Dynamic behavior during noninvasive ventilation: chaotic support?

Acute noninvasive ventilation is generally applied via face mask, with modified pressure support used as the initial mode to assist ventilation. Although an adequate seal can usually be obtained, leaks frequently develop between the mask and the patient's face. This leakage presents a theoretical problem, since the inspiratory phase of pressure support terminates when flow falls to a predetermined fraction of peak inspiratory flow. To explore the issue of mask leakage and machine performance, we used a mathematical model to investigate the dynamic behavior of pressure-supported noninvasive ventilation, and confirmed the predicted behavior through use of a test lung. Our mathematical and laboratory analyses indicate that even when subject effort is unvarying, pressure-support ventilation applied in the presence of an inspiratory leak proximal to the airway opening can be accompanied by marked variations in duration of the inspiratory phase and in autoPEEP. The unstable behavior was observed in the simplest plausible mathematical models, and occurred at impedance values and ventilator settings that are clinically realistic.     

Widespread use of gastric acid inhibitors in infants:Are they needed? Are they safe?

Gastroesophageal reflux is a common phenomenon in infants,but the differentiation between gastro-esophageal reflux and gastroesophageal reflux disease can be difficult.Symptoms are non-specific and there is increasing evidence that the majority of symptoms may not be acid-related.Despite this,gastric acid inhibitors such as proton pump inhibitors are widely and increasingly used,often without objective evidence or investigations to guide treatment.Several studies have shown that these medications are ineffective at treating symptoms associated with reflux in the absence of endoscopically proven oesophagitis.With a lack of evidence for efficacy,attention is now being turned to the potential risks of gastric acid suppression.Previously assumed safety of these medications is being challenged with evidence of potential side effects including GI and respiratory infections,bacterial overgrowth,adverse bone health,food allergy and drug interactions.     

JNC-7 guidelines: Are they still relevant?

The recommendations of the Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), published in 2003, are largely relevant today. Lowering blood pressure (BP) to goal in hypertensive patients is of primary importance in reducing cardiovascular risk. Antihypertensive drugs vary in their efficacy to lower BP and can have BP-independent effects on cardiovascular events, as seen especially with regard to preventing heart failure and stroke. Thiazide-type diuretics were recommended as the preferred initial drugs for treatment of hypertension in most patients, and this is still an appropriate recommendation. Several other classes were recommended as next in priority, but beta-blockers should now have a lesser role in the management of uncomplicated hypertension. Although a new JNC report would be reassuring to practitioners and should include some changes since JNC 7, I consider most of the recommendations to still be relevant today.     

Extracellular vesicles and viruses: Are they close relatives?

Extracellular vesicles (EVs) released by various cells are small phospholipid membrane-enclosed entities that can carry miRNA. They are now central to research in many fields of biology because they seem to constitute a new system of cell–cell communication. Physical and chemical characteristics of many EVs, as well as their biogenesis pathways, resemble those of retroviruses. Moreover, EVs generated by virus-infected cells can incorporate viral proteins and fragments of viral RNA, being thus indistinguishable from defective (noninfectious) retroviruses. EVs, depending on the proteins and genetic material incorporated in them, play a significant role in viral infection, both facilitating and suppressing it. Deciphering the mechanisms of EV-cell interactions may facilitate the design of EVs that inhibit viral infection and can be used as vehicles for targeted drug delivery.     

Reactive oxygen species: Are they important for haematopoiesis?

The production of reactive oxygen species (ROS) has traditionally been related to deleterious effects for cells. However, it is now widely accepted that ROS can play an important role in regulating cellular signalling and gene expression. NADPH oxidase ROS production seems to be especially important in this regard. Some lines of evidence suggest that ROS may be important modulators of cell differentiation, including haematopoietic differentiation, in both physiologic and pathologic conditions. Here we shall review how ROS can regulate cell signalling and gene expression. We shall also focus on the importance of ROS for haematopoietic stem cell (HSC) biology and for haematopoietic differentiation. We shall review the involvement of ROS and NADPH oxidases in cancer, and in particular what is known about the relationship between ROS and haematological malignancies. Finally, we shall discuss the use of ROS as cancer therapeutic targets.     

Classification of the vasculitides: Are they clinically useful?

Several classification systems for the vasculitides have been developed over the second half of the past century. These classifications systems have been modified according to the advances made in the differentiation of these syndromes, particularly their histopathologic features (the vessel size involved) and their clinical features. Although these classifications have been widely used in the clinical setting for the diagnosis of these disorders, they were developed for research purposes. Given the common clinical and, sometimes, histopathologic features of the different vasculitides, a classification system that facilitates a diagnosis and the formulation of a therapeutic plan is still needed. The development and utilization of novel serum markers and new imaging modalities coupled with advances in the understanding of these disorders, may allow the development of a classification system for the vasculitides that will be of greater value in the clinical setting.     

Triggers of asthma and COPD: Are they different?

BackgroundAsthma symptoms can be triggered by a variety of factors commonly referred to as “triggers”. Some of these factors can also induce severe asthma exacerbations. Thus, it can be assumed that actions taken against such triggers may prevent the progression of the disease. However, limited data exist on the clinical importance of these triggers in patients with chronic obstructive pulmonary disease (COPD).ObjectiveTo compare the effect of triggers on symptoms and actions taken against certain modifiable triggers in patients with asthma and COPD.MethodsThe study was conducted in a university hospital between June 2009 and June 2010. Patients with asthma and COPD were asked to complete a questionnaire in which both the factors triggering symptoms and the actions taken against several triggers were assessed.ResultsThree hundred consecutive adult patients (150 asthma, 150 COPD) were enrolled to the study. The frequency of triggering factors was similar in both groups. Vaccination rates for influenza and pneumococcus were significantly higher in patients with COPD. However, such anti-allergic approaches as the use of strategies to decrease dust exposure, the use of anti-mite bed sheets, and the removal of pets from the home were more commonly employed by asthmatic patients.ConclusionThis study revealed that certain triggers affected COPD and asthma patients to the same degree. Therefore, triggers and strategies for controlling modifiable triggers should be more concentrated on during education in both groups. However, the preventive effect of these strategies on disease progression, particularly in patients with COPD, needs clarification.