The effects of elastase-induced emphysema on vagal pulmonary reflexes were studied in seven rabbits, given 600 IU of porcine pancreatic elastase intratracheally (E group), and eight untreated rabbits (U group) under pentobarbital anaesthesia. The presence of emphysema was confirmed by histological and pathological criteria and by documented changes in lung ...

Noninvasive rebreathing measurements of pulmonary tissue volume (Vt) and pulmonary capillary blood flow (Qc) theoretically and experimentally vary with the rebreathing maneuver. To determine the cause of these variations and identify ways to minimize them, we examined the consequences of varying the volume inspired (VI), rebreathing rate (f), volume rebreathed ...

The effects of selective restriction of rib cage (Res,rc) and abdominal wall (Res,ab) movements on endurance of short-term constant-load heavy exercise and on diaphragmatic function during such exercise were examined in five normal young men. An inelastic surgical corset was used to achieve Res,rc and Res,ab. Subjects exercised on a ...

We assessed the effects of selective restriction of movements of the rib cage (Res,rc) and abdomen (Res,ab) on ventilatory pattern, transdiaphragmatic pressure (Pdi), and electrical activity of the diaphragm (Edi) in five normal subjects exercising at a constant work rate (80% of maximum power output) on a cycle ergometer till ...

We studied the effect of abdominal loading on exercise performance in 7 patients with severe chronic air-flow obstruction (CAO). The patients were exercised to exhaustion on a bicycle ergometer at a work rate equivalent to 80% of their maximal work rate. Three exercise studies were completed in the same afternoon. ...

To investigate respiratory control during high-frequency oscillation (HFO), ventilation was monitored in conscious humans by respiratory inductive plethysmography during application at the mouth of high-frequency pressure oscillations. Studies were conducted before and after airway and pharyngeal anesthesia. During HFO, breathing became slow and deep with an increase in tidal volume ...

Thirty five printers who had work related wheeze, chest tightness, or breathlessness kept two hourly records of their peak expiratory flow for at least two weeks. They all worked in a factory supplied by air from contaminated humidifiers. The peak flow records showed consistent work related deterioration in 15 workers, ...

Ventilatory responses to stimulation of chemoreceptor afferents were studied in the anesthetized, spontaneously breathing cat. Short bursts of electrical stimuli were applied, at various times in the inspiratory or expiratory phase of consecutive breaths, to the carotid sinus (CSN) and aortic nerves (AN) and to the ventral medulla (VM), and ...

The purpose of this study was to evaluate the effects of continuous and interval training on changes in lactate and ventilatory thresholds during incremental exercise. Seventeen males were assigned to one of three training groups: group 1:55 min continuous exercise at approximately 50% maximum O2 consumption (VO2max); group 2: 35 ...

We measured, in 11 healthy volunteers, the contributions of rib cage and abdomen--diaphragm compartments to increased ventilation caused by hypercapnia, hypoxia, and exercise to determine whether different stimuli produce similar or different patterns of ventilation with respect to the motion of rib cage and abdominal compartments. Progressive hyperoxic hypercapnia and ...

To investigate the effects of inspiratory muscle resistive loading training (IMT) on exercise performance in chronic obstructive pulmonary disease (COPD), 13 patients undergoing standard pulmonary rehabilitation were divided into control (n = 6) and experimental (n = 7) groups. Prior to training, we measured inspiratory muscle strength and endurance, resting ...

The purpose of this investigation was to measure changes in transdiaphragmatic pressure (Pdi) developed during graded elastic (E) and resistive (R) loaded breaths and to correlate the emergence of such changes with the load-dependent alterations in latency for detection (Tdet). Five healthy adults were studied using three protocols, i.e., graded ...

We demonstrate the effectiveness of a new conditioning technique for increasing the strength and endurance of the inspiratory muscles. The technique employs a threshold loading device which allows for maximization of exercise intensity with a minimum of exercise duration. After ten weeks, with approximately 25 minutes of exercise time per ...

In order to assess the effect of breathing pattern on measurements of dead space ventilation (VD/VT) during exercise, we studied 6 patients with the complaint of exertional dyspnea. They had essentially normal resting pulmonary function studies and the only abnormality noted during an initial exercise study was an elevated VD/VT ...

The respiratory performance was studied after intraperitoneal administration of the adenosine agonists N6-phenyl-isopropyl-adenosine (PIA) and adenosine-5-ethylcarboxamide to preterm (gestational age 29-30 days) newborn halothane-anesthetized rabbits. Both agonists induced marked hypoventilation and irregular breathing by decreases in the breathing frequency as well as the tidal volume. Expiratory time was markedly prolonged, ...

We looked for evidence of changes in lung elastic recoil and of inspiratory muscle fatigue at maximal exercise in seven normal subjects. Esophageal pressure, flow, and volume were measured during spontaneous breathing at increasing levels of cycle exercise to maximum. Total lung capacity (TLC) was determined at rest and immediately ...

Ventilation and the breathing pattern of 12 intact, unanesthetized, unrestrained kittens, were recorded at intervals from the second postnatal day to the end of the eighth month. Five of the animals were also studied at 12 months of age. Ventilation (VE) became stable by the 5th month, whereas body weight ...

Although exercise-induced ventricular tachycardia (VT), whether sustained or nonsustained, is usually associated with significant organic heart disease, its prevalence, associated characteristics and prognostic significance in an asymptomatic, unreferred community-dwelling population are unknown. Therefore, the prevalence of VT associated with maximal treadmill exercise was assessed in 597 male and 325 female ...

We compared the ventilatory effects of prenalterol (beta 1-selective adrenoceptor agonist) with those of salbutamol (beta 2-selective adrenoceptor agonist) in 6 healthy volunteers. Two intravenous doses of prenalterol (1 mg/60 min, 2 mg/60 min) and of salbutamol (300 micrograms/60 min, 600 micrograms/60 min) were given in random order in 4 ...

We examined the respiratory activity of the posterior cricoarytenoid muscle (PCA) simultaneously with the movements of the vocal cords during tidal breathing and panting in four normal seated subjects. A bipolar electrode was constructed to record the surface electromyogram (EMG) of the PCA. The glottis was visualized with a fiberoptic ...

The theoretical estimation of the mechanical work of breathing during inspiration at rest is based on the common assumption that the inspiratory airflow wave is a sine function of time. Different analytical studies have pointed out that from an energetic point of view a rectangular wave is more economical than ...

The effects of CO2 concentration on the timing of inspiratory duration (TI) and expiratory duration (TE) and the responses to lung inflation were studied in decerebrate paralyzed cats. With lung volume held at functional residual capacity during the breath cycle, hypercapnia (fractional concentration of inspired CO2 = 0.04) caused variable ...

The ventilatory effects of biceps tendon vibration were studied in healthy human subjects at rest and at two levels of light leg exercise. This was performed with intent to add the ventilatory effects of selective stimulation of muscle spindles to nervous and humoral respiratory inputs from contracting muscles. Tendon vibration ...

We studied changes in breathing pattern and mouth occlusion pressure (P0.1) in 11 healthy subjects performing graded steady-state exercise on a cycle ergometer up to the maximal load sustainable for 4 min. With increasing work intensity both the tidal volume (VT) and end-inspiratory volume relations to inspiratory (TI) and expiratory ...

Respirators (respiratory personal protective devices), used for protection against occupational toxic exposures, may impose flow resistance and dead space respiratory loading. Effects of exercise level, a 300 mL deadspace and single respirator cartridge inspiratory load were determined in ten healthy volunteers. Subjects tended to limit peak work rate (pressure generated ...

A mouthpiece plus noseclip (MP + NC) is frequently used in performing measurements of breathing patterns. Although the effects the apparatus exerts on breathing patterns have been studied, the mechanism of the changes it causes remains unclear. The current study examines the effects on respiratory patterns of a standard (17-mm-diam) ...

Utilizing the conceptual scheme of Kim, this study focused on the effect of inspiratory muscle training on the strength of the respiratory muscles, exercise performance, clinical manifestations, and activities of daily living. Unlike previous studies, inspiratory muscle training was performed by the use of an ISRBD that gave alinear inspiratory ...

The role of slowly adapting pulmonary stretch receptors (PSR) in the reflex control of expiratory duration was investigated in anesthetized, spontaneously breathing rabbits. Graded resistive and elastic loads were applied for single expirations to produce expiratory volume-time curves. The PSR were selectively blocked by administration of 200-400 ppm sulfur dioxide ...

The purpose of this study was to analyze changes in respiratory resistance (Rrs) and breathing pattern in normal and asthmatic subjects after exposure to ultrasonically nebulized distilled water (UNDW). After measurement of baseline Rrs and breathing pattern, ten normals inhaled UNDW for 30, 60, 120, 240 and 480 s administered ...

To analyze the interdependence of respiratory drive, ventilation and airway resistance during exercise, mouth occlusion pressure (P0.1), minute ventilation (V) and mean inspiratory flow (VT/TI) were studied in eight normal subjects performing cycle-ergometer exercise at loads ranging from 0 W to 200 W under two different ambient conditions: 1) during ...

Ventilatory responses to graded elastic and resistive loads from 20 quadriplegic men were analyzed. During the 1st, 5th, and 10th consecutively loaded inspirations 1) responses from different subjects ranged from a weak tidal volume defense coupled with an increased breathing frequency to a strong tidal volume defense coupled with a ...

The pattern of breathing during maximal oxygen uptake (Vo2max) was studied in 26 patients with chronic airflow obstruction (CAO), in whom the vital capacity (VC), forced expiratory volume in 1 s (FEV1) and residual volume (RV) were measured. The patients performed, on a cycle ergometer, in a sitting position, a ...

In eleven young healthy subjects, vital capacity was reduced by 30% by thoracic or abdominal strapping and the effects of this on maximal work capacity, ventilation and circulation were examined. During exercise as well as at rest, tidal volume and stroke volume were reduced and respiratory frequency and heart rate ...

Fourteen patients with exercise-induced ventricular tachycardia (VT) underwent serial treadmill testing, and those with reproducible arrhythmia were treated with a beta-adrenergic blocking agent. In 11 patients (79%), VT of similar rate, morphologic characteristics and duration was reproduced on 2 consecutive treadmill tests performed 1 to 14 days apart. Beta blockade ...

The interrelationships of ventilation (V), tidal volume (VT), inspiratory (T1), expiratory (TE) and total breath (Ttot) durations, mean inspiratory (VT/TI) and expiratory (VT/TE) flows, and lung volumes were studied in normal subjects at rest and during exercise on a cycle ergometer. The ergometric load was increased by 10 W every ...

Changes in respiratory drive, as assessed by mouth occlusion pressure (P0.1), and in breathing pattern were studied in 19 healthy subjects who exercised on a cycle ergometer with work loads ranging from loadless pedalling up to the highest load that could be sustained for 4 min. In the P0.1 studies, ...

Ability to judge ventilation (VI) and respiratory rate (RR) was examined in healthy subjects using the standard psychophysical technique of magnitude production. The relationships between objective and subjective magnitudes of VI could be adequately described by power function with the mean exponent 1.9. The mean deviation from the regression line ...

Respiratory responses to a single breath during which a resistive load was applied were studied in 8 conscious subjects. There was an increase in inspiratory time (TI), an increase in end-tidal PCO2 (PETCO2) and a decrease in end-tidal PO2 (PETO2) on the resisted breath. 12 subjects were given a single ...

To determine whether the rib cage and abdomen-diaphragm contributions to tidal volume (VT) during CO2 rebreathing are affected by postural change, using respiratory inductive plethysmography, we measured in eight healthy volunteers the compartmental VT responses to progressive hypercapnia in both seated and supine postures. The ventilatory, frequency, and VT responses ...

We studied the dynamic mechanical properties of the chest wall in 7 patients with severe chronic air-flow obstruction (CAO). Measurements were made during quiet breathing at rest and during exercise on a bicycle ergometer at work rates equivalent to 50 and 100% of their maximal work rate (Wmax). The peak ...

Responses of expiratory duration (TE) and laryngeal aperture to small flow resistance loads (2 and 5 cm H2O/LPS) applied to single expirations were measured using repeated applications in four subjects during quiet breathing. All subjects significantly prolonged TE in response to the higher load and 3 of the 4 showed ...

The simple T-piece is frequently used as a weaning system during respirator treatment. It is modified with an expiratory non-compliant reservoir (EnCR), an inspiratory compliant reservoir (ICR) and/or an expiratory one-way valve. The distribution of expiratory gases and rebreathing were studied in a model set-up in the corresponding systems at ...

Forty-nine men performed progressive submaximal treadmill exercise to determine the cardiopulmonary and subjective response to added resistance to breathing. Twenty subjects (controls), FEV1/FVC% = 79.2 +/- 1.4 (mean +/- SEM), were compared with 19 mildly obstructed men (OB1), FEV1/FVC% = 66.9 +/- 0.5, and 10 with moderate obstruction (OB2), FEV1/FVC% ...

The responses to exercise were studied in 41 patients with pulmonary fibrosis, in whom vital capacity (VC) was reduced to 62% of predicted normal values. Maximum power output (POmax) was 53% predicted; there was a significant relationship between POmax and VC (r = 0.564). The maximum ventilation achieved during exercise ...

Ventilatory responses to inspiratory elastic and resistive loads of 67 men were analyzed. During the 1st, 5th, and 10th consecutively loaded breaths 1) individual responses ranged from a rapid-shallow to a slow-deep breathing pattern; 2) strong tidal volume (VT) defenders employed longer inspirations than did weak VT defenders; and 3) ...

We measured the single breath diffusing capacity for carbon monoxide (DLcoSB) using a three-equation method to describe CO uptake in 10 normal seated subjects who either voluntarily inhaled slowly (0.5 L/sec) to total lung capacity (TLC), or inhaled slowly to TLC with maximal effort through a high inspiratory resistance which ...

The purpose of our study was to identify central nervous system sites involved in the respiratory depressant effect of drugs that stimulate opioid receptors. Diacetylmorphine (heroin) was administered into several cerebroventricular regions of chloralose-anesthetized cats, while monitoring pulmonary ventilation with a Fleisch pneumotachograph. Administration of heroin (17, 50, 150, and ...

Vertices are the points in an arborescence which interconnect segments and comprise terminal or pendant vertices (Vp), nodal or branching points and the root point. Branching points may be dichotomous (Vd) or trichomtomous (Vt), etc., and are subdivided into distinct two-dimensional topological entities according to the number of terminal vertices ...

We previously demonstrated that specific behavioral styles influenced recognition of resistive loads to breathing. However, the basis for this finding remained unclear. Because others have found a relationship between behavioral style and ventilatory drive, we evaluated the relationships among resting ventilatory drive, behavioral style, and recognition of loads to breathing. ...

Minute ventilation (VE) and breathing pattern during an abrupt increase in fractional CO2 were compared in 10 normal subjects before and after airway anesthesia. Subjects breathed 7% CO2-93% O2 for 5 min before and after inhaling aerosolized lidocaine. As a result of airway anesthesia, VE and tidal volume (VT) were ...