A prospective observational study of the effects of sugammadex on peri-operative oestrogen and progesterone levels in women who take hormonal contraception.

Pharmacokinetic modelling suggests that sugammadex may interact with endogenous progesterone and reduce levels by 34% in patients taking hormonal contraception. Due to this potential interaction that may be equivalent to missing one dose of an oral contraceptive pill, both the manufacturer and professional anaesthesia organisations recommend counselling patients to use additional non-hormonal contraception after administration of sugammadex. We performed a prospective observational study examining the changes in serum oestrogen and progesterone concentrations in premenopausal adult women undergoing an operative procedure. Sixty participants who were on hormonal contraception received sugammadex. Two additional control groups were recruited, consisting of 30 participants who were not on hormonal contraception and did not receive sugammadex, and 32 who were not on hormonal contraception and did receive sugammadex. Three blood samples were taken: before sugammadex; 15 min post-sugammadex; and 240 min post-sugammadex or end of operating theatre time. Median oestrogen levels decreased from baseline by around 40% at 240 min in all three groups (p ≤ 0.001). Progesterone levels rose significantly at 15 min (p = 0.002) in patients on contraception then decreased non-significantly to 20% below baseline at 240 min. The decrease in oestrogen and the rise in progesterone could both act to minimise the risk of ovulation and thus protect contraception in this population. We found no evidence of a change in hormone levels that might threaten contraceptive efficacy in women on hormonal contraception receiving sugammadex.

Unilateral diaphragmatic paresis following supracostal post-percutaneous nephrolithotomy.

Unilateral acquired diaphragmatic paresis is a known complication of thoracic surgeries. Direct mechanical injury to the phrenic nerve during surgery results in this complication. However its occurrence post-percutaneous nephrolithotomy (PCNL) has not been described. We report a 43-year-old man who underwent prone PCNL for endourological management of left complete staghorn calculus. Access via the 10th left intercostal space, under fluoroscopy, was carried out to remove the calculus. Post-operative, the routine chest radiograph revealed left hemidiaphragmatic blunting. Computerized tomography of the chest confirmed left hemidiaphragmatic elevation, suggesting unilateral diaphragmatic paresis. He did not have any respiratory symptoms, was managed conservatively with chest physiotherapy and incentive spirometry and responded extremely well. The absence of reported cases of diaphragmatic paresis post PCNL lends to a dearth in knowledge regarding recognition and management. This case report aims to acquaint urologists with this rare complication associated with supracostal PCNL and provide a rational management plan.

Robustness of convolutional neural networks to physiological electrocardiogram noise.

The electrocardiogram (ECG) is a widespread diagnostic tool in healthcare and supports the diagnosis of cardiovascular disorders. Deep learning methods are a successful and popular technique to detect indications of disorders from an ECG signal. However, there are open questions around the robustness of these methods to various factors, including physiological ECG noise. In this study, we generate clean and noisy versions of an ECG dataset before applying symmetric projection attractor reconstruction (SPAR) and scalogram image transformations. A convolutional neural network is used to classify these image transforms. For the clean ECG dataset, F1 scores for SPAR attractor and scalogram transforms were 0.70 and 0.79, respectively. Scores decreased by less than 0.05 for the noisy ECG datasets. Notably, when the network trained on clean data was used to classify the noisy datasets, performance decreases of up to 0.18 in F1 scores were seen. However, when the network trained on the noisy data was used to classify the clean dataset, the decrease was less than 0.05. We conclude that physiological ECG noise impacts classification using deep learning methods and careful consideration should be given to the inclusion of noisy ECG signals in the training data when developing supervised networks for ECG classification. This article is part of the theme issue 'Advanced computation in cardiovascular physiology: new challenges and opportunities'.

Is it safe to perform elective orthopaedic surgery with high community rates of COVID-19? An observational cohort study.

INTRODUCTION: During the first wave of the COVID-19 pandemic, University Hospitals Birmingham NHS Foundation trust was able to recommence elective orthopaedic surgery using private hospitals procured by the NHS as COVID-19 free 'green' sites. We report on the safety of elective orthopaedic surgery with high rates of community transmission. METHODS: We conducted an observational cohort study on consecutive NHS patients attending three private hospitals between 4 May 2020 and 16 June 2020. Patients attended preoperative assessment, including coronavirus disease (COVID-19) symptom screening, were instructed to self-isolate for 14 days and had a negative COVID-19 swab within 72 hours of surgery. Patient age, American Society of Anesthesiologists (ASA) grade, body mass index, surgery performed, type of anaesthetic and length of stay were collected. Our primary outcome was a positive COVID-19 swab, secondary outcomes were COVID-19 symptoms, readmission, surgical complications and mortality. RESULTS: Between 4 May 2020 and 16 June 2020, 191 patients were admitted to three private hospitals for elective surgery; 121 (67%) patients underwent general or regional anaesthetic, 179 patients were ASA grades 1 or 2 (94%) and 12 (6%) were ASA 3. In total, 187 (98%) patients were successfully contacted at 30 days postoperative and no COVID-19 symptoms, positive COVID-19 swabs or mortality or were recorded. One patient was readmitted following a pulmonary embolism and two patients were treated as outpatients for a deep vein thrombosis and a superficial infection. CONCLUSION: With 'green pathways' elective orthopaedic surgery can safely be performed while rates of COVID-19 in the community are high.

The evolution of mammalian brain size.

Relative brain size has long been considered a reflection of cognitive capacities and has played a fundamental role in developing core theories in the life sciences. Yet, the notion that relative brain size validly represents selection on brain size relies on the untested assumptions that brain-body allometry is restrained to a stable scaling relationship across species and that any deviation from this slope is due to selection on brain size. Using the largest fossil and extant dataset yet assembled, we find that shifts in allometric slope underpin major transitions in mammalian evolution and are often primarily characterized by marked changes in body size. Our results reveal that the largest-brained mammals achieved large relative brain sizes by highly divergent paths. These findings prompt a reevaluation of the traditional paradigm of relative brain size and open new opportunities to improve our understanding of the genetic and developmental mechanisms that influence brain size.

The use of triclosan-coated sutures to prevent surgical site infections: a systematic review and meta-analysis of the literature.

INTRODUCTION AND OBJECTIVES: Surgical site infections (SSIs) represent a common and serious complication of all surgical interventions. Microorganisms are able to colonise sutures that are implanted in the skin, which is a causative factor of SSIs. Triclosan-coated sutures are antibacterial sutures aimed at reducing SSIs. Our objective is to update the existing literature by systematically reviewing available evidence to assess the effectiveness of triclosan-coated sutures in the prevention of SSIs. METHODS: A systematic review of EMBASE, MEDLINE, AMED (Allied and complementary medicine database) and CENTRAL was performed to identify full text randomised controlled trials (RCTs) on 31 May 2019. INTERVENTION: Triclosan-coated sutures versus non-triclosan-coated sutures. PRIMARY OUTCOME: Our primary outcome was the development of SSIs at 30 days postoperatively. A meta-analysis was performed using a fixed-effects model. RESULTS: Twenty-five RCTs were included involving 11 957 participants. Triclosan-coated sutures were used in 6008 participants and non triclosan-coated sutures were used in 5949. Triclosan-coated sutures significantly reduced the risk of SSIs at 30 days (relative risk 0.73, 95% CI 0.65 to 0.82). Further sensitivity analysis demonstrated that triclosan-coated sutures significantly reduced the risk of SSIs in both clean and contaminated surgery. CONCLUSION: Triclosan-coated sutures have been shown to significantly reduced the risk of SSIs when compared with standard sutures. This is in agreement with previous work in this area. This study represented the largest review to date in this area. This moderate quality evidence recommends the use of triclosan-coated sutures in order to reduce the risk of SSIs particularly in clean and contaminated surgical procedures. PROSPERO REGISTRATION NUMBER: CRD42014014856.

Therapeutic doses of neostigmine, depolarising neuromuscular blockade and muscle weakness in awake volunteers: a double-blind, placebo-controlled, randomised volunteer study.

Neostigmine reverses non-depolarising neuromuscular blockade, but may cause muscle weakness when administered after full recovery of neuromuscular function. We hypothesised that neostigmine in therapeutic doses impairs muscle strength and respiratory function in awake healthy volunteers. Twenty-one volunteers were randomised to receive two doses of either intravenous (i.v.) neostigmine 2.5 mg with glycopyrrolate 450 µg (neostigmine group, n = 14) or normal saline 0.9% (placebo group, n = 7). The first dose was administered immediately after obtaining baseline measurements, and the second dose was administered 15 min later. All 14 volunteers in the neostigmine group received the first dose, mean (SD) 35 (5.8) µg.kg-1 , but only nine of these volunteers agreed to receive the second dose, 34 (3.5) ?g.kg-1 . The primary outcome was hand grip strength. Secondary outcomes were train-of-four ratio, single twitch height, forced expiratory volume in 1 s, forced vital capacity, forced expiratory volume in 1 s/forced vital capacity ratio, oxygen saturation, heart rate and mean arterial pressure. The first dose of intravenous neostigmine with glycopyrrolate resulted in reduced grip strength compared with placebo, -20 (20) % vs. +4.3 (9.9) %, p = 0.0016; depolarising neuromuscular blockade with decreased single twitch height, -14 (11) % vs. -3.8 (5.6) %, p = 0.0077; a restrictive spirometry pattern with decreased predicted forced expiratory volume in 1 s, -15 (12) % vs. -0.47 (3.4) %, p = 0.0011; and predicted forced vital capacity, -20 (12) % vs. -0.59 (3.2) %, p < 0.0001 at 5 min after administration. The second dose of neostigmine with glycopyrrolate further decreased grip strength mean (SD) -41 (23) % vs. +1.0 (15) %, p = 0.0004; single twitch height -25 (15) % vs. -2.5 (6.6) %, p = 0.0030; predicted forced expiratory volume in 1 s -23 (24) % vs. -0.7 (4.4) %, p = 0.0063; and predicted forced vital capacity, -27.1 (22.0) % vs. -0.66 (3.9) %, p = 0.0010. Train-of-four ratio remained unchanged (p = 0.22). In healthy volunteers, therapeutic doses of neostigmine induced significant and dose-dependent muscle weakness, demonstrated by a decrease in maximum voluntary hand grip strength and a restrictive spirometry pattern secondary to depolarising neuromuscular blockade.

Survey of occupational fatigue in anaesthetists in Australia and New Zealand.

Occupational fatigue in anaesthetists is recognised as a patient safety risk. Better understanding of the issues surrounding their fatigue is needed. This study aimed to ascertain the sources and effects of occupational fatigue amongst anaesthetists in Australia and New Zealand. An anonymous online survey was sent to 979 anaesthetists. The response rate was 38.0%. Most participants reported regularly working over 40 hours per week; men reported five more hours per week than women. Stated contributors to fatigue included long work hours, mental strain at work, and personal and family demands. Fatigue-related behaviour was reported more by men (OR [odds ratio]=2.6) and less by respondents reporting eight or more hours of sleep before work (OR=0.6). Reporting at least one instance of less than five hours off between shifts was predictive of falling asleep while administering an anaesthetic (OR=1.6). More data are required to support practices and policies that promote more time off between work periods and increased time for sleep to reduce risk of fatigue.

A pilot randomized trial of meniscal allograft transplantation versus personalized physiotherapy for patients with a symptomatic meniscal deficient knee compartment.

AIMS: Meniscal allograft transplantation is undertaken to improve pain and function in patients with a symptomatic meniscal deficient knee compartment. While case series have shown improvements in patient reported outcome measures (PROMs), its efficacy has not been rigorously evaluated. This study aimed to compare PROMs in patients having meniscal transplantation with those having personalized physiotherapy at 12 months. PATIENTS AND METHODS: A single-centre assessor-blinded, comprehensive cohort study, incorporating a pilot randomized controlled trial (RCT) was performed on patients with a symptomatic compartment of the knee in which a (sub)total meniscectomy had previously been performed. They were randomized to be treated either with a meniscal allograft transplantation or personalized physiotherapy, and stratified for malalignment of the limb. They entered the preference groups if they were not willing to be randomized. The Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score and Lysholm score and complications were collected at baseline and at four, eight and 12 months following the interventions. RESULTS: A total of 36 patients entered the study; 21 were randomized and 15 chose their treatments. Their mean age was 28 years (range 17 to 46). The outcomes were similar in the randomized and preference groups, allowing pooling of data. At 12 months, the KOOS4 composite score (mean difference 12, p = 0.03) and KOOS subscales of pain (mean difference 15, p = 0.02) and activities of daily living (mean difference 18, p = 0.005) were significantly superior in the meniscal transplantation group. Other PROMs also favoured this group without reaching statistical significance. There were five complications in the meniscal transplantation and one in the physiotherapy groups. CONCLUSION: This is the first study to compare meniscal allograft transplantation to non-operative treatment. The results provide the best quality evidence to date of the symptomatic benefits of meniscal allograft transplantation in the short term, but a multicentre RCT is required to investigate this question further. Cite this article: Bone Joint J 2018;100-B:56-63.

Postoperative troponin measurement as a screening tool for adverse cardiac events in adult patients undergoing moderate or major non-cardiac surgery.

Elevated troponin levels within three days of surgery are strongly linked to major adverse cardiac events (MACE). However, the value of screening with troponin measurements is controversial. The extent to which this is done in routine practice is uncertain. We examined the medical records of all patients ≥45 years of age undergoing moderate or major non-cardiac surgery in our tertiary referral hospital over a six-month period. We determined how many patients had a troponin (TnT) measurement recorded in the first three days postoperatively, how many of these were abnormal, and the occurrence of MACE within 30 days. Two thousand and two hundred patients underwent 2,577 operations that met the study criteria. A postoperative TnT was measured after 4.5% of operations. Thirty-eight percent of patients with a recorded TnT measurement, and 44% of those with an abnormal measurement, experienced a MACE within 30 days. The sensitivity of an abnormal TnT to detect MACE was 86%. The specificity was low at 32% with a false positive rate of 56%. Patients with an abnormal TnT result had an increased risk of MACE (23%). The 'number needed to measure' to detect one patient with MACE was 4.4. In our institution, postoperative TnT levels were rarely measured and were used as a diagnostic rather than as a screening tool. The high false positive rate for MACE prediction limits its potential value as a screening tool. The test could be considered useful if it leads to further investigation, and may be best considered as one component of a multivariate approach to cardiac risk evaluation and diagnosis.

Measuring the anaesthesia clinical learning environment at the department level is feasible and reliable.

BACKGROUND: The learning environment describes the context and culture in which trainees learn. In order to establish the feasibility and reliability of measuring the anaesthetic learning environment in individual departments we implemented a previously developed instrument in hospitals across New South Wales. METHODS: We distributed the instrument to trainees from 25 anaesthesia departments and supplied summarized results to individual departments. Exploratory and confirmatory factor analyses were performed to assess internal structure validity and generalizability theory was used to calculate reliability. The number of trainees required for acceptable precision in results was determined using the standard error of measurement. RESULTS: We received 172 responses (59% response rate). Suitable internal structure validity was confirmed. Measured reliability was acceptable (G-coefficient 0.69) with nine trainees per department. Eight trainees were required for a 95% confidence interval of plus or minus 0.25 in the mean total score. Eight trainees as assessors also allow a 95% confidence interval of approximately plus or minus 0.3 in the subscale mean scores. Results for individual departments varied, with scores below the expected level recorded on individual subscales, particularly the 'teaching' subscale. CONCLUSIONS: Our results confirm that, using this instrument, individual departments can obtain acceptable precision in results with achievable trainee numbers. Additionally, with the exception of departments with few trainees, implementation proved feasible across a training region. Repeated use would allow departments or accrediting bodies to monitor their individual learning environment and the impact of changes such as the introduction of new curricular elements, or local initiatives to improve trainee experience.

A new silicon tracker for proton imaging and dosimetry.

For many years, silicon micro-strip detectors have been successfully used as tracking detectors for particle and nuclear physics experiments. A new application of this technology is to the field of particle therapy where radiotherapy is carried out by use of charged particles such as protons or carbon ions. Such a treatment has been shown to have advantages over standard x-ray radiotherapy and as a result of this, many new centres offering particle therapy are currently under construction around the world today. The Proton Radiotherapy, Verification and Dosimetry Applications (PRaVDA) consortium are developing instrumentation for particle therapy based upon technology from high-energy physics. The characteristics of a new silicon micro-strip tracker for particle therapy will be presented. The array uses specifically designed, large area sensors with technology choices that follow closely those taken for the ATLAS experiment at the HL-LHC. These detectors will be arranged into four units each with three layers in an x-u-v configuration to be suitable for fast proton tracking with minimal ambiguities. The sensors will form a tracker capable of tracing the path of ~200 MeV protons entering and exiting a patient allowing a new mode of imaging known as proton computed tomography (pCT). This will aid the accurate delivery of treatment doses and in addition, the tracker will also be used to monitor the beam profile and total dose delivered during the high fluences used for treatment. We present here details of the design, construction and assembly of one of the four units that will make up the complete tracker along with its characterisation using radiation tests carried out using a 90Sr source in the laboratory and a 60 MeV proton beam at the Clatterbridge Cancer Centre.

Use of the Montreal Cognitive Assessment test to investigate the prevalence of mild cognitive impairment in the elderly elective surgical population.

Postoperative cognitive disorders are common in elderly patients. Pre-existing cognitive impairment including mild cognitive impairment may be an important risk factor for developing postoperative cognitive dysfunction and may not be detected in a standard preoperative interview, yet is not routinely sought. Our primary aim was to estimate the prevalence of mild cognitive impairment among elderly patients presenting to our hospital for elective surgery using a simple established screening tool: the Montreal Cognitive Assessment test. Secondarily, we wished to determine the proportion of patients with mild cognitive impairment who presented with this information available, the effect of increasing age on the prevalence of mild cognitive impairment and whether the timing and location of testing influenced results. We used the Montreal Cognitive Assessment test to screen preoperative patients aged 65 years and over. Our results suggested a potential prevalence of mild cognitive impairment of 56%, with prevalence increasing with age. No patients in the sample had a recorded diagnosis of mild cognitive impairment. Testing in either the preadmission clinic or on admission on the day of surgery yielded similar results. We found the Montreal Cognitive Assessment test to be a simple screening tool that was easily administered during the pre-admission visit.

Relationship between parity and brachial plexus injuries.

OBJECTIVE: Few characteristics have been identified as risk factors for brachial plexus injuries. We sought to investigate a potential relationship with multiparity based on clinical observation at our institution. STUDY DESIGN: In this retrospective case series, we analyzed all brachial plexus injuries recognized at or after delivery between October 2003 and March 2013 (n=78) at a single academic medical institution. Patient, infant, labor and delivery characteristics were compared for women with and without prior vaginal deliveries. RESULT: Of the 78 injuries, 71 (91%) occurred after a vaginal delivery and 7 (9%) after a cesarean delivery. Of the 71 injuries after a vaginal delivery, 58% occurred in women with a prior vaginal delivery (n=41, 5.7 per 10 000 live births) compared with 42% without a prior vaginal delivery (n=30, 4.0 per 10 000 live births). Multiparous patients had shorter labor courses and fewer labor interventions than nulliparous patients. Providers clinically underestimated the birth weights to a greater extent in multiparas than in nulliparas (median underestimation 590 vs 139 g, P=0.0016). The median birth weight was 4060 g in the multiparous group, which was significantly larger than affected infants born to the nulliparous group (3591 g, P=0.006). The affected infants of the multiparous group were, as expected, significantly larger than their previously born siblings (median 567 g larger, P<0.001). CONCLUSION: Brachial plexus injuries occurred as frequently in multiparous patients as in nulliparous patients. In general, multiparous patients are more likely to have larger infants; however, providers significantly underestimate the birth weight of their infants. The findings of this study should deter providers from assuming that a prior vaginal delivery is protective against brachial plexus injuries.

Second trimester dilation and evacuation: a risk factor for preterm birth?

OBJECTIVE: To evaluate whether second trimester pregnancy termination with dilation and evacuation (D&E) vs induction of labor (IOL) affects subsequent risk of preterm birth. STUDY DESIGN: Our cohort was a retrospective cohort of women undergoing second trimester pregnancy termination for fetal anomalies, fetal death or previable premature rupture of membranes. We analyzed the rates of spontaneous delivery <37 weeks in the first pregnancy following the termination. We also compared preterm birth rates in our cohort with national averages and analyzed by the total number of prior procedures. RESULT: There were 173 women in our cohort. Women who had undergone a D&E (n=130) were less likely to have a subsequent preterm birth (6.9 vs 30.2%; P<0.01). This held true for a low risk subset without obstetric risk factors. There was no statistical difference in preterm birth rates for women who had undergone a D&E as compared with national averages, nor between the rates of preterm birth for women with 0, 1, 2 or 3 or more prior first or second trimester procedures. CONCLUSION: We did not find that D&E was a risk factor for preterm delivery when compared with women with a prior IOL or national rates.

Meniscal Transplantation and its Effect on Osteoarthritis Risk: an abridged protocol for the MeTEOR study: a comprehensive cohort study incorporating a pilot randomised controlled trial.

OBJECTIVES: Subtotal or total meniscectomy in the medial or lateral compartment of the knee results in a high risk of future osteoarthritis. Meniscal allograft transplantation has been performed for over thirty years with the scientifically plausible hypothesis that it functions in a similar way to a native meniscus. It is thought that a meniscal allograft transplant has a chondroprotective effect, reducing symptoms and the long-term risk of osteoarthritis. However, this hypothesis has never been tested in a high-quality study on human participants. This study aims to address this shortfall by performing a pilot randomised controlled trial within the context of a comprehensive cohort study design. METHODS: Patients will be randomised to receive either meniscal transplant or a non-operative, personalised knee therapy program. MRIs will be performed every four months for one year. The primary endpoint is the mean change in cartilage volume in the weight-bearing area of the knee at one year post intervention. Secondary outcome measures include the mean change in cartilage thickness, T2 maps, patient-reported outcome measures, health economics assessment and complications. RESULTS: This study is expected to report its findings in 2016. Cite this article: Bone Joint Res 2015;4:93-8.

Meniscal allograft transplantation: rationale for treatment.

The anatomy and microstructure of the menisci allow the effective distribution of load across the knee. Meniscectomy alters the biomechanical environment and is a potent risk factor for osteoarthritis. Despite a trend towards meniscus-preserving surgery, many tears are irreparable, and many repairs fail. Meniscal allograft transplantation has principally been carried out for pain in patients who have had a meniscectomy. Numerous case series have reported a significant improvement in patient-reported outcomes after surgery, but randomised controlled trials have not been undertaken. It is scientifically plausible that meniscal allograft transplantation is protective of cartilage, but this has not been established clinically to date.

Measuring the clinical learning environment in anaesthesia.

The learning environment describes the way that trainees perceive the culture of their workplace. We audited the learning environment for trainees throughout Australia and New Zealand in the early stages of curriculum reform. A questionnaire was developed and sent electronically to a large random sample of Australian and New Zealand College of Anaesthetists trainees, with a 26% final response rate. This new instrument demonstrated good psychometric properties, with Cronbach's α ranging from 0.81 to 0.91 for each domain. The median score was equivalent to 78%, with the majority of trainees giving scores in the medium range. Introductory respondents scored their learning environment more highly than all other levels of respondents (P=0.001 for almost all comparisons). We present a simple questionnaire instrument that can be used to determine characteristics of the anaesthesia learning environment. The instrument can be used to help assess curricular change over time, alignment of the formal and informal curricula and strengths and weaknesses of individual departments.

Anaesthesia priorities for Australian and New Zealand medical school curricula: a Delphi consensus of academic anaesthetists.

The role of anaesthetists has expanded and evolved to include critical care, perioperative and pain medicine and general clinical skills, as well as operating theatre-based clinical anaesthesia. Across Australia and New Zealand, these topics are taught to varying degrees, however no uniform curriculum or standardisation exists between universities. In this study, we used a Delphi technique to develop consensus-based priorities to guide medical educators when reviewing and implementing student anaesthesia curricula. A range of appropriate content has been defined, as well as details relating to duration, timing, teaching environment, faculty, feedback and assessment methods. Future enquiry to assess the efficacy of future and current teaching practices is needed to facilitate continued improvement.