Biomedical subjects

C Tantucci

Publications and source records attributed to C Tantucci.

At least 37 records · Page 2Linked to original sources

PubMed1997

Influence of autonomic neuropathy of different severities on the hypercapnic drive to breathing in diabetic patients.

To investigate the effects of the autonomic nervous system on control of breathing, the neuromuscular (mouth occlusion pressure at 0.1 s after onset of inspiration [P0.1]) and ventilatory (minute ventilation [VE]) response to progressive hyperoxic hypercapnia was assessed in diabetic patients with autonomic dysfunction of different severity. Eighteen diabetics with autonomic neuropathy, nine with parasympathetic damage (DANp), and nine with parasympathetic and sympathetic damage (DANp+s), as indicated by marked postural hypotension, low increment of diastolic BP during sustained handgrip, and lowest resting catecholamine plasma levels, were studied together with a group of 10 diabetic patients without autonomic neuropathy (D) and a group of 10 normal subjects (C). All subjects had pulmonary function tests, including maximal voluntary ventilation and diffusion of carbon monoxide, measurements of respiratory muscle strength as maximal inspiratory mouth pressure (MIP) and maximal expiratory mouth pressure (MEP), and a CO2 rebreathing test (Read's method). Although in the normal range, lung volumes and FEV1 and forced expiratory flows were lower in the DANp and DANp+s groups than in the D and C groups, MIP and MEP were similar among C and diabetic groups, as well as resting P0.1, VE, tidal volume (VT), and respiratory rate (RR). The slope of the linear relationship between P0.1 and end-tidal PCO2 (PETCO2) was higher in DANp+s (0.63+/-0.07 cm H2O/mm Hg) than in C (0.45+/-0.06 cm H2O/mm Hg; p<0.05) and three times greater in DANp+s than in D (0.26+/-0.03 cm H2O/mm Hg; p<0.001) and DANp (0.24+/-0.03 cm H2O/mm Hg; p<0.001), who in turn showed a lower deltaP0.1/deltaPETCO2 than C. The VE increase with increasing PETCO2 was greater in DANp+s (3.70+/-0.85 L/min/mm Hg) than in DANp (2.13+/-0.20 L/min/mm Hg; p<0.05) and D (2.37+/-0.40 L/min/mm Hg; p=0.07), but not significantly higher from that of C (3.17+/-0.36 L/min/mm Hg). No differences were found for deltaVT/deltaPETCO2 among the groups, whereas the deltaRR/deltaPETCO2 relationship was steeper in DANp+s than in DANp (p<0.05) and D (p=0.055). These data reflect a depressed CO2 response both in D and DANp. The presumable decrease of the sympathetic nerve traffic in DANp+s appears to reverse this abnormality. DANp+s, however, exhibit an enhanced CO2 neuromuscular response even in respect to C, suggesting that the sympathetic nervous system might modulate the output of the respiratory centers to hypercapnic stimulus.

Adult↗

PubMed1997

Ineffectiveness of a four week treatment with the thromboxane synthetase inhibitor, imidazole salycilate, in reducing airway hyperresponsiveness to methacholine in asthmatics.

In a randomized, double-blind, placebo-controlled study, the acute and long-term effects of the reduction of thromboxane A2 (TxA2) synthesis on airway sensitivity and maximal airway narrowing in response to methacholine was evaluated in 12 subjects with mild-to-moderate stable asthma, using imidazole salycilate (IS), an anti-inflammatory drug which selectively inhibits the TxA2 synthetase. Dose-response curves with methacholine (MCh) were performed in basal conditions (baseline); 1-1.5 h after administration of 1,500 mg of IS or placebo (acute); at 15 and 30 days of treatment with 750 mg t.i.d. of IS or placebo; and after a 2 week period of run-off (45 days). The serum levels of thromboxane B2 (TxB2) were measured at the same time points, except after acute administration, in five patients from each group. Baseline forced expiratory volume in one second (FEV1) was 78 +/- 7 and 85 +/- 8% of predicted in the IS and control group, respectively (NS). Throughout the study FEV1 remained unchanged in both groups, indicating that IS did not caused substantial modification of resting bronchial calibre. The initial provocative dose of methacholine causing a 20% fall in FEV1 (PD20) amounted to 27.0 +/- 1.5 micrograms in the IS group and 41.7 +/- 1.5 micrograms in the control group (geometric mean +/- GSEM) (NS). Despite a reduction of TxB2 serum levels with IS vs placebo at 15 days (24.9 +/- 8.5 vs 45.5 +/- 3.4 pg.mL-1; p < 0.05) and 30 days (27.0 +/- 6.3 vs 45.0 + 3.2 pg.mL-1; p < 0.05), MCh-induced bronchoconstriction, evaluated either as PD20 or maximal airway narrowing, did not change significantly during active treatment compared to placebo. These results show that prolonged reduction of thromboxane A2 synthesis does not improve airway sensitivity and limit maximal bronchoconstriction in asthmatic subjects, suggesting that thromboxane A2 per se does not play a substantial role in the pathogenesis of the airway hyperresponsiveness in human asthma.

Adult↗

PubMed1996

Aging and the respiratory system.

All the components of the respiratory system are affected by aging, though at different rates: i) the lung elastic recoil decreases; ii) PaO2 decreases and the D(A-a)O2 increases; iii) the chest wall becomes stiffer; iv) the inspiratory muscles loose strength; and v) the respiratory centres are less sensitive. Residual volume, closing volume and function residual capacity increase, whereas vital capacity and FEV1 progressively decrease. The flow volume curve becomes more convex to the volume axis at low lung volume. Whether these changes are due to aging or associated with aging is a matter of debate. However, the aging lung is more fragile in the face of respiratory and systemic diseases than the respiratory system of young adults. Nutrition, smoking habits and sleep-related disorders also affect the respiratory system. Although bronchial asthma may also appear in the elderly, chronic obstructive pulmonary disease is one of the most common respiratory diseases in advanced life and is a major cause of respiratory failure and ICU admission. Age in itself is not a risk factor of respiratory failure, but elderly patients have an increased risk of mortality for both acute respiratory failure (the failing lung), and exacerbated chronic ventilatory failure (the failing pump). Although advanced age can influence the final outcome of elderly patients from the intensive care unit (ICU), admission to the ICU as well as the institution of mechanical ventilation should not be denied on the basis of age alone, since the severity of illness, prior health status and admitting diagnosis have more weight than age in the final outcome.

Adult↗

PubMed1996

Ventilatory response to exercise in diabetic subjects with autonomic neuropathy.

We have used diabetic autonomic neuropathy as a model of chronic pulmonary denervation to study the ventilatory response to incremental exercise in 20 diabetic subjects, 10 with (Dan+) and 10 without (Dan-) autonomic dysfunction, and in 10 normal control subjects. Although both Dan+ and Dan- subjects achieved lower O2 consumption and CO2 production (VCO2) than control subjects at peak of exercise, they attained similar values of either minute ventilation (VE) or adjusted ventilation (VE/maximal voluntary ventilation). The increment of respiratory rate with increasing adjusted ventilation was much higher in Dan+ than in Dan- and control subjects (P < 0.05). The slope of the linear VE/VCO2 relationship was 0.032 +/- 0.002, 0.027 +/- 0.001 (P < 0.05), and 0.025 +/- 0.001 (P < 0.001) ml/min in Dan+, Dan-, and control subjects, respectively. Both neuromuscular and ventilatory outputs in relation to increasing VCO2 were progressively higher in Dan+ than in Dan- and control subjects. At peak of exercise, end-tidal PCO2 was much lower in Dan+ (35.9 +/- 1.6 Torr) than in Dan- (42.1 +/- 1.7 Torr; P < 0.02) and control (42.1 +/- 0.9 Torr; P < 0.005) subjects. We conclude that pulmonary autonomic denervation affects ventilatory response to stressful exercise by excessively increasing respiratory rate and alveolar ventilation. Reduced neural inhibitory modulation from sympathetic pulmonary afferents and/or increased chemosensitivity may be responsible for the higher inspiratory output.

Adult↗

PubMed1996

Ineffectiveness of intravenous beta 2-agonists on improving exercise tolerance in patients with reversible chronic airway obstruction.

The effects on exercise tolerance after acute administration of beta 2-agonists were investigated in 11 patients with partly reversible chronic airway obstruction after 400 micrograms of salbutamol (S) given intravenously (i.v.) and after 400 micrograms i.v. of a new selective beta 2-agonist, broxaterol (B), by a cardiopulmonary incremental exercise test. At rest, while VE increased in respect to basal conditions (C) after S (from 13.3 +/- 2.2 to 14.4 +/- 2.8 l/min; p < 0.05) and after B (from 13.6 +/- 3.1 to 15.5 +/- 3.6 l/min; p < 0.05), VO2, VCO2 and VO2/HR showed no substantial variations. A small, not significant reduction of PaO2 was observed both after S (from 82.7 +/- 11.7 to 79.1 +/- 16.7 mm Hg) and B (from 81.6 +/- 10.5 to 78.0 +/- 11.0 mm Hg). The maximum workload increased neither after S (from 67.5 +/- 39.1 to 66.6 +/- 37.0 W) nor after B (from 65.7 +/- 39.3 to 60.0 +/- 35.8 W). At peak of exercise, VO2, VCO2 and VO2/HR did not change after S and B as compared with C, whereas VE remained higher after both beta 2-agonists throughout the effort. VO2 at ventilatory anaerobic threshold (AT) was significantly greater either after S (from 744 +/- 378 to 815 +/- 302 ml/min; p < 0.05) and after B (from 756 +/- 290 to 842 +/- 292 ml/min; p < 0.05). The PaO2 increase shown by these patients during effort was greater after beta 2-agonists administration, delta PaO2 from rest to peak of exercise amounting to 14.9 +/- 14.3 vs. 7.8 +/- 8.2 mm Hg after S and to 17.8 +/- 15.1 vs. 8.8 +/- 10.9 mm Hg after B, in respect to relative baseline (p < 0.05). We conclude that beta 2-agonists, when given acutely, do not improve exercise tolerance in patients with reversible chronic airflow obstruction, although these drugs can induce a small increment of ventilatory AT. In addition, arterial blood gases do not deteriorate at rest and are better preserved during exercise after beta 2-agonists.

Adrenergic beta-Agonists↗

PubMed1996

Energy cost of exercise in multiple sclerosis patients with low degree of disability.

In 10 patients (five females) suffering from multiple sclerosis with mild degree of disability, (EDSS ranging from 0 to 2) and in 10 age and sex matched control subjects we investigated lung function, respiratory muscles strength and cardiorespiratory response to incremental exercise in order to assess the metabolic cost of exercise. In the absence of any impairment of lung volumes and flows and in- and expiratory maximal mouth pressures, at peak of exercise oxygen consumption (VO2max = 1886 +/- 145 ml/min) and workload (Wmax = 137 +/- 9.8 watts) were slightly diminished in patients, as compared with controls (VO2max = 2246 +/- 196 ml/min and Wmax = 164 +/- 14.7 watts). These findings were associated with an increased heart rate (HR) and reduced oxygen pulse (VO2/HR) at the same workloads. During the whole exercise, however, the slope of the linear relationship between VO2 and work exhibited by the patients, amounting to 9.9 +/- 0.6 ml/min/watt, was similar to that of the controls (10.9 +/- 0.42 ml/min/watt). Incidentally, both at rest and during exercise, the patients showed a significantly greater minute ventilation (VE) due to a faster respiratory rate, associated with an augmented dead space (P < 0.05). We conclude that an increase of metabolic cost of exercise does not occur in multiple sclerosis patients with mild disability, suggesting a lack or a low degree of spasticity and/or ataxia elicited by the effort. Thus, their exertional capacity appears to be limited mainly by a poor training. The tachypnea observed in these patients at rest and during exercise was unexpected and the reason for adopting such a pattern of breathing is unclear.

Adult↗

PubMed1996

Diurnal change of bronchial caliber and airway responsiveness in asthmatics during long-term treatment with long-acting beta 2-agonist salmeterol.

Measurements of bronchial caliber and airway sensitivity were performed 4 times during the day (at 9, 11, 16, and 22 hr) at basal conditions (baseline), following the first inhalation of 50 micrograms salmeterol (acute) and at the 21st, 90th and 150th day after the initiation of an uninterrupted long-term treatment with inhaled salmeterol (50 micrograms b.i.d., at 10 and 22 hr). In each period of the protective effect was assessed by computing the increase of the methacholine dose able to induce a 20% fall of the forced expiratory volume in the first second (PD20FEV1) in terms of doubling dose (DD), either against the respective 9-hour PD20FEV1 value (DD9hr) or against the corresponding baseline PD20FEV1 value (DDbaseline). After the first dose of salmeterol the forced expiratory volume in the first second (FEV1) increased significantly as compared with the 9-hour FEV1 and the corresponding baseline FEV1 at each observation time (p < 0.01). During regular treatment FEV1 was higher than baseline at the 21st and 90th day at each observation time (p < 0.05), whereas at the 150th day no significant FEV1 increments were observed at 9 hr and 22 hr. The acute protective effect exerted by salmeterol amounted to about 2 DD9hr (p < 0.05) and 2 DDbaseline (p < 0.05) at each observation time. At the 21st, 90th, and 150th day, however, no significant increase of DD9hr was found, although a mild decrease of airway sensitivity of 1 DDbaseline of magnitude was observed for all periods at each observation time. We conclude that in mild to moderate asthma salmeterol appears to rapidly lose its ability to improve bronchial responsiveness while it is effective in maintaining a well-sustained bronchodilation despite a small degree of tachyphylaxis.

Administration, Inhalation↗

PubMed1995

Cardiovascular response to exercise in diabetic patients: influence of autonomic neuropathy of different severity.

We investigated cardiovascular function and plasma catecholamine response during incremental exercise and recovery in diabetic patients with (DAN+) and without autonomic neuropathy (DAN-). The former group was divided according to the presence of parasympathetic (DAN+PH-) or associated parasympathetic and sympathetic (DAN+PH+) damage to the autonomic nervous system. A group of healthy volunteers was studied as a control group. All the patients and control subjects underwent a submaximal or symptom-limited incremental exercise test using a cycle-ergometer. Air flow and respiratory gas fractions were sampled at the level of the mouth allowing a breath-by-breath analysis of oxygen consumption (VO2). Heart rate and systolic blood pressure were recorded and venous blood samples were obtained from the patients at rest and during each minute of exercise and recovery to measure norepinephrine and epinephrine plasma levels. Haemodynamic parameters and plasma catecholamines were computed at rest and at 25, 50, 75 and 100% of the peak VO2 (VO2max). The breath-by-breath relationships among VO2, heart rate and VO2/heart rate against work were assessed during exercise for patients and control subjects. While VO2max in absolute values was not significantly different among the diabetic groups, VO2 max was much less in diabetic patients than in control subjects (p < 0.01). During exercise the rate of heart rate, systolic blood pressure, norepinephrine and epinephrine increase was different among the diabetic groups, being significantly blunted in DAN+PH+. The VO2/work relationship of the three diabetic groups was similar but markedly reduced in respect to that of control subjects (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Uremic lung.

Explore the source record for details and available documents.

Humans↗

PubMed1994

Control of breathing and respiratory muscle strength in patients with multiple sclerosis.

In 11 patients with moderately severe multiple sclerosis, lasting 11.2 +/- 7.3 years, in stable condition, and in 10 age- and sex-matched control subjects, we investigated lung function, respiratory muscle strength, and ventilatory control system. Respiratory muscle strength was assessed by measuring maximal inspiratory and expiratory mouth pressures (Pimax and Pemax, respectively). Respiratory central drive was evaluated in terms of neuromuscular (P0.1) and ventilatory (Ve) output, breathing room air and during CO2 rebreathing. In the absence of any significant impairment of lung function, patients showed a reduction of Pimax and Pemax amounting to about 40 percent and 60 percent of the predicted value at functional residual capacity (FRC), respectively; a significant, inverse correlation was found between both Pimax and Pemax at FRC and the severity score of the disease. While at rest Ve was similar to that of control subjects, baseline P0.1 was significantly higher in patients (1.97 +/- 0.79 vs 0.97 +/- 0.20 cm H2O, p < 0.005). Compared with the control group, during CO2 rebreathing P0.1/PetCO2 slope, although less steep, was not dissimilar in patients (0.34 +/- 0.13 vs 0.46 +/- 0.19 cm H2O/mm Hg, NS); on the other hand, Ve/PetCO2 slope was much lower in the patient group (1.93 +/- 0.91 vs 3.27 +/- 1.11 L/min/mm Hg, p < 0.01) and was significantly related to the functional stage of disease and to Pimax and Pemax values at FRC. These results indicate that in patients with clinically stable, moderately severe multiple sclerosis, the respiratory muscle function is abnormal. Moreover, the inspiratory drive at rest is increased and the drive response to CO2 appears normal, while the ventilatory response to CO2 is significantly impaired. Respiratory muscle weakness (and/or lack of coordination) could explain, at least in part, the lower ventilatory response in these patients, whereas the mechanism of increased rate of the initial inspiratory force generation remains unclear.

Adult↗

PubMed1994

Cardiorespiratory intermediate intensive unit: heart-lung interactions.

The heart and lung (the body's gas transport system) are neurally, mechanically, humorally and functionally linked. Several clinical-therapeutic consequences involve heart-lung interactions. Three of these conditions are described here: 1) pulsus paradoxus in asthma; 2) survival in chronic cor pulmonale; and 3) Cheyne-Stokes breathing in congestive heart failure. They provide examples of the pathophysiological and clinical complexity that such correlations involve. The most remarkable "effects" of the heart-lung relationship as a metabolic unit are represented by development of cardiorespiratory intensive care units, and efforts to bring about methods of monitoring cardiorespiratory function.

Asthma↗

PubMed1994

Effects of beta 2-agonists during cardiopulmonary exercise test in COPD patients.

The aim of this study was to evaluate endocrine-metabolic, respiratory and cardiovascular effects of two beta 2-sympathomimetic selective agents, such as broxaterol and salbutamol, before and during cardiopulmonary exercise test (CPX). Twelve in-patients with chronic obstructive pulmonary disease (COPD) (with partially reversible airways obstruction) were included. Broxaterol (400 micrograms) and salbutamol (400 micrograms) were administered i.v., according to a double-blind, cross-over study. Before treatment and within 60 min after the administration of each agent, the patients underwent incremental CPX by bicycle ergometer to the maximum tolerable threshold. At these times the following variables were assessed: minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production (VCO2), VE/VO2 ratio and O2 pulse, glycaemia, insulinaemia, plasma norepinephrine (NE) and epinephrine (E), arterial oxygen and carbon dioxide tension (PaO2 and PaCO2), plasma lactates, heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure. Spirometry was performed before and after the administration of each beta 2-adrenoceptor agonist. CPX brought about a significant increase in VE, VO2, VCO2, and O2 pulse. Broxaterol or salbutamol administration did not significantly modify the increases caused by CPX. At rest, 60 min after treatment, both bronchodilators caused a significant rise in glycaemia. A significant reduction of PaO2 (after broxaterol) and PaCO2 (after salbutamol) was observed at rest. In contrast, both agents caused no modification to potassium and insulin levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Flow resistance in mechanically ventilated patients with severe neurological injury.

In 5 mechanically ventilated patients with severe neurological injury (SNI), we measured the respiratory system's flow resistance (Rrs) over a range of inspiratory flows between 0.2 to 2 L/s, at inflation volumes (delta V) ranging from 0.1 to 1 L. Under baseline ventilatory conditions (V = 1 L/s; delta V = 0.95 L), we also partitioned Rrs into airway resistance (Raw) and the additional resistance offered by the tissues of the lung and chest wall (delta Rrs). At all inflation volumes, Rrs decreased hyperbolically with increasing flow but was higher than in normal anesthetized paralyzed subjects (N). At V of 1 L/s and delta V of 0.5 L, Rrs was significantly greater in SNI than in N (7.7 +/- 1.5 v 4.2 +/- 0.5 cm H2O/L/s; P < .01). This discrepancy was due to higher Raw in SNI. Indeed, at V of 1 L/s, Raw (mean +/- SEM) was significantly higher in SNI than in N (4.0 +/- 0.9 v 2.4 +/- 0.2 cm H2O/L/s; P < .001), whereas delta Rrs did not differ significantly. The increased Raw in SNI was due to the fact that these patients were therapeutically hyperventilated (PaCO2 = 30.4 +/- 4.2 mm Hg) and as a result their airways were bronchoconstricted. We conclude that in the intensive care unit setting, hyperventilated patients with severe neurological injury can not be considered to be adequate controls in terms of Rrs and Raw, because hypocapnia induces an increase of Raw and consequently also in Rrs (= Raw+delta Rrs).

Adult↗

PubMed1993

Respiratory prognosis in chest wall diseases.

In this short review focusing essentially on thoracic kyphoscoliosis, respiratory and cardiovascular abnormalities observed in different forms of this rib cage disorder are briefly described. Chest wall and pulmonary mechanics, respiratory muscles, gas exchange, pulmonary vasculature and regulation of ventilation can be markedly affected by kyphoscoliosis and a substantial growth of knowledge of these functional alterations has been allowed recently by new technological approaches. The pathophysiological process which leads to cor pulmonale and respiratory failure in some patients with kyphoscoliosis is analysed. The prognostic aspects of surgical and non-surgical management on pulmonary function are addressed.

Adult↗

PubMed1992

Flow and volume dependence of respiratory system flow resistance in patients with adult respiratory distress syndrome.

Using a simple and rapid technique, we studied the flow and volume dependence of the total resistance of the respiratory system (Rrs) in six patients with ARDS. At any given inflation volume, Rrs decreased progressively with increasing flow (V) according to the following hyperbolic function: Rrs = a/V + b, where a and b are constants. At any fixed inflation flow, Rrs increased progressively with increasing inflation volume. The observed flow and volume dependence of Rrs is probably mainly due to the viscoelastic properties of the pulmonary and chest wall tissues. The flow and volume dependence of Rrs found in the patients with ARDS is qualitatively similar to that previously observed in normal anesthetized paralyzed subjects. In ARDS, however, Rrs was considerably greater than in the normal subjects, indicating that besides a low respiratory compliance ARDS is characterized by a high flow resistance. This mainly reflects increased effective flow resistance of the pulmonary and chest wall tissues, although airway resistance is also higher than normal.

Adult↗

PubMed1992

Acute respiratory effects of sublingual buprenorphine: comparison with intramuscular morphine.

In this randomized, double-blind, placebo study, the respiratory effects of a single dose of sublingual buprenorphine (0.4 mg) were examined and compared with those induced by one dose of intramuscular morphine (10 mg) in a population of women, aged 25-65 years, admitted at the Hospital for Elective Surgery because of uterine fibromyomatosis. Some indices of control of breathing (P0.1, VT/TI, VE, VA, TI, TE, TI/TTot, RR), gas exchange parameters (D[A-a]O2, VD/VT, PAO2) and blood gases (PaO2, PaCO2) were measured in basal condition and at 30, 60, 90, 180 and 360 min after the administration of the drugs. No significant changes of the respiratory function were observed in patients who have received sublingual buprenorphine. In the morphine-group, however, mild PaO2 decrease and PaCO2 increase were found at 60 and 90 min (p less than 0.05), without any reduction of the respiratory drive activity, as shown by P0.1, VT/TI and VE. The significant FRC reduction, observed in the morphine-group (p less than 0.05), could have induced both TE shortening and RR increase with larger dead space ventilation and consequent fall of VA (p less than 0.05). These results suggest that the administration of one dose of sublingual buprenorphine (0.4 mg) does not cause any detrimental respiratory effect; on the other hand, an appreciable, although clinically trivial, worsening of the respiratory function results from intramuscular morphine (10 mg), in the absence of any obvious respiratory depression.

Administration, Sublingual↗

PubMed1991

Flow resistance in patients with chronic obstructive pulmonary disease in acute respiratory failure. Effects of flow and volume.

The flow and volume dependence of the total resistance of the respiratory system (Rrs) was investigated in six mechanically ventilated patients with chronic obstructive pulmonary disease (COPD) using a simple, rapid method. Isovolume Rrs-flow (V) relationships obtained at different inflation volumes (range 0.1 to 1 L) fitted (p less than 0.001) the following function: Rrs = a/V + b + cV, where a, b, and c are constants. The term "a/V" in this equation represents the hyperbolic decrease in thoracic tissue resistance with increasing flow; the term "cV" represents the linear increase in airway resistance with increasing flow. Rrs initially decreased with increasing V because at low flow the weight of the a/V was greater than that of the cV. At higher flow, however, cV became predominant and hence Rrs tended to increase. At an inflation volume of 0.5 L, minimum Rrs occurred at average inflation flow of 1.28 L/s. At low flow, Rrs increased progressively with increasing inflation volume; at inflation V greater than 1 L/s, the highest values of Rrs were obtained at low inflation volumes. The flow and volume dependence of Rrs implies that, for comparative purposes, measurements of Rrs should be standardized to a fixed inflation flow and volume.

Aged↗

PubMed1990

Comparative evaluation of cardioselectivity of metoprolol OROS and atenolol: a double-blind, placebo-controlled crossover study.

Cardioselectivity of a single oral dose of metoprolol oral osmotic (OROS) (14/190 mg) and atenolol (100 mg) was compared in 12 patients with reversible obstructive airway disease by assessing the dose-response curve to increasing doses of inhaled salbutamol. The beta-blocking activity of the two drugs, which was determined by measuring heart rate, blood pressure, and derived indexes at peak plasma drug levels, was similar. Both metoprolol and atenolol significantly reduced forced vital capacity and peak expiratory flow, with no difference between drugs. Atenolol but not metoprolol also significantly reduced forced expiratory volume in 1 second and specific airway conductance. Both metoprolol and atenolol shifted the dose-response curve of specific airway conductance to the right. The results indicate that the new OROS delivery system for metoprolol, which produces a relatively constant plasma drug level, provides a cardioselectivity comparable to or greater than that of atenolol at maximum plasma levels.

Adolescent↗