Establishment of CT diagnostic reference levels (DRLs) for a Singapore healthcare cluster

INTRODUCTION

The use of computed tomography (CT) in healthcare institutions has increased rapidly in recent years. The Singapore Health Services (SingHealth) cluster of healthcare institutions has taken the first step in establishing a local cluster-wide CT Diagnostic Reference Levels (DRL) in Singapore. CT dose data from each institution were collected through two primary dosimetry metrics: volume CT dose index (CTDI_vol measured in mGy) and dose-length product (DLP measured in mGy.cm).

METHODS

Data from 19 CT scanners in seven institutions under one of Singapore healthcare cluster were retrospectively collected and analysed. The five common adult CT examinations analysed were CT Brain (non-contrast enhanced), CT Chest (IV contrast enhanced), CT Kidney-Ureter-Bladder (CT KUB, non-contrast enhanced), CT Pulmonary Angiogram (CT PA, IV contrast enhanced) and CT Abdomen-Pelvis (CT AP, IV contrast enhanced, single phase). Median CTDI_vol and DLP values for the five CT examinations from each institution were derived, with the cluster DRLs determined as the 75th percentile of the distribution of the institution median dose values.

RESULTS

A total of 2413 dose data points were collected over a six-month period from June to November 2020. The cluster CT DRLs for the five CT examinations were determined to be 47 mGy and 820 mGy.cm for CT Brain, 5.4 mGy and 225 mGy.cm for CT Chest, 6.7 mGy and 248 mGy.cm for CT PA, 4.6 mGy and 190 mGy.cm for CT KUB and 6.9 mGy and 349 mGy.cm for CT AP.

CONCLUSION

The establishment of the cluster CT DRLs provided individual institutions with a better understanding if their CT doses are unusually high or low, while emphasising that these DRLs are not meant as hard dose limits or constraints to follow strictly.

Reference ranges for functional and structural echocardiographic parameters in asian athletes: a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Background/Introduction

Physiologic cardiac remodelling is common in elite athletes, including changes such as increased left ventricle size and left ventricular wall thickness. These changes often overlap with those from pathological cardiac conditions - for instance dilated cardiomyopathy and hypertrophic cardiomyopathy - leading to diagnostic uncertainty. The availability of reference ranges specific to elite athletes, particularly Caucasian and Black ethnicities, facilitates accurate differentiation between physiology and pathology. However, there remains a paucity of Asian data despite an increased representation in global sport.

Purpose

To perform a systematic review and meta-analysis of cardiac imaging studies in Asian elite athletes and obtain reference values for commonly utilised parameters in this population.

Methods

We searched MEDLINE via PubMed, Embase, and the Cochrane Database for relevant studies from inception till 27th July 2021. We included observational studies that reported relevant cardiac imaging parameters in Asian elite athletes. We excluded studies that did not report gender-specific cardiac imaging parameters. After study selection and data extraction, we performed random effects meta-analysis of means to obtain the weighted mean of each relevant cardiac imaging parameter stratified by gender.

Results

We included a total of eight studies with relevant echocardiographic data from East Asia, South Asia and West Asia which comprised a total of 799 male and 206 female elite athletes participating in endurance and mixed sport disciplines. We excluded data pertaining to athletes participating in skill and power disciplines in a post-hoc manner due to paucity of data and extreme data ranges. The weighted mean left ventricular mass (g) was 211.5 (95% CI 202.6 - 220.3, I2 = 85.8%) for males, and 139.3 (95% CI 132 - 146.7, I2 = 88.2%) for females. The weighted mean left ventricular mass indexed to body surface area (g/m2) was 103.1 (95% CI 99.2 - 106.9, I2 = 79.4%) for males, and 75.1 (95% CI 71.5 - 78.6, I2 = 86.1%) for females. For left ventricular end diastolic diameter (mm), the weighted mean was 54.4 (95% CI 53.1 - 55.7, I2 = 97.3%) for males, and 47.2 (95% CI 46.2 - 48.3, I2 = 89.3%) for females. Lastly, the weighted mean left ventricular wall thickness (mm) was 9.9 (95% CI 9.6 - 10.2, I2 = 91.3%) for males, and 8.7 (95% CI 8.5 - 9, I2 = 80.7%) for females.

Conclusions

This is the first meta-analysis that provides preliminary echocardiographic reference ranges for Asian elite athletes. Statistical heterogeneity, however, is high in most outcome measures. This is likely due to the presence of confounders such as study demographics. Due to a paucity of studies, further subgroup or stratified analyses could not be performed meaningfully. More large-scale observational studies are required such that more sport, gender or region-specific data could be generated.

Association between lung compliance phenotypes and mortality in COVID-19 patients with acute respiratory distress syndrome

ABSTRACT Introduction: Acute respiratory distress syndrome (ARDS) in COVID-19 is associated with a high mortality rate, though outcomes of the different lung compliance phenotypes are unclear. We aimed to measure lung compliance and examine other factors associated with mortality in COVID-19 patients with ARDS. Methods: Adult patients with COVID-19 ARDS who required invasive mechanical ventilation at 8 hospitals in Singapore were prospectively enrolled. Factors associated with both mortality and differences between high (<40mL/cm H2O) and low (<40mL/cm H2O) compliance were analysed. Results: A total of 102 patients with COVID-19 who required invasive mechanical ventilation were analysed; 15 (14.7%) did not survive. Non-survivors were older (median 70 years, interquartile range [IQR] 67–75 versus median 61 years, IQR 52–66; P<0.01), and required a longer duration of ventilation (26 days, IQR 12–27 vs 8 days, IQR 5–15; P<0.01) and intensive care unit support (26 days, IQR 11–30 vs 11.5 days, IQR 7–17.3; P=0.01), with a higher incidence of acute kidney injury (15 patients [100%] vs 40 patients [46%]; P<0.01). There were 67 patients who had lung compliance data; 24 (35.8%) were classified as having high compliance and 43 (64.2%) as having low compliance. Mortality was higher in patients with high compliance (33.3% vs 11.6%; P=0.03), and was associated with a drop in compliance at day 7 (-9.3mL/cm H2O (IQR -4.5 to -15.4) vs 0.2mL/cm H2O (4.7 to -5.2) P=0.04). Conclusion: COVID-19 ARDS patients with higher compliance on the day of intubation and a longitudinal decrease over time had a higher risk of death. Keywords: ARDS, COVID-19-associated respiratory failure, high-flow nasal cannula therapy, HFNC, post-intubation, ventilation strategies

Clinical features and predictors of severity in COVID-19 patients with critical illness in Singapore

We aim to describe a case series of critically and non-critically ill COVID-19 patients in Singapore. This was a multicentered prospective study with clinical and laboratory details. Details for fifty uncomplicated COVID-19 patients and ten who required mechanical ventilation were collected. We compared clinical features between the groups, assessed predictors of intubation, and described ventilatory management in ICU patients. Ventilated patients were significantly older, reported more dyspnea, had elevated C-reactive protein and lactate dehydrogenase. A multivariable logistic regression model identified respiratory rate (aOR 2.83, 95% CI 1.24–6.47) and neutrophil count (aOR 2.39, 95% CI 1.34–4.26) on admission as independent predictors of intubation with area under receiver operating characteristic curve of 0.928 (95% CI 0.828–0.979). Median APACHE II score was 19 (IQR 17–22) and PaO2/FiO2 ratio before intubation was 104 (IQR 89–129). Median peak FiO2 was 0.75 (IQR 0.6–1.0), positive end-expiratory pressure 12 (IQR 10–14) and plateau pressure 22 (IQR 18–26) in the first 24 h of ventilation. Median duration of ventilation was 6.5 days (IQR 5.5–13). There were no fatalities. Most COVID-19 patients in Singapore who required mechanical ventilation because of ARDS were extubated with no mortality.

Children's and parents' attitudes towards dentists' appearance, child dental experience and their relationship with dental anxiety

AIM

To evaluate child and parental attitudes towards dentists' appearance, subsequently related to a child's dental experience and their association with child's anxiety levels.

METHODS

402 parent-child pairs were surveyed using interviewer-administered questionnaires at the School Dental Service, Health Promotion Board, Singapore. Standardised pictures of models with different attires, ages, genders and ethnicities were shown to the parent-child pairs. Information on each child's dental experience was obtained. Parental proxy was used to evaluate the children's dental fear levels based on the Children's Fear Survey Schedule-Dental Subscale (CFSS-DS).

RESULTS

Personal protective equipment (PPE) was the attire of choice for both parents and children, followed by the paediatric coat. Formal and informal attire was least preferred by children and parents, respectively. Parents preferred female dentists to treat their child, whereas children preferred a dentist of the same gender (p < 0.001). Parent's and child's preferences for the child's dentist's appearance were shown to be significantly different (p < 0.001). CFSS-DS scores were also significantly associated with the number of previous dental visits (p = 0.002) as well as a history of extractions (p = 0.02), but not with child's demographics, dmft or preference for dentist's appearance (p > 0.05).

CONCLUSION

Regardless of child anxiety levels, the PPE followed by paediatric coats were preferred over other choices of dentists' attire. Children tended to choose a dentist who was of a younger age, and of the same gender and ethnicity as themselves. Parents tended to choose younger, female dentists of the same ethnicity as themselves. Subjective experience of extractions, as well as multiple dental visits appeared to play a more significant role in the development of dental fear than dental caries experience per se.

Mutations in LAMB2 causing a severe form of synaptic congenital myasthenic syndrome

Background:

We describe a severe form of congenital myasthenic syndrome (CMS) associated with congenital nephrosis and ocular malformations caused by two truncating mutations in the gene encoding the laminin β2 subunit (LAMB2).

Methods and results:

Mutational analysis in the affected patient, who has a history of a serious untoward reaction to treatment with acetylcholinesterase inhibition, revealed two frame-shifting heteroallelic mutations, a maternally inherited 1478delG and a paternally inherited 4804delC. An anconeus muscle biopsy demonstrated a profound distortion of the architecture and function of the neuromuscular junction, which was strikingly similar to that seen in mice lacking laminin β2 subunit. The findings included: pronounced reduction of the axon terminal size with encasement of the nerve endings by Schwann cells, severe widening of the primary synaptic cleft and invasion of the synaptic space by the processes of Schwann cells, and moderate simplification of postsynaptic folds and intact expression of the endplate acetylcholinesterase. The endplate potential quantal content was notably reduced, while the frequencies and amplitudes of miniature endplate potentials were only moderately diminished and the decay phases of miniature endplate potentials were normal. Western blot analysis of muscle and kidney tissue and immunohistochemistry of kidney tissue showed no laminin β2 expression.

Conclusion:

This case, which represents a new type of synaptic CMS, exemplifies the wide variability of phenotypes associated with LAMB2 mutations and underscores the fundamental role that laminin β2 plays in the development of the human neuromuscular junction.

Finishing/polishing of composite and compomer restoratives: effectiveness of one-step systems

This study investigated the surface texture of composite (Z100, 3M ESPE) and compomer (F2000, 3M ESPE) restoratives after treatment with different one-step finishing/polishing systems (One-Gloss [OG], Shofu; PoGo [PG], Dentsply; Sof-Lex Brush [SB], 3M ESPE). The surface roughness obtained was compared to that using a matrix strip [MS], a two-step rubber abrasive (CompoSite [CS], Shofu) and a graded abrasive disk (Super Snap [SS], Shofu) system. Eight specimens (3-mm long x 3-mm wide x 2-mm deep) of each material were made according to manufacturer's instructions. With exception of the MS group, all groups were roughened with 320 grit grinding paper using a lapping device prior to finishing/polishing with the different systems. The mean surface roughness (microm) was measured with a profilometer. Data was subjected to ANOVA/Scheffe's tests and independent samples t-test at significance level 0.05. Mean Ra ranged from 0.22 to 0.32 microm for Z100 and 0.45 to 0.68 for F2000. For both materials, the smoothest surfaces were obtained with MS. The roughest surfaces were observed after treatment with SS and OG for Z100 and F2000, respectively. The effectiveness of the finishing/polishing systems was material dependent. The surface finish produced by PG and SB was superior or comparable to that obtained with CS, SS and OG.

Surface finish of resin-modified and highly viscous glass ionomer cements produced by new one-step systems

This study investigated the surface finish of resin-modified (Fuji II LC, GC) and highly viscous (Fuji IX GP Fast, GC) glass ionomer cements after treatment with three one-step finishing/polishing systems (One-Gloss [OG], Shofu; Pogo [PG], Dentsply; Sof-Lex Brush [SB], 3M-ESPE). The surface roughness obtained was compared to that using a matrix strip [MS], a two-step rubber abrasive (CompoSite [CS], Shofu) and a graded abrasive disk (Super Snap [SS], Shofu) system. Eight specimens (3-mm long x 3-mm wide x 2-mm deep) of each material were made for the various treatment groups. With the exception of the MS group, all groups were roughened with 320 grit grinding paper using a lapping device prior to finishing/polishing with the different systems. The mean surface roughness (microm) was measured with a profilometer. Data was subjected to ANOVA/Scheffe's tests at significance level 0.05. Mean Ra ranged from 0.13 to 1.04 microm for Fuji II LC and 0.14 to 0.81 for Fuji IX GP. For both materials, the smoothest surface was obtained with MS and the roughest with OG. Depending on the materials, the surface finish produced by PG and SB was superior or comparable to that obtained with CS and SS. The effectiveness of one-step systems, when used to finish/polish resin-modified and highly viscous glass ionomer cements, is product dependent.

Comparison of surface finish of new aesthetic restorative materials

This study compared the surface finish of eight different types of aesthetic restorative materials. The materials included resin-modified (Fuji II LC [FL], GC) and highly viscous (Fuji IX GP Fast [FN], GC) glass ionomer cements, a compomer (F2000 [FT], 3M-ESPE), minifilled (Z100 [ZO], 3M-ESPE) and microfilled (A110 [AO], 3M-ESPE) composites and materials based on recently introduced ormocer (Admira [AM], Voco), nanomer (Filtek Supreme Translucent [FST], 3M-ESPE) and nanocluster technology (Filtek Supreme [FS], 3M-ESPE). Sixteen specimens (3-mm long x 3-mm wide x 2-mm deep) of each material were divided into two equal groups. Specimens in Group 1 received no further treatment after polymerization against a matrix strip, while the specimens in Group 2 were roughened with 320 grit grinding paper using a lapping device and were finished/polished with a graded abrasive disk system (Super-Snap, Shofu). The mean roughness (Ra, microm) of materials was determined using a surface profilometry. Data was analyzed by ANOVA/Scheffe's test at significance level 0.05. Mean Ra values ranged from 0.04 to 0.16 microm for Group 1 specimens and 0.15 to 0.68 microm for Group 2 specimens. Results of statistical analysis were as follows: Group 1-FS, FST, FL, FN, AM > FT, AO, ZO; Group 2-FN, FT, FL > AO, FS, ZO, AM, FST (> indicates significantly greater Ra values). For the finished/polished composite materials, Ra values observed for AM and FST were significantly lower than for AO and FS. The surface finish of glass ionomers and compomer was significantly poorer than composites. Composite materials based on ormocer and nanomer technology were significantly smoother than those based on microfillers and nanoclusters.

An examination of HIV/AIDS patients who have excellent adherence to HAART

This paper examines the attitudes and beliefs of HIV/AIDS patients with excellent adherence to highly active antiretroviral therapy (HAART) and how they differ from those with suboptimal adherence. Forty-four persons with HIV/AIDS, 28 men and 16 women, participated in a qualitative semi-structured interview which was based on the Health Belief Model. The main outcomes were themes consistent with several dimensions of this model, reflecting differences in the health-related attitudes and beliefs of the excellent adherers compared to the suboptimal adherers. Patients with excellent adherence voiced the following themes when compared to less adherent patients: (1) believed adherence rates needed to be 90-100% for medication efficacy; (2) trusted their primary providers greatly; (3) took medications even when actively using substances of abuse; (4) were open about their HIV status and received substantial social support; (5) cited staying healthy as their key motivator; (6) were not actively depressed; all had normal CESD scores. Our study suggests that patients with excellent adherence to HAART differ from their less adherent counterparts in terms of key health-related attitudes and beliefs. Identifying and studying excellent adherers provides new insights and strategies for enhancing adherence to HAART.