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Results 451 - 500 of 826
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Carroll J L - - 1991
In awake lambs we investigated the role of the peripheral chemoreceptors in producing dynamic ventilatory (VE) responses to CO2. The immediate VE response, within 15 s, to transient CO2 inhalation was studied in two groups: 1) five lambs before carotid denervation and 2) the same lambs after carotid denervation. The ...
Furilla R A - - 1991
Garter snakes increase ventilation in response to elevated venous PCO2 without a concomitant rise in arterial PCO2 (Furilla et al. Respir. Physiol. 83: 47-60, 1991). Elevating venous PCO2 will increase the PCO2 gradient between pulmonary arterial blood and intrapulmonary gas during inspiration, leading to a greater rate of rise of ...
Fadic R - - 1991
In pentobarbitone anesthetized cats, raising body temperature from 37 to 40 degrees C by external heat increased respiratory frequency, tidal volume, frequency of spontaneous gasps and mean inspiratory flow. It reduced end-tidal CO2 pressure, together with inspiratory and expiratory durations. After bilateral section of the carotid nerves, raising body temperature ...
Nattie E E - - 1991
Kainic acid (KA) injections into the retrotrapezoid nucleus (RTN) of anesthetized deafferented cats profoundly decreased phrenic activity (PA) and CO2 sensitivity (J. Appl. Physiol. 68: 1157-1166, 1990). In this study small electrolytic lesions of the RTN produced the same results, indicating that the KA destroyed cells. We then asked whether ...
Bidani A - - 1991
The importance of perfusate nonbicarbonate buffer capacity (beta nonHCO3) to intracapillary CO2-HCO3(-)-H+ reactions was assessed by theoretical analysis of CO2 exchange in saline-perfused pulmonary capillaries. Time courses for perfusate PCO2, [HCO3-], and [H+] were computed for capillaries containing different activities of luminal vascular carbonic anhydrase and different amounts of perfusate ...
Dunn W F - - 1991
Using the recruitment threshold technique, we measured the CO2 responsiveness of the unloaded respiratory pump in 14 mechanically ventilated patients prior to weaning. The CO2 recruitment threshold (CO2RT) was compared with the arterial CO2 tension during unassisted breathing (CO2SB) and with the PaCO2 during mechanical ventilation (CO2MV) at machine settings ...
Kasim Y A - - 1991
Many studies of Dengue Hemorrhagic Fever (DHF) have been done but only a few revealed the respiratory status. Respiratory problems arise because of plasma leakage through the damaged capillaries, causing lung edema and in turn result in hypoxemia. This later on will be compensated by a hyperventilation state. During a ...
Berkenbosch A - - 1991
We studied the peripheral ventilatory response dynamics to changes in end-tidal O2 tension (PETO2) in 13 cats anesthetized with alpha-chloralose-urethan. The arterial O2 tension in the medulla oblongata was kept constant using the technique of artificial perfusion of the brain stem. At constant end-tidal CO2 tension, 72 ventilatory on-responses due ...
Koike A - - 1991
The effect of low levels of carbon monoxide (CO) was studied during exercise in order to determine the work-rate dependent effect of CO breathing on exercise ventilation (VE). Ten normal subjects (aged 32.8 +/- 7.1 years) were studied during air breathing and air with added CO to bring carboxyhemoglobin (COHb) ...
Hachamovitch R - - 1991
BACKGROUND: The output of carbon dioxide (VCO2) is controlled by both hemodynamics and ventilation. To understand VCO2 in patients who have chronic heart failure (CHF), we studied 14 patients who had New York Heart Association functional class III failure by measurements of hemodynamics, ventilation, and arterial and venous blood gases ...
Jones B R - - 1991
A small disposable carbon dioxide detector that can be used to provide evidence of correct endotracheal tube placement is now commercially available (FEF). The device contains an indicator that changes color when exposed to carbon dioxide. This study measured the lowest concentration of carbon dioxide causing a perceivable color change ...
Erickson B K - - 1991
We investigated changes in arterial PCO2 (PaCO2) and pulmonary ventilation (VE) in normal, carotid chemoreceptor-denervated, and hilar nerve-denervated ponies during intravenous lactic acid infusion at rest and treadmill exercise at 1.8 mph-5% grade (mild) and 1.8 mph-15% grade (moderate). Lactic acid, (0.5 M) infusion of 0.10, 0.13, and 0.20 ml.min-1.kg-1 ...
Cummin A R - - 1991
The importance of carbon dioxide in the control of ventilation during exercise was tested by emptying CO2 stores by voluntary hyperventilation. Healthy subjects were studied after 3 min hyperventilation down to an end-tidal PCO2 of about 20 mmHg on a background of steady exercise at 75 W. Control runs were ...
Mercer R R - - 1991
This study addressed the question of whether variations in the volume of alveoli and alveolar ducts forming single units of ventilation can significantly influence the distribution and uptake of inspired reactive gases. Quantitative serial section analyses of vascular perfusion-fixed rat lungs were used to determine the anatomic dead space proximal ...
Takahashi E - - 1991
We examined the effect of sudden withdrawal of respiratory oscillations of arterial PCO2 (CO2 oscillations) at resting metabolic rate on the control of respiration in 11 anesthetized paralyzed vagotomized dogs in normoxic normocapnia. A double-lumen endotracheal tube was inserted so that the left and right lungs were ventilated independently. By ...
Anton W R - - 1991
STUDY OBJECTIVE: We compared the performance of the Fenem FEF end-tidal CO2 detector with the TRIMED capnometer to verify endotracheal intubation. DESIGN: The FEF indicates the presence of CO2 by the color change of a chemically treated indicator; the TRIMED uses infrared technology. Both devices were used during 60 intubations. ...
Pianosi P - - 1991
Adults with sickle cell anemia (SCA) have restrictive lung impairment, increased alveolar dead space, and hypoxemia. These factors, together with increased anaerobic metabolism, are thought to cause exercise hyperventilation. To assess the role of each of these in children, 34 patients with SCA and 16 control subjects performed pulmonary function ...
Lewis N P - - 1991
The cardiorespiratory responses to exercise and forced hyperventilation were measured in 17 unselected patients with syndrome X (angina, positive exercise test, normal coronary arteriogram, no other cardiovascular disease) and compared with those in 15 healthy subjects. Forced hyperventilation produced hypocapnia and metabolic alkalosis but no chest pain or electrocardiographic change. ...
Matsumoto H - - 1991
We investigated the ventilatory responses to hypoxia and hypercapnia in patients with essential hypertension (HT) as compared with healthy subjects (NV). Further, to evaluate the contribution of the peripheral chemoreceptors to ventilatory response, we used a withdrawal test. Hypoxic ventilatory drive (HVR) was measured as the parameter A denoting the ...
Samonte B R - - 1991
The milliwatt carbon dioxide (CO2) laser has been shown to be an effective device for performing laser-assisted microvascular anastomosis (LAMA) with consistently high patency rates, minimal tissue disruption, and rapid surgical time as well as the potential for reduced inflammation due to fewer foreign bodies (sutures) in the wound. The ...
Oku Y - - 1991
A dynamic model of the CO2 respiratory control system is proposed, which can provide a qualitative basis for predicting breathing sensations. The discomfort index, which represents breathing sensations, is assumed to be composed of two sources: the arterial CO2 level and the respiratory motor command. The respiratory controller receives inhibitory ...
McLellan T M - - 1991
The purpose of the present study was to examine the influence of a respiratory acidosis on the blood lactate (La) threshold and specific blood La concentrations measured during a progressive incremental exercise test. Seven males performed three step-incremental exercise tests (20 W.min-1) breathing the following gas mixtures; 21% O2 balance-nitrogen, ...
Poon C S - - 1991
A recent model of respiratory control suggested that the steady-state respiratory responses to CO2 and exercise may be governed by an optimal control law in the brainstem respiratory neurons. It was not certain, however, whether such complex optimization behavior could be accomplished by a realistic biological neural network. To test ...
Lynch P - - 1991
This report represents a pilot investigation of the role of chest muscle electromyographic (EMG) activity in developing panic episodes. Chest EMG activity was obtained as part of a larger study examining ventilatory differences between panic sufferers and normal controls. Frontalis EMG, heart rate, and minute ventilation (breathing rate and tidal ...
Newstead C G - - 1990
Six renal transplant recipients underwent a series of incremental exercise experiments. Minute ventilation (VE), carbon dioxide production rate (VCO2), and arterial blood chemistry were measured at rest and while subjects exercised on a stationary bicycle. Four of the subjects performed a similar experiment while exercising on a static rowing machine. ...
Pan L G - - 1990
We addressed the role of spinal afferent information in the exercise hyperpnea. Arterial PCO2 (PaCO2) was assessed in 10 normal ponies during low (1.8 mph 7% or 17% grade) or moderate (6 mph 7% grade) treadmill exercise. After control studies, bilateral spinal ablation (SA) of the dorsolateral sulcus and dorsolateral ...
Pokorski M - - 1990
The purpose of this study was to evaluate the ventilatory and cardiovascular responses to static handgrip exercise at different levels of arterial chemoreceptor activation. The study was done on 10 healthy subjects. They performed handgrip of 50% of maximal voluntary contraction on a background of either hypoxia (PE'O2 approximately 47 ...
Craske M G - - 1990
To examine the role of ventilatory response in nocturnal panic, subjects experiencing nocturnal panic were compared with those who experienced daytime panic attacks only. In particular, measures of chronic hyperventilation (baseline pCO2) and CO2 hypersensitivity (response to ventilatory challenges) were assessed. Subjective and psychophysiological measures were obtained during baseline, forced ...
Mitchell G S - - 1990
Our objectives were to determine 1) the effects of increased respiratory dead space (VD) on the ventilatory response to exercise and 2) whether changes in the ventilatory response are due to changes in chemoreceptor feedback (rest to exercise) vs. changes in the feedforward exercise stimulus. Steady-state ventilation (VI) and arterial ...
Eugenin J - - 1990
In pentobarbitone-anesthetized cats breathing spontaneously, we studied whether excision of one petrosal ganglion would modify the reflex efficacy of the remaining carotid and aortic chemoafferences in ventilatory control. Resting ventilation was not affected shortly after the ganglionectomy, but decreased sensitivities and reactivities for changes in tidal volume and respiratory frequency ...
Minnich M E - - 1990
Oxygen saturation and end-tidal CO2 tension were monitored in 15 healthy women during labor. Oxygen saturation was determined with a pulse oximeter and end-tidal CO2 with a CO2 monitor. Fetal heart rate, uterine contractions and maternal blood pressure were also monitored. End-tidal CO2 tension was followed to determine if falls ...
Maranetra N - - 1990
To determine the range of normal values of respiratory centre sensitivity and exercise tolerance in Thais, 69 healthy subjects, 18 to 72 years of age, participated in a series of tests, i.e. ventilatory drive, ventilatory response, musculo-ventilation transfer and the two-minute walking test with rating of the breathing sensation on ...
Barstow T J - - 1990
The effect of changes in metabolic rate on the dynamics of CO2 exchange among its various compartments in the human body is not well understood. We examined CO2 dynamics in six healthy male subjects using an intravenous bolus of [13C]bicarbonate. Subjects were studied while resting, during light exercise [50% of ...
Adams J M - - 1990
To determine the respiratory effects of inhibiting carbonic anhydrase in brain tissue, we infused acetazolamide (ACZ) into the cisterna magna in anesthetized rats. Three concentrations, 4.5, 45 and 450 microM in artificial cerebrospinal fluid, were infused continuously at 2 microliter/min for 20 min and the responses to CO2 rebreathing trials ...
Gilbert S B - - 1990
Total parenteral nutrition (TPN), specifically amino acid infusions, has been shown to increase the ventilatory response to inhaled CO2. The hypothesis tested was that morphine sulfate (known to depress ventilatory CO2 responsiveness) would diminish the augmented ventilatory CO2 response in patients receiving TPN. The influence of morphine on hyperoxic hypercapnic ...
Cummin A R - - 1990
Almitrine has potential as a tool for testing the physiological role of the peripheral chemoreceptor. The effects of almitrine on CO2 chemosensitivity were studied at rest and during light exercise using a constant inflow technique that avoids the hyperoxia of rebreathing methods. The steady-state ventilatory response to CO2 was measured ...
Sipinková I - - 1990
To study pulmonary gas transport in panting, expirograms of several inert and respiratory gases were simultaneously measured in panting dogs. The experiments were performed on 5 conscious dogs (mean body weight 34.4 kg) provided with a chronic tracheostomy. Panting at a mean frequency of 312/min (5.2 Hz) was induced by ...
Miyamoto Y - - 1990
This paper reviewed in short neural and humoral factors which might be responsible for inducing exercise hyperpnea. As one of the neural factors afferent signals which arise in the exercising limbs and are transmitted via group III or IV high threshold sensory fibres were involved. The other neural factor is ...
Daristotle L - - 1990
This study was designed to examine the influence of carotid body (CB) hypocapnia on ventilation by selectively perfusing the CB through an extracorporeal circuit in 19 goats. When PcbCO2 was decreased from normocapnic levels in 14 awake goats (delta PcbCO2 = 10.9 Torr), PaCO2 increased 5.6 Torr (P less than ...
Powell G L - - 1990
The carbon dioxide laser is used in the oral cavity for a variety of procedures. Although the procedures may not involve the teeth directly, precaution should be exercised to preserve their integrity. The results of this study indicate that the most limiting parameter for oral use of the CO2 laser ...
Bashir Y - - 1990
We have studied the effect of acetazolamide 500 mg bd for three days on ventilatory response to CO2 (HCVR) and hypoxia under both isocapnic and poikilocapnic conditions (isocapnic and poikilocapnic HVR) in five normal subjects. Although acetazolamide reduced calculated arterial pH (7.41 [SEM] 0.01 to 7.37 [SEM] 0.01: p less ...
Caflisch C R - - 1990
The present experiments have employed microelectrode techniques (pH and PCO2) and microcalorimetry (total CO2 concentration) to define parameters of acidification in specific structures of the rat testis and epididymis during control conditions and after administration of the carbonic anhydrase inhibitor acetazolamide (20 or 50 mg/kg). Values for in situ pH ...
Paulev P E - - 1990
In five persons the transient ventilatory response was measured to three step levels of exercise, inhaled constant fraction of CO2, and inhaled constant flux of CO2. With constant CO2 fraction inhalation (3, 5, and 7%), the transient response of the minute-ventilation (VE) is associated with on- and off-time delays (Td). ...
Hoffmann U - - 1990
Static relationships between arterial, transcutaneous and end-tidal PCO2 (PaCO2, PtcCO2, PetCO2) as well as the dynamic relationship between PetCO2 and PtcCO2 were studied during moderate bicycle ergometer exercise with and without external CO2 loading. The exercise pattern consisted of 5-min intervals of constant power at 40 W and 100 W ...
Essfeld D - - 1990
Nine subjects performed a sequence of sustained and randomised changes between 40 W and 100 W on a cycle ergometer while the end-tidal PO2 was kept close to 17.3 kPa (130 mm Hg) by means of a dynamic forcing technique (reference experiment). In a second series inspiratory CO2 was additionally ...
Mussell M J - - 1990
This paper reports the expired minute-ventilation (VE) responses of 5 subjects to three step levels in a) work rate on a bicycle ergometer (30, 50, and 70 W), b) inhaled constant fraction (CF) of CO2 (3, 5, and 7%), and c) inhaled constant flux (CFlux) of CO2 (0.3, 0.4, and ...
Gorissen-Bosselmann S E - - 1990
During twenty animal experiments the effectiveness of the gas exchange during extracorporeal membrane oxygenation (ECMO) was evaluated. Arteriovenous, venovenous and venoarterial perfusion systems were compared. While PO2 saturation values were sufficient in all three groups the PO2 values were significant higher during arteriovenous perfusion (84.22 +/- 3.5 mmHg) compared to ...
D'Urzo A D - - 1990
The effect of oral caffeine on resting ventilation (VE), ventilatory responsiveness to progressive hyperoxic hypercapnia (HCVR), isocapnic hypoxia (HVR), and moderate exercise (EVR) below the anaerobic threshold (AT) was examined in seven healthy adults. Ventilatory responses were measured under three conditions: control (C) and after ingestion of either 650 mg ...
Douse M A - - 1989
The effects of body temperature (Tb) on pulmonary stretch receptor (PSR) and CO2-sensitive intrapulmonary chemoreceptor (IPC) response characteristics may have important effects on ventilatory control in reptiles. In this study, three questions were addressed: (1) what are the effects of Tb on PSR and IPC responses to airway pressure (Paw) ...
Swaminathan S - - 1989
Infants with myelomeningocele have abnormalities in ventilatory control. To determine whether these persist into later life, we studied 14 patients with myelomeningocele and Arnold-Chiari malformation (age 18.0 +/- 0.8 (SE) years), and compared them with 14 control subjects (age 24.0 +/- 0.9 years). Pulmonary function and ventilatory muscle strength did ...
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