P057 Virus aerosol propagation by CPAP is proportional to mask leak and can be prevented by use of a hood and air filtration system

Introduction

Nosocomial transmission of SARS-CoV-2 has caused significant morbidity/mortality in the COVID-19 pandemic. Because patients auto-emit aerosols containing viable virus, these aerosols can be further propagated when patients undergo certain treatments including continuous positive airway pressure (PAP) therapy. This study aimed to assess the degree of viable virus propagated from mask leak in a PAP circuit.

Methods

Bacteriophage PhiX174 (108copies/mL) was nebulised into a custom PAP circuit. Mask leak was systematically varied to 0, 7, 21, 28 and 42 L/min at the mask interface. Plates containing Escherichia coli assessed the degree of viable virus settling on surfaces around the room. In order to contain virus spread a ventilated headboard and high efficiency particulate air (HEPA) filter was tested.

Results

Increasing mask leak was associated with virus contamination in a dose response manner (χ2= 58.24, df=4, p<0.001). Clinically relevant levels of leak (≥21 L/min) were associated with virus counts equivalent to using PAP with a standard vented mask. Viable viruses were recorded on all plates (up to 3.86m from source). A plastic hood with HEPA filtration significantly reduced viable viruses on all plates. HEPA exchange rates of 170 and 470m3/hr eradicated all evidence of virus contamination.

Discussion

Mask leak from PAP circuits may be a major source of environmental contamination and nosocomial spread of infectious respiratory diseases. Subclinical levels of leak should be treated as an infectious risk. Cheap and low-cost patient hoods with HEPA filtration are an effective countermeasure.

Vertebroplasty and Kyphoplasty for Osteoporotic Vertebral Fractures: What Are the Latest Data?

Osteoporotic vertebral compression fractures frequently result in significant morbidity and health care resource use. For patients with severe and disabling pain, vertebral augmentation (vertebroplasty and kyphoplasty) is often considered. Although vertebroplasty was introduced >30 years ago, there are conflicting opinions regarding the role of these procedures in the treatment of osteoporotic vertebral compression fractures. This review article updates clinicians on the published prospective randomized controlled data, including the most recent positive trials that followed initial negative trials in 2009. Analysis of multiple national claim datasets has also provided further insight into the utility of these procedures. Finally, we considered the recent recommendations of national organizations and medical societies that advise on the use of vertebral augmentation procedures for osteoporotic vertebral compression fractures.

Impact of analgesic modality on stress response following laparoscopic colorectal surgery: a post-hoc analysis of a randomised controlled trial

BACKGROUND

Epidural analgesia is perceived to modulate the stress response after open surgery. This study aimed to explore the feasibility and impact of measuring the stress response attenuation by post-operative analgesic modalities following laparoscopic colorectal surgery within an enhanced recovery after surgery (ERAS) protocol.

METHODS

Data were collected as part of a double-blinded randomised controlled pilot trial at two UK sites. Patients undergoing elective laparoscopic colorectal resection were randomised to receive either thoracic epidural analgesia (TEA) or continuous local anaesthetic infusion to the extraction site via wound infusion catheter (WIC) post-operatively. The aim of this study was to measure the stress response to the analgesic modality by measuring peripheral venous blood samples analysed for serum concentrations of insulin, cortisol, epinephrine and interleukin-6 at induction of anaesthesia, at 3, 6, 12 and 24 h after the start of operation. Secondary endpoints included mean pain score in the first 48 h, length of hospital stay, post-operative complications and 30-day re-admission rates.

RESULTS

There was a difference between the TEA and WIC groups that varies across time. In the TEA group, there was significant but transient reduced level of serum epinephrine and a higher level of insulin at 3 and 6 h. In the WIC, there was a significant reduction of interleukin-6 values, especially at 12 h. There was no significant difference observed in the other endpoints.

CONCLUSIONS

There is a significant transient attenuating effect of TEA on stress response following laparoscopic colorectal surgery and within ERAS as expressed by serum epinephrine and insulin levels. Continuous wound infusion with local anaesthetic, however, attenuates cytokine response as expressed by interleukin-6.

Henipavirus microsphere immuno-assays for detection of antibodies against Hendra virus

Hendra and Nipah viruses (HeV and NiV) are closely related zoonotic pathogens of the Paramyxoviridae family. Both viruses belong to the Henipavirus genus and cause fatal disease in animals and humans, though only HeV is endemic in Australia. In general and due to the acute nature of the disease, agent detection by PCR and virus isolation are the primary tools for diagnostic investigations. Assays for the detection of antibodies against HeV are fit more readily for the purpose of surveillance testing in disease epidemiology and to meet certification requirements in the international movement of horses. The first generation indirect ELISA has been affected by non-specific reactions which must be resolved using virus neutralisation serology conducted at laboratory bio-safety level 4 containment (PC4). Recent developments have enabled improvements in the available serology assays. The production of an expressed recombinant truncated HeV G protein has been utilised in ELISA and in Luminex-based multiplexed microsphere assays. In the latter format, two Luminex assays have been developed for use in henipavirus serology: a binding assay (designed for antibody detection and differentiation) and a blocking assay (designed as a surrogate for virus neutralisation). Equine and canine field sera were used to evaluate the two Luminex assays relative to ELISA and virus neutralisation serology. Results showed that Luminex assays can be effective as rapid, sensitive and specific tests for the detection of HeV antibody in horse and dog sera. The tests do not require PC4 containment and are appropriate for high throughput applications as might be required for disease investigations and other epidemiological surveillance. Also, the results show that the Luminex assays detect effectively HeV vaccine-induced antibodies.

Rectal impalement injury through the pelvis, abdomen and thorax

Impalement rectal injuries with intraperitoneal organ injuries are rare. It is even rarer for such injuries to result in pelvic, abdominal and thoracic internal injuries. We present the case of a 39-year-old man who was admitted after an assault where a broken broomstick was inserted forcibly into his rectum. Surgery revealed penetration through the rectum, dome of the bladder, mesentery, liver and right lung. The patient survived following management by a multispecialty surgical team. Our literature review identified four similar cases with one fatality only. Prognosis seems to be good in these types of injuries provided there is an early presentation, the penetrating object is left in situ before the operation and, most importantly, an organised team approach to deal with the various injuries.

Obesity-dependent metabolic signatures associated with nonalcoholic fatty liver disease progression

Our understanding of the mechanisms by which nonalcoholic fatty liver disease (NAFLD) progresses from simple steatosis to steatohepatitis (NASH) is still very limited. Despite the growing number of studies linking the disease with altered serum metabolite levels, an obstacle to the development of metabolome-based NAFLD predictors has been the lack of large cohort data from biopsy-proven patients matched for key metabolic features such as obesity. We studied 467 biopsied individuals with normal liver histology (n=90) or diagnosed with NAFLD (steatosis, n=246; NASH, n=131), randomly divided into estimation (80% of all patients) and validation (20% of all patients) groups. Qualitative determinations of 540 serum metabolite variables were performed using ultraperformance liquid chromatography coupled to mass spectrometry (UPLC-MS). The metabolic profile was dependent on patient body-mass index (BMI), suggesting that the NAFLD pathogenesis mechanism may be quite different depending on an individual's level of obesity. A BMI-stratified multivariate model based on the NAFLD serum metabolic profile was used to separate patients with and without NASH. The area under the receiver operating characteristic curve was 0.87 in the estimation and 0.85 in the validation group. The cutoff (0.54) corresponding to maximum average diagnostic accuracy (0.82) predicted NASH with a sensitivity of 0.71 and a specificity of 0.92 (negative/positive predictive values=0.82/0.84). The present data, indicating that a BMI-dependent serum metabolic profile may be able to reliably distinguish NASH from steatosis patients, have significant implications for the development of NASH biomarkers and potential novel targets for therapeutic intervention.