Transmission and absorption in a waveguide with a metamaterial cavity

The reflection and transmission of acoustic waves along a waveguide of uniform width by a metamaterial cavity is considered. The metamaterial is comprised of a closely spaced array of micro-channels separated by thin plates between which the field may be damped. Exact equations governing the field in the microstructured metamaterial cavity are replaced by an effective field using the homogenisation approach. This allows a solution to be formulated in terms of an integral equation across the interface between the metamaterial cavity and the waveguide. Attention focuses on the resonant and damping effects of a metamaterial cavity of tapered height where rainbow trapping phenomena are encountered. It is shown that near-perfect broadbanded absorption of the incoming wave energy can be achieved.

Defining a mood stabiliser: novel framework for research and clinical practice

The term 'mood stabiliser' is ill-defined and lacks clinical utility. We propose a framework to evaluate medications and effectively communicate their mood stabilising properties - their acute and prophylactic efficacy across the domains of mania and depression. The standardised framework provides a common definition to facilitate research and clinical practice.

DECLARATION OF INTEREST

The Treatment Algorithm Group (TAG) was supported logistically by Servier who provided financial assistance with travel and accommodation for those TAG members travelling interstate or overseas to attend the meeting in Sydney (held on 18 November 2017). None of the committee were paid to participate in this project and Servier have not had any input into the content, format or outputs from this project.

Fungal infections in adult patients on extracorporeal life support

BACKGROUND

Patients on extracorporeal membrane oxygenation (ECMO) are often among the most severely ill in the intensive care unit. They are often receiving broad-spectrum antibiotics; they have multiple entry points for pathogens; and their immune system is impaired by blood circuit interaction. These factors are thought to predispose them to fungal infections. We thus aimed to evaluate the prevalence, risk factors, and prognosis of fungal infections in adults on ECMO.

METHODS

We conducted a retrospective cohort study using the Extracorporeal Life Support Organization registry, which compiles data on ECMO use from hundreds of international centers. We included all adult patients from 2006 to 2016 on any mode of ECMO with either a diagnosis of fungal infection or a positive fungal culture.

RESULTS

Our study comprised 2129 adult patients (10.8%) with fungal colonization or infection. Aspergillus involvement (colonization or infection) was present in 272 patients (1.4%), of whom 35.7% survived to hospital discharge. There were 245 patients (1.2%) with Candida invasive bloodstream infection, with 35.9% survival. Risk factors for Aspergillus involvement included solid organ transplant (OR 1.83; p = 0.008), respiratory support (OR 2.75; p < 0.001), and influenza infection (OR 2.48; p < 0.001). Risk factors for candidemia included sepsis (OR 1.60; p = 0.005) and renal replacement therapy (OR 1.55; p = 0.007). In multivariable analysis, Aspergillus involvement (OR 0.40; p < 0.001) and candidemia (OR 0.47; p < 0.001) were both independently associated with decreased survival.

CONCLUSIONS

The prevalence of Aspergillus involvement and Candida invasive bloodstream infection were not higher in patients on ECMO than what has been reported in the general intensive care population. Both were independently associated with a reduced survival. Aspergillus involvement was strongly associated with ECMO for respiratory support and influenza.

Use of a tracheal dilator for percutaneous insertion of 27F and 31F Avalon© dual-lumen cannulae for veno-venous extracorporeal membrane oxygenation in adults

Veno-venous extracorporeal membrane oxygenation can be performed either by two cannulae or by a single dual-lumen cannula. The dual-lumen cannulation configuration offers multiple advantages: it avoids the femoral site which may be at greater risk of infection, it improves patient mobility, eases prone positioning and greatly reduces recirculation. The Avalon was the first commercially available dual-lumen cannula for adults. It has gained much popularity, but, for more than a year now, the adult vascular access kit with the 30Fr dilator has been discontinued in the United Kingdom. In this article, we share our experience with an alternative insertion method, using a percutaneous dilatational tracheostomy kit. This off-label use of the tracheostomy dilator appears to be safe. It may allow the continuing use of Avalon dual-lumen cannulae while waiting for a more permanent solution to be provided by the manufacturer.

Treatment of severe depression – non-pharmacological aspects

Depression, in its severest forms, causes severe morbidity, has a high incidence of mortality and requires emergency treatment. In a previous article in this journal (Porter & Ferrier, 1999), we discussed the emergency treatment of severe depression by pharmacological means and electroconvulsive therapy (ECT). Here, we will discuss the contribution of non-pharmacological aspects of management to fast, effective and safe treatment of severe depression. We will also complete our review of this subject by examining the efficacy of some emerging therapeutic interventions for severe depression.

Anticonvulsants as mood stabilisers

Recent research has highlighted the fact that a significant number of patients with bipolar affective disorder have a poor outcome (Cole et al, 1993). The most common poor outcome is the development of rapid or ultra-rapid cycling, but mixed states, prolonged depression and severe mania are also associated with poor outcome. It is estimated that approximately one-third of patients with bipolar affective disorder do not respond fully to lithium and a significant number of patients discontinue lithium (Post, 1990) which may itself cause further problems.

Body Mass Index and Mortality Among Adults Undergoing Cardiac Surgery: A Nationwide Study With a Systematic Review and Meta-Analysis

BACKGROUND

In an apparent paradox, morbidity and mortality are lower in obese patients undergoing cardiac surgery, although the nature of this association is unclear. We sought to determine whether the obesity paradox observed in cardiac surgery is attributable to reverse epidemiology, bias, or confounding.

METHODS

Data from the National Adult Cardiac Surgery registry for all cardiac surgical procedures performed between April 2002 and March 2013 were extracted. A parallel systematic review and meta-analysis (MEDLINE, Embase, SCOPUS, Cochrane Library) through June 2015 were also accomplished. Exposure of interest was body mass index categorized into 6 groups according to the World Health Organization classification.

RESULTS

A total of 401 227 adult patients in the cohort study and 557 720 patients in the systematic review were included. A U-shaped association between mortality and body mass index classes was observed in both studies, with lower mortality in overweight (adjusted odds ratio, 0.79; 95% confidence interval, 0.76-0.83) and obese class I and II (odds ratio, 0.81; 95% confidence interval, 0.76-0.86; and odds ratio, 0.83; 95% confidence interval, 0.74-0.94) patients relative to normal-weight patients and increased mortality in underweight individuals (odds ratio, 1.51; 95% confidence interval, 1.41-1.62). In the cohort study, a U-shaped relationship was observed for stroke and low cardiac output syndrome but not for renal replacement therapy or deep sternal wound infection. Counter to the reverse epidemiology hypotheses, the protective effects of obesity were less in patients with severe chronic renal, lung, or cardiac disease and greater in older patients and in those with complications of obesity, including the metabolic syndrome and atherosclerosis. Adjustments for important confounders did not alter our results.

CONCLUSIONS

Obesity is associated with lower risks after cardiac surgery, with consistent effects noted in multiple analyses attempting to address residual confounding and reverse causation.

Treating and Reducing Anxiety and Pain in the Paediatric Emergency Department (The Trapped 2 Survey): Time for Action – A Pediatric Emergency Research Canada (Perc) Project

BACKGROUND: Multiples barriers to appropriate analgesia provision are reported in the paediatric emergency department (PED), including limited accessibility to effective strategies.

OBJECTIVES: To evaluate the improvement in the accessibility of pain and anxiety management strategies in PEDs in Canada, after the creation of a national pediatric pain quality improvement collaborative, through Pediatric Emergency Research Canada.

DESIGN/METHODS: In 2013, the TRAPPED 1 survey was administered across Canadian PEDs, in order to evaluate the resources in place for pain and anxiety management. Subsequent to the TRAPPED 1, a pain Quality Improvement Collaborative was created to stimulate the implementation of new pain and anxiety management strategies through the sharing of information between PEDs. The TRAPPED 2 survey involved a cross sectional survey similar to TRAPPED 1, after a two year interval. Its main focus was to evaluate the improvement in the accessibility of specific, preferred strategies reported by each centre, after participating in this collaborative between December 2014 to November 2015, and then working to implement change within their own PEDs.

RESULTS: All 15/15 Canadian PEDs responded to TRAPPED 1 in 2013. In 2014, 11/15 agreed to participate in the national pain Quality Improvement Collaborative, with a goal of introducing new pain and anxiety management strategies within their own PEDs. An in-person meeting, email communication, and telephone meetings were employed for information sharing regarding experiences/challenges within each of the participating centres. Newly introduced strategies included education, distraction, nurse-initiated protocols, and policies/education to encourage the use of intranasal (IN) medications. 11/11 centres have responded to the interim follow up surveys in 2015. At the end of the project (Fall 2105), 15/15 Canadian PEDs agreed to complete the final TRAPPED 2 survey. When comparing the results of 2015 with 2013, an increased number of PEDs used face-based pain scales (14/15 vs 6/15) and behavioural scales (5/15 vs 1/15) for pain assessment of school-aged children and infants, respectively. Use of assessment room wall decoration for distraction increased from 7/15 to 11/15. Reminder posters for pain management at triage increased from 4/15 to 6/15. Availability of electronic distraction strategies (e.g. using tablets) increased from 4/15 to 10/15 centres. For skin-piercing procedure, nurses initiated protocols to use topical anesthetic creams and oral sucrose was available in 12/15 centres (compared to 10/15 in 2013), and 14/15 (compared to 12/15 in 2013) respectively. Availability of IN medications increased in the last two years: fentanyl 14/15 (9/15 in 2013) and midazolam in at least 10/15 (8/15 in 2013). 10/11 PEDS involved in the QI strategy reported the implementation of at least one of their strategies identified.

CONCLUSION: This study suggests that the use of a pain Quality Improvement Collaborative may improve the introduction of new strategies in multiple PEDs. It can help guide other centres when introducing new strategies to reduce pain and anxiety for children in community EDs. Future research can focus on the sustainability of the strategies, and as well the effect of the collaborative on the introduction of other pain treatment strategies.

Stimulants for depression: On the up and up?

The use of traditional psychostimulants (methylphenidate and dexamphetamine) and stimulant-like drugs (modafinil and armodafinil) for the treatment of depression is a growing concern given the lack of research evidence supporting their effectiveness. The current article describes the role of stimulants in treating depression--specifically their risks and benefits and their potential use alongside antidepressants. Clinically, the rapid amelioration of depressive symptoms with traditional psychostimulants is often dramatic but short-lived, and this suggests that they likely operate via different mechanisms to conventional antidepressants. More importantly, there is little evidence from randomised controlled trials supporting their efficacy in treating depression, although modafinil has been shown to be effective in reducing prominent depressive symptoms, such as fatigue. Research is urgently required to clarify psychostimulants' mechanisms of action and to evaluate their long-term benefits and risks in the treatment of major and bipolar depression. Ultimately, specificity of action needs to be determined to inform the sophisticated clinical use of psychostimulants in the management of depression. Until then they should only be prescribed if absolutely necessary, and even then their prescription should be facilitatory and time limited unless it is for investigational purposes.

Effect of transmeridian travel and jetlag on mood disorders: evidence and implications

OBJECTIVES

Given the sensitivity of individuals with mood disorders to circadian disruption, transmeridian travel would likely be a high-risk endeavour leading to onset or relapses in mood. A systematic review was undertaken to identify the evidence of the impact of transmeridian travel on people with mood disorders.

METHODS

Databases search included the following: CINAHL, MEDLINE, PsycINFO and manual searching using the keywords jetlag, transmeridian travel, circadian rhythm disruption, mood disorder, bipolar, major depression, seasonal affective disorder, depression, mania and hypomania.

RESULTS

Only three studies were identified that related to transmeridian travel and jetlag in people with mood disorders. There is some suggestion that transmeridian travel does appear to precipitate mood episodes with an increased rate of episodes of depression with westward compared with an increased rate of manic/hypomanic episodes with eastward travel. Individuals with a previous history of mood disorder appear to be more vulnerable if adherence to medication is compromised.

CONCLUSION

Given the limited evidence that transmeridian travel precipitates mood episodes, this poses difficulties in identifying suitable ways to mitigate the effects of transmeridian travel in mood disorders. However, in the absence of mood-specific guidelines, some guidance can be given based on our current understanding of the relevance of circadian disruption to both jetlag and mood disorders. Further research is required to identify more focused strategies to mitigate the impact of transmeridian travel for individuals with mood disorders.

Distribution-based estimates of minimal important difference for hospital anxiety and depression scale and impact of event scale-revised in survivors of acute respiratory failure

OBJECTIVE

This study will estimate distribution-based minimal important difference (MID) for the Hospital Anxiety and Depression Scale anxiety (HADS-A) and depression (HADS-D) subscales, and the Impact of Event Scale-Revised (IES-R) in survivors of acute respiratory failure (ARF).

METHODS

Secondary analyses of data from two US and three UK studies of ARF survivors (total N=1223). HADS-D and HADS-A were used to assess depression and anxiety symptoms. IES-R assessed post-traumatic stress disorder symptoms. Standard error of measurement, minimal detectable change90, 0.5 standard deviation (S.D.), and 0.2 S.D. were used to estimate MID for the combined sample, by studies, 6- and 12-month follow-ups, country and mental health condition.

RESULTS

Overall, MID estimates converged to 2.0-2.5 for the HADS-A, 1.9-2.3 for the HADS-D and 0.17-0.18 for the IES-R. MID estimates were comparable across studies, follow-up, country and mental health condition.

CONCLUSION

Among ARF survivors, 2.0-2.5 is a reasonable range for the MID for both HADS subscales, and 0.2 is reasonable for IES-R. Until anchor-based MIDs for these instruments are available, these distribution-based estimates can help researchers plan future studies and interpret the clinical importance of findings in ARF patient populations.

Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for mood disorders

OBJECTIVES

To provide guidance for the management of mood disorders, based on scientific evidence supplemented by expert clinical consensus and formulate recommendations to maximise clinical salience and utility.

METHODS

Articles and information sourced from search engines including PubMed and EMBASE, MEDLINE, PsycINFO and Google Scholar were supplemented by literature known to the mood disorders committee (MDC) (e.g., books, book chapters and government reports) and from published depression and bipolar disorder guidelines. Information was reviewed and discussed by members of the MDC and findings were then formulated into consensus-based recommendations and clinical guidance. The guidelines were subjected to rigorous successive consultation and external review involving: expert and clinical advisors, the public, key stakeholders, professional bodies and specialist groups with interest in mood disorders.

RESULTS

The Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for mood disorders (Mood Disorders CPG) provide up-to-date guidance and advice regarding the management of mood disorders that is informed by evidence and clinical experience. The Mood Disorders CPG is intended for clinical use by psychiatrists, psychologists, physicians and others with an interest in mental health care.

CONCLUSIONS

The Mood Disorder CPG is the first Clinical Practice Guideline to address both depressive and bipolar disorders. It provides up-to-date recommendations and guidance within an evidence-based framework, supplemented by expert clinical consensus.

MOOD DISORDERS COMMITTEE

Professor Gin Malhi (Chair), Professor Darryl Bassett, Professor Philip Boyce, Professor Richard Bryant, Professor Paul Fitzgerald, Dr Kristina Fritz, Professor Malcolm Hopwood, Dr Bill Lyndon, Professor Roger Mulder, Professor Greg Murray, Professor Richard Porter and Associate Professor Ajeet Singh.

INTERNATIONAL EXPERT ADVISORS

Professor Carlo Altamura, Dr Francesco Colom, Professor Mark George, Professor Guy Goodwin, Professor Roger McIntyre, Dr Roger Ng, Professor John O'Brien, Professor Harold Sackeim, Professor Jan Scott, Dr Nobuhiro Sugiyama, Professor Eduard Vieta, Professor Lakshmi Yatham.

AUSTRALIAN AND NEW ZEALAND EXPERT ADVISORS

Professor Marie-Paule Austin, Professor Michael Berk, Dr Yulisha Byrow, Professor Helen Christensen, Dr Nick De Felice, A/Professor Seetal Dodd, A/Professor Megan Galbally, Dr Josh Geffen, Professor Philip Hazell, A/Professor David Horgan, A/Professor Felice Jacka, Professor Gordon Johnson, Professor Anthony Jorm, Dr Jon-Paul Khoo, Professor Jayashri Kulkarni, Dr Cameron Lacey, Dr Noeline Latt, Professor Florence Levy, A/Professor Andrew Lewis, Professor Colleen Loo, Dr Thomas Mayze, Dr Linton Meagher, Professor Philip Mitchell, Professor Daniel O'Connor, Dr Nick O'Connor, Dr Tim Outhred, Dr Mark Rowe, Dr Narelle Shadbolt, Dr Martien Snellen, Professor John Tiller, Dr Bill Watkins, Dr Raymond Wu.

Five-year experience with mobile adult extracorporeal membrane oxygenation in a tertiary referral center

INTRODUCTION

Mobile extracorporeal membrane oxygenation (ECMO) is reserved for critically unstable patients who may not otherwise survive transfer to the ECMO center. We describe our experience with mobile ECMO.

METHODS

We retrospectively reviewed adult patients between 2010 and 2014 who were referred for ECMO support and were too unwell for conventional transfer. They were cannulated at their referring center by our team and subsequently transported back to our hospital on ECMO.

RESULTS

A total of 102 patients were put on ECMO by our team. Of 102 patients, 95 (93%) were managed by venovenous ECMO, and 7 (7%), by venoarterial ECMO. The average distance traveled was 195 miles (SD, ±256.8; range, 3.6-980). Transportation was via road in 77 cases (77%), by air in 22 cases (22%), and in 3 cases (3%) a combination of road and air was used. A double-lumen Avalon cannula was used in 72 patients (70%). One patient had a ventricular tachycardia arrest during cannulation but was successfully resuscitated. There was no mortality or major complications during transfer.

CONCLUSION

The use of mobile ECMO in adult patients is a safe modality for transfer of critically unwell patients. We have safely used double-lumen cannulas in most of these patients.

Conducting qualitative research in mental health: Thematic and content analyses

OBJECTIVE

The objective of this paper is to describe two methods of qualitative analysis - thematic analysis and content analysis - and to examine their use in a mental health context.

METHOD

A description of the processes of thematic analysis and content analysis is provided. These processes are then illustrated by conducting two analyses of the same qualitative data. Transcripts of qualitative interviews are analysed using each method to illustrate these processes.

RESULTS

The illustration of the processes highlights the different outcomes from the same set of data.

CONCLUSION

Thematic and content analyses are qualitative methods that serve different research purposes. Thematic analysis provides an interpretation of participants' meanings, while content analysis is a direct representation of participants' responses. These methods provide two ways of understanding meanings and experiences and provide important knowledge in a mental health context.