Pitfalls in rate and rhythm control: Severe concomitant orthostatic hypotension unmasked after conversion to sinus rhythm

Rate control is an acceptable strategy in management of patients with recurrent atrial fibrillation. Typically, it is more simple approach than rhythm control. Once optimal ventricular rate control is achieved patients with long-lasting atrial fibrillation commonly remain in good clinical status and do not require subsequent readmissions and change of prescribed drugs and their doses. We report a case of effective rate control strategy failure after relatively long period due to transformation of atrial fibrillation into atypical atrial flutter. Subsequent spontaneous conversion to sinus rhythm improved patient's hemodynamic but unmasked concomitant orthostatic hypotension that was severe and had significant impact on treatment of patient.Learning objectiveTransformation to atrial flutter may cause failure of rate control strategy even in previously stable patients with long time persistent atrial fibrillation. Spontaneous conversion to sinus rhythm can unmask orthostatic hypotension. Management of comorbid orthostatic hypotension might be challenging as it could be severe and have significant impact on patients’ condition.     

Evaluation of exposure–response relationships for health effects of microbial bioaerosols – A systematic review

Studies suggest adverse health effects following exposure to bioaerosols in the environment and in particular at workplaces. However, there is still a lack of health-related exposure limits based on toxicological or epidemiological studies from environmental health or from the working environment. The aim of this study was to derive health-based exposure limits for bioaerosols that can protect the general population as group “at risk” via environmental exposure using analysis of peer-reviewed studies related to occupational medicine, indoor air and environmental health. The derivation of exposure limits should be conducted by the members of a bioaerosol expert panel according to established toxicological criteria. A systematic review was performed in Medline (PubMed) including studies containing both data on exposure measurements and observed health outcomes. In addition, literature recommended by the experts was considered. A comprehensive search strategy was generated and resulted in a total of n = 1569 studies in combination with the literature recommendations. Subsequently, abstracts were screened using defined exclusion criteria yielding a final number of n = 44 studies. A standardized extraction sheet was used to combine data on health effects and exposure to different bioaerosols. After full-text screening and extraction according to the defined exclusion criteria n = 20 studies were selected all related to occupational exposures comprising the working areas wood processing, farming, waste processing and others. These studies were analyzed in collaboration with the bioaerosol expert network in terms of suitability for derivation of health-related exposure limits. The bioaerosol expert network concluded that none of the analyzed studies provided suitable dose–response relationships for derivation of exposure limits. The main reasons were: (1) lack of studies with valid dose–response data; (2) diversity of employed measuring methods for microorganisms and bioaerosol-emitting facilities; (3) heterogeneity of health effects; (4) insufficient exposure assessment. However, several indicator parameters and exposure concentrations could be identified for different bioaerosol-emitting facilities. Nevertheless, health-related exposure limits are urgently needed especially in approval procedures of facilities like composting plants or livestock farms emitting bioaerosols in the neighbourhood of residents. In the regulatory toxicology framework, it is common to use animal experimental studies for derivation of general exposure limits if appropriate environmental epidemiological studies on harmful substances are lacking. This might be another possibility to obtain health-related exposure limits for specific bioaerosol parameters. Furthermore, we recommend to use suitable measurable outcome parameters related to bioaerosols; to measure bioaerosols according to a protocol representative for exposure pattern and duration at the particular work place; to develop standardized detection methods for indicator parameters; to combine different detection methods to compensate for the limitations of each method; to apply new analysis methods to identify the real risk potential.     

Conversion factors for determining organ doses received by paediatric patients in high-resolution single slice computed tomography with narrow collimation

Estimations of organ doses D_T received during computed tomographic examinations are usually performed by applying conversion factors to basic dose indicators like the computed tomography dose index (CTDI) or the dose-length-product (DLP). In addition to the existing conversion factors for beam apertures of 5 mm or 10 mm, we present new DLP-D_T conversion factors adapted to high-resolution CT (HRCT) examinations of infants and young children with beam apertures of the order of 1 mm and under consideration of bow tie filtration. Calculations are performed on mathematical MIRD phantoms for an age range from 0, 1, 5, 10, 15 up to (for comparison) 30 years by adapting PCXMC, a Monte Carlo algorithm originally developed by STUK (Helsinki, Finland) for dose reconstructions in projection radiography. For this purpose, each single slice CT examination is approximated by a series of corresponding virtual planar radiographies comprising all focus positions. The transformation of CT exposure parameters into exposure parameters of the series of corresponding planar radiographies is performed by a specially developed algorithm called XCT. The DLP values are evaluated using the EGSRay code. The new method is verified at a beam aperture of 10 mm by comparison with formerly published conversion factors. We show that the higher spatial resolution leads to an enhanced DLP-D_T conversion factor if a small organ (e. g. thyroid gland, mammae, uterus, ovaries, testes) is exactly met by the chosen CT slice, while the conversion factor is drastically reduced if the chosen CT slice is positioned above or below the organ. This effect is utilized for dose-saving examinations with only a few single slices instead a full scan, which technique is applied in about 10% of all paediatric chest CT examinations.     

Diphenhydramine dose–response: a novel approach to determine triage thresholds

Context. It is unclear how much diphenhydramine (DPH) is toxic in humans. Previous dose–response studies have had conflicting results. Objective. We sought to evaluate DPH dose–response using a unique method that utilizes acetaminophen (APAP) serum concentrations to estimate DPH doses in patients ingesting APAP/DPH in a fixed-combination product. Methods. We retrospectively analyzed APAP/DPH-only exposures in patients 2–80 years of age using case data from 15 U.S. poison centers. DPH dose was extrapolated from measured serum APAP concentrations. A clinically significant response (CSR) was predefined in terms of eight specific manifestations (e.g., coma) that would warrant emergency department intervention. Nominal logistic regression was used to model the probability of each recorded manifestation across DPH dose ranges examining fits for mg, mg/kg, log10 mg, and log10 mg/kg DPH doses. The threshold value where patients reliably became symptomatic was determined by further examining receiver operating characteristic curves. Results. There were 509 cases that met inclusion criteria. Forty-five patients (9%) developed CSRs. A higher percentage of patients developed CSR at ≥ 7.5 mg/kg DPH and ≥1 g total DPH cutoff points (p < 0.05, Fisher's exact test). The best model for predicting the probability of CSR was a logistic fit of log₁₀ mg/kg dose (p < 0.05). By this model, for every 1 log₁₀ unit increase of mg/kg DPH dose, the odds of developing a CSR increased 47-fold (95% CI 17, 154). Receiver operating characteristic analyses showed a dose-related progression of symptoms. The cut-point with greatest sensitivity (98%) versus 1-specificity (57%) corresponded to an extrapolated mg/kg DPH dose of 8.2 mg/kg (95% CI 5.6, 10.5). Conclusion. Our findings support the current American Association of Poison Control Centers' guideline recommendation to refer patients to the hospital for evaluation if they have ingested greater than or equal to 7.5 mg/kg of DPH.     

不可切除中晚期肝癌的转化治疗后肝切除术

多数肝癌起病隐匿，早期症状不明显，就诊时往往已属中晚期，预后不佳。转化治疗可使不可切除晚期肝癌病人获得手术治疗机会，并达到R0切除。在转化治疗后，对病人肿瘤、肝脏及其他器官细致全面的评估，将为安全肝切除的术前决策提供依据。转化治疗期间建议采用多学科综合治疗协作组模式定期评估转化治疗效果，并及时制定手术切除方案。     

Investigating perceptions of ‘dose creep’ amongst student radiographers: A grounded theory study

IntroductionThe dose creep phenomenon is now a widely recognized concept in diagnostic radiography in light of recent technological advancements transnationally. However, this still remains underexplored amongst radiography students preparing to enter the radiography profession. In response, this study explores the perceptions of dose creep amongst undergraduate student radiographers.MethodsThe methodological approach utilized in this research study was grounded theory. The qualitative approach aimed to uncover findings from a higher education institution in Australia. Six students were recruited and took part in semi-structured interviews. This enabled the exploration of previously uncovered data, leading to the construction of original theory within the clinical and academic environment. The data analysis employed was constant comparative analysis (CCA).ResultsA number of insights emerged from the qualitative data set. For instance, the radiography students understanding of the term ‘dose creep’ and decision making leading to dose creep in the clinical environment is captured. This is further supported with assessment of image evaluation determining appropriate exposure factor selection and future impact upon graduation as diagnostic radiographers. The findings identify some important learning needs and actions for both clinical and academic settings which may help foster good use of X-ray exposures.ConclusionThis paper concludes by affirming some challenges surrounding optimal exposure selection and the known phenomenon, dose creep. Further, this study identifies the importance of learning and teaching in the clinical environment whereby learned behaviour leads to suboptimum practices.Implications for practiceThis study advances the existing evidence base by providing a unique lens into the knowledge and understanding of dose creep amongst radiography students in both academic and clinical contexts. It is anticipated this paper will help practitioners and educators better understand potential instances of dose creep within the clinical environment.     

Clinical Benefit-Risk Profile of Lenalidomide in Patients With Lower-risk Myelodysplastic Syndromes Without del(5q): Results of a Phase III Trial

BackgroundIn the phase III MDS-005 study of patients with lower-risk, non-del(5q) myelodysplastic syndromes, lenalidomide was associated with a higher rate of ≥ 8 weeks red blood cell transfusion independence (RBC-TI) compared with placebo, but also with a higher risk of hematologic adverse events (AEs).Patients and MethodsThis analysis evaluated the ratio of clinical benefit-risk in patients treated with lenalidomide or placebo, and assessed the effect of lenalidomide dose reductions on response. Clinical benefit was a composite endpoint defined as RBC-TI, transfusion reduction ≥ 4 units packed red blood cells, hemoglobin increase ≥ 1.5 g/dL, or cytogenetic response.ResultsThe rate of clinical benefit was higher with lenalidomide than with placebo (31.9% vs. 3.8%). The ratio of response (RBC-TI and clinical benefit) to risk (hematologic AEs) favored lenalidomide over placebo. Patients who underwent ≥ 1 lenalidomide dose reduction had a longer duration of treatment, received a higher cumulative dose, and were more likely to experience clinical benefit versus patients without dose reductions.ConclusionDespite the occurrence of hematologic AEs, the overall benefit-risk profile supported lenalidomide treatment. Appropriate management of hematologic AEs by dose reductions may help patients with myelodysplastic syndromes to remain on treatment and achieve clinical benefit.     

局部晚期非小细胞肺癌放疗剂量提升研究进展

局部晚期非小细胞肺癌的RTOG0617研究显示进一步提高放疗剂量并没有带来生存获益,这促进了剂量提升策略的改变。目前多项研究通¹⁸FDG高摄取区域局部加量、同步加量调强放疗、改变剂量分割模式等探索更为有效的剂量提升手段,并取得一系列进展。PET-CT技术及调强放疗技术的广泛应用,为放疗剂量优化和提升提供了广阔空间。