10种中药材及饮片亚硫酸盐残留检测结果分析

目的 对市场上抽取的10种中药材及其饮片进行二氧化硫残留量测定,并对结果进行统计分析,提出标准建议和监管建议.方法 采用《中国药典》2010年版第一增补本中二氧化硫残留量测定法,按照《中国药典》2010年版第二增补本中的限量要求对检测结果进行统计分析.结果与结论 共检测10个品种896批中药材及饮片,开展过中药饮片无硫化专项整治工作地区的样品结果满意.建议应加强对二氧化硫残留量限度标准的实施,严格市场监管,加大政策扶持力度,指导规范加工方法的转化,进而保证中药饮片质量安全.     

Linear and nonlinear analysis of pressure and flow during mechanical ventilation

Objective: Linear modeling as a method of exploring respiratory mechanics during mechanical ventilation, was compared to nonlinear modeling for flow dependence of resistance in three distinct groups of patients, those with: (a) normal respiratory function (NRF), (b) chronic obstructive pulmonary disease (COPD), or (c) adult respiratory distress syndrome (ARDS). Design and patients: Airways opening pressure (Pao), flow (V′), and volume (V) signals were recorded in 32 ICU mechanically ventilated patients, under sedation and muscle relaxation (10 NRF, 11 COPD, 11 ARDS). All patients were ventilated with controlled mandatory ventilation mode at three levels of end-expiratory pressure (PEEPe): 0, 5, and 10 hPa. Data were analyzed according to: (a) Pao = PE + Ers V + Rrs V′ and (b) Pao = PE + Ers V + k ₁V′ + k ₂|V′|V′, where Ers and Rrs represent the intubated respiratory system (RS) elastance and resistance, k ₁ and k ₂ the linear and the nonlinear RS resistive coefficients, and PE the end-expiratory pressure. The model's goodness of fit to the data was evaluated by the root mean square difference of predicted minus measured Pao values. Results: NRF data fit both models well at all PEEPe levels. ARDS and particularly COPD data fit the nonlinear model better. Values of k ₂ were often negative in COPD and ARDS groups, and they increased in parallel with PEEPe. A gradual increase in PEEPe resulted in better fit of ARDS and COPD data to both models. Conclusions: The model of V′ dependence of resistance is more suitable for the ARDS and particularly the COPD groups. PEEP tends to diminish the V′ dependence of respiratory resistance during the respiratory cycle, particularly in the COPD group, probably through an indirect effect of the increased lung volume. Received: 14 June 1999 Final revision received: 19 November 1999 Accepted: 11 April 2000     

Limiting factors to oxygen transport on Mount Everest 30 years after: a critique of Paolo Cerretelli’s contribution to the study of altitude physiology

In 1976, Paolo Cerretelli published an article entitled Limiting factors to oxygen transport on Mount Everest in the Journal of Applied Physiology . The paper demonstrated the role of cardiovascular oxygen transport in limiting maximal oxygen consumption (O_2max). In agreement with the predominant view of O_2max limitation at that time, however, its results were taken to mean that cardiovascular oxygen transport does not limit O_2max at altitude. So it was argued that the limiting factor could be in the periphery, and muscle blood flow was proposed as a possible candidate. Despite this suggestion, the conclusion generated a series of papers on muscle structural characteristics. These experiments demonstrated a loss of muscle oxidative capacity in chronic hypoxia, and thus provided an unambiguous refutation of the then widespread hypothesis that an increased muscle oxidative capacity is needed at altitude to compensate for the lack of oxygen. This analysis is followed by a short account of Cerretellis more recent work, with a special attention to the subject of the so-called lactate paradox.     

Competition–defense tradeoffs and the maintenance of plant diversity

Ecologists have long observed that consumers can maintain species diversity in communities of their prey. Many theories of how consumers mediate diversity invoke a tradeoff between species’ competitive ability and their ability to withstand predation. Under this constraint, the best competitors are also most susceptible to consumers, preventing them from excluding other species. However, empirical evidence for competition–defense tradeoffs is limited and, as such, the mechanisms by which consumers regulate diversity remain uncertain. We performed a meta-analysis of 36 studies to evaluate the prevalence of the competition–defense tradeoff and its role in maintaining diversity in plant communities. We quantified species’ responses to experimental resource addition and consumer removal as estimates of competitive ability and resistance to consumers, respectively. With this analysis, we found mixed empirical evidence for a competition–defense tradeoff; in fact, competitive ability tended to be weakly positively correlated with defense overall. However, when present, negative relationships between competitive ability and defense influenced species diversity in the manner predicted by theory. In the minority of communities for which a tradeoff was detected, species evenness was higher, and resource addition and consumer removal reduced diversity. Our analysis reframes the commonly held notion that consumers structure plant communities through a competition–defense tradeoff. Such a tradeoff can maintain diversity when present, but negative correlations between competitive ability and defense were less common than is often assumed. In this respect, this study supports an emerging theoretical paradigm in which predation interacts with competition to both enhance and reduce species diversity.     

An association between length of stay and co-morbidity in chronic airflow limitation.

OBJECTIVE: To examine factors which impact on the length of stay and readmission for patients with chronic airflow limitation at a South Australian hospital from December 1996 until March 1998. DESIGN: Discharges from Flinders Medical Centre for patients aged > or = 18 years, where chronic airflow limitation was an active problem, and including a subset with a primary diagnosis of chronic airflow limitation, were identified, retrospectively, by the center's Clinical Coding Service from the hospital's in-patient separation database. SETTING: Flinders Medical Centre, Adelaide, South Australia. OUTCOME MEASURES: Length of stay; number of co-morbidities; readmission within 28 days. RESULTS: Five-hundred and twenty discharges (male:female, 258:262) with a primary diagnosis of chronic airflow limitation (ANDRG-3 177, chronic obstructive airways disease) were identified. Readmission within 28 days was related to the number of co-morbidities and to age. A relationship between length of stay and the number of co-morbidities was identified. A mean length of stay of 6.39 days was found for patients with less than five co-morbidities, 5.36 at their first admission to Flinders Medical Centre and 3.25 at their first admission to Flinders Medical Centre with no co-morbidities. These mean lengths of stay fall below overseas data previously published and are consistent with Kong's estimate of an ideal mean length of stay of 3.2 days when a clinical management guideline is used in low-risk chronic airflow limitation patients. CONCLUSIONS: Length of stay and readmission to hospital within 28 days of patients with a primary diagnosis of chronic airflow limitation is at least partly related to the number of co-morbidities and to age. The study has highlighted the difficulty of relying on changes to aggregate data as outcome measures for these patients.     

Availability and need of home adaptations for personal mobility among individuals with spinal cord injury

Objective: To identify the availability and unmet need of home adaptations (HAs) among the Swiss population with spinal cord injury (SCI).

Design: Cross-sectional study.

Setting: Swiss Spinal Cord Injury Community Survey 2012.

Participants: Individuals aged 16 or older with chronic SCI living in Switzerland.

Interventions: Not applicable.

Outcome measures: The availability of ten HAs (self-report) was analyzed by sex, age, living situation, indoor mobility, SCI severity, SCI etiology and time since SCI. The unmet need (self-report of not having a HA but needing it) of HAs was analyzed by financial hardship.

Results: Among the 482 study participants (mean age 55.2 years, standard deviation 15.0 years, 71.6% males), 85.1% had at least one HA. The most frequent HA was a wheelchair accessible shower (62.7%). Availability of HAs markedly varied with indoor mobility (e.g. 38.4% of participants using a wheelchair had a stair lift compared to 17.4% of those walking) and with SCI severity (e.g. 54.8% of those with complete paraplegia had a wheelchair accessible kitchen worktop compared to 26.0% of those with incomplete paraplegia). Unmet need was highest for adjustable kitchen worktops (78.7% of those with a need) and adjustable kitchen cabinets (75.7%) and lowest for wheelchair accessible showers (9.4%) and grab bars next to the toilet (8.5%). No significant differences in unmet need were found when stratifying for financial hardship.

Conclusion: Availability of HAs is dependent on indoor mobility and SCI severity. There is a considerable degree of unmet need for selected HAs, which couldn't be explained by financial hardship.     

Assessing the 16 hour intern shift limit: Results of a multi-center,mixed-methods study of residents and faculty in general surgery

Background

The study explores how residents and faculty assess the ACGME's 16-h limit on intern shifts.

Effects of extrinsic positive end-expiratory pressure on mechanically ventilated patients with chronic obstructive pulmonary disease and dynamic hyperinflation

Objective To examine the circulatory and respiratory effects of extrinsic positive end-expiratory pressure (PEEPe) in patients with chronic obstructive pulmonary disease (COPD) and dynamic hyperinflation during controlled mechanical ventilation.Design Different levels of PEEPe were applied randomly in mechanically ventilated patients with COPD and dynamic hyperinflation.Setting Respiratory Intensive Care Unit of a University Hospital.Patients 9 patients with acute respiratory failure and dynamic hyperinflation due to acute exacerbation of COPD.Interventions PEEPe 35%, 58% and 86% of intrinsic PEEP (PEEPi) were applied.Measurements and results Using flow-directed pulmonary artery catheters hemodynamic measurements were obtained, while simultaneously lung volumes, airflows and airway pressures were recorded. In order to estimate alveolar pressures (P_alv), rapid airway occlusions during passive expiration were also performed. At no level of PEEPe were significant changes in cardiac output, gas exchange variables, dead space, airways inflation resistances and respiratory system static end-inspiratory compliance observed. At high level of PEEPe central venous, mean pulmonary arterial and pulmonary capillary wedge pressures were increased significantly. All but one patient were flow-limited during passive expiration. PEEPe 86% of PEEPi caused a significant increase in end-expiratory lung volume and total PEEP. Iso-volume pressure-flow curves showed volume-dependence expiratory flow limitation in 2 patients, while in 8 patients volume-dependence of critical driving pressure (P_alv-mouth pressure) that decreased flows was also observed.Conclusions The effects of PEEPe on iso-volume flow and hence on lung mechanics and hemodynamics, depend on many factors, such as airways resistances, lung volumes and airway characteristics, making the patient response to PEEPe unpredictable.