Effect of gas compression on pulmonary pressure, flow, and volume relationship

Ingram, R. H.; Schilder, Donald P.

doi:10.1152/jappl.1966.21.6.1821

Cited by 117 publications

(88 citation statements)

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“…4), 10 patients would be classified as FL (nos. 2,5,6,9,12,15,16,18,20,22). Their FEV1 and IC ranged, respectively, from 16-81 and 33-99% pred normal.…”

Section: Expiratory Flow Limitationmentioning

confidence: 96%

“…In this case, volume was measured with the body plethysmograph to avoid errors due to thoracic gas compression [18]. The experimental set-up used to assess FL by NEP (Raytech Instruments, Vancouver, Canada) has been previously described in detail [2].…”

Section: Expiratory Flow Limitationmentioning

confidence: 99%

“…Volume was measured with the body plethysmograph to avoid artifacts due to thoracic gas compression [18]. With this method, defined as the conventional method, patients in whom, at comparable lung volume, flows during tidal expiration were similar to or higher than those obtained during the FVC manoeuvre were considered as FL.…”

Section: Procedures and Data Analysismentioning

confidence: 99%

“…Only three of these patients, all with type 3 pattern, were found to be FL with the NEP method (nos. 15,16,18).…”

Section: Expiratory Flow Limitationmentioning

confidence: 99%

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Tidal expiratory flow limitation and chronic dyspnoea in patients with cystic fibrosis

Goetghebeur

Sarni²,

Grossi³

et al. 2002

European Respiratory Journal

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Cystic fibrosis (CF) eventually leads to hyperinflation linked to tidal expiratory flow limitation (FL) and ventilatory failure.Presence of FL was assessed at rest in 22 seated children and adults with CF (forced expiratory volume in one second (FEV1) range: 16-92% predicted), using both the negative expiratory pressure (NEP) technique and the "conventional" method based on comparison of tidal and maximal expiratory flow/volume curves. In addition, chronic dyspnoea was scored with the modified Medical Research Council (MRC) scale. Measurements were made before and 15 min after inhalation of salbutamol.With NEP, FL was present in only three malnourished patients, who had the lowest FEV1 values (16-27% pred) and claimed very severe dyspnoea (MRC score 5). By contrast, an additional seven patients were classified as FL with the conventional method. Six of these patients had little or no dyspnoea (MRC scores 0-1). Salbutamol administration had no effect on the extent of FL, and the concomitant decrease in functional residual capacity (FRC) was too small to play any clinically significant role.This study concluded that in seated patients with cystic fibrosis, expiratory flow limitation is absent at rest, unless the forced expiratory volume in one second is v30% predicted. If present, expiratory flow limitation is associated with severe chronic dyspnoea. The conventional method for assessing expiratory flow limitation is not reliable and bronchodilator administration has little effect on expiratory flow limitation.

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“…4), 10 patients would be classified as FL (nos. 2,5,6,9,12,15,16,18,20,22). Their FEV1 and IC ranged, respectively, from 16-81 and 33-99% pred normal.…”

Section: Expiratory Flow Limitationmentioning

confidence: 96%

Section: Expiratory Flow Limitationmentioning

confidence: 99%

Section: Procedures and Data Analysismentioning

confidence: 99%

“…Only three of these patients, all with type 3 pattern, were found to be FL with the NEP method (nos. 15,16,18).…”

Section: Expiratory Flow Limitationmentioning

confidence: 99%

See 2 more Smart Citations

Tidal expiratory flow limitation and chronic dyspnoea in patients with cystic fibrosis

Goetghebeur

Sarni²,

Grossi³

et al. 2002

European Respiratory Journal

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“…The diagnosis of expiratory flow limitation (EFL) has traditionally been based on the comparison of tidal and maximal flow/volume curves [7,8].…”

mentioning

confidence: 99%

Expiratory flow limitation and obstruction in the elderly

Bisschop

Marty²,

Tessier³

et al. 2005

European Respiratory Journal

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Elderly people commonly suffer from dyspnoea, which may stem from expiratory flow limitation (EFL). The relationship between EFL, as assessed by the negative expiratory pressure method and spirometric indices, was investigated in an elderly French population. Subjects, aged 66-88 yrs, filled in socio-demographic and standardised questionnaires, which dealt with: medical history, smoking status and respiratory symptoms. EFL measurements and forced expiratory manoeuvres were performed.Validated measurements were obtained in 750 out of 1,318 subjects: 47% were EFL+ (EFL .0), with a higher prevalence in females than in males. EFL and forced expiratory volume in one second (FEV1) were correlated with age. A total of 116, from the 750 subjects, with no medical history and no symptoms, served as a healthy group. The prevalence of EFL+ subjects increased with the grade of dyspnoea and was highest in respiratory and cardiac patients when compared with the healthy subjects. EFL did not correlate with FEV1/forced vital capacity (FVC), the usual index of obstruction. Some elderly subjects (15%) with dyspnoea but with no medical history, mainly females with small FVC and normal FEV1/FVC, had a greater EFL than the healthy subjects.In elderly people, expiratory flow limitation measurements, along with the usual forced expiratory volume in one second/ forced vital capacity ratio, may be of value for the interpretation of dyspnoea.

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Expiratory Flow Limitation

Pedersen

Butler

2011

Comprehensive Physiology

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Expiratory flow limitation occurs when flow ceases to increase with increasing expiratory effort. The equal pressure point concept has been largely successful in providing intuitive understanding of the phenomenon, wherein maximal flows are determined by lung recoil and resistance upstream of the site where bronchial transmural pressure is zero (the EPP). Subsequent work on the fluid dynamical foundations led to the wave-speed theory of flow limitation, where flow is limited at a site when the local gas velocity is equal to speed of propagation of pressure waves. Each is a local theory; full predictions require knowledge of both density-dependent Bernoulli pressure drops and viscosity-dependent pressure losses due to dissipation. The former is dominant at mid to high lung volumes, whereas the latter is more important at low lung volumes as the flow-limiting site moves peripherally. The observation of relative effort independence of the maximal flow versus volume curves is important clinically insofar as such maneuvers, when carefully performed, offer a unique window into the mechanics of the lung itself, with little confounding effects. In particular, the important contributions of lung recoil and airways resistance can often be assessed, with implications and applications to diagnosis and management of pulmonary disease.

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Effect of gas compression on pulmonary pressure, flow, and volume relationship

Cited by 117 publications

References 0 publications

Tidal expiratory flow limitation and chronic dyspnoea in patients with cystic fibrosis

Tidal expiratory flow limitation and chronic dyspnoea in patients with cystic fibrosis

Expiratory flow limitation and obstruction in the elderly

Expiratory Flow Limitation

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