Autonomic responses to orthostatic stress in head-up tilt testing: Relationship to test-induced prolonged asystole

Background: Prolonged asystole is sometimes an extreme manifestation of neurally mediated syncope. Hypothesis: To investigate the mechanism of head-up tilt testing-induced prolonged (life-threatening) cardiac asystole, we measured temporal changes in frequency domain heart rate variability indices in 25 patients with syncope of undetermined etiology. Methods: Head-up tilt testing (80°) was performed in 25 patients for up to 40 min or until asystole or syncope occurred. Three patients (Group 1; 37 ±13 years, 1 man, 2 women) had an episode of prolonged cardiac asystole (≥ 10 s) during testing, necessitating cardiopulmonary resuscitation. Syncope, but no asystole, was induced in 10 patients (Group 2; 48 ± 31 years, 6 men, 4 women), and 12 patients (Group 3; 55 ± 20 years, 5 men, 7 women) failed to show asystole or syncope during testing. Power spectra of low (0.04–0.15 Hz) and high (0.15–0.40 Hz) frequency, and total (0.01–1.00 Hz) frequency spectra were measured in consecutive 2 min segments throughout the test. Results: Maximally changed values in heart rate, systolic blood pressure, and heart rate variability indices during testing were compared among the three groups (maximally changed values did not include the values during tilt-induced symptoms). High frequency spectra in Groups 2 and 3, but not in Group 1, decreased during the test. High frequency spectra, low frequency spectra, and total spectra in Group 1 were significantly higher than those in Groups 2 and 3 during testing. In Group 1 patients, findings at test-induced asystole were consistent with exaggerated sympathetic and concurrent persistent parasympathetic activity. Conclusion: Unusual autonomic responses to orthostatic stress can cause prolonged asystole, and this autonomic nerve dysregulation may relate to asystolic episodes associated with cardiovascular collapse.     

Analysis of temporal requirements for myocardial tissue velocity imaging.

AIMS: Movements of myocardial walls include components of high velocity and short duration calling for a high sampling rate in the acquisition of tissue velocity imaging data. This study aims at establishing the optimal sampling requirements for tissue velocity imaging measurements. METHODS AND RESULTS: In 16 healthy individuals, tissue velocity imaging data were acquired at a frame rate of 141-203 frames/s for a subsequent off-line analysis using software enabling a reduction of the sampling rate to 50%, 25% and 12.5% of the initial frame rate. Different components of the myocardial velocity profile were measured at each of these frame rates. The deviation of the results from the initial values increased markedly at decreasing frame rates, producing an underestimation of peak systolic and diastolic velocities, most other measured parameters being overestimated. A cut-off point for an acceptable < or =10% deviation of the results corresponded to at least 70 frames/s for peak systolic and early diastolic velocity, and to at least 100 frames/s for other systolic and diastolic parameters. CONCLUSION: A high sampling rate is essential for a proper rendering of tissue velocity imaging signals, too low frame rates resulting in inferior accuracy of the results. This should be kept in mind while viewing reported tissue velocity imaging data.     

Tuberculosis treatment in complex emergencies: are risks outweighing benefits?

Tuberculosis (TB) is a major public health problem in complex emergencies. Humanitarian agencies usually postpone the decision to offer TB treatment and opportunities to treat TB patients are often missed. This paper looks at the problem of tuberculosis treatment in these emergencies and questions whether treatment guidelines could be more flexible than international recommendations. A mathematical model is used to calculate the risks and benefits of different treatment scenarios with increasing default rates. Model outcomes are compared to a situation without treatment. An economic analysis further discusses the findings in a trade-off between the extra costs of treating relapses and failures and the savings in future treatment costs. In complex emergencies, if a TB programme could offer 4-month treatment for 75% of its patients, it could still be considered beneficial in terms of public health. In addition, the proportion of patients following at least 4 months of treatment can be used as an indicator to help evaluate the public health harm and benefit of the TB programme.     

目标管理方案降低导尿管相关性尿路感染发生率的临床实践

目的 实施目标管理方案降低导尿管相关性尿路感染发生率,通过制订目标、实施目标、完成目标,推进质量改善。方法 对某三级甲等综合医院2020年4月—9月留置导尿管的住院患者,应用目标管理方案,依次制订质量改善目标、质量改善计划,实施计划并对过程进行质量评价,通过评估结果的反馈改进行动,实现质量改善。设定1个月为1个质量周期,首个周期的质量为基线,之后各周期质量与之比较,同时与前1周期质量比较。结果 12个过程指标与基线质量比较,6个指标在第2个周期得以改善（P<0.05）,此后凡优于第2周期和基线质量的指标,较基线质量比较,差异均具有统计学意义（均P<0.001）。5个过程指标基线完成率已达到较高水平,与后续测量数据持平。结果指标导尿管相关性尿路感染发生率项目末期较基线显著降低（P<0.05）。过程指标10项措施执行完成率≥95%,2项措施执行率≥91%,达成目标。结论 应用目标管理方案进行质量改善,实现目标导向指标具体化管理,对护理质量进行客观测量,科学比较,切实降低了留置导尿管住院患者的导尿管相关性尿路感染发生率,促进护理质量提升。     

Increased blood–brain barrier vulnerability to systemic inflammation in an Alzheimer disease mouse model

Behavioral and psychological problems are often observed in patients with dementia such as that associated with Alzheimer disease, and these noncognitive symptoms place an extremely heavy burden on the family and caregivers. Although it is well know that these symptoms often are triggered by infection of peripheral organs, the underlying mechanisms for these pathological conditions are still unclear. In this study, using an Alzheimer amyloid precursor protein (APP)-transgenic mouse, we analyzed behavioral changes and brain inflammatory response induced by peripheral administration of lipopolysaccharide. Application of a unique in vivo microdialysis system revealed that the increase in brain inflammatory cytokine (interleukin-6) level was significantly higher in APP-Tg than in wild-type mice after peripheral lipopolysaccharide injection, which was associated with more severe sickness behaviors. The blood–brain barrier became more permeable in APP-Tg mice during peripherally evoked inflammation, suggesting the increased vulnerability of the blood–brain barrier to inflammation in this animal model of Alzheimer's disease. These findings might provide insight into the pathogenesis of noncognitive symptoms in dementia and a basis to develop new therapeutic treatments for them.     

Infection resistance of degradable versus non-degradable biomaterials: An assessment of the potential mechanisms

Extended life expectancy and medical development has led to an increased reliance on biomaterial implants and devices to support or restore human anatomy and function. However, the presence of an implanted biomaterial results in an increased susceptibility to infection. Due to the severity of the potential outcomes of biomaterial-associated infection, different strategies have been employed to reduce the infection risk. Interestingly, degradable biological materials demonstrate increased resistance to bacterial infection compared to non-degradable synthetic biomaterials. Current knowledge about the specific mechanisms of how degradable biological materials are afforded increased resistance to infection is limited. Therefore, in this paper a number of hypotheses to explain the decreased infection risk associated with the use of degradable versus non-degradable biomaterials are evaluated and discussed with reference to the present state of knowledge.     

Mindfulness (Vipassana) meditation: Effects on P3b event-related potential and heart rate variability

The concept of mindfulness is based on Vipassana, a Buddhist meditation technique. The present study examines the physiological indices of attention and autonomic regulation in experienced Vipassana meditators to test the claim that mindfulness is an effective therapeutic tool due to its effects on increasing awareness of present experience and emotional self-regulation. Ten male experienced Vipassana meditators underwent two assessment sessions, one where they practiced Vipassana meditation and another where they rested with no meditation (random thinking). Each meditation/no-meditation session lasted 30 min and was preceded and followed by an auditory oddball task with two tones (standard and target). Event-related potentials to the tones were recorded at the Fz, Cz, and Pz locations. Heart rate variability, derived from an EKG, was recorded continuously during the meditation/no-meditation sessions and during a 5-minute baseline before the task. The Vipassana experts showed greater P3b amplitudes to the target tone after meditation than they did both before meditation and after the no-meditation session. They also showed a larger LF/HF ratio increase during specific Vipassana meditation. These results suggest that expert Vipassana meditators showed increased attentional engagement after meditation and increased autonomic regulation during meditation supporting, at least partially, the two claims concerning the clinical effectiveness of mindfulness.     

Carbon dioxide inhalation as a human experimental model of panic: The relationship between emotions and cardiovascular physiology

Inhaling carbon dioxide (CO₂)-enriched air induces fear and panic symptoms resembling real-life panic attacks, the hallmark of panic disorder. The present study aimed to describe the emotional and cardiovascular effects evoked by inhaling CO₂, taking shortcomings of previous studies into account. Healthy volunteers underwent a double inhalation of 0, 9, 17.5, and 35% CO₂, according to a randomized, cross-over design. In addition to fear, discomfort, and panic symptom ratings, blood pressure and heart rate were continuously monitored. Results showed a dose-dependent increase in all self-reports. Systolic and diastolic blood pressure rose with increasing CO₂ concentration, whereas heart rate results were less consistent. Diastolic blood pressure and heart rate variation correlated with fear and discomfort. Based on this relationship and the observation that the diastolic blood pressure most accurately mimicked the degree of self-reported emotions, it might serve as a putative biomarker to assess the CO₂-reactivity in the future.