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C Veriter

Publications and source records attributed to C Veriter.

At least 19 recordsLinked to original sources
PubMed1999

Pulmonary gas exchange in life-long nonsmoking patients with diabetes mellitus.

In a companion paper, we have found that the alveolar epithelial basal lamina, endothelial basal lamina and both fused were significantly thicker in 6 autopsied diabetics than in 6 control subjects. The purpose of the present work was to assess whether these lesions have detrimental effects on gas exchange. We investigated 20 life-long nonsmoking subjects: 10 healthy subjects and 10 insulin-dependent diabetics. All of them had one to four diabetic complications of the following organs: kidney, retina, nerves or arteries. Their pulmonary gas exchange and their transfer factor were measured at rest and during two levels of submaximal exercise. Spirometric data, specific airway conductance, transfer factor, transfer coefficient, oxygen consumption and arterial blood gases were normal and almost identical in both groups. In conclusion, the thickening of lung basal laminae has no detrimental effect on pulmonary gas exchange in insulin-dependent diabetics with peripheral complications.

Adult↗
PubMed1999

Influence of gas density on simulated snoring.

According to a recent theoretical model, snoring is related to instability of the upper airway (UA). Factors promoting UA instability include increased gas density. The aim of this study was to test the influence of gas density on simulated snoring production and supraglottic resistance. Supraglottic pressure and flow rate (V') were measured in 10 healthy seated subjects during simulated snoring. Subjects breathed three different gas mixtures: Helium-oxygen, He 79%-O2 21% (He-O2); air; and sulphur hexafluoride-oxygen, F6S 79%-O2 21% (F6S-O2) administered in a random order. Supraglottic resistance (Rsg) was measured on its linear range during quiet breathing and V' was measured at the onset and middle of snoring. Linear Rsg increased and V' conversely decreased with gas density. These data are in agreement with predictions of a mathematical model of the upper airway showing that snoring occurs at lower flow rates when gas density is increased.

Adult↗
PubMed1998

Identification of smokers susceptible to development of chronic airflow limitation: a 13-year follow-up.

BACKGROUND: Cigarette smoking is the cardinal cause of COPD, but only a relatively small percentage of smokers have development of clinically overt disease. OBJECTIVES: To identify high-risk subjects and to assess the prognostic significance of "small airways" tests. SETTING: University teaching hospital. SUBJECTS: Fifty-six smokers and ex-smokers of mean age 62.5 years (SD, 2.7) with a smoking history of 40.6 (18.9) pack-years were studied at the end of a 13-year follow-up period. MEASUREMENTS: Questionnaire and lung function tests, including static and dynamic lung volumes, airway resistance, maximal expiratory flow rates, and small airways tests, such as nitrogen slope of the alveolar plateau (N2 slope) and closing volume. RESULTS: Eighty-two percent of subjects with a normal FEV1/vital capacity (VC) ratio at the start of the study (half of them with abnormal results of small airways tests) still had a normal FEV1/VC ratio 13 years later. In the remainder, all but one had final FEV1/VC values >60%. About 80% of subjects with a decreased FEV1/VC at the start (subjects with airflow obstruction) reached at the end of study lower than predicted FEV1/VC values. Only about 10% of these subjects showed an accelerated loss of FEV1, reaching end FEV1/VC values of <45%. Initial N2 slope predicted about 80% of end FEV1 values. CONCLUSION: Middle-aged smokers are at no evident risk of functional deterioration if their FEV1/VC ratio is normal. This is so even if results of small airways tests are abnormal. A decreased FEV1/VC ratio has no serious implications in itself. Only an associated high N2 slope adds the necessary information to predict a low FEV1. Present data suggest that a subgroup of smokers in their 50s, characterized by a low FEV1/VC ratio and a high N2 slope, are probably the susceptible smokers at high risk for development of COPD.

Airway Obstruction↗
PubMed1998

Validation of cardiac echocardiography for measuring cardiac output to be applied for the multiple inert gas elimination technique.

The multiple inert gas elimination technique (MIGET) is being increasingly used in respiratory physiology and pathophysiology. Six inert gases are given as an intravenous infusion then measured in samples of expired air and mixed arterial and venous blood. This requires right-sided catheterization, a procedure that is sometimes ethically inappropriate. The present article reports a method in which inert gas levels in mixed venous blood were calculated, rather than measured, using Fick's law. Echocardiography was used to measure arterial inert gas levels and cardiac output. The method was validated in 11 men scheduled to undergo coronary bypass surgery. Cardiac output was either calculated based on biometrical (C) data or measured using four different methods in random order, namely Fick's law with oxygen (FiO2) or the inert gases (FiIG) as the tracers, thermodilution (TH), and echocardiography (E). Cardiac output values in L.min-1 (mean +/- SD) were as follows: C, 4.99 +/- 0.39; FiO2, 5.44 +/- 0.86; FiIG, 5.55 +/- 0.92; TH, 5.77 +/- 0.88; and E, 5.53 +/- 0.64. No significant differences were found among the four measured cardiac output values, of which the mean was 5.57 +/- 0.70 L/min, a value that was significantly higher than the calculated value. This difference is probably ascribable to the use of dopamine, dobutamine, or epinephrine in six of the 11 patients. A 1 L/min-1 cardiac output error, in either direction, was found to have a marked influence on the distribution of alveolar perfusion at various VA/Q ratios. Conversely, as expected, ventilation distribution was not influenced by cardiac output. In conclusion, echocardiography provides satisfactory cardiac output estimations using the MIGET except in patients with septal hypertrophy, subaortic membranes, a mitral valve prosthesis, or a mitral valve ring.

Adult↗
PubMed1997

Effect of alveolar volume on the interpretation of single breath DLCO.

Single-breath carbon monoxide diffusing capacity in the whole lung (DLCO) and per unit alveolar volume (DLCO/VA), as expressed in percentage of normal values, gave discordant results when VA of the patients was abnormal. It was hypothesized that normal reference values were inappropriate to interpret data collected in such patients. To substantiate this hypothesis, DLCO and DLCO/VA were measured in four groups: (1) normal volunteers in whom both indices were measured at five different VA; (2) patients with high VA; (3) emphysematous patients; and (4) patients with diffuse interstitial lung diseases (DILD). In normal subjects, DLCO increased and DLCO/VA decreased with VA. In patients with overinflated lungs, the percentage of DLCO was more increased than DLCO/VA. In the emphysematous patients, both indices were equally decreased. In patients with DILD, DLCO was significantly more decreased than DLCO/VA in those suffering from a restrictive pattern. Theoretical values were re-calculated taking into account their true VA and using the relationships observed between DLCO, DLCO/VA and VA. The divergences between DLCO and DLCO/VA were strongly minimized. Therefore, the authors suggest the need to correct theoretical formulas in the presence of a restrictive pattern.

Adult↗
PubMed1996

Airways obstruction, chronic expectoration, and rapid decline of FEV1 in smokers are associated with increased levels of sputum neutrophils.

BACKGROUND: Smoking may cause inflammation of the airways and impairment of lung function. To determine the relationship between the type and degree of airways inflammation and the decline in lung function, leucocytes in the sputum of smokers and ex-smokers were examined. METHODS: Forty six smokers and ex-smokers of median age 64 years (25%; 75% percentiles 62;66) with a smoking history of 40.1 (31.7;53) pack years were studied with lung function tests and a questionnaire at the end of a 15 year follow up period. Sputum was induced by inhalation of hypertonic saline and differential leucocyte counts were performed on cytospin preparations. RESULTS: Adequate sputum samples were obtained in 38 subjects (78%). The ratio of forced expiratory volume in one second (FEV1) to vital capacity (VC) was 67.1 (60; 72)% and the annual decline in FEV1 was 19.4 (12;30) ml/year. Subjects with airways obstruction (FEV1/VC < 63%) had more neutrophils (77 (50;86)%) than those without airways obstruction (60 (43;73)%). The percentage of neutrophils was also significantly greater (77 (62;85)%) in those with chronic expectoration than in those without expectoration (57 (45;75)%. Increased levels of neutrophils in the sputum were correlated with a rapid decline in FEV1 over the 15 year follow up period. CONCLUSIONS: Airways obstruction and chronic expectoration, as well as accelerated decline in lung function, are associated with increased numbers of neutrophils in the sputum of smokers and ex-smokers which suggests that neutrophilic inflammation of the airways may be involved in the pathogenesis of chronic obstructive pulmonary disease.

Cough↗
PubMed1996

Integrin upregulation on sputum neutrophils in smokers with chronic airway obstruction.

To determine the relationship between the expression of leukocyte-specific integrins in the airways and the airway obstruction in smokers, we analyzed hypertonic saline-induced sputum in 33 male subjects, age 64.7 +/- 0.5 yr (mean +/- SEM), with a smoking history of 12 to 94 pack-years, at the end of a 15-yr follow-up study. Average FEV1/VC ratio was 69 +/- 1% at the beginning of the study and 66 +/- 2% at the end of the follow-up period, and annual decline of FEV1 was 20 +/- 3 ml/yr. Fourteen individuals exhibited airway obstruction as assessed by a FEV1/VC ratio lower than 63.3%. Differential leukocyte count was performed on cytospin preparations and the expression of integrin alpha (CD11a, CD11b, CD11c) and beta (CD18) chains was assessed on granulocytes and mononuclear cells by immunocytology. The numbers of neutrophils expressing CD11b and CD18, but not CD11c or CD11a, were increased in the subjects with airway obstruction compared with those without airway obstruction. CD11b- and CD18-positive neutrophils were negatively correlated with FEV1/VC ratio (p < 0.01). No significant correlations were found between CD11a-, CD11b-, CD11c-, CD18-positive mononuclear cells and lung function measurements. In conclusion, our results suggest that leukocyte-specific integrin CD11b/CD18 expressed on sputum polymorphonuclear leukocytes represents a marker for the smokers who develop chronic airway obstruction.

Aged↗
PubMed1996

Tracheal distensibility in cystic fibrosis.

Size and distensibility of large airways have important implications for flow limitation and the efficacy of coughing. From radiological and functional data, some authors have suggested an increased size and distensibility of the trachea in cystic fibrosis (CF). Using computed tomography (CT) we compared size and distensibility of the trachea in 5 cystic fibrosis patients and five age- and height-matched healthy volunteers. Tracheal cross-sectional area was measured 25 mm below the cricoid cartilage. CT recordings were made at functional residual capacity, at 0 and +20 cmH2O mouth pressure. Inductive plethysmography was used to check that during these manoeuvres lung volume did not change and that the glottis remained open. Tracheal cross-sectional area and derived indices of tracheal distensibility were similar in the two groups. This study does not support the concept of an increased size and distensibility of the trachea in cystic fibrosis.

Adult↗
PubMed1996

Expiratory flow limitation during sleep in heavy snorers and obstructive sleep apnoea patients.

Inspiratory flow limitation (FL) during sleep has previously been reported both in obstructive sleep apnoea (OSA) patients and heavy snorers (HS). Recent results from this laboratory have shown the occurrence both of inspiratory and expiratory flow limitation during muscular relaxation in awake healthy subjects and OSA patients. In this study, we have investigated whether expiratory flow limitation occurs during sleep in heavy snorers and in patients with OSA. We studied four nonapnoeic, heavy snorers and five OSA patients. Airflow was measured with a pneumotachograph attached to a tight-fitting mask, and supraglottic pressure with a catheter placed at the supraglottic level. Scoring for flow limitation was achieved by visual inspection of 200 breaths recorded during sleep. About 20% of the respiratory cycles presented isolated inspiratory flow limitation. Approximately the same percentage was observed in heavy snorers and OSA patients. Isolated expiratory flow limitation was less frequently recorded. Coupled inspiratory and expiratory flow limitations were more numerous, especially in heavy snorers. We conclude that both in heavy snorers and obstructive sleep apnoea patients, inspiratory flow limitation is associated with expiratory flow limitation. This suggests that upper airway obstruction during sleep is both an inspiratory and expiratory event.

Adult↗
PubMed1995

Effect of preinspiratory maneuver on the single-breath DLCO.

We have observed in some patients with pulmonary disease and normal subjects that the difference between two successive measurements for single-breath DLCO amounted to 10%. By scrutinizing data from these subjects, we observed that they spontaneously changed their preinspiratory maneuver just before inhaling the test gas mixture. The purpose of the present work is to assess the influence of five different preinspiratory maneuvers on DLCO. Nine healthy males were investigated. They performed at random the five following maneuvers: (A) rapid exhalation from functional residual capacity (FRC) to residual volume (RV), (B) rapid exhalation from FRC to RV and long apnea at RV, (C) rapid exhalation from FRC to RV and short apnea at RV, (D) slow exhalation at a constant speed from FRC to RV, and (E) curvilinear exhalation from FRC to RV. The DLCO values after maneuver B were higher than those after the four other maneuvers; there was a significant relationship between DLCO and the duration of the preinspiratory maneuver. The data are best explained by an alteration in the distribution of the inspired gas mixture to areas with different diffusing capacities. In conclusion, the preinspiratory maneuvers must be standardized in order to improve the reproducibility of the single-breath DLCO measurements.

Adult↗
PubMed1995

Expiratory supraglottic obstruction during muscular relaxation.

Some reports have suggested occurrence of expiratory upper airway narrowing in patients with obstructive sleep apnea (OSA) during sleep and in awake humans during respiratory muscles relaxation. This is compatible with the hypothesis that upper airway muscles are activated during expiration. We studied five healthy volunteers and four patients with OSA in a tank respirator (Emerson; Cambridge, Mass). Supraglottic pressure (Psg) was measured with a catheter with the tip at the retroepiglottic level, tidal volume with an inductance plethysmograph and airflow with a pneumotachograph at the mouth. Diaphragmatic electromyogram was recorded with an esophageal bipolar electrode. Measurements were done at -30 cm H2O. Subjects were asked to breathe in phase with the respirator and then asked to breathe in phase with the respirator and then to relax their muscles. During muscular relaxation, there was supraglottic obstruction and flow limitation. This was observed during both inspiration and expiration. Upper airway obstruction was more severe in patients with OSA than in healthy subjects. In two healthy volunteers, fiberoptic bronchoscopy showed a wide-open oropharyngeal isthmus during active breathing that narrowed during muscular relaxation. This was true during both inspiration and expiration. We conclude that muscular relaxation is associated with upper airway narrowing and flow limitation occurring during both inspiration and expiration. We suggest that to preserve an open upper airway, airway muscles have to be activated during both inspiration and expiration.

Adult↗
PubMed1994

Effect of cold pressor test on single-breath DLCO in normal subjects.

We hypothesized that the decrease in single-breath diffusing capacity of CO (DLCO) as observed in patients with Raynaud's phenomenon (P.J. Fahey et al. Am. J. Med. 76:263-269, 1984) may be present in normal subjects. Therefore, we examined 31 healthy subjects in two different laboratories. Two series of experiments were performed. In the first series DLCO was measured in 22 volunteers before (twice) and 5, 10, and 30 min after a cold pressor test (CPT), which consisted of immersing both hands in a 12 degrees C water bath for 2 min. In the second series right heart catheterization was performed in nine healthy seated subjects. Cardiac output, mean pulmonary arterial pressure, heart rate, and pulmonary wedge pressure were measured before, during, and 10, 20, and 30 min after the CPT. In every volunteer the CPT induced a decrease in DLCO that was still present 30 min after the test. In the nine catheterized subjects DLCO increased above control values during the CPT and then decreased below control values for 30 min. The CPT had no effect on cardiac output, heart rate, or pulmonary wedge pressure. In contrast, pulmonary arterial pressure and pulmonary vascular resistance increased during the CPT and then became lower than the control values for at least 30 min. In summary, the CPT induced a biphasic evolution of DLCO in normal subjects, being increased during the CPT and decreased after it. Our data are best explained by the West model of the lung. Our data suggest that the pulmonary Raynaud's phenomenon is not specific to patients with primary Raynaud's phenomenon.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Bronchodilator effect of inhaled nitric oxide in healthy men.

Studies in animals have shown that inhalation of nitric oxide (NO) either reduced pulmonary resistance after an induced bronchospasm or protected animals from bronchoconstriction. To evaluate whether NO inhalation (80 parts per million) influences basal bronchial tone or reverses methacholine-induced bronchospasm, we determined specific airway conductance (SGaw) as a measure of airway caliber in seven healthy men. After methacholine-induced bronchoconstriction NO increased SGaw by 23% (p < 0.05). One week later, NO inhalation did not change baseline SGaw values. However, albuterol inhaled after NO, or on a separate day, significantly increased SGaw (p < 0.05). The bronchodilator effect of NO in men with methacholine-induced bronchospasm is much less than that reported in animals or that regularly observed in asthmatic patients after the inhalation of beta-sympathomimetic drugs.

Administration, Inhalation↗
PubMed1994

Contraction and relaxation of upper airway muscles during expiratory application of negative pressure at the mouth.

Upper airway muscles (UAM) are activated during inspiration, but little is known about their activity during expiration. We studied six healthy volunteers in supine position. Negative pressure (-10 to -30 cm H2O) was applied cyclically at the mouth during expiration. Subjects actively breathed during inspiration and either contracted or relaxed their UAM during expiration. Supraglottic pressure (Psg) was measured with a catheter with the tip at the supraglottic level. During relaxation, but not during contraction, there was expiratory flow limitation (FL) accompanied by high frequency pressure and flow oscillations (70 +/- 5.7 Hz at -30 cm H2O). The average linear supraglottic resistance was higher during relaxation than during contraction at both -10 and -20 cm H2O (p < 0.05), but not at -30 cm H2O. Amplitude of expiratory genioglossus electromyogram was 3.6 +/- 2.5 mm during quiet breathing, 7.0 +/- 3.8 mm during contraction (p < 0.05) and 4.1 +/- 1.8 mm during relaxation. Average mouth pressure, which immediately preceded pressure (and flow) oscillations was -2.1 +/- 0.9 cm H2O. In one subject cineradiography of the neck during expiratory application of -30 cm H2O showed anterior flexion and high frequency oscillations of the soft palate during relaxation. During contraction, the soft palate was close to the posterior pharyngeal wall without oscillations. We conclude that cyclically applied negative pressure at the mouth during expiration produced expiratory flow limitation during relaxation but not during contraction, and that expiratory contraction of UAM stabilizes upper airways during negative pressure application at the mouth.

Adult↗
PubMed1993

Upper airway obstruction induced by negative-pressure ventilation in awake healthy subjects.

Negative-pressure ventilation (NPV) induces sleep-related upper airway obstruction. However, the precise mechanism and site of upper airway obstruction during NPV have not been worked out. We studied seven awake healthy volunteers (23-30 yr old) in an Emerson tank respirator. Subjects had the head outside the iron lung and breathed through a pneumotachograph, which yielded the airflow (V) signal. Supraglottic pressure (Psg) was measured with a catheter with the tip at the retroepiglottic level. Diaphragmatic electromyograms (EMGdi) were obtained from an esophageal bipolar electrode. Tidal volume was measured with an inductance plethysmograph. Measurements were done at -10, -20, and -30 cmH2O. At each pressure run subjects were asked to repeatedly relax or to actively breathe in phase with the respirator. Subjects had been previously trained to relax during NPV. During the relax runs there was no EMGdi activity. Stridor or wheezing occurred in all seven subjects during the relax runs but not during the active runs. Two patterns were associated with NPV during relax runs. One pattern was decreases in both V and Psg followed by zero values of these indexes, which corresponded to an inspiratory narrowing and closure of the glottis. These changes were visualized by fiber-optic bronchoscopy in one subject. The second pattern was a decrease in V and increase in Psg, which corresponded to an inspiratory supraglottic obstruction. In five subjects a supraglottic pattern was observed, whereas in two subjects glottic closure was seen. We conclude that muscular relaxation during NPV produces a decrease in the caliber of the upper airways at the glottic or supraglottic level. An uncoupling of upper airway muscle activity and the diaphragm might be the mechanism responsible for these changes.

Adult↗
PubMed1992

Upper airway anesthesia induces airflow limitation in awake humans.

Upper airway receptors are thought to contribute to upper airway stability by reducing collapsing forces. Their activity can be abolished by topical anesthesia. We have measured in 16 healthy volunteers (mean +/- SD age, 23.7 +/- 1.6 yr) specific airway conductance (SGaw), maximal inspiratory (MIFR) and expiratory (MEFR) flow rates before and 15, 35, and 45 min after extensive upper airway anesthesia (UAA) with 10% lidocaine. Average values of MIFR decreased (p less than 0.01) 15 min after UAA, but they returned to or near to control values at 45 min: MIF25 (4.8 versus 6.0 L/s); MIF50 (5.1 versus 6.2 L/s); MIF75 (4.4 versus 5.3 L/s). Transient decreases in flow (V) rates, reaching zero flow in some subjects, were observed in 13 subjects during forced inspiratory vital capacity (FIVC) maneuvers and in seven subjects during forced expiratory vital capacity (FEVC) maneuvers. MEFR at 25, 50, and 75% FVC, SGaw, and FVC did not change after anesthesia. Simultaneous measurements of supraglottic pressure, V, and lung volume in 12 of the 16 subjects showed that the site of flow limitation was localized at the level of the glottis in all except one subject in whom there was both a glottic and a supraglottic obstruction. We conclude that extensive upper airway anesthesia induced a profound but transitory upper airway obstruction during FIVC and FEVC maneuvers. These findings are compatible with the concept of reflex regulation of upper airway caliber.

Adult↗
PubMed1992

[The effect of inhaled salbutamol on pulmonary gas exchange in patients with chronic obstructive bronchopneumopathy].

The aim of this study is to establish whether or not the inhalation of a puff of salbutamol (Ventoline, 100 micrograms) could induce hypoxemia. Twenty-five chronic obstructive pulmonary disease (COPD) patients were investigated. In a first group of 20 patients arterial blood gases and related indices were measured before and 5, 10, 30, 60 and 90 minutes after inhalation of salbutamol. The oxyhemoglobin dissociation curve was traced before and 90 minutes after the drug intake. Except in two subjects in whom salbutamol dramatically improves arterial blood gases, the drug had no effect on the investigated parameters. It is concluded that salbutamol does not affect the blood gases in COPD patients. In this respect the behaviour of COPD patients differs from that of asthmatics in whom salbutamol generally induced hypoxemia.

Administration, Inhalation↗