Effects of Electrical Stimulation of Respiratory Center in the Event of Termination of Its Natural Rhythmic Activity

The possibility of restoration of the natural rhythmic activity of the respiratory system by transcutaneous electrical stimulation of the respiratory center after termination of spontaneous respiratory movements caused by narcosis was shown in experiments on mongrel cats of both sexes under nembutal anesthesia. Natural rhythmic activity of respiratory center was stopped by additional administration of sodium thiopental. The proposed method of electrical stimulation of the respiratory center allows maintaining the rhythmic respiratory movements and their recovery after narcotic apnea up to complete recovery of spontaneous respiration.     

基于脉搏波的呼吸频率计算方法

为了在可穿戴医疗领域中快速检测出人体的呼吸频率,提出一种基于光电容积脉搏波的呼吸频率计算方法。首 先,通过MIMIC Database数据集获取人体同时段的脉搏波信号与呼吸波信号;其次,通过对脉搏波信号运行经验模态分 解算法,从而获得脉搏波信号的有限个本征模态函数,再选取合适的本征模态函数重构呼吸波信号;最后,通过对重构的 呼吸波信号进行特征提取,计算出呼吸频率。结果表明:经过脉搏波分解得到的呼吸信号与原始呼吸信号的相对相干系 数在0.6以上,呼吸频率也十分接近,准确率高达0.9以上。说明通过光电容积脉搏波信号计算呼吸频率的可行性,这对于 可穿戴医疗领域、无创医疗诊断具有重要意义。     

不同的本征呼吸周期对兔呼吸周期曲线的影响

除吸气抑制反向射外,肺充气通过迷走神经对呼吸中枢可能产生了另一种作用,其作用效果主要体现在呼吸周期的改变上。本文介绍对麻醉和肌肉麻麻痹的大白兔,用不同相位的肺充气的方法,在消除吸气抑制反射,保持吸气周期不变的条件下,通过改变兔的每分通气量来改变本征呼吸周期,研究了本征呼吸周期对呼吸周期曲线的影响。实验结果表明,对于不同的本征呼吸周期,呼吸周期曲线第一个最低点的位置不同,第二个上升段斜率相同,但沿着垂红方向存在上下移动,第二个最低点的位置相同,第三个上升段重合,但终点位置不同。这说明不同的体征呼吸周期使兔的呼吸周期曲线产生了有一定规律的移动。     

Consistency and signal strength of respiratory neuronal activity

The concerns of this study are taxonomic. We demonstrate a defining characteristic of respiratory neuronal activity. This characteristic is the degree or size of the respiratory component in the activity of a respiratory cell. The essential feature of respiratory activity is that it occurs in phase with some portion of the respiratory cycle. Therefore, neuronal activity can be arranged within a matrix in which the columns are fractions of the respiratory cycle and the rows are breaths and, as Netick and Orem (10) have shown, this matrix can be analyzed with an analysis of variance to determine whether the activity contains a respiratory component. However, the analysis of variance indicates nothing about the size of a statistically significant respiratory component. We hypothesized that the size of the respiratory component in the activity of different respiratory cells differed among cells but was a stable characteristic of any given cell. The index used to quantify the degree of respiratory activity was eta 2, the proportion of the total variance of the activity of a respiratory neuron consisting of the variance occurring across fractions of the respiratory cycle. This index theoretically depends on a) the range of activity levels across a respiratory cycle and the dispersion of activity levels over this range (parameters signifying the strength of the respiratory signal) and b) the variability in the activity of the cell across breaths (a parameter signifying the consistency of the respiratory activity). Theoretically, eta 2 values can vary from 0.0 to 1.0 indicating, respectively, that none or all of the variability in the activity of a cell across breaths is accounted for by a respiratory effect. eta 2 was used to analyze the size of the respiratory component in the activity of 32 medullary respiratory neurons recorded during nonrapid eye movement (NREM) sleep in chronic cats. These different respiratory cells had activity patterns with eta 2 values ranging from 0.1 to 0.9. However, the activity of a given cell produced eta 2 values that were consistent from sample to sample. Therefore, the eta 2 value of the activity of a cell was a defining, stable characteristic of that cell. The eta 2 values of the activity of the cells were strongly correlated with the consistency of their discharge pattern from breath to breath (r x,y = 0.975).(ABSTRACT TRUNCATED AT 400 WORDS)     

Detection of respiratory viruses by molecular methods

SUMMARY: Clinical laboratories historically diagnose seven or eight respiratory virus infections using a combination of techniques including enzyme immunoassay, direct fluorescent antibody staining, cell culture, and nucleic acid amplification tests. With the discovery of six new respiratory viruses since 2000, laboratories are faced with the challenge of detecting up to 19 different viruses that cause acute respiratory disease of both the upper and lower respiratory tracts. The application of nucleic acid amplification technology, particularly multiplex PCR coupled with fluidic or fixed microarrays, provides an important new approach for the detection of multiple respiratory viruses in a single test. These multiplex amplification tests provide a sensitive and comprehensive approach for the diagnosis of respiratory tract infections in individual hospitalized patients and the identification of the etiological agent in outbreaks of respiratory tract infection in the community. This review describes the molecular methods used to detect respiratory viruses and discusses the contribution that molecular testing, especially multiplex PCR, has made to our ability to detect respiratory viruses and to increase our understanding of the roles of various viral agents in acute respiratory disease.     

Opioidergic and dopaminergic modulation of respiration

Opioids, dopamine and their receptors are present in many regions of the bulbar respiratory network. The physiological importance of endogenous opioids to respiratory control has not been explicitly demonstrated. Nonetheless, studies of opioidergic respiratory mechanisms are important because synthetic opiate drugs have respiratory side effects that in some situations pose health risks and limit their therapeutic usefulness. They can depress breathing depth and rate, blunt respiratory responsiveness to CO2 and hypoxia, increase upper airway resistance and reduce pulmonary compliance. The opiate respiratory disturbances are mainly due to agonist activation of mu- and delta-subtypes of receptor and involve specific types of respiratory-related neurons in the ventrolateral medulla and the dorsolateral pons. Endogenous dopaminergic modulation in the CNS and carotid bodies enhances CO2-dependent respiratory drive and depresses hypoxic drive. In the CNS, synthetic agonists with selectivity for D1-and D4-types of receptor slow respiratory rhythm, whereas D2-selective agonists modulate acute and chronic responses to hypoxia. D1-receptor agonists also act centrally to increase respiratory responsiveness to CO2, and counteract opiate blunting of CO2-dependent respiratory drive and depression of breathing. Cellular targets and intracellular mechanisms responsible for opioidergic and dopaminergic respiratory effects for the most part remain to be determined.     

Habituation in neural processing and subjective perception of respiratory sensations

Reduced perception of respiratory sensations is associated with negative treatment outcome in asthma. We examined whether habituation in the neural processing of repeatedly experienced respiratory sensations may underlie subjective reports of reduced respiratory perception. Respiratory-related evoked potentials (RREP) elicited by inspiratory occlusions and reports of respiratory perception were compared between early and late experimental periods in healthy subjects. Reports of respiratory perception were reduced during late, compared to early, experimental periods. This was paralleled by reduced magnitudes in RREP components N1, P2, and P3 in late, compared to early, experimental periods. Habituation in the neural processing of respiratory sensations is a potential mechanism that underlies subjective reports of reduced respiratory perception and might represent a risk factor for reduced perception of respiratory sensations in asthma.     

Impact of nasopharyngeal microbiota on the development of respiratory tract diseases

Knowledge of whether and how respiratory microbiota composition can prime the immune system and provide colonisation resistance, limiting consecutive pathobiont overgrowth and infections, is essential to improving the prevention and therapy of respiratory disorders. Modulation of dysbiotic ecosystems or reconstitution of missing microbes might be a possible measure to reduce respiratory diseases. The aim of this review is to analyse the role of nasopharyngeal microbiota in the development of respiratory tract disease in paediatric-age subjects. PubMed was used to search for all studies published over the last 15 years using the following key words: “microbiota” or “microbioma” and “nasopharyngeal” or “respiratory” or “nasal” and “children” or “paediatric” or “infant”. Analysis of the literature showed that respiratory microbiota can regulate health and disease development in the respiratory tract. Like the gut microbiota, the respiratory microbiota is established at birth, and early respiratory microbiota composition determines bacterial succession patterns and respiratory health in children. Protective and dangerous bacteria have been identified, and this can be considered the base for developing new approaches to diseases that respond poorly to traditional interventions. Reconstitution of missing microbes can be achieved by the administration of pre- and probiotics. Modulation of respiratory microbiota by favouring colonisation of the upper respiratory tract by beneficial commensals can interfere with the proliferation and activity of resident pathobionts and is a possible new measure to reduce the risk of disease. However, further studies are needed because a deeper understanding of these and related issues can be transferred to clinical practice.     

Organization of the brain stem neural mechanisms for generation of respiratory rhythm--current problems

The brain stem neural mechanism for central regulation of breathing is regarded as a complex neuronal mechanism consisting of several functional subsystems subserving different functions. One of its functions is the generation of the respiratory rhythm. Evidence indicates with certainty that the subsystem for respiratory rhythm-generating mechanisms is located in the medullary structure outside the DRG and VRG regions which have been postulated for many years as the hypothetical site generating respiratory rhythm. DRG and VRG are thought to be premotor neuron pools. Rhythmic activity originating in the medulla is dominant in terms of the spontaneity over other rhythmic activity in the pontine mechanisms as well as those in the spinal cord. Evidences for heterogeneity of functional properties of respiratory neurons in the brain stem are demonstrated. Possible functional differentiation among respiratory neurons is suggested. Neuronal mechanisms involving respiratory neurons identified as members of primary respiratory neuron populations or neuronal networks consisting of various types of respiratory neurons located in the lateral region of the bulbar reticular formation may play important roles in generation of respiratory rhythms. Precise neural processes within the neuronal mechanisms for respiratory rhythm generation are rather equivocal and remain to be determined by further investigation.     

光学表面成像系统实时运动监测精度研究

目的:探究光学表面成像系统实时运动监测的精度。方法:将30例患者的呼吸曲线输入到模体中模拟呼吸运动， 同时利用Catalyst系统对模体进行实时运动监测，比较系统监测的呼吸曲线与参考曲线，从而得到光学表面成像系统实时 运动监测的精度。结果:光学表面成像系统监测的呼吸曲线与参考曲线具有较高的一致性，相关系数均大于0.99，显著相 关。监测误差的平均值为（0.24±0.04）mm，并且随着呼吸信号频率的增加而减小。结论:光学表面成像系统的实时运动 监测精度较高，可用于对患者呼吸运动的监测。在进行呼吸门控治疗时，应考虑呼吸监测系统引入的误差。     

Evaluation of an enzyme membrane immunoassay (Directigen RSV) for the rapid diagnosis of respiratory syncytial virus infections

A rapid enzyme immunoassay (EIA) membrane test, the Directigen respiratory syncytial virus (Becton Dickinson), was compared with cell culture, an indirect immunofluorescence (IF) test, the Monofluokit respiratory syncytial virus (Diagnostics Pasteur), and a conventional enzyme immunoassay antigen test, the Abbott respiratory syncytial virus enzyme immunoassay in nasal aspirates specimens from children with suspected respiratory syncytial virus (RSV) bronchiolitis. The sensibility and specificity of the Directigen, respiratory syncytial virus were 91% and 98% respectively, as compared with those of culture, and of 93% and 86% as compared with the Monofluokit respiratory syncytial virus. In the comparison of the two enzyme immunoassays, Directigen respiratory syncytial virus detected more positive specimens: 68/127 than the other: 46/127. Directigen respiratory syncytial virus is a very rapid test, (15-min), sensitive and specific, which can be used as an alternative technique for detection of respiratory syncytial virus in nasal samples when viral isolation or immunofluorescence direct are not available.     

Impact of breathing pattern on work of breathing in healthy subjects and patients with COPD

The impact of the respiratory pattern on respiratory muscle workload represents an unresolved controversy and is important for the treatment of patients with respiratory disorders and respiratory muscle failure. We designed this study to investigate the relationship of respiratory pattern and inspiratory workload. We measured esophageal pressure and inspiratory flow and calculated work of breathing, tidal volume and respiratory rate. Ten healthy subjects and 10 COPD patients participated and performed five different breathing patterns starting from respiratory rate 12 and tidal volume 1l or quiet breathing, respectively. They were instructed to increase respiratory rate by 50 and 100% as well as tidal volume by 50 and 100% while maintaining constant minute-ventilation. In healthy subjects Delta VT was the single best parameter to predict Delta WOB (R=0.958, R(2)=0.918, p<0.0001). The relationships of changes in tidal volume, respiratory rate and rapid shallow breathing index to changes in WOB were linear. In the COPD Delta VT was also the single best parameter to predict changes in work of breathing (R=0.777, R(2)=0.604, p<0.0001), however the relation of respiratory rate and rapid shallow breathing index to work of breathing was exponential (e-function) with lower indices generating higher workload. We conclude that rapid shallow breathing might be a strategy to compensate for burdensome respiratory mechanics. In COPD patients however we observed a critical threshold where any further increases in rapid shallow breathing index will be of no further benefit.     

Comparative Characteristics of Respiratory Pattern Responses to Microinjection of Kainic Acid into Different Parts of the Nucleus Ambiguus

Experiments on anesthetized rats were performed using local chemical exclusion of neurons with kainic acid to study the relative roles of the rostral, intermediate, and caudal parts of the nucleus ambiguus in the mechanisms controlling respiration. The characteristics of the respiratory rhythm and pattern responses to chemical exclusion of different parts of this nucleus were observed. In particular, sequential exclusion of the left and right rostral parts of the nucleus ambiguus reproducibly induced significant decreases in the respiration rate and respiratory volume in the first minutes; in 83% of experiments, there was also irreversible respiratory arrest. Exclusion of symmetrical intermediate parts of the nucleus ambiguus was followed by bradypnea and decreases in pulmonary ventilation, the greatest respiratory effects being noted only after injection of kainic acid into the second symmetrical area, irreversible respiratory arrest being seen in 50% of cases. Exclusion of symmetrical caudal areas of the nucleus ambiguus resulted only in small decreases in respiratory frequency without significant changes in respiratory volume and gave rise to the smallest incidence of respiratory arrest, i.e., 33%.     

Changes in pattern of breathing following baroreceptor stimulation in cats

The effects of baroreceptor stimulation produced by a sudden rise in arterial pressure on respiratory pattern were studied at various levels of PaCO2 and PaO2 in 8 anesthetized cats. A sudden rise in arterial pressure decreased both tidal volume and respiratory frequency. For a given increase in arterial pressure, the decrease in tidal volume was constant at all levels of PaCO2 and PaO2 examined, whereas the decrease in respiratory frequency became progressively lower as the level of chemical drive increased, regardless of the type of chemical stimuli. Analysis of respiratory duration revealed that the decrease in respiratory frequency during baroreceptor stimulation was solely due to prolongation of expiration. These observations were obtained in the intact as well as in the vagotomized animals but were not seen after bilateral sinus nerve section. They suggest that the central respiratory mechanisms controlling respiratory frequency are directly involved in the reduction in respiratory frequency during baroreceptor stimulation.     

Maturation of respiratory control in the behaving mammal

Whereas in vitro techniques have contributed greatly to our understanding of detailed neuronal mechanisms of respiratory control, the integrated function of respiratory behavior requires studying conscious, unsedated subjects. Noninvasive approaches, meticulous chronic instrumentation for the recording of multiple respiratory indices, and correlations with brain studies performed after physiological manipulations in vivo can all be employed to get to some understanding of the maturation of respiratory control in the mammal. This article is a selective and critical overview of recent literature on methodologies that can be used in behaving subjects, the relationship of respiration to sleep-wake states, respiratory patterns during normoxia, and on respiratory responsiveness to hypercarbia and hypoxia, all emphasizing processes during development. It is hoped that this review will encourage new investigators interested in the regulation of breathing to resort to experimental approaches that will reveal the mysteries of respiratory behavior in the integrated organism.     

Replication and clearance of respiratory syncytial virus: apoptosis is an important pathway of virus clearance after experimental infection with bovine respiratory syncytial virus

Human respiratory syncytial virus is an important cause of severe respiratory disease in young children, the elderly, and in immunocompromised adults. Similarly, bovine respiratory syncytial virus (BRSV) is causing severe, sometimes fatal, respiratory disease in calves. Both viruses are pneumovirus and the infections with human respiratory syncytial virus and BRSV have similar clinical, pathological, and epidemiological characteristics. In this study we used experimental BRSV infection in calves as a model of respiratory syncytial virus infection to demonstrate important aspects of viral replication and clearance in a natural target animal. Replication of BRSV was demonstrated in the luminal part of the respiratory epithelial cells and replication in the upper respiratory tract preceded the replication in the lower respiratory tract. Virus excreted to the lumen of the respiratory tract was cleared by neutrophils whereas apoptosis was an important way of clearance of BRSV-infected epithelial cells. Neighboring cells, which probably were epithelial cells, phagocytized the BRSV-infected apoptotic cells. The number of both CD4(+) and CD8+ T cells increased during the course of infection, but the T cells were not found between the epithelial cells of the bronchi up until apoptosis was no longer detected, thus in the bronchi there was no indication of direct contact-dependent T-cell-mediated cytotoxicity in the primary infection.     

Estimation of the respiratory frequency using spatial information in the VCG

A new method for extracting respiratory signals from the ECG/VCG is presented. The method is based on the alignment of an observed VCG loop to a reference loop with respect to the transformations of rotation and time synchronisation. The resulting series of estimated rotation angles reflects respiratory-induced changes in the electrical axis of the heart. The respiratory frequency is estimated by power spectral analysis of the derived respiration signal. The value of respiratory modulation of the heart rate is considered by analysing the cross power spectrum of the signals related to rotation angles and heart rate. For comparison, a respiratory signal derived from the QRS area of two different leads is implemented. The performance of the methods is validated on a database with simultaneously recorded VCG and respiratory signals acquired from 20 healthy subjects. The agreement between the respiratory frequencies obtained from the derived and the respiratory signals is presented. The angle-based respiratory signal is found to produce the best agreement with a gross median error of only 4.2%.     

The management of respiratory motion in radiation oncology report of AAPM Task Group 76

This document is the report of a task group of the AAPM and has been prepared primarily to advise medical physicists involved in the external-beam radiation therapy of patients with thoracic, abdominal, and pelvic tumors affected by respiratory motion. This report describes the magnitude of respiratory motion, discusses radiotherapy specific problems caused by respiratory motion, explains techniques that explicitly manage respiratory motion during radiotherapy and gives recommendations in the application of these techniques for patient care, including quality assurance (QA) guidelines for these devices and their use with conformal and intensity modulated radiotherapy. The technologies covered by this report are motion-encompassing methods, respiratory gated techniques, breath-hold techniques, forced shallow-breathing methods, and respiration-synchronized techniques. The main outcome of this report is a clinical process guide for managing respiratory motion. Included in this guide is the recommendation that tumor motion should be measured (when possible) for each patient for whom respiratory motion is a concern. If target motion is greater than 5 mm, a method of respiratory motion management is available, and if the patient can tolerate the procedure, respiratory motion management technology is appropriate. Respiratory motion management is also appropriate when the procedure will increase normal tissue sparing. Respiratory motion management involves further resources, education and the development of and adherence to QA procedures.     

Development of adaptive behaviour of the respiratory network: implications for the pontine Kolliker-Fuse nucleus

Breathing is constantly modulated by afferent sensory inputs in order to adapt to changes in behaviour and environment. The pontine respiratory group, in particular the Kolliker-Fuse nucleus, might be a key structure for adaptive behaviours of the respiratory network. Here, we review the anatomical connectivity of the Kolliker-Fuse nucleus with primary sensory structures and with the medullary respiratory centres and focus on the importance of pontine and medullary postinspiratory neurones in the mediation of respiratory reflexes. Furthermore, we will summarise recent findings from our group regarding ontogenetic changes of respiratory reflexes (e.g., the diving response) and provide evidence that immaturity of the Kolliker-Fuse nucleus might account in neonates for a lack of plasticity in sensory evoked modulations of respiratory activity. We propose that a subpopulation of neurones within the Kolliker-Fuse nucleus represent command neurones for sensory processing which are capable of initiating adaptive behaviour in the respiratory network. Recent data from our laboratory suggest that these command neurones undergo substantial postnatal maturation.     

Development of respiratory rhythm generation in ectothermic vertebrates

Compared with birds and mammals, very little is known about the development and regulation of respiratory rhythm generation in ectothermic vertebrates. The development and regulation of respiratory rhythm generation in ectothermic vertebrates (fish, amphibians and reptiles) should provide insight into the evolution of these mechanisms. One useful model for examining the development of respiratory rhythm generation in ectothermic vertebrates has emerged from studies with the North American bullfrog (Rana catesbeiana). A major advantage of bullfrogs as a comparative model for respiratory rhythm generation is that respiratory output may be measured at all stages of development, both in vivo and in vitro. An emerging view of recent studies in developing bullfrogs is that many of the mechanisms of respiratory rhythm generation are very similar to those seen in birds and mammals. The overall conclusion from these studies is that respiratory rhythm generation during development may be highly conserved during evolution. The development of respiratory rhythm generation in mammals may, therefore, reflect the antecedent mechanisms seen in ectothermic vertebrates. The main focus of this brief review is to discuss recent data on the development of respiratory rhythm generation in ectothermic vertebrates, with particular emphasis on the North American bullfrog (R. catesbeiana) as a model.