C.P.M. van der Grinten

Standardisation of spirometry

[⇓][1] SERIES “ATS/ERS TASK FORCE: STANDARDISATION OF LUNG FUNCTION TESTING” Edited by V. Brusasco, R. Crapo and G. Viegi Number 2 in this Series [1]: #F13

Standardisation of the measurement of lung volumes

[⇓][1] SERIES “ATS/ERS TASK FORCE: STANDARDISATION OF LUNG FUNCTION TESTING” Edited by V. Brusasco, R. Crapo and G. Viegi Number 3 in this Series [1]: #F7

General considerations for lung function testing.

SERIES “ATS/ERS TASK FORCE: STANDARDISATION OF LUNG FUNCTION TESTING” Edited by V. Brusasco, R. Crapo and G. Viegi Number 1 in this Series ⇓In preparing the joint statements on lung function testing for the American Thoracic Society (ATS) and the European Respiratory Society (ERS), it was agreed by the working party that the format of the statements should be modified so that they were easier to use by both technical and clinical staff. This statement contains details about procedures that are common for many methods of lung function testing and, hence, are presented on their own. A list of abbreviations used in all the documents is also included as part of this statement. All terms and abbreviations used here are based on a report of the American College of Chest Physicians/ATS Joint Committee on Pulmonary Nomenclature 1. The metrology definitions agreed by the International Standards Organization (ISO) are recommended 2 and some important terms are defined as follows. Accuracy is the closeness of agreement between the result of a measurement and the conventional true value. Repeatability is the closeness of agreement between the results of successive measurements of the same item carried out, subject to all of the following conditions: same method, same observer, same instrument, same location, same condition of use, and repeated over a short space of time. In previous documents, the term reproducibility was used in this context, and this represents a change towards bringing this document in line with the ISO. Reproducibility is the closeness of agreement of the results of successive measurements of the same item where the individual measurements are carried out with changed conditions, such as: method of measurement, observer, instrument, location, conditions of use, and time. Thus, if a technician tests a subject several times, this is looking at the …

Definition of COPD: based on evidence or opinion?

To the Editors: In 1986, the American Thoracic Society (ATS) first suggested a fixed ratio of forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) <0.75 to define airflow obstruction 1. Subsequent ATS documents published in 1991 2 and 1995 3 generically defined airflow obstruction as a reduction of FEV1/FVC, without recommending any numerical cut-off point. By contrast, the European Respiratory Society (ERS) guidelines 4 suggested the diagnosis of airflow obstruction be based on a ratio of FEV1 to slow vital capacity (VC) <88 and <89% of predicted in males and females, respectively. These values were not arbitrarily chosen as they roughly correspond to the lower 95th percentiles of frequency distributions of a healthy population. More importantly, they are consistent with the well-known decrease of lung elastic recoil and, by inference, of forced expiratory flow with ageing. In 2001, the Global Initiative for …

Time to peak tidal expiratory flow and the neuromuscular control of expiration

The ratio of the time needed to reach peak tidal expiratory flow (tPTEF) and the duration of expiration (tE) is used to detect airflow obstruction in young children. tPTEF is decreased in patients with asthma, but knowledge about the physiological determinants of this parameter is scarce. This study examined the relationship between tPTEF and postinspiratory activities of inspiratory muscles and evaluated the effects of changing sensory information from the lung. Airflow patterns and electromyographic (EMG) activity of inspiratory muscles were recorded in seven spontaneously breathing, anaesthetized cats. The trachea was cannulated and, as a result, the larynx and upper airways were bypassed. Changes in postinspiratory muscle activity were induced by changing afferent sensory nerve information (by cooling the vagus nerves, by administration of histamine and by additional application of continuous positive airway pressure (CPAP)). Durations of postinspiratory activities of the diaphragm and intercostal muscles (characterized by their time constants tau diaphr and tau interc) correlated strongly with tPTEF (r=0.85 and 0.77, respectively). Tau diaphr, tau interc and tPTEF were significantly increased during cooling of the vagus nerves (4-8 degrees C) compared with values at 22 and 37 degrees C (p<0.05). Conversely, administration of histamine and CPAP caused significant decreases in tau diaphr, tau interc and tPTEF, which were absent during cooling of the vagus nerves. In conclusion, the time needed to reach peak tidal expiratory flow is highly influenced by the activities of inspiratory muscles during the early phase of expiration which, in turn, depend on the activities of vagal receptors in the lung.

Standardisation of lung function testing: the authors' replies to readers' comments.

To the Editors: A few questions have been raised following the publication in 2005 of the joint American Thoracic Society (ATS)/European Respiratory Society (ERS) series of documents on standardising lung function testing and these are answered below. The following questions and answers pertain to the standardisation document for spirometry 1. ### Start of test criteria Should blows be rejected solely on the basis of a poor back extrapolated volume (EV)? #### Reply Usually. The forced vital capacity (FVC) may be usable, but the forced expiratory volume in 1 s (FEV1) is likely to be falsely high or low. #### Rationale The acceptability criteria for spirometry were designed to help technologists improve the subject’s technique in order to get the best and most reliable result. EV is important for determining that a fast start to the blow was achieved and this is crucial for getting the best values for FEV1 and peak expiratory flow (PEF). ### End of test criteria In the original document, there was an error in table 5. #### Reply In table 5, the within-manoeuvre criteria for a satisfactory completion of a blow should have read “Duration of ≥6 s (3 s for children) and a plateau in the volume–time curve, or if the subject cannot or should not continue to exhale.” The original table had “or” in twice, whereas the accompanying text was correct, as above. #### Rationale The end of test (EOT) criteria are applied in order to ensure that efforts are made to achieve the best estimate of FVC. When a subject cannot meet the plateau criterion (<25 mL exhaled in the previous second of the blow) this may be for reasons other than premature volitional cessation of the blow. For example, in some young subjects or patients with a rigid chest wall, it is chest wall limitation that suddenly causes exhalation to stop 2 and it is difficult for …

Fatigue Associated with Obstructive Sleep Apnea in a Patient with Sarcoidosis

Many patients with sarcoidosis suffer from persistent constitutional symptoms such as fatigue and general weakness, even though physiological measures of disease activity returned within normal limits. The following case report demonstrates a sarcoidosis patient with recurring fatigue caused by an obstructive sleep apnea syndrome developed during the course of the disease.

Tonic activity in inspiratory muscles during continuous negative airway pressure

We studied tonic inspiratory activity (TIA) induced by continuous negative airway pressure (CNAP) in anaesthetized, spontaneously breathing cats. TIA in the diaphragm and parasternal intercostal muscles (ICM) was quantified in response to tracheal pressure (PTR) = -0.3 to -1.2 kPa. To differentiate between reflexes from rapidly adapting receptors (RARs), slowly adapting receptors (SARs) and C-fiber endings different temperatures of the vagus nerves (TVG) were used between 4 and 37 degrees C. At PTR = -1.2 kPa mean TIA values were 41% and 62% of peak inspiratory EMG activity of control breaths for the diaphragm and ICM, respectively. After vagotomy and for TVG < 6 degrees C CNAP did not induce TIA anymore. Changes in inspiratory and expiratory time during vagal cooling down to 4 degrees C confirmed the selective block of conductance in vagal afferents of the three types of lung receptors. We conclude that CNAP-induced TIA results from stimulation of RARs. Our data strongly indicate that stimulation of SARs suppresses TIA, whereas C-fiber endings are not involved in TIA at all. The results suggest that part of the hyperinflation in bronchial asthma may be caused by TIA in response to mechanical stimulation of RARs.

Histamine induced bronchoconstriction and end tidal inspiratory activity in man.

BACKGROUND: End tidal inspiratory activity (ETIA) in diaphragm and parasternal intercostal muscles can be evoked in man and in animals by administration of histamine. Exacerbations of asthma and administration of histamine are often accompanied by hyperinflation. The aims of the study were to determine (1) the magnitude of ETIA in response to histamine in man, (2) the relative contributions of chemical and mechanical stimulation of airway receptors to ETIA, and (3) the importance of ETIA to hyperinflation. METHODS: The effects of inhalation of histamine on the electrical activities of the diaphragm and parasternal intercostal muscles measured with surface electrodes were studied in 21 subjects. The experiments were repeated after inhalation of 600 micrograms of salbutamol to prevent histamine induced bronchoconstriction and concomitant mechanical stimulation of airway receptors. Subjects were connected to a closed breathing circuit to measure the changes in functional residual capacity (FRC) for the different experiments. RESULTS: The mean values of histamine induced ETIA were 60.6% and 46.9% of peak inspiratory activities during control conditions for the diaphragm and intercostal muscles, respectively. After salbutamol histamine induced ETIA was reduced to about one quarter of pre-salbutamol values. FRC increased by 427 ml as a result of inhalation of histamine, but after salbutamol this increase was only 53 ml. The data for ETIA and FRC were interpreted as indicating that the contributions of airflow limitation and ETIA to histamine induced hyperinflation are comparable. CONCLUSIONS: Histamine is a forceful stimulus for inducing ETIA. Both chemical and mechanical stimulation of airway receptors contribute to evoke ETIA, of which the contribution of mechanical stimulation is the more important one. ETIA contributes substantially to histamine induced hyperinflation.

Standardisation de la mesure des volumes pulmonaires

Definitions et subdivisions du volume pulmonaire 17S48 Preparation du patient 17S49 Determination des subdivisions pulmonaires ........ 17S49 Mesure de la CRF par plethysmographie corporelle 17S50 Introduction et theorie 17S50 Materiel 17S50 Technique de mesure 17S50 Controle qualite 17S51 Calculs 17S52 Mesure de la CRF par rincage de l’azote 17S52 Introduction et theorie 17S52 Materiel 17S52 Technique de mesure 17S53 Controle qualite 17S53 Calculs 17S54 Mesure de la Crf par dilution de l’helium 17S54 Introduction et theorie 17S54 Materiel 17S54 Technique de mesure 17S55 Controle qualite 17S56 Calculs 17S56 Mesure des volumes pulmonaires par des techniques d’imagerie 17S56 Radiographies conventionnelles 17S57 Tomodensitometrie 17S57 Imagerie par resonance magnetique 17S57 Controverses et questions critiques 17S57 Valeurs de reference 17S58 Prevention des infections 17S58 Abreviations 17S58