Ventilatory changes during exercise and arterial PCO2 oscillations in chronic airway obstruction patients

Ventilatory kinetics during exercise (30 W for 6 min) were studied in 3 asthmatics, 14 patients with chronic airway obstruction (11 with bronchial or type B disease, 3 with emphysematous or type A disease), and in 5 normal age-matched controls. The measure of ventilatory increase during early exercise, alpha 1-3%, was calculated as (avg minute ventilation over 1st-3rd min of exercise--resting minute ventilation)/(avg minute ventilation over 4th-6th min of exercise--resting minute ventilation) X 100. Arterial pH, PO2, and PCO2 (PaCO2) were measured in vitro at rest and within 20 s of termination of exercise. Respiratory PaCO2 oscillations had previously been monitored at rest in the patients (indirectly as in vivo arterial pH, using a fast-response pH electrode) and quantified by upslope (delta PaCO2/delta t). alpha 1-3% was normal in asthmatics (whose respiratory oscillations as a group showed least attenuation) and in type A patients (whose respiratory oscillations as a group were most attenuated). In type B patients reduction in alpha 1-3% correlated with attenuation of delta PaCO2/delta t (r = 0.75; P less than 0.01). There was no significant correlation between delta PaCO2/delta t and change of in vitro PaCO2 from rest to the immediate postexercise period. These findings are consistent with the hypothesis that attenuation of delta PaCO2/delta t slows ventilatory kinetics during exercise in type B but not type A patients. Intact respiratory oscillations are not necessary for CO2 homeostasis after the first few minutes of exercise.     

无创通气在AECOPD机械通气患者撤机中的研究

目的：通过前瞻性随机对照研究比较应用NIPPV与PSV两种撤机方法在治疗AECOPD合并II型呼吸衰竭进行机械通气撤机困难患者中的优越性。方法：达到撤机标准但经两小时自主呼吸试验（SBT）失败的患者被分为两组：PSV组和无创通气组。观测有创通气时间、机械通气总时间、再插管率、住呼吸重症监护室时间和VAP发生率等指标。结果：NIPPV组较PSV组气管插管时间显著缩短,VAP发生率、再插管率及住院费用均较PSV通气组显著降低。结论：采用无创通气撤机法治疗AECOPD合并II型呼吸衰竭较传统的机械通气方式在有效缩短有创通气时间,降低VAP发生率,改善患者预后方面更优越。     

经鼻高流量湿化氧疗与无创正压通气在改善AECOPD患者二氧化碳潴留临床疗效的比较

目的:经鼻高流量氧疗(HFNC)已广泛应用于缺氧性呼吸衰竭患者的治疗。本研究分析了HFNC治疗对慢性阻塞性肺疾病急性加重(AECOPD)合并Ⅱ型呼吸衰竭的治疗效果。方法:本研究前瞻性观察分析了2017年1月至2019年1月入住我院呼吸科和重症医学科,诊断为AECOPD且合并有中度II型呼吸衰竭(血气分析PaO₂/Fi O2<200 mm Hg,PaCO₂>45 mm Hg,pH7.25~7.35)的患者44例,随机平均分为两组,参照组22例患者采纳无创正压通气(NIV)技术治疗,实验组22例患者予以HFNC治疗。观察两组患者治疗效果(治疗失败改为有创通气、28天死亡率)、血气分析对比血pH、PaCO₂、PaO₂。结果:HFNC组患者(22例,平均年龄73岁,男性占63.6%)同NIV组患者(22例,平均年龄77岁,男性占54.5%)相比,血pH、PaCO₂、PaO₂等血气分析指标两组无显著统计学差异。治疗失败率分别为22.7%(5/22)和27.2%(6/22),P=0.857。28天死亡率无统计学差异(HFNC组为13.6%,NIV组为18.2%,P=0.845)。结论:在AECOPD合并Ⅱ型呼吸衰竭的患者中,HFNC在改善氧合缓解CO2潴留方面具有同NIV相似的效应,因其具有更好的舒适性和耐受性,可成为NIV的有益补充。     

Disturbances of Pulmonary Function in Mitral Valve Disease

To study the sequence of changes in respiratory function that occur in the natural history of mitral stenosis, and the physiological basis of “cardiac dyspnea”, 30 patients with chronic mitral valve disease were subjected to detailed pulmonary function tests. There was no significant change in vital capacity and functional residual capacity. The reduction in maximal mid-expiratory flow rate showed excellent correlation with the respiratory symptoms. The pulmonary capillary blood volume was increased in moderately advanced cases but was consistently reduced in the severest cases. Hyperventilation was due to an increased respiratory rate. Dyspnea was associated with increased respiratory work owing to the interrelation between the reduction in diffusion capacity, compliance, cardiac output, the increase in airway resistance, and the uneven ventilation and perfusion of the lungs. The amount of “effort” required to breathe is incommensurate with the external load in these patients.     

序贯机械通气联合尼可刹米治疗AECOPD合并Ⅱ型呼吸衰竭的临床观察

目的：观察序贯机械通气联合尼可刹米在慢性阻塞性肺疾病急性加重期（AECOPD）合并Ⅱ型呼吸衰竭中的的临床疗效及安全性。方法：按照随机原则将64例AECOPD合并Ⅱ型呼吸衰竭分成两组,对照组32例给予常规有创机械通气,治疗组患者给予序贯机械通气联合尼可刹米治疗,对两组治疗前、后24 h和48h的pH值、PaO2、PaCO2以及VAP、总机械通气时间、ICU时间,总住院时间,再插管率以及死亡率进行评价。结果：治疗组与对照组相比,pH值改善明显、PaO2明显增长、PaCO2下降显著,有统计学差异（P〈0.05）;治疗组ICU时间,总住院时间,再插管率以及死亡率与对照组相比,下降明显,有统计学差异（P〈0.05）。结论：序贯机械通气联合尼可刹米治疗AECOPD合并Ⅱ型呼吸衰竭的临床疗效确切,值得临床推广。     

Physiology of ventilatory regulation during sleep

During light slow-wave sleep, ventilation is principally regulated by automatic metabolic control system. An instability in the respiratory control may be the predominant disturbance leading to very irregular or periodic breathing. During deep sleep, ventilation is progressively more stable. During REM sleep, automatic regulation is abolished and ventilation is particularly dependent on the compartmental control system. The reduction in airways and respiratory muscles tone favors the occurrence of obstructive apneas. The elevation in arousal threshold leads prolongation of the obstructive events.     

Activity of medullary respiratory neurons during ventilator-induced apnea in sleep and wakefulness

Mechanical ventilation of cats in sleep andwakefulness causes apnea, often within two to three cycles of theventilator. We recorded 137 medullary respiratory neurons in four adultcats during eupnea and during apnea caused by mechanical ventilation. We hypothesized that the residual activity of respiratory neurons during apnea might reveal its cause(s). The results showed that residual activity depended on 1) theamount of nonrespiratory inputs to the cell (cells with morenonrespiratory inputs had greater amounts of residual activity);2) the cell type (expiratory cellshad more residual activity than inspiratory cells); and 3) the state of consciousness (moreresidual activity in wakefulness and rapid-eye-movement sleep than innon-rapid-eye-movement sleep). None of the cells showed an activationduring ventilation that could explain the apnea. Residual activity ofapproximately one-half of the cells was modulated in phase with theventilator. The strength of this modulation was quantified by using aneffect-size statistic and was found to be weak. The patterns ofmodulation did not support the idea that mechanoreceptors excite somerespiratory cells that, in turn, inhibit others. Indeed, most cells,inspiratory and expiratory, discharged during the deflation-inflationtransition of ventilation. Residual activity failed to reveal the causeof apnea but showed that during apnea respiratory neurons act as ifthey were disinhibited and disfacilitated.

     

Severe hypophosphataemia during recovery from acute respiratory acidosis.

Three elderly patients with established chronic obstructive airways disease were admitted with a short history of increasing dyspnoea and tiredness and (in two cases) a deterioration in mental state. Acute respiratory acidosis was diagnosed and mechanical ventilation instituted. Two hours after beginning mechanical ventilation the mean arterial pH had risen to 7.40, but all patients showed a dramatic fall in the serum phosphate concentration (lowest value 0.3 mmol/l (0.9 mg/100 ml] accompanied by a low urinary excretion of phosphate. No patient could tolerate withdrawal of mechanical ventilation until the serum and urinary concentrations of phosphate had returned to normal. Recovery from acute respiratory acidosis should be added to the list of conditions associated with severe hypophosphataemia.     

Descripción de los resultados y costes de una intervención preventiva a nivel respiratorio en el anciano institucionalizado: ensayo controlado aleatorizado

Introduction

The institutionalized elderly with functional impairment show a greater decline in respiratory muscle (RM) function. The aims of the study are to evaluate outcomes and costs of RM training using Pranayama in institutionalized elderly people with functional impairment.

Material and methods

A randomized controlled trial was conducted on institutionalized elderly people with walking limitation (n = 54). The intervention consisted of 6 weeks of Pranayama RM training (5 times/week). The outcomes were measured at 4 time points, and were related to RM function: the maximum respiratory pressures and the maximum voluntary ventilation. Perceived satisfaction in the experimental group (EG) was assessed by means of an ad hoc questionnaire. Direct and indirect costs were estimated from the social perspective.

Results

The GE showed a significant improvement related with strength (maximum respiratory pressures) and endurance (maximum voluntary ventilation) of RM. Moreover, 92% of the EG reported a high satisfaction. The total social costs, direct and indirect, amounted to €21,678.

Conclusions

This evaluation reveals that RM function improvement is significant, that intervention is well tolerated and appreciated by patients, and the intervention costs are moderate.     

腹式呼吸训练法对COPD伴Ⅱ型呼吸衰竭患者肺通气状态、血气指标及运动耐力的影响

摘要 目的：探讨腹式呼吸训练法对慢性阻塞性肺疾病（COPD）伴Ⅱ型呼吸衰竭患者肺通气状态、血气指标及运动耐力的影响。方法：选择我院2020年07月2022年12月期间收治的100例COPD伴Ⅱ型呼吸衰竭患者,根据随机数字表法将患者分为对照组[常规治疗基础上接受双水平气道正压（BIPAP）辅助通气,n=50]和研究组（对照组的基础上接受腹式呼吸训练法干预,n=50）。对比两组临床相关指标、肺通气状态、血气指标及运动耐力指标。结果：研究组的喘憋消失时间、体温恢复正常时间、住院时间、肺部啰音消失时间短于对照组（P<0.05）。两组干预1周后第1秒呼气的最大容积（FEV₁）、最大自主分钟通气量（MVV）、用力肺活量（FVC）均升高,且研究组高于对照组（P<0.05）。两组干预1周后氧分压（PaO2₂）、血氧饱和度（SpO₂）均升高,且研究组高于对照组;二氧化碳分压（PaCO₂）下降,且研究组低于对照组（P<0.05）。两组干预1周后6 min步行距离（6MWT）升高,且研究组高于对照组（P<0.05）。结论：腹式呼吸训练法有助于改善COPD伴Ⅱ型呼吸衰竭患者的临床症状,调节肺通气状态、血气指标,提高运动耐力。     

The effect of head-down hypokinesia on functional state of diaphragm in rats

The effects of long-term (21 days) head-down (-30 degrees) hypokinesia (HDH) on respiratory system and a functional state of diaphragm were investigated in rats. Minute ventilation, oesophageal and abdominal pressure, integrated electrical activity of diaphragm were measured in control and experimental group (after 21 days of HDH) of animals. The measurements were made in several body positions atresting and in occlusion breathing. The results indicate that HDH causes reduction in minute ventilation of lungs, decrease in orthostatic stability and functional reserve of the respiratory system capacity. It was established that the basic mechanism of HDH respiratory effects is contractile failure of diaphragm related to damage in excitation-contraction coupling in its muscular fibres.     

Rib cage deformities alter respiratory muscle action and chest wall function in patients with severe osteogenesis imperfecta

Background

Osteogenesis imperfecta (OI) is an inherited connective tissue disorder characterized by bone fragility, multiple fractures and significant chest wall deformities. Cardiopulmonary insufficiency is the leading cause of death in these patients.

Methods

Seven patients with severe OI type III, 15 with moderate OI type IV and 26 healthy subjects were studied. In addition to standard spirometry, rib cage geometry, breathing pattern and regional chest wall volume changes at rest in seated and supine position were assessed by opto-electronic plethysmography to investigate if structural modifications of the rib cage in OI have consequences on ventilatory pattern. One-way or two-way analysis of variance was performed to compare the results between the three groups and the two postures.

Results

Both OI type III and IV patients showed reduced FVC and FEV₁ compared to predicted values, on condition that updated reference equations are considered. In both positions, ventilation was lower in OI patients than control because of lower tidal volume (p<0.01). In contrast to OI type IV patients, whose chest wall geometry and function was normal, OI type III patients were characterized by reduced (p<0.01) angle at the sternum (pectus carinatum), paradoxical inspiratory inward motion of the pulmonary rib cage, significant thoraco-abdominal asynchronies and rib cage distortions in supine position (p<0.001).

Conclusions

In conclusion, the restrictive respiratory pattern of Osteogenesis Imperfecta is closely related to the severity of the disease and to the sternal deformities. Pectus carinatum characterizes OI type III patients and alters respiratory muscles coordination, leading to chest wall and rib cage distortions and an inefficient ventilator pattern. OI type IV is characterized by lower alterations in the respiratory function. These findings suggest that functional assessment and treatment of OI should be differentiated in these two forms of the disease.     

AECOPD并重度呼吸衰竭患者有创机械通气的治疗时机探讨及其预后的影响因素分析

摘要 目的：探讨慢性阻塞性肺疾病急性加重（AECOPD）合并重度呼吸衰竭患者有创机械通气的治疗时机,并分析其预后的影响因素。方法：选取2020年3月~2021年12月期间于首都医科大学附属北京世纪坛医院治疗的161例AECOPD合并重度呼吸衰竭患者,按照气管插管时间分为早期组（n=89）和延期组（n=72）,对比两组治疗后临床指标、血气分析指标及28 d内病死率（预后）。根据预后的不同将患者分为死亡组（n=29）和存活组（n=132）,收集患者的一般资料和实验室资料,采用Logistic回归分析预后的影响因素。结果：早期组的总机械通气时间、有创通气时间、重症监护室（ICU）住院时间均短于延期组（P<0.05）。两组治疗后动脉血二氧化碳分压（PaCO₂）较治疗前下降,氧合指数（OI）、动脉血氧分压（PaO₂）较治疗前升高,且早期组变化程度大于延期组（P<0.05）。延期组28 d内病死率为15/72（20.83%）。早期组28 d内病死率为14/89（15.73%）,两组患者的28 d病死率对比无差异（P>0.05）。单因素分析结果显示,AECOPD合并重度呼吸衰竭患者的预后影响因素与并发呼吸机相关肺炎、并发多脏器功能不全综合征、年龄、PaCO₂、血红蛋白（Hb）、血尿素氮（BUN）、白细胞计数（WBC）、pH值、中性粒细胞计数/淋巴细胞计数比值（NLR）、血小板计数/淋巴细胞计数（PLR）、C反应蛋白（CRP）、D-二聚体（D-D）、B型尿钠肽有关（P<0.05）。AECOPD合并重度呼吸衰竭患者预后不良的危险因素主要有并发呼吸机相关肺炎、并发多脏器功能不全综合征、PaCO₂偏高、年龄偏大、Hb偏低、pH值偏低、D-D偏高（P<0.05）。结论：AECOPD合并重度呼吸衰竭患者早期使用有创机械通气,可有效改善血气分析,缩短有创通气时间、总机械通气时间、ICU住院时间。并发呼吸机相关肺炎、并发多脏器功能不全综合征、PaCO₂偏高、年龄偏大、Hb偏低、pH值偏低、D-D偏高均是导致AECOPD合并重度呼吸衰竭患者预后不良的危险因素。     

Regional Lung Function in Patients with Obstructive Lung Diseases

Regional lung function was measured, using radioactive xenon-133, in a group of normal subjects and in three carefully defined groups of patients with obstructive lung disease. When compared with the normal subjects, patients in the emphysematous group showed a relative reduction of ventilation and perfusion to the upper zones, while patients having chronic bronchitis without cardiac or respiratory failure showed a predominantly lower zone defect. In the group of patients with chronic bronchitis with cardiac and respiratory failure no consistent pattern was found.     

Effects of Adaptive Support Ventilation and Synchronized Intermittent Mandatory Ventilation on Peripheral Circulation and Blood Gas Markers of COPD Patients with Respiratory Failure

The objective of the study was to investigate the effects of adaptive support ventilation (ASV) and synchronized intermittent mandatory ventilation (SIMV) on peripheral circulation of chronic obstructive pulmonary disease (COPD) patients with respiratory failure. 86 COPD patients with respiratory failure were recruited in this study. Self-control method was used to compare the effect of ASV and SIMV on the parameters of ventilation machine, heart rate, blood pressure, central venous pressure (CVP), and blood gas markers. When the patients in ASV and SIMV groups were compared, respiratory rate, tidal volume, and peak airway pressure (PIP) showed significant difference. When minute ventilation (MV) was compared, no significant difference was shown. When peripheral circulation parameters were compared, peripheral circulation heart rate, SBP, DBP, and CVP showed significant difference. Compared with SIMV group, PaO₂, pH, and SaO₂ values were remarkably increased (P < 0.01) while no significant difference was found for partial pressure of carbon dioxide (pCO₂) when two groups were compared. In conclusion, when mechanical ventilation was used in COPD patients with respiratory failure, ASV can significantly improve clinical outcomes.     

Noninvasive positive-pressure ventilation in acute respiratory failure

Noninvasive positive-pressure ventilation is a type of mechanical ventilation that does not require an artificial airway. Studies published in the 1990s that evaluated the efficacy of this technique for the treatment of diseases as chronic obstructive pulmonary disease, congestive heart failure and acute respiratory failure have generalized its use in recent years. Important issues include the selection of the ventilation interface and the type of ventilator. Currently available interfaces include nasal, oronasal and facial masks, mouthpieces and helmets. Comparisons of the available interfaces have not shown one to be clearly superior. Both critical care ventilators and portable ventilators can be used for noninvasive positive-pressure ventilation; however, the choice of ventilator type depends on the patient''s condition and therapeutic requirements and on the expertise of the attending staff and the location of care. The best results (decreased need for intubation and decreased mortality) have been reported among patients with exacerbations of chronic obstructive pulmonary disease and cardiogenic pulmonary edema.Noninvasive positive-pressure ventilation is the delivery of mechanical ventilation to patients with respiratory failure without the requirement of an artificial airway. The key change that led to the recent increase in the use of this technique occurred in the early 1980s with the introduction of the nasal continuous positive airway pressure mask for the treatment of obstructive sleep apnea. Studies published in the 1990s that evaluated the efficacy of noninvasive positive-pressure ventilation for treatment of diseases such as chronic obstructive pulmonary disease, congestive heart failure and acute respiratory failure have generalized its use in recent years.¹ In 1998, an international study on the use of mechanical ventilation found that 5% of patients admitted to intensive care units received noninvasive positive-pressure ventilation.²Noninvasive positive-pressure ventilation includes various techniques for augmenting alveolar ventilation without an endotracheal airway. The clinical application of noninvasive ventilation by use of continuous positive airway pressure alone is referred to as “mask CPAP,” and noninvasive ventilation by use of intermittent positive-pressure ventilation with or without continuous positive airway pressure is called noninvasive positive-pressure ventilation.     

呼吸道感染患者多重耐药菌肺炎克雷伯菌的耐药及危险因素分析

摘要 目的：探讨与分析呼吸道感染患者多重耐药菌肺炎克雷伯菌的耐药及危险因素。方法：选择2015年1月到2020年2月本院诊治的呼吸道感染患者65例作为研究对象,收集患者的临床样本进行细菌分离与耐药分析,调查患者的临床资料并进行危险因素分析。结果：在呼吸道感染患者65例中,分离出多重耐药菌肺炎克雷伯菌32株,占比49.2 %,其中下呼吸道、上呼吸道、灌洗液、血液标本分别占50.0 %、9.4 %、25.0 %、6.3 %。32株多重耐药菌肺炎克雷伯菌对头孢曲松、头孢呋辛、氨苄西林、头孢吡肟、头孢噻肟的耐药率分别为71.9 %、87.5 %、96.9 %、84.4 %、81.3 %,对阿米卡星、头孢替坦、左氧氟沙星、亚胺培南、环丙沙星的敏感率分别为59.4 %、68.8 %、81.3 %、75.0 %、81.3 %。非条件 Logistic回归分析显示血型A型、碳青霉烯类抗菌药物使用、引流、机械通气、糖尿病等为导致多重耐药菌肺炎克雷伯菌感染的独立危险因素(P<0.05)。结论：多重耐药菌肺炎克雷伯菌感染在呼吸道感染患者中比较常见,对头孢呋辛、氨苄西林的耐药率比较高,对左氧氟沙星、环丙沙星的敏感率比较高,血型A型、碳青霉烯类抗菌药物使用、引流、机械通气、糖尿病等为导致多重耐药菌肺炎克雷伯菌感染的独立危险因素。     

Characterizing spatial-temporal patterns of landscape disturbance and recovery in western Alberta,Canada using a functional data analysis approach and remotely sensed data

Landscape regionalization approaches are frequently used to summarize and visualize complex spatial patterns, environmental factors, and disturbance regimes. However, landscapes are dynamic and contemporary regionalization approaches based on spatial patterns often do not account for the temporal component that may provide important insight on disturbance, recovery, and how ecological processes change through time. The objective of this research was to quantify spatial patterns of disturbance and recovery over time for use as inputs in a regionalization that characterizes unique spatial-temporal trajectories of disturbance in western Alberta, Canada. Cumulative spatial patterns of disturbance, representing the proportion, arrangement, size, and number of disturbances, and adjusted annually for spectral recovery, were quantified in 223 watersheds using a Landsat time series dataset where disturbance events are detected and classified annually from 1985 to 2011. Using a functional data analysis approach, disturbance patterns metrics were modelled as curves and scores from a functional principal components analysis were clustered using a Gaussian finite mixture model. The resulting eight watershed clusters were mapped with mean curves representing the temporal trajectory of disturbance. The cumulative mean disturbance pattern metric curves for each cluster showed considerable variability in curve amplitude which generally increased markedly in the mid-1990's, while curve amplitude remained low in parks and protected areas. A comparison of mean curves by disturbance type (e.g., fires, harvest, non-stand replacing, roads, and well-sites) using a functional analysis of variance showed that anthropogenic disturbance contributed substantially to curve amplitude in all clusters, while curve amplitude associated with natural disturbances was generally low. These differences enable insights regarding how cumulative spatial disturbance patterns evolve through time on the landscape as a function of the type of disturbance and rates of recovery.     

Respiratory insufficiency in patients with myasthenia gravis

We evaluated 20 patients who required prolonged mechanical ventilation for respiratory failure associated with myasthenia gravis. All 20 patients survived and were weaned from the ventilator after 3 to 14 days (mean 6.5 days) of respiratory support. Progressing bulbar symptoms and respiratory infection were the most frequent causes of the myasthenic crisis. During a period of assisted mechanical ventilation, anticholinesterase medication was interrupted and the patients were treated with steroids and antibiotics. Plasmapheresis may be considered in the management of myasthenic crisis.     

Lung Volume,Breathing Pattern and Ventilation Inhomogeneity in Preterm and Term Infants

Background

Morphological changes in preterm infants with bronchopulmonary dysplasia (BPD) have functional consequences on lung volume, ventilation inhomogeneity and respiratory mechanics. Although some studies have shown lower lung volumes and increased ventilation inhomogeneity in BPD infants, conflicting results exist possibly due to differences in sedation and measurement techniques.

Methodology/Principal Findings

We studied 127 infants with BPD, 58 preterm infants without BPD and 239 healthy term-born infants, at a matched post-conceptional age of 44 weeks during quiet natural sleep according to ATS/ERS standards. Lung function parameters measured were functional residual capacity (FRC) and ventilation inhomogeneity by multiple breath washout as well as tidal breathing parameters. Preterm infants with BPD had only marginally lower FRC (21.4 mL/kg) than preterm infants without BPD (23.4 mL/kg) and term-born infants (22.6 mL/kg), though there was no trend with disease severity. They also showed higher respiratory rates and lower ratios of time to peak expiratory flow and expiratory time (t _PTEF/t _E) than healthy preterm and term controls. These changes were related to disease severity. No differences were found for ventilation inhomogeneity.

Conclusions

Our results suggest that preterm infants with BPD have a high capacity to maintain functional lung volume during natural sleep. The alterations in breathing pattern with disease severity may reflect presence of adaptive mechanisms to cope with the disease process.