurb software and the preliminary design results of its low-emission combustor. The Volume of Fluid (VOF) model was applied to simulate the breakup feature of the near field of LJIC. The numerical method was validated and calibrated through comparison with the public test data at atmospheric conditions. The results showed that the numerical method can capture most of the jet breakup structure and predict the jet trajectory with an error not exceeding ±5%. The verified numerical method was applied to simulate the breakup of LJIC at the real engine operating condition. The breakup mode of LJIC was shown to be surface shear breakup at elevated condition. The trajectory of the liquid jet showed good agreement with Ragucci’s empirical correlation.
Since December 2019, the clinical symptoms of coronavirus disease 2019 (COVID-19) and its complications are evolving. As the number of COVID patients requiring positive pressure ventilation is increasing, so is the incidence of subcutaneous emphysema (SE). We report 10 patients of COVID-19, with SE and pneumomediastinum. The mean age of the patients was 59 ± 8 years (range, 23–75). Majority of them were men (80%), and common symptoms were dyspnoea (100%), fever (80%) and cough (80%). None of them had any underlying lung disorder. All patients had acute respiratory distress syndrome on admission, with a median PaO2/FiO2 ratio of 122.5. Eight out of ten patients had spontaneous pneumomediastinum on their initial chest x-ray in the emergency department. The median duration of assisted ventilation before the development of SE was 5.5 days (interquartile range, 5–10 days). The highest positive end-expiratory pressure (PEEP) was 10 cmH2O for patients recieving invasive mechanical ventilation, while 8 cmH2O was the average PEEP in patients who had developed subcutaneous emphysema on non-invasive ventilation. All patients received corticosteroids while six also received tocilizumab, and seven received convalescent plasma therapy, respectively. Seven patients died during their hospital stay. All patients either survivor or non-survivor had prolonged hospital stay with an average of 14 days (range 8−25 days). Our findings suggest that it is lung damage secondary to inflammatory response due to COVID-19 triggered by the use of positive pressure ventilation which resulted in this complication. We conclude that the development of spontaneous pneumomediastinum and SE whenever present, is associated with poor outcome in critically ill COVID-19 ARDS patients.
The aim of this study was to evaluate contact endoscopy in detecting local treatment failures post-radiotherapy in squamous cell carcinoma of the upper aerodigestive tract.
A total of 135 consecutive patients with suspected residual or recurrent cancer after definitive radiotherapy underwent contact endoscopy before biopsy. Contact endoscopy findings were compared with histopathological examination findings. Contact endoscopy could not be completed in 7 patients (5.9 per cent) and histopathological examination was inconclusive in 5 patients (3.7 per cent). The findings of the remaining 123 patients were compared.
The sensitivity, specificity and accuracy of contact endoscopy were 88.75, 88.72 and 86.99 per cent, respectively, with similar results across various sites of upper aerodigestive tract. Inter-observer kappa value was 0.86 (95 per cent confidence interval: 0.79–0.93). The intra-observer kappa value was 0.93 (95 per cent confidence interval: 0.87–1.00) for the first observer and 0.95 (95 per cent confidence interval: 0.90–1.00) for second and third observers.
Contact endoscopy showed the same high sensitivity and specificity with low inter- and intra-observer variability in detecting post-radiotherapy failures in cancer of the upper aerodigestive tract as has been shown in non-irradiated tissues in earlier studies.
This study aimed to evaluate the effect of neck dissection on survival and complication rates in patients with no clinical or radiological evidence of cervical nodal disease (N0) undergoing salvage laryngectomy.
A retrospective study was conducted of patients with squamous cell carcinoma of the larynx following primary radiotherapy that required salvage laryngectomy. Disease-free and overall survival rates were compared over three years using Kaplan–Meier analysis. Pharyngocutaneous fistula rate, hospitalisation length and the requirement for further surgical intervention were also compared across cohorts.
Twenty-three cases met the inclusion criteria (17 neck dissections, 6 undissected). No significant differences in survival outcomes were identified. One patient who underwent neck dissection for advanced, recurrent transglottic squamous cell carcinoma showed evidence of occult lymph node metastases. Fistula rates did not differ significantly between dissected and non-dissected groups; however, two patients required surgical repair of post-operative pharyngocutaneous fistula following neck dissection.
In this study, elective neck dissection did not appear to alter survival outcomes or complication rates during salvage laryngectomy. Given the small but significant risk of occult neck metastases, its true value remains unclear.
We describe the case of a 52-day-old child who was diagnosed with a rare combination of corrected transposition of great vessels – hypoplastic right ventricle with supracardiac total anomalous pulmonary venous connection.
To investigate discrepancies in dose calculation algorithms used for lung stereotactic body radiotherapy (SBRT) plans.
Methods and materials
In total, 30 patients lung SBRT treatment plans, initially generated using BrainLab Pencil Beam (BL_PB) algorithm for 10 Gy×5 Fractions to the planning target volume (PTV) were included in the study. These plans were recalculated using BrainLab Monte Carlo (BL_MC), Eclipse AAA (EC_AAA), Eclipse Acuros XB (EC_AXB) and ADAC Pinnacle CCC (AP_CCC) algorithms. Dose volume histograms of PTV were used to calculate dosimetric and radiobiological quality indices, and equivalent dose to 2 Gy per fraction using linear-quadratic-linear model. The BL_MC algorithm is considered gold standard tool to compare PTV parameters and quality indices to investigate dose calculation discrepancies of abovementioned plans.
BL_PB overestimates doses that may be due to inability of the algorithm to properly account for electron scattering and transport in inhomogeneous medium. Compared with BL_MCNO plans, the EC_AAA and EC_AXB yield lower homogeneity indices and overestimate the dose in the penumbra region, whereas AP_CCC plans were comparable for small PTV (≈8 cc) and had significant difference for large PTV.
BL_PB algorithm overestimates PTV doses than BL_MC calculated doses. The EC_AAA, EC_AXB and AP_CCC algorithms calculate doses within acceptable limits of radiotherapy dose delivery recommendations.
Oxidative stress has been documented in chronic schizophrenia and in the first episode of psychosis, but there are very little data on oxidative stress prior to the disease onset.
This work aimed to compare serum levels of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in young individuals at ultra-high risk (UHR) of developing psychosis with a comparison healthy control group (HC).
Thirteen UHR subjects and 29 age- and sex-matched healthy controls (HC) were enrolled in this study. Clinical assessment included the Comprehensive Assessment of At-Risk Mental States (CAARMS), the Semi-Structured Clinical Interview for DSM-IV Axis-I (SCID-I) or the Kiddie-SADS-Present and Lifetime Version (K-SADS-PL), and the Global Assessment of Functioning (GAF) scale. Activities of SOD and GPx were measured in serum by the spectrophotometric method using enzyme-linked immunosorbent assay kits.
After adjusting for age and years of education, there was a significant lower activity of SOD and lower GPX activity in the UHR group compared to the healthy control group (rate ratio [RR]=0.330, 95% CI 0.187; 0.584, p<0.001 and RR=0.509, 95% CI 0.323; 0.803, p=0.004, respectively). There were also positive correlations between GAF functioning scores and GPx and SOD activities.
Our results suggest that oxidative imbalances could be present prior to the onset of full-blown psychosis, including in at-risk stages. Future studies should replicate and expand these results.
Increasing use of daily chlorhexidine gluconate (CHG) bathing can potentially lead to selection for organisms with reduced susceptibility to CHG, limiting the utility of CHG. We examined reduced susceptibility to CHG of fluoroquinolone-resistant gram-negative bacilli and methicillin-resistant Staphylococcus. No evidence suggested reduced susceptibility to CHG.
Within acute psychiatric inpatient services, patients exhibiting severely disturbed behaviour can be transferred to a psychiatric intensive care unit (PICU) and/or secluded in order to manage the risks posed to the patient and others. However, whether specific patient groups are more likely to be subjected to these coercive measures is unclear. Using robust methodological and statistical techniques, we aimed to determine the demographic, clinical and behavioural predictors of both PICU and seclusion.
Data were extracted from an anonymised database comprising the electronic medical records of patients within a large South London mental health trust. Two cohorts were derived, (1) a PICU cohort comprising all patients transferred from general adult acute wards to a non-forensic PICU ward between April 2008 and April 2013 (N = 986) and a randomly selected group of patients admitted to general adult wards within this period who were not transferred to PICU (N = 994), and (2) a seclusion cohort comprising all seclusion episodes occurring in non-forensic PICU wards within the study period (N = 990) and a randomly selected group of patients treated in these wards who were not secluded (N = 1032). Demographic and clinical factors (age, sex, ethnicity, diagnosis, admission status and time since admission) and behavioural precursors (potentially relevant behaviours occurring in the 3 days preceding PICU transfer/seclusion or random sample date) were extracted from electronic medical records. Mixed effects, multivariable logistic regression analyses were performed with all variables included as predictors.
PICU cases were significantly more likely to be younger in age, have a diagnosis of bipolar disorder and to be held on a formal section compared with patients who were not transferred to PICU; female sex and longer time since admission were associated with lower odds of transfer. With regard to behavioural precursors, the strongest predictors of PICU transfer were incidents of physical aggression towards others or objects and absconding or attempts to abscond. Secluded patients were also more likely to be younger and legally detained relative to non-secluded patients; however, female sex increased the odds of seclusion. Likelihood of seclusion also decreased with time since admission. Seclusion was significantly associated with a range of behavioural precursors with the strongest associations observed for incidents involving restraint or shouting.
Whilst recent behaviour is an important determinant, patient age, sex, admission status and time since admission also contribute to risk of PICU transfer and seclusion. Alternative, less coercive strategies must meet the needs of patients with these characteristics.
The Murchison Widefield Array is a new low-frequency interferometric radio telescope built in Western Australia at one of the locations of the future Square Kilometre Array. We describe the automated radio-frequency interference detection strategy implemented for the Murchison Widefield Array, which is based on the aoflagger platform, and present 72–231 MHz radio-frequency interference statistics from 10 observing nights. Radio-frequency interference detection removes 1.1% of the data. Radio-frequency interference from digital TV is observed 3% of the time due to occasional ionospheric or atmospheric propagation. After radio-frequency interference detection and excision, almost all data can be calibrated and imaged without further radio-frequency interference mitigation efforts, including observations within the FM and digital TV bands. The results are compared to a previously published Low-Frequency Array radio-frequency interference survey. The remote location of the Murchison Widefield Array results in a substantially cleaner radio-frequency interference environment compared to Low-Frequency Array’s radio environment, but adequate detection of radio-frequency interference is still required before data can be analysed. We include specific recommendations designed to make the Square Kilometre Array more robust to radio-frequency interference, including: the availability of sufficient computing power for radio-frequency interference detection; accounting for radio-frequency interference in the receiver design; a smooth band-pass response; and the capability of radio-frequency interference detection at high time and frequency resolution (second and kHz-scale respectively).
Post-operative facial palsy is the most important potential complication of parotid surgery for benign lesions. The published prevalence of facial weakness is up to 57 per cent for temporary weakness and up to 7 per cent for permanent weakness. We aimed to identify potential risk factors for post-operative facial palsy.
Materials and methods:
One hundred and fifty patients who had undergone parotid surgery for benign disease were retrospectively reviewed. Tumour factors (size, location and histopathology), patient factors (age and sex) and operative factors (operation, surgeon grade, surgeon specialty and use of intra-operative facial nerve monitoring) were all analysed for significant associations with post-operative facial palsy.
Results and analysis:
The overall incidence of facial palsy was 26.7 per cent for temporary weakness and 2.6 per cent for permanent weakness. The associations between facial palsy and all the above factors were analysed using Pearson's chi-square test and found to be non-significant.
These outcomes compare favourably with the literature. No significant risk factors were identified, suggesting that atraumatic, meticulous surgical technique is still the most important factor affecting post-operative facial palsy.
Current guidelines for control of Clostridium difficile infection (CDI) suggest that contact precautions be discontinued after diarrhea resolves. However, limited information is available regarding the frequency of skin contamination and environmental shedding of C. difficile during and after treatment.
We conducted a 9-month prospective, observational study involving 52 patients receiving therapy for CDI. Stool samples, skin (chest and abdomen) samples, and samples from environmental sites were cultured for C. difficile before, during, and after treatment. Polymerase chain reaction ribotyping was performed to determine the relatedness of stool, skin, and environmental isolates.
Fifty-two patients with CDI were studied. C. difficile was suppressed to undetectable levels in stool samples from most patients during treatment; however, 1-4 weeks after treatment, 56% of patients who had samples tested were asymptomatic carriers of C. difficile. The frequencies of skin contamination and environmental shedding remained high at the time of resolution of diarrhea (60% and 37%, respectively), were lower at the end of treatment (32% and 14%, respectively), and again increased 1-4 weeks after treatment (58% and 50%, respectively). Skin and environmental contamination after treatment was associated with use of antibiotics for non-CDI indications. Ninety-four percent of skin isolates and 82% of environmental isolates were genetically identical to concurrent stool isolates.
Skin contamination and environmental shedding of C. difficile often persist at the time of resolution of diarrhea, and recurrent shedding is common 1-4 weeks after therapy. These results provide support for the recommendation that contact precautions be continued until hospital discharge if rates of CDI remain high despite implementation of standard infection-control measures.
Sphenoid sinus mucoceles represent only 1–2 per cent of all paranasal sinus mucoceles. Patients may present with a myriad of symptoms. Pre-operative investigations include nasoendoscopy, computed tomography and/or magnetic resonance imaging. Treatment is by endoscopic sinus surgery.
A retrospective review of the archives of the Singapore General Hospital otolaryngology department (1999–2006) identified 10 cases of sphenoid sinus mucocele. Patient demographics, presenting symptoms, investigations and treatment were evaluated.
The 10 patients identified (three women and seven men) had a mean age of 54.5 years (range 24–70 years). Thirty per cent of patients had a history of nasopharyngeal carcinoma treated with radiotherapy. Presenting symptoms, in order of decreasing frequency, were: ocular symptoms (50 per cent), headaches (30 per cent), nasal discharge (30 per cent) and facial pain (10 per cent). All patients underwent pre-operative computed tomography or magnetic resonance imaging. Twenty per cent of patients had evidence of intracranial involvement on imaging. All patients underwent uncomplicated transnasal sphenoidotomy and drainage of the mucocele. There was no clinical or radiological evidence of recurrence at a mean follow up of 29 months (range 4–90 months).
Sphenoid sinus mucocele is a rare condition. In this study, radiation to the head and neck appeared to be a predisposing factor, and eye symptoms were the commonest presentation. Endoscopic sinus surgery is a safe and effective treatment modality.
Functional endoscopic sinus surgery is the mainstay of surgical treatment for chronic sinusitis. Day-case surgery has the advantage over in-patient surgery of being cost-effective and resource sparing. The objectives of this study were to assess our results for day-case functional endoscopic sinus surgery.
This was a retrospective case note review of day-case functional endoscopic sinus surgery procedures performed at Leeds General Infirmary from February 2004 to February 2007. We recorded patients' demographic data, operative details, post-operative course and follow-up results.
A total of 105 day-case functional endoscopic sinus surgery procedures were included in the study. Patients' ages ranged from 16 to 93 years; 44 (41.9 per cent) were female and 61 (58.1 per cent) were male. Of these patients, 39 (37.1 per cent) had chronic sinusitis and the rest (66; 62.8 per cent) had nasal polyposis and sinusitis. Sixty-one patients (58.1 per cent) underwent surgery on the morning operating list, while the rest (44; 41.9 per cent) underwent surgery in the afternoon. Of the 105 patients, 24 (22.8 per cent) had undergone previous nasal surgery. The majority of patients (90/105; 85.7 per cent) were discharged on the same day as surgery. The only complication recorded in this study was bleeding, noted in seven patients (6.7 per cent). At the follow-up appointment, 90/105 (85.7 per cent) patients were satisfied with their post-operative results.
Day-case endoscopic sinus surgery can be performed safely as a day-case procedure. The most important factors for a successful outcome are correct patient selection, in terms of general health and social circumstances, and a dedicated day-case team.
We report a rare case of giant petrous carotid aneurysm.
Case report and a review of the literature regarding treatment options for such aneurysms.
A 30-year-old man presented with epistaxis, headaches and visual disturbance. Definitive diagnosis was achieved by non-invasive imaging techniques, including magnetic resonance angiography and carotid angiography. Carotid angiography demonstrated a giant petrous carotid aneurysm effacing the petrous apex. The aneurysm was obliterated by internal carotid artery ligation, following successful tolerance of the balloon occlusion test. However, despite internal carotid artery ligation, this patient continued to have minor episodes of epistaxis.
Some aneurysms are too large to be treated with endovascular occlusion techniques; in such cases, ligation of the parent vessel is indicated. However, our patient continued to experience persistent, mild epistaxis despite internal carotid artery ligation, as a result of the reperfusion phenomenon.
To analyse current trends in our population with respect to the presentation, diagnosis and management of tubercular and chronic pyogenic osteomyelitis of the cranio-facial bones.
Tertiary healthcare centre.
Patients and methods:
The study population comprised 14 patients with tubercular and chronic pyogenic osteomyelitis who were managed in the otorhinolaryngology department between May 2002 and December 2005.
Odontogenic infections, sinus infections and aural infections were the most commonly identified aetiological factors. Most of the patients presented with swelling, pain and discharging sinus. The diagnosis was established on the basis of clinical evaluation, radiological investigations and histopathological analysis, with six cases diagnosed with tubercular osteomyelitis and eight cases with chronic pyogenic osteomyelitis. All the patients were initially commenced on oral antibiotics, which were continued for two weeks in all cases with chronic pyogenic osteomyelitis. All the patients with pyogenic osteomyelitis underwent surgical management, with one patient requiring repeated surgical interventions. All the patients with tubercular osteomyelitis received anti-tubercular chemotherapy, with complete cure.
Osteomyelitis of the cranio-facial bones is an uncommon entity which requires a high index of clinical suspicion along with radiological and histopathological investigations in order to establish the diagnosis. Tubercular osteomyelitis is clinically and radiologically indistinguishable from pyogenic osteomyelitis, and the two conditions can be differentiated only on the basis of histopathological evaluation of involved tissue.