The thorax in chronic obstructive lung disease

Sharp, John T.; Lith, P Van; Nuchprayoon, Chai vej; Briney, Robert; Johnson, F

doi:10.1016/0002-9343(68)90235-0

Cited by 97 publications

(42 citation statements)

References 5 publications

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“…Hyperinflation is accompanied by a reduced mechanical advantage of the inspiratory muscles and, consequently, maximum static inspiratory pressure (PI,max) measured at RV or FRC is often less (strictly less negative) than in normal subjects at the same "relative" lung volumes, as originally reported by SHARP et al [17]. However, BYRD and HYATT [18] showed that, in many patients with COPD, PI,max was actually greater (more negative) than would have been expected for the "absolute" lung volume (FRC) at which the measurements were made.…”

Section: Respiratory Muscle Functionmentioning

confidence: 62%

Pulmonary hyperinflation a clinical overview

Gibson

1996

Eur Respir J

106

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P Pu ul lm mo on na ar ry y h hy yp pe er ri in nf fl la at ti io on n a a c cl li in ni ic ca al l o ov ve er rv vi ie ew w G.J. GibsonPulmonary hyperinflation a clinical overview. G.J. Gibson. ERS Journals Ltd 1996. ABSTRACT: Pulmonary hyperinflation is usually defined as an abnormal increase in functional residual capacity, i.e. lung volume at the end of tidal expiration. As such, it is virtually universal in patients with symptomatic diffuse airway obstruction. Hyperinflation inferred from a standard chest radiograph implies an increase in total lung capacity.The relaxation volume of the respiratory system (Vr) increases in patients with chronic airway disease as a result of changes in the elastic properties of the lungs and chest wall. In addition, a variable degree of dynamic hyperinflation may be present. This results from the onset of inspiration before lung volume has fallen to Vr. Dynamic hyperinflation is frequently present at rest in patients with moderate-to-severe airway obstruction, and it increases further on exercise, thereby increasing the mechanical load on the inspiratory muscles and at the same time reducing their mechanical advantage.Important clinical consequences and associations of hyperinflation include: distortions of chest wall motion; impaired inspiratory muscle function; increased oxygen cost of breathing; greater likelihood of hypercapnia; impaired exercise performance; and greater severity of breathlessness. The symptomatic improvement after treatment with a bronchodilator may be due, in part, to lessening of hyperinflation.

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Section: Respiratory Muscle Functionmentioning

confidence: 62%

Pulmonary hyperinflation a clinical overview

Gibson

1996

Eur Respir J

106

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“…Thoracic hyperinflation in patients with COPD can be detected by physical examination. Recognised clinical features of severe hyperinflation include the inward motion of the lower lateral ribcage during inspiration, as originally described by STOKES [20], and paradoxical inward motion of the anterior abdominal wall in synchrony with inspiratory flow [21,22]. Hyperinflation in its earlier stages is often underestimated, even after assiduous clinical assessment.…”

Section: Detection Measurement and Definitions Of Lung Hyperinflationmentioning

confidence: 99%

Physiology and consequences of lung hyperinflation in COPD

O’Donnell¹,

Laveneziana²

2006

European Respiratory Review

168

149

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Lung hyperinflation commonly accompanies expiratory flow limitation in patients with chronic obstructive pulmonary disease (COPD) and contributes importantly to morbidity and an impoverished quality of life. It is not surprising, therefore, that lung hyperinflation has become an important therapeutic target in symptomatic COPD patients. Acute dynamic increases in lung hyperinflation under conditions of worsening expiratory flow limitation and increased ventilatory demand (or both) can seriously stress cardiopulmonary reserves in patients with more advanced disease. The present understanding of the physiological mechanisms of dynamic hyperinflation during exacerbations of COPD and during physical activity continues to grow, together with an appreciation of its negative mechanical and sensory consequences. In this brief overview, definitions and measurement of lung hyperinflation during rest and exercise will be discussed and its potential clinical importance will be considered. The focus will mainly be on current concepts of the mechanisms of air trapping and its role in inducing respiratory discomfort and activity limitation in COPD.

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“…EV represents the overinflation above its relaxation volume of the part of the lungs participating in tidal ventilation. Therefore, it does not include the increase in the actual relaxation volume seen in emphysema due to a loss of lung recoil and in long-standing airflow obstruction due to a loss of chest wall recoil [11,27]. Nor does it include the volume of gas trapped behind airways closed in the tidal range.…”

Section: Disscussionmentioning

confidence: 99%

Analysis of expiratory tidal flow patterns as a diagnostic tool in airflow obstruction

Morris

Madgwick²,

Collyer³

et al. 1998

Eur Respir J

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In 1981, we made the observation that tidal flow versus time has a distinctive pattern in patients with airflow obstruction that is different from the sinusoidal appearance seen in normal subjects. To quantify this difference, we described timing indices derived from the analysis of tidal expiratory flow [1]. These indices, volume expired when the peak tidal expiratory flow reached (VPTEF)/tidal volume (VT) and (time to peak expiratory tidal flow (tPTEF)/ expiratory time (tE) closely correlated with each other and correlated significantly with other indices of airflow obstruction [1]. The index tPTEF/tE, has been demonstrated to be useful in predicting wheezy illness in the new-born [2], in discriminating between asthmatic and nonasthmatic children [3][4][5] and between healthy control subjects and children with cystic fibrosis [5] and showing response to histamine [5,6], methacholine [7] and bronchodilator [3][4][5] in asthmatic children, though recently has not been found to be useful in the diagnosis of narrowed airways in infants [8][9][10].In our original description of the typical flow time pattern of tidal expiration in patients with airflow obstruction, we described three parts to the curve: 1) a rapid rise to maximum flow; 2) a slow decline in flow over most of expiration, followed by; 3) an abrupt fall of flow to zero as the next inspiration is triggered while there is still a measurable expiratory flow. In contrast, in normal subjects, expiratory flow rises more slowly to a maximum, and then decreases gradually to zero, resulting in a smoother appearance of the tidal expiratory flow-time curve.The index tPTEF/tE uses only information from the first part of the expiratory flow-time curve, based on a single point. We have described two further indices [11,12] in an attempt to use the information contained in the period of declining expiratory flow after the maximum flow has been reached (figs. 1 and 2). These indices are: 1) the time constant of the respiratory system (Trs); and 2) extrapolated volume (EV) (the volume of dynamic overinflation), i.e. the extra volume that would have been expired if expiration had continued to the elastic equilibrium volume.The theoretical basis of this analysis is that if expiration is relaxed the decay of flow against time reflects the compliance and resistance of the respiratory system. OTIS et al.[13] described a simple model of the respiratory system consisting of a single compartment of constant elastance served by a pathway of constant resistance. When, in this model, expiratory flow is driven by the relaxation pressures of the lung and chest wall, there is a linear volumeflow relationship. This slope is the time constant of relaxed expiration and by analogy with an electrical model Trs is equal to resistance×compliance of the total respiratory system (lungs+ chest wall). COMROE et al. [14] suggested that volume-flow curves of passive expiration could be used to assess the mechanical properties of the lung and chest wall.In patients with airflow obstruction, there ...

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The thorax in chronic obstructive lung disease

Cited by 97 publications

References 5 publications

Pulmonary hyperinflation a clinical overview

Pulmonary hyperinflation a clinical overview

Physiology and consequences of lung hyperinflation in COPD

Analysis of expiratory tidal flow patterns as a diagnostic tool in airflow obstruction

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