Refining mass casualty plans with simulation-based iterative learning

BACKGROUND

Preparatory, written plans for mass casualty incidents are designed to help hospitals deliver an effective response. However, addressing the frequently observed mismatch between planning and delivery of effective responses to mass casualty incidents is a key challenge. We aimed to use simulation-based iterative learning to bridge this gap.

METHODS

We used Normalisation Process Theory as the framework for iterative learning from mass casualty incident simulations. Five small-scale 'focused response' simulations generated learning points that were fed into two large-scale whole-hospital response simulations. Debrief notes were used to improve the written plans iteratively. Anonymised individual online staff surveys tracked learning. The primary outcome was system safety and latent errors identified from group debriefs. The secondary outcomes were the proportion of completed surveys, confirmation of reporting location, and respective roles for mass casualty incidents.

RESULTS

Seven simulation exercises involving more than 700 staff and multidisciplinary responses were completed with debriefs. Usual emergency care was not affected by simulations. Each simulation identified latent errors and system safety issues, including overly complex processes, utilisation of space, and the need for clarifying roles. After the second whole hospital simulation, participants were more likely to return completed surveys (odds ratio=2.7; 95% confidence interval [CI], 1.7-4.3). Repeated exercises resulted in respondents being more likely to know where to report (odds ratio=4.3; 95% CI, 2.5-7.3) and their respective roles (odds ratio=3.7; 95% CI, 2.2-6.1) after a simulated mass casualty incident was declared.

CONCLUSION

Simulation exercises are a useful tool to improve mass casualty incident plans iteratively and continuously through hospital-wide engagement of staff.

Ambulatory management of primary spontaneous pneumothorax: an open-label, randomised controlled trial

BACKGROUND

Primary spontaneous pneumothorax occurs in otherwise healthy young patients. Optimal management is not defined and often results in prolonged hospitalisation. Data on efficacy of ambulatory options are poor. We aimed to describe the duration of hospitalisation and safety of ambulatory management compared with standard care.

METHODS

In this open-label, randomised controlled trial, adults (aged 16-55 years) with symptomatic primary spontaneous pneumothorax were recruited from 24 UK hospitals during a period of 3 years. Patients were randomly assigned (1:1) to treatment with either an ambulatory device or standard guideline-based management (aspiration, standard chest tube insertion, or both). The primary outcome was total length of hospital stay including re-admission up to 30 days after randomisation. Patients with available data were included in the primary analysis and all assigned patients were included in the safety analysis. The trial was prospectively registered with the International Standard Randomised Clinical Trials Number, ISRCTN79151659.

FINDINGS

Of 776 patients screened between July, 2015, and March, 2019, 236 (30%) were randomly assigned to ambulatory care (n=117) and standard care (n=119). At day 30, the median hospitalisation was significantly shorter in the 114 patients with available data who received ambulatory treatment (0 days [IQR 0-3]) than in the 113 with available data who received standard care (4 days [IQR 0-8]; p<0·0001; median difference 2 days [95% CI 1-3]). 110 (47%) of 236 patients had adverse events, including 64 (55%) of 117 patients in the ambulatory care arm and 46 (39%) of 119 in the standard care arm. All 14 serious adverse events occurred in patients who received ambulatory care, eight (57%) of which were related to the intervention, including an enlarging pneumothorax, asymptomatic pulmonary oedema, and the device malfunctioning, leaking, or dislodging.

INTERPRETATION

Ambulatory management of primary spontaneous pneumothorax significantly reduced the duration of hospitalisation including re-admissions in the first 30 days, but at the expense of increased adverse events. This data suggests that primary spontaneous pneumothorax can be managed for outpatients, using ambulatory devices in those who require intervention.

FUNDING

UK National Institute for Health Research.

Case of steroid-resistant Crohn's-associated bronchiolitis in the setting of quiescent gastrointestinal disease treated with infliximab

A fit, 36-year-old man with a history of Crohn's disease previously treated with azathioprine, presented acutely with progressive shortness of breath on exertion and pleuritic chest pain. At the time of presentation, his Crohn's disease was quiescent, supported by a normal faecal calprotectin. The initial chest CT suggested the presence of a diffuse inflammatory disorder and he was subsequently started on high dose oral steroids. Despite 4 months of steroid therapy, there was minimal improvement. Following discussion at the inflammatory bowel disease multidisciplinary team meeting, a decision was made to commence infliximab. Subsequently, he made a dramatic clinical and physiological recovery. His forced expiratory volume in 1 s improved from 2.22 L/min (50% predicted) to 3.65 L/min (93% predicted) and he returned to baseline levels of exercise.

British Thoracic Society Guideline for the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD)

The full guideline for the management of non-tuberculous mycobacterial pulmonary disease is published in Thorax. The following is a summary of the recommendations and good practice points. The sections referred to in the summary refer to the full guideline.

Early intracardiac thrombus and pulmonary embolus after trauma

Here, we present the case of a patient with the findings of an early intracardiac thrombus and a pulmonary embolus after major trauma. A large clot was identified extending from the inferior vena cava into the right atrium and ventricle in the setting of preserved right ventricular function. Post-traumatic intracardiac thrombus is extremely rare and no comparable cases have previously been described in the absence of a congenital heart defect and obvious myocardial injury. Best practice afterpost-traumatic intracardiac thrombus is not well established but we found that early inferior vena cava filter placement and treatment with therapeutic coagulation resulted in clinical improvement, resolution of the thrombus and no further emboli. The successful use of rivaroxaban, a direct-acting oral anticoagulant, to treat a right heart thrombus has, to our knowledge, not previously been reported. Early acute traumatic coagulopathy has received much attention but the hypercoagulable state that often follows is less well appreciated.

Right-sided bronchial isomerism diagnosed in adulthood

This case report describes a diagnosis of right-sided isomerism and specifically right-sided bronchial isomerism in a patient who was being investigated for deteriorating bronchiectasis. Right-sided bronchial isomerism is a variation of the normal bronchial anatomy (situs solitus) consisting of a left lung that is identically configured at the bronchial and lobar level to the right. It is sometimes referred to as bilateral right lung and is usually associated with congenital asplenia and therefore impaired immunity with susceptibility to pneumococcal sepsis and cardiac abnormalities which may be severe and result in a high mortality in infancy. Ivemark syndrome (also known as right atrial isomerism) combines these associations with malrotation of the gut and a midline liver.2 Interestingly, left-sided isomerism is associated with polysplenia as well as midline liver, malrotation of the gut, partially anomalous pulmonary venous drainage and cardiac septal defects.3 To the best of our knowledge cases of right-sided isomerism are sufficiently rare in adulthood that there are only two other reports in the literature and only one of the patients had bronchial isomerism.4,5.

Human Albumin Solution Resuscitation in Severe Sepsis and Septic Shock

There has been a recent resurgence of interest in the use of human albumin solution (HAS) for the resuscitation of critically ill patients. In particular, it may be beneficial for patients with severe sepsis and septic shock. We outline the evidence for the biological plausibility of this effect, perform a meta-analysis of randomised controlled trials comparing the effect of HAS with other fluid resuscitation on mortality in this group of patients and discuss the likely contribution of recently completed trials in this area. We included nine trials of 1,435 patients in the meta-analysis. Although HAS resuscitation was associated with a trend to lower mortality (relative risk 0.90, 95% confidence interval 0.79–1.02), we found that most trials reported to date are small and of variable methodological quality. The questions of a potential differential effect of dose on outcome and the pharmacological variability of HAS products have not been adequately addressed to date. We conclude that the routine administration of HAS to patients with severe sepsis and septic shock is difficult to justify on the basis of current knowledge.

Next generation sequencing analysis reveals a relationship between rDNA unit diversity and locus number in Nicotiana diploids

BACKGROUND

Tandemly arranged nuclear ribosomal DNA (rDNA), encoding 18S, 5.8S and 26S ribosomal RNA (rRNA), exhibit concerted evolution, a pattern thought to result from the homogenisation of rDNA arrays. However rDNA homogeneity at the single nucleotide polymorphism (SNP) level has not been detailed in organisms with more than a few hundred copies of the rDNA unit. Here we study rDNA complexity in species with arrays consisting of thousands of units.

METHODS

We examined homogeneity of genic (18S) and non-coding internally transcribed spacer (ITS1) regions of rDNA using Roche 454 and/or Illumina platforms in four angiosperm species, Nicotiana sylvestris, N. tomentosiformis, N. otophora and N. kawakamii. We compared the data with Southern blot hybridisation revealing the structure of intergenic spacer (IGS) sequences and with the number and distribution of rDNA loci.

RESULTS AND CONCLUSIONS

In all four species the intragenomic homogeneity of the 18S gene was high; a single ribotype makes up over 90% of the genes. However greater variation was observed in the ITS1 region, particularly in species with two or more rDNA loci, where >55% of rDNA units were a single ribotype, with the second most abundant variant accounted for >18% of units. IGS heterogeneity was high in all species. The increased number of ribotypes in ITS1 compared with 18S sequences may reflect rounds of incomplete homogenisation with strong selection for functional genic regions and relaxed selection on ITS1 variants. The relationship between the number of ITS1 ribotypes and the number of rDNA loci leads us to propose that rDNA evolution and complexity is influenced by locus number and/or amplification of orphaned rDNA units at new chromosomal locations.

Diagnosis of myocardial infarction following hospitalisation for exacerbation of COPD

Cardiovascular disease is common in chronic obstructive pulmonary disease (COPD) and raised troponin is common in exacerbations. However, the prevalence of myocardial infarction following hospitalisation for exacerbation of COPD is unknown. Patients aged ≥ 40 yrs hospitalised with acute exacerbation of COPD (n = 242) with ≥ 10 pack-yrs of cigarette smoking were included in a prospective case series conducted in four hospitals. Patients whose primary presenting complaint was chest pain or who had an alternative diagnosis were excluded. Chest pain histories, serial ECGs and troponin levels were obtained. The mean ± SD age was 69 ± 9 yrs; 108 (45%) patients were male and almost half were current smokers. 124 (51%; 95% CI 48-58%) patients had chest pain, which was exertional in 62 (26%). 24 (10%) had raised troponin, among whom, 20 (8.3%; 95% CI 5.1-12.5%) had chest pain and/or serial ECG changes, fulfilling the 2007 Universal Definition of Myocardial Infarction. Neither chest pain (p = 0.77) nor serial ECG changes (p = 0.39) were associated with raised troponin. Raised troponin, chest pain and serial ECG changes are common in patients admitted to hospital with exacerbation of COPD. Overall, one in 12 patients met the criteria for myocardial infarction. Whether these patients would benefit from further cardiac investigation is unknown.

Parental origin and genome evolution in the allopolyploid Iris versicolor

BACKGROUND AIMS

One of the classic examples of an allopolyploid is Iris versicolor, 'Blue Flag' (2n = 108), first studied by Edgar Anderson and later popularized by George Ledyard Stebbins in cytogenetics and evolutionary text-books. It is revisited here using modern molecular and cytogenetic tools to investigate its putative allopolyploid origin involving progenitors of I. virginica (2n = 70) and I. setosa (2n = 38).

METHODS

Genomic in situ hybridization (GISH), fluorescent in situ hybridization (FISH) and Southern hybridization with 5S and 18-26S ribosomal DNA (rDNA) probes were used to identify the parental origin of chromosomes, and to study the unit structure, relative abundance and chromosomal location of rDNA sequences.

KEY RESULTS

GISH shows that I. versicolor has inherited the sum of the chromosome complement from the two progenitor species. In I. versicolor all the 18-26S rDNA units and loci are inherited from the progenitor of I. virginica, those loci from the I. setosa progenitor are absent. In contrast 5S rDNA loci and units from both progenitors are found, although one of the two 5S loci expected from the I. setosa progenitor is absent.

CONCLUSIONS

These data confirm Anderson's hypothesis that I. versicolor is an allopolyploid involving progenitors of I. virginica and I. setosa. The number of 18-26S rDNA loci in I. versicolor is similar to that of progenitor I. virginica, suggestive of a first stage in genome diploidization. The locus loss is targeted at the I. setosa-origin subgenome, and this is discussed in relation to other polyploidy systems.

Transcription activity of rRNA genes correlates with a tendency towards intergenomic homogenization in Nicotiana allotetraploids

This paper establishes relationships between two aspects of ribosomal DNA (rDNA) biology: epigenetic silencing of rDNA loci; and homogenization leading to concerted evolution. Here, we examined rDNA inheritance and expression patterns in three natural Nicotiana allopolyploids (closest living descendants of diploid parents are given), N. rustica (N. paniculata x N. undulata), N. tabacum (N. sylvestris x N. tomentosiformis) and N. arentsii (N. undulata x N. wigandioides), and synthetic F(1) hybrids and allopolyploids. The extent of interlocus rDNA homogenization decreased in the direction N. arentsii > N. tabacum > N. rustica. The persistence of parental rDNA units in one of the subgenomes was associated with their transcription inactivity and likely heterochromatization. Of synthetic hybrids and polyploids only N. paniculata x N. undulata showed strong uniparental transcriptional silencing of rDNA triggered already in F(1). Epigenetic patterns of expression established early in allopolyploid nucleus formation may render units susceptible or resistant to homogenization over longer time-frames. We propose that nucleolus-associated transcription leaves rDNA units vulnerable to homogenization, while epigenetically inactivated units, well-separated from the nucleolus, remain unconverted.

Reducing the potential for phlebotomy tourniquets to act as a reservoir for meticillin-resistant Staphylococcus aureus

The contamination rate of phlebotomy tourniquets with meticillin-resistant Staphylococcus aureus (MRSA) was assessed, and it was determined whether this could be reduced by changes in practice or by the use of a physical barrier. Initially, the tourniquets of both preregistration house officers and phlebotomists were investigated, but as phlebotomists reported significantly more venepunctures daily, the trial continued solely with phlebotomists. Each day, the phlebotomists were supplied with a fresh sterile tourniquet, and after use, the tourniquets were swabbed and cultured. The rate of contamination with MRSA was 32 of 131 (25%) tourniquets. An audit of hand hygiene practice was undertaken and revealed that phlebotomists were performing hand decontamination inadequately between patients and wore wristwatches while working. Education comprising standard infection control methods to encourage good practice was given. After this, a polythene strip was used as a barrier by half of the phlebotomists during all venepunctures. Tourniquets were cultured and replaced daily as before. During this stage of the trial, the rates of contamination were 1 of 46 tourniquets (using a polythene strip) and 1 of 42 tourniquets (without using a polythene strip). In conclusion, phlebotomy tourniquets may be potential vectors for transferring bacteria, including MRSA. Contamination rates, and hence potential risk, can be reduced if hand decontamination is performed. This suggests that contamination of tourniquets is via phlebotomists' hands, not directly from patients' skin. Hand hygiene should be regarded as the most important method by which the spread of organisms can be reduced.

Nuclear thymidylate synthase expression, p53 expression and 5FU response in colorectal carcinoma

Thymidylate synthase (TS) is a key enzyme in DNA synthesis and is inhibited by metabolites of the chemotherapeutic agent 5-fluorouracil (5FU). Nuclear expression of TS in human tissue in vivo has not been characterised and its clinicopathological correlates in malignancy are unknown. 52 cases of primary colorectal carcinoma (CRC) and 24 cases of matched metastatic carcinoma were studied immunohistochemically using the monoclonal antibody TS106. The degree of nuclear TS immunostaining correlated closely with levels of TS mRNA expression amongst 10 CRCs studied. Strong nuclear immunostaining was seen in normal basal crypt colonocytes and germinal centre cells, and in a varying proportion of adenocarcinoma cells. Amongst the primary carcinomas, higher TS nuclear expression was associated with prominent extracellular mucin production and right-sided location. Higher TS nuclear expression also showed a significant association with poorer response to protracted venous infusional 5FU therapy. There was no clear association between TS nuclear expression and Ki67 or p53 expression assessed immunohistochemically. There was a strong positive correlation between TS nuclear expression in primary and metastatic CRC but the latter generally showed higher expression than matched primary tumour tissue. These findings confirm the nuclear expression of TS protein in human cells in vivo and provide new insight into how such expression may relate to the behaviour of CRCs.

Variability in CpNpG methylation in higher plant genomes

The methylation status of ribosomal gene (rRNA) clusters have been investigated in a large variety of angiosperm species. Here we have analysed methylation in ribosomal gene (rRNA) clusters using MspI, HpaII, BstNI, EcoRII and CfoI restriction enzymes in combination with Southern hybridization to the 25S rDNA probe. It was shown that cytosine methylation at CpG dinucleotides and CpNpG trinucleotides occurred in all plant genomes examined. Methylation of rDNA units at CpG dinucleotides (studied with CfoI) was high in all species tested with approx. 40-70% of units being completely or nearly completely methylated. In contrast, the extent of the CpNpG methylation (studied with MspI and EcoRII) varied significantly between species; the percentage of the rDNA fraction entirely methylated at CpNpG trinucleotides ranged from less than 1% to almost 90% depending on the genome studied. Larger interspecies than within species variation was also observed among several non-transcribing repetitive sequences. In a small genome of A. thaliana, the CpNpG methylation appeared to be highly compartmentalized into the repetitive fraction. The methylation of trinucleotides was abundant in large A+T-rich genomes and it is proposed that the CpA(T)pG trinucleotides may help to maintain a high density of methylatable targets in plant repeated sequences.

A placebo controlled comparison of the effects of metoprolol and celiprolol on echo-Doppler measurements of cardiovascular function in normal volunteers

1. This study used a continuous-wave echo-Doppler method (Exerdrop) to investigate the effects of beta-adrenoceptor antagonism and partial agonism on cardiovascular responses at rest and during dynamic exercise. 2. A double-blind, randomised, placebo controlled comparison of metoprolol (50 mg) and celiprolol (200 mg) was undertaken in nine normal volunteers; single oral doses of medication were administered at weekly intervals. Rest and exercise (supine bicycle) haemodynamics were assessed at 0, 2, 4, 6 and 8 h following dosing. 3. Before dosing and after placebo, the aortic flow velocity, acceleration and velocity integral increased progressively during exercise, as did heart rate, blood pressure and cardiac output. 4. Following metoprolol 50 mg, heart rate was significantly reduced without change in systolic or diastolic blood pressure. Echo-Doppler peak acceleration and velocity decreased at rest. On exercise, heart rate and systolic blood pressure fell significantly; the increase in acceleration was significantly blunted compared with placebo (a decrease of 15.2% at rest and 22.9% at 75 watts; P < 0.01 vs placebo). Peak velocity fell significantly by 75 watts exercise. 5. Celiprolol 200 mg at rest significantly increased systolic blood pressure, peak acceleration and velocity. On exercise celiprolol, in contrast to metoprolol, did not reduce peak acceleration or peak velocity; however exercise heart rate and systolic blood pressure were significantly reduced. The difference between celiprolol and metoprolol in respect of peak acceleration persisted over the 8 h of the study. 6. These differences between metoprolol and celiprolol are compatible with the partial agonism of celiprolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Key features of cereal genome organization as revealed by the use of cytosine methylation-sensitive restriction endonucleases

Unlike mammalian genomes, cereal (Gramineae) genomes exhibit little suppression of CpG dinucleotides. In cereal genomes, however, most of the numerous potential recognition sites for CpG methylation-sensitive restriction enzymes are methylated. Analysis of cereal genomic libraries and of regions flanking genes indicates that unmethylated NotI sites are useful landmarks for regions containing genes/single-copy sequences. Studies of a rye chromosome arm indicate that its pericentromeric region has a reduced density of unmethylated NotI (and MluI) sites and therefore of genes. Unmethylated MluI and NruI sites are distributed nonrandomly in the genomes of wheat, barley, and rice. Analysis of the genomic blocks defined by these sites in wheat and barley indicates that they are most likely to have arisen by amplification. These observations form the basis of a proposed model for the organization and evolution of the wheat, barley, and rice genomes.