Platelets play a crucial role in the pathogenesis of acute cardiac events, such as angina, myocardial infarction and sudden death. It is believed that regular low-intensity exercise can reduce, while high-intensity exercise may provoke acute cardiac events. The aim of the present study was to investigate the effect of acute ...

Clinical evaluation of the pattern and timing of breathing during submaximal exercise can be valuable for the identification of the mechanical ventilatory consequences of different disease processes and for assessing the efficacy of certain interventions. Sedentary individuals (60 male/60 female, aged 20-80 yrs) were randomly selected from >8,000 subjects and ...

Near-infrared spectroscopy (NIRS) was utilized to gain insights into the kinetics of oxidative metabolism during exercise transitions. Ten untrained young men were tested on a cycle ergometer during transitions from unloaded pedaling to 5 min of constant-load exercise below (<VT) or above (>VT) the ventilatory threshold. Vastus lateralis oxygenation was ...

This study examined ratings of perceived exertion (RPE) using Borg's 6-20 scale at 50 W, 80 W, and ventilatory threshold (VT) in 10-year-old children (n = 15) during two different graded exercise tests. Power output was increased by 10 W.min(-1) in one protocol and by 30 W.3 min(-1) in the ...

The exercise volume and intensity are reported of a male professional cyclist (age 30; VO2max 75.0 ml/kg/min) who successfully completed the 2001 Giro d'Italia (May), Tour de France (July), and Vuelta a España (September). The total exercise time during the Giro, Tour, and Vuelta was 90 hours 44 minutes (5444 ...

Mapping strategies for ventricular tachycardia (VT) have evolved significantly in the past 2 decades. This review discusses mapping techniques that can help in successful VT ablation. The electrocardiogram (ECG) remains a vital component of VT mapping and can help to identify the chamber of origin of VT. The ECG morphology ...

The aim of this study was to determine if thoracic respiratory interneurons (TRINs) might receive peripheral noxious somatic and visceral inputs. Extracellular potentials of 78 respiration-related T(3) neurons, whose activity was driven by central respiratory output, were recorded from the intermediate zone in pentobarbital anesthetized, paralyzed, and ventilated male rats. ...

The purpose of this study was to determine the effect of imposed external resistance on the ventilatory response to He-O(2) breathing during peak exercise. To accomplish this purpose, separate inspiratory and expiratory external resistances were applied to offset for the decrease in intrapulmonary airway resistance with He-O(2) breathing. Seven men ...

This article reviews recent studies on the importance of glycine receptors for both the spontaneous and the reflex respiratory modulation of the laryngeal abductors and adductors. Our findings show that strychnine blockade of glycine receptors within the brainstem changes the eupneic three-phase respiratory pattern into two phases. This has major ...

This study investigated the effect of inspiratory muscle strength training (IMST) on inspiratory motor drive [mouth occlusion pressure at 0.1 s (P(0.1))] and respiratory-related evoked potentials (RREP). It was hypothesized that, if IMST increased inspiratory muscle strength, inspiratory motor drive would decrease. If motor drive were related to the RREP, ...

CONTEXT: Dyspnea remains a therapeutic challenge, especially in chronic respiratory conditions. Recent studies have shown that the induction of unpleasant dyspnea sensations activates areas in the insular cortex. OBJECTIVE: This study was designed to investigate the potential effects of ondansetron, a potent anti-serotonin agent, on induced dyspnea sensation. TYPE OF ...

Dorsal displacement of the soft palate (DDSP) is one of the most common obstructive conditions of the upper respiratory tract in the racehorse. The present study was conducted to determine the effects of intermittent dorsal displacement of the soft palate (DDSP) on ventilation and respiratory airflow during high intensity exercise. ...

STUDY OBJECTIVES: To determine the accuracy of a portable magnetometer designed to measure tidal volume (VT), inspiratory time (TI), and expiratory time (TE). PARTICIPANTS: Fourteen healthy subjects. DESIGN: Subjects breathed over a sixfold range of VTs while at rest (sitting and standing) and during treadmill exercise. We then compared VT, ...

BACKGROUND: Critical sites within reentry circuits of postinfarction ventricular tachycardia (VT) were identified during sinus rhythm (SR) and VT to determine whether electrogram characteristics during SR may be helpful in identifying successful ablation sites. METHODS: In 33 patients (mean age 67 +/- 11 yrs) with prior infarction, mapping and radiofrequency ...

The role played by the Bötzinger complex (BötC), the pre-Bötzinger complex (pre-BötC), and the more rostral extent of the inspiratory portion of the ventral respiratory group (iVRG) in the genesis of the eupneic pattern of breathing was investigated in anesthetized, vagotomized, paralyzed, and artificially ventilated rabbits by means of kainic ...

BACKGROUND: The role of dispersion of refractoriness and reentry for the genesis of polymorphic ventricular tachycardia (VT) has recently become emphasized. We investigated the mechanisms of polymorphic arrhythmias in a 2D preparation confining an area of prolonged refractoriness. METHODS AND RESULTS: In 16 Langendorff-perfused rabbit hearts, a sheet of left ...

To understand how externally applied expiratory flow limitation (EFL) leads to impaired exercise performance and dyspnea, we studied six healthy males during control incremental exercise to exhaustion (C) and with EFL at approximately 1. We measured volume at the mouth (Vm), esophageal, gastric and transdiaphragmatic (Pdi) pressures, maximal exercise power ...

Patients with isolated diaphragm paralysis depend on recruitment of extradiaphragmatic respiratory muscles to increase ventilation, but little is known about exercise performance or the response of the inspiratory muscles to loaded breathing. By convention, unilateral diaphragm paralysis is regarded as a trivial condition whereas bilateral paralysis is considered to be ...

The ARDSNet trial revealed that the use of a smaller tidal volume (VT) reduced mortality by 22%. However, three earlier studies that lowered VT did not find a decrease in mortality. We tested the hypothesis that the increased respiratory rate used in the ARDSNet lower VT strategy might have led ...

We tested the hypothesis that sildenafil, singly or in combination with nitric oxide (NO) donors, promotes ventricular tachycardia (VT) and ventricular fibrillation (VF). Vulnerability to VT/VF was tested by rapid pacing in eight isolated normal swine right ventricles (RV). The endocardial activation was optically mapped, and the dynamic action potential ...

To determine how decreasing velocity of shortening (U) of expiratory muscles affects breathing during exercise, six normal men performed incremental exercise with externally imposed expiratory flow limitation (EFLe) at approximately 1 l/s. We measured volumes of chest wall, lung- and diaphragm-apposed rib cage (Vrc,p and Vrc,a, respectively), and abdomen (Vab) ...

STUDY OBJECTIVE: Estimating lung volume using inspiratory capacity (IC) maneuvers is a useful way of tracking dynamic hyperinflation. An understanding of the repeatability of the IC in a clinical setting is important when evaluating an individual's response to a therapeutic intervention that might influence lung volume. This is the first ...

INTRODUCTION: Multiple forms of ventricular tachycardia (VT) after myocardial infarction may result from multiple reentrant circuits that share an isthmus or from separate reentrant circuits. The prevalence of a shared isthmus in patients with multiple hemodynamically tolerated VTs has not been determined. METHODS AND RESULTS: Criteria for a shared isthmus ...

The influences of body posture and tidal volume (VT) on inter- and intraregional ventilation inhomogeneity were assessed by normalized phase III slope (Sn(III)) analysis of multiple-breath washout recordings of SF(6) and He in 11 healthy men. Washouts with target VT of 750, 1,000, and 1,250 ml were performed standing and ...

Chest wall mechanics was studied in four subjects on changing gravity in the craniocaudal direction (G(z)) during parabolic flights. The thorax appears very compliant at 0 G(z): its recoil changes only from -2 to 2 cmH(2)O in the volume range of 30-70% vital capacity (VC). Increasing G(z) from 0 to ...

Although the value of T wave alternans as an index of electrical instability has been extensively investigated, little is known about QRS alternans during VT. Intracardiac electrograms of 111 episodes of spontaneous monomorphic regular VT retrieved from implantable defibrillators in 25 patients were retrospectively selected. Three beat series, representing the ...

Thirteen intubated, high dependency patients with neurological injuries were studied in order to investigate the short term respiratory effects of neurophysiological facilitation and passive movement on tidal volume (VT), minute ventilation (VE), respiratory rate (VR) and oxygen saturation (SpO2). The subjects were studied under four conditions: no intervention (control) and ...

This descriptive study analyzed serial, individual changes in the exercise pattern of breathing (POB) of patients with stable chronic heart failure (CHF). Twenty-two CHF patients underwent maximal, symptom-limited cardiopulmonary exercise test on a treadmill. Minute ventilation (VE), tidal volume (VT), breathing frequency (f), the ventilatory equivalent for carbon dioxide (VE/VCO2) ...

PURPOSE: This research was undertaken to validate a combination of methodologies to determine ventilatory threshold (VT). METHODS: Three methods were used individually and then combined to determine VT as follows: 1) ventilatory equivalencies, 2) excess CO2 production, and 3) a modified V-slope method. Three groups of participants-endurance athletes (N = ...

Hyperventilation (HV) is often considered part of a defense response, implying an unpleasant emotion (negative valence) combined with a strong action tendency (high arousal). In this study, we investigated the importance of arousal and valence as triggers for HV responses. Forty women imagined eight different scripts varying along the arousal ...

Variable extra thoracic obstruction has been found in spirometric studies in subjects with unilateral vocal fold paralysis. The aim of the study was to further evaluate airflow dynamics in these subjects with body plethysmography and tracheal sound analysis. Ten patients with unilateral vocal fold paralysis without a history of chronic ...

The purpose of this study was to evaluate the effect of exercise training intensity relative to the ventilatory threshold (VT) on changes in work (watts) and VO2 at the ventilatory threshold and at maximal exercise in previously sedentary participants in the HERITAGE Family Study. We hypothesized that those who exercised ...

To evaluate the effects of endotoxemia on respiratory controller function, 12 subjects were randomized to receive endotoxin or saline; six also received ibuprofen, a cyclooxygenase inhibitor, and six received placebo. Administration of endotoxin produced fever, increased respiratory frequency, decreased inspiratory time, and widened alveolar-arterial oxygen tension gradient (all p < ...

An 11-yr-old female without any pulmonary disorders underwent laser resections of laryngotracheal tumors using high-frequency jet ventilation (HFJV) 6 times over a period of 17 months at our institute. In this series of surgeries, we studied the effects on PaO2 and PaCO2 during HFJV of changes of either frequency or ...

This study evaluated performance of individuals exercising at a fixed workload and wearing full-facepiece respirators modified to provide expiratory resistances of 0.27, 0.47, 1.81, 4.43, and 12.27 cmH20 x s x L(-1). On five separate occasions, 15 volunteers exercised to voluntary endpoint on a treadmill at fixed speeds and grades ...

Patients with advanced muscular dystrophy frequently develop ventilatory failure. Currently respiratory impairment usually is assessed by measuring vital capacity and the mouth pressure generated during a maximal inspiratory maneuver (PI,max), neither of which directly measures ventilatory capacity. We assessed inspiratory flow reserve in 26 boys [mean (SD) age 12.8 (3.8) ...

INTRODUCTION: The stability of reentry is thought to depend on a critical balance between the spatial extent of refractory tissue in a reentrant wave (i.e., wavelength lambda) and the reentrant path length. Because considerable evidence suggests that lambda changes continuously in space and time during abrupt rate changes associated with ...

BACKGROUND: This study was designed to examine whether nostril dilatation would affect the ventilatory muscle (VM) function and the mean power output (PO) during prolonged all-out intermittent exercise. METHODS: Eight untrained young male subjects each completed 30 bouts of all-out exercise 20-sec each on a cycle ergometer interspersed with 40-sec ...

Expiratory flow limitation (FL) at rest is frequently present in chronic obstructive pulmonary disease (COPD) patients. It promotes dynamic hyperinflation with a consequent decrease in inspiratory capacity (IC). Since in COPD resting IC is strongly correlated with exercise tolerance, this study hypothesized that this is due to limitation of the ...

The Powerbreathe is an inspiratory muscle trainer promoted as improving inspiratory muscle strength (and consequently exercise performance) in athletes and patients with respiratory disease. No published evidence supports its efficacy. We performed a prospective randomized controlled study in which 12 normal subjects received either Powerbreathe training or sham training for ...

PURPOSE: Exercise prescription in patients with left ventricular systolic dysfunction (LVSD) is difficult. Exercising beyond ventilatory threshold (VT) can have negative physiologic effects; therefore, exercise prescribed above VT may be detrimental. A majority of cardiac rehabilitation programs use the Karvonen/heart rate reserve (HRR) method, rating of perceived exertion (RPE), and/or ...

Airway function is largely preserved during exercise or isocapnic hyperventilation in humans and guinea pigs despite likely changes in airway milieu during hyperpnea. It is only on cessation of a hyperpneic challenge that airway function deteriorates significantly. We tested the hypothesis that nitric oxide, a known bronchodilator that is produced ...

Fog inhalation induces cough and bronchoconstriction in patients with asthma, but only cough in normal subjects; whether it also influences the pattern of breathing is unclear. Nedocromil sodium (NCS) inhibits the cough response to inhalation of several pharmacological agents but its effects on fog-induced cough and changes in the pattern ...

To study the effect of ventilation strategy on perfluorochemical (PFC) elimination profile (evaporative loss profile; E(L)), 6 ml/kg of perflubron were instilled into anesthetized normal rabbits. The strategy was to maintain minute ventilation (VE, in ml/min) in three groups: VE(L) (low-range VE, 208 +/- 2), VE(M) (midrange VE, 250 +/- ...

The aim of this longitudinal study was to clarify the changes induced by endurance training on the breathing pattern of 13 professional cyclists (age+/-SD: 24+/-2 years; VO(2 max) approximately 75 ml x kg(-1) x min(-1)) during the three periods (rest, precompetition, and competition) of a sports season. Both the volume ...

The aim of this work was to investigate seasonal variations in oxygen consumption, ventilation, lung volumes and their relationships in healthy adult inhabitants of West Siberia. The investigations were performed in Novosibirsk. Thirty healthy male adult volunteers were studied 4 times during a year: in summer (mean monthly temperature +20 ...

The dependence of O(2) uptake (V(O(2))) kinetics on the muscle mass recruited under conditions when fiber and muscle recruitment patterns are similar following the onset of exercise has not been determined. We developed a motorized cycle ergometer that facilitated one-leg (1L) cycling in which the electromyographic (EMG) profile of the ...

INTRODUCTION: Discriminating between ventricular tachycardia (VT) with 1:1 ventriculoatrial association and sinus tachycardia can be difficult, even when assisted by intracardiac tracings. In this study, we used a new computer algorithm to perform correlation waveform analyses on intracardiac atrial electrograms to help distinguish between VT and sinus tachycardia. METHODS AND ...

Using a rapidly responding nitric oxide (NO) analyzer, we measured the steady-state NO diffusing capacity (DL(NO)) from end-tidal NO. The diffusing capacity of the alveolar capillary membrane and pulmonary capillary blood volume were calculated from the steady-state diffusing capacity for CO (measured simultaneously) and the specific transfer conductance of blood ...

To clarify the ventilatory effects of a 5-cm H2O positive end expiratory pressure (PEEP) in healthy men during incremental exercise in normoxic conditions, 22 subjects were subjected to a constant workload (0 W, 50 W, 100 W, 150 W and 200 W) on a cycle ergometer for periods of 8 ...