Search Results
Results 201 - 250 of 817
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Farmer C G - - 2000
Low respiratory exchange ratios (R) occur in reptiles. In crocodilians they have been attributed to the loss of respiratory CO2 into the urine and to the immediate exercise-history of an animal. In this study, expired ventilation (V(E)), oxygen consumption (V(O2)), and carbon dioxide excretion (V(CO2)) were measured during recovery from ...
Brauner C J - - 2000
A quantitative analysis of CO2 transport and excretion was conducted in seawater acclimated rainbow trout (Oncorhynchus mykiss) swimming at different sustained swimming velocities. CO2 excretion increased linearly with cardiac output during exercise but arterial P(CO2) (Pa(CO2)) and total CO2 levels also increased indicating a diffusion limitation to CO2 excretion. The ...
Pedersen M E - - 1999
1. Somatostatin depresses the ventilatory response to hypoxia (AHVR). This study sought to determine whether somatostatin also reduced the peripheral chemoreflex sensitivity to hypercapnia, and if so, whether this was related to the reduction in AHVR. 2. Nine subjects completed the study. AHVR and the ventilatory responses to hypercapnia under ...
Entin P L - - 1999
At the onset of exercise, adult animals increase ventilation to match or exceed the metabolic requirement. This error-free regulation of arterial blood gas tensions may be attributable to 'adaptive feed-forward control'--respiratory control based on experience gained in infancy. This hypothesis predicts that neonates exhibit hypercapnia at the onset of exercise. ...
Barra Bisinotto F M - - 1999
PURPOSE: To determine the effect of heat and moisture exchange (HME) on the tracheobronchial tree (TBT) using a unidirectional anesthesic circuit with or without CO2 absorber and high or low fresh gas flow (FGF), in dogs. METHODS: Thirty-two dogs were randomly allocated to four groups: G1 (n=8) valvular circuit without ...
Bradley S - - 1999
BACKGROUND: In patients with cystic fibrosis (CF), it has been proposed that hypoxemia and hypercapnia occur during episodes of stress, such as exercise and sleep, and that respiratory muscle weakness because of malnutrition may be responsible. METHODS: Pulmonary function, respiratory muscle strength, and nutrition were assessed and correlated with the ...
Ozcelik O - - 1999
The lactate threshold is a widely used and, at times, controversial construct in exercise physiology and pathophysiology. Its non-invasive estimation during incremental exercise depends upon CO2 output increasing as a function of O2 uptake, i.e. 'V-slope', as a result of bicarbonate buffering during the lactic acidosis. However, we hypothesised that ...
von Schéele B H - - 1999
Hyperventilation (HV) occurring out of appropriate context, under some circumstances, can be potentially harmful to health. Nixon (1994) discusses convincingly the negative effects of long-term HV on the alkaloid buffering system and the potential challenge to a person's health status. Using capnography to measure respiration, percent expired CO2, to determine ...
Loewenstein R - - 1999
The concentration of expired oxygen and carbon dioxide that a rescuer may give during cardiopulmonary resuscitation was originally determined without adjusting for conditions that can exist in real life. This study was devised to investigate how simulated field conditions might effect the concentrations of these gases that a rescuer would ...
Serra R - - 1999
The authors illustrate the application possibilities in occupational and preventive medicine of a recently computerized system for the evaluation of peripheral ventilatory non-homogeneities with or without alveolar air trapping. The method consists of an improved individual multiple breath by breath test utilizing the analysis of the respiratory gases CO2 and ...
Scheuermann B W - - 1999
The effect of carbonic anhydrase inhibition with acetazolamide (Acz) on CO2 output (VCO2) and ventilation (VE) kinetics was examined during moderate- and heavy-intensity exercise. Seven men [24 +/- 1 (SE) yr] performed cycling exercise during control (Con) and Acz (10 mg/kg body wt iv) sessions. Each subject performed step transitions ...
Yunoki T - - 1999
In order to clarify the kinetics of excess CO2 output during and after intensive exercise, six male subjects were each instructed to perform 40-, 60- and 80-s cycle ergometer exercises (282 +/- 9 W, 90 rpm). Ventilation and gas exchange parameters were recorded breath-by-breath, and lactate concentration (La) was repeatedly ...
Böning D - - 1999
Before and 7-12 days after an Himalayan expedition CO2 equilibration curves were determined in the blood plasma of 12 mountaineers by in vitro and in vivo CO2 titration; in vivo osmolality changes (delta Osm x deltaPCO2(-1), deltaOsm x delta pH(-1), where PCO2 is the partial pressure of CO2) during the ...
Warburton D E - - 1999
For exercise physiologists and sport cardiologists, one of the greatest challenges is to develop a valid, reliable, noninvasive and affordable measure of cardiac output (Q). There are several techniques available to measure Q during exercise conditions. These procedures generally provide accurate and reliable determinations of Q during submaximal exercise, but ...
Ohuchi H - - 1999
To investigate the difference in ventilatory response to exercise between children and young adults, we administered a treadmill progressive exercise test to seven boys (aged 8 to 11 y [group A]) and six male young adults (aged 14 to 21 y [group B]), who had a history of Kawasaki disease ...
Powell M E - - 1999
BACKGROUND AND PURPOSE: Carbogen (95%O2, 5%CO2) is being used in clinical trials as a hypoxic radiosensitiser. Tolerance to carbogen can be a problem, this study compares tumour oxygenation during inhalation of hyperoxic gas containing either 2% or 5% CO2. MATERIALS AND METHODS: Tumour pO2 was measured in 16 patients using ...
Smith S A - - 1999
PURPOSE: Eight subjects, aged 27.0+/-1.6 yr, performed incremental workload cycling to investigate the contribution of skeletal muscle mechano- and metaboreceptors to ventilatory control during dynamic exercise. METHODS: Each subject performed four bouts of exercise: exercise with no intervention (CON); exercise with bilateral thigh cuffs inflated to 90 mm Hg (CUFF); ...
Bellone A - - 1999
The objective of the study was investigate the pulmonary gas exchange response to exercise in 16 male patients with chronic heart failure (CHF) due to previous myocardial infarction and left ventricular dysfunction (ejection fraction < 45%). All patients underwent a symptom-limited exercise test during which cardiac frequency (fC), tidal volume ...
Light R W - - 1999
STUDY OBJECTIVE: The purpose of this study was to determine whether the administration of sodium bicarbonate to normal individuals would increase their PaCO2 and thereby decrease the ventilatory requirements at a given workload. DESIGN: In this double-blind crossover study, six normal men ingested either 3 mEq/kg NaHCO3 or 1 mEq/kg ...
Henderson D R - - 1999
Fluoxetine (Prozac) inhibits serotonin (5-HT) re-uptake. thereby enhancing serotonergic effects. Since serotonin is known to affect ventilation in a variety of circumstances, we investigated the effects of chronic serotonin re-uptake inhibition with fluoxetine on selected ventilatory responses including: (1) eupnea; (2) the hypercapnic ventilatory response at rest; (3) the exercise ...
Babb T G - - 1999
Mechanical ventilatory constraints in aging, lung disease, and obesity; perspectives and brief review. Med. Sci. Sports Exerc., Vol. 31, No. 1 (Suppl.), pp. S12-S22, 1999. One of the most difficult tasks of cardiopulmonary exercise testing is to determine the influence of ventilatory limitations on the ventilatory response to exercise. Currently ...
Kintner D B - - 1999
A unique method for simultaneously measuring interstitial (pHe) as well as intracellular (pHi) pH in the brains of lightly anesthetized rats is described. A 4-mm microdialysis probe was inserted acutely into the right frontal lobe in the center of the area sampled by a surface coil tuned for the collection ...
Scheuermann B W - - 1998
The fall in end-tidal and arterial P(CO2) may be delayed relative to the lactate threshold (LT) or absent, depending on the slope of the ramp exercise function. Ventilation (VE), gas exchange (V(O2), V(CO2)) and acid-base status were examined during slow (SR, 8 W x min(-1)) and fast (FR, 65 W ...
Tschernko E M - - 1998
Many patients with emphysema are able to meet ventilatory demands during resting conditions, but they show severe limitations during exercise. To examine the effect of lung volume reduction (LVR) surgery on exercise performance and the mechanism of possible improvement, we measured ventilatory mechanics (pulmonary resistance [RL], work of breathing [WOB], ...
Buerk D G - - 1998
It is hypothesized that carotid body chemosensory activity is coupled to neurosecretion. The purpose of this study was to examine whether there was a correspondence between carotid body tissue dopamine (DA) levels and neuronal discharge (ND) measured from the carotid sinus nerve of perfused cat carotid bodies and to characterize ...
Pan L G - - 1998
The purpose of the present study was to determine the effect on breathing in the awake state of carotid body denervation (CBD) over 1-2 wk after denervation. Studies were completed on adult goats repeatedly before and 1) for 15 days after bilateral CBD (n = 8), 2) for 7 days ...
Herselman M J - - 1998
Four dry and four lactating (wk 6 of lactation) Alpine does [50.5 +/- 2.2 and 45.9 +/- 2.2 kg of initial body weight (BW), respectively] that consumed a 67% alfalfa diet for ad libitum intake were used 1) to compare estimates of CO2 entry rate (via continuous infusion of NaH13CO3 ...
Cloosterman S G - - 1998
BACKGROUND: Dyspnoea is a common and disabling symptom in patients with cardiopulmonary disease. Unfortunately the mechanisms that produce dyspnoea are still poorly understood. The relationship between dyspnoea and the load on the ventilatory muscles, chemical drive, and ventilatory indices was therefore assessed in patients with obstructive pulmonary disease during an ...
Sommer L Z - - 1998
Many clinical and research situations require maintenance of isocapnia, which occurs when alveolar ventilation (V'A) is matched to CO2 production. A simple, passive circuit that minimizes changes in V'A during hyperpnoea was devised. It is comprised of a manifold, with two gas inlets, attached to the intake port of a ...
Bar-Joseph G - - 1998
OBJECTIVES: During cardiopulmonary resuscitation (CPR), elimination of CO2 was shown to be limited by low tissue perfusion, especially when very low perfusion pressures were generated. It has therefore been suggested that sodium bicarbonate (NaHCO3), by producing CO2, might aggravate the hypercarbic component of the existing acidosis and thereby worsen CPR ...
Boggs D F - - 1998
Armadillos have a low resting metabolic rate and high hemoglobin affinity for their size, a rigid carapace and a semi-fossorial life style. These characteristics could contribute to unusual respiratory responses to hypoxia and hypercapnia which were investigated in this study. Ventilatory and oxygen consumption responses of six adult unanesthetized armadillos ...
Di Giulio C - - 1998
The hypothesis that the maximal response to pCO2 of carotid body chemoreceptors would be the same regardless of pO2, if the receptor molecule behaves like a hemoglobin molecule, was investigated using single or a few fiber carotid body chemoreceptors in cats in vivo which were anesthetized and artificially ventilated. In ...
Lejuez C W - - 1998
Four college students were exposed to a Sidman avoidance procedure to determine if an avoidance contingency involving 20% carbon dioxide-enriched air (CO2) would produce and maintain responding. In Phase 1, two conditions (contingent and noncontingent) were conducted each day. These conditions were distinguished by the presence or absence of a ...
Phatak M S - - 1998
The normal respiratory responses and changes in acid base status in twenty normal height, weight and age matched subjects were studied; using Auto Spiro AS 300 spirometer for ventilatory parameters and NOVA stat profile 3 analyser for gas analysis. Each subject performed a progressive incremental treadmill exercise by Bruce protocol ...
Cao K - - 1998
It has been reported that injection of somatostatin into the brain-stem will lead to apnoea in animals. The aim of this study was to determine whether peripheral administration of octreotide, an analogue of somatostatin, could influence the control of breathing. We measured the tidal volume, respiratory rate and ventilatory response ...
Luebbe N - - 1998
The aim of the present study was to investigate the effect of intravenously (i.v.) administered fentanyl and clonidine on ventilation in 12 healthy male volunteers (age 30.8 +/- 4.9 years) who either received fentanyl alone (1.5 > or = micrograms kg-1) or fentanyl (1.5 > or = micrograms kg-1) in ...
Beaufort-Krol G C - - 1998
Substrate oxidation by various organs in animals as well as in humans is usually studied by experiments in which radioactively labeled substrates are used and the production of 14CO2 is measured. In vivo, substrate oxidation by an organ has, up to now, not been determined by means of stable isotopes. ...
Hoffmann U - - 1998
As part of a joint NASA-ESA-DARA study on the effects of chronically increased CO2 concentrations in ambient air, changes in parameters indicating aerobic capacity were investigated by cycle ergometry. Two potential sources for reductions of aerobic capacities were hypothesized: 1) the adaptations to CO2 such as reduction in H(+)-buffer capacities ...
Elliott A R - - 1998
Alterations in ventilation and the chemoreceptor response to CO2 during 23 d of 1.2% inspired CO2 were studied in four male subjects. Resting ventilation (VE), tidal volume (VT), respiratory frequency (fR), inspired and end tidal O2 and CO2 and the hypercapnic ventilatory response (HCVR) measured by CO2 rebreathing were measured ...
Dekker T - - 1998
Field studies on responses of two mosquito sibling species, Anopheles arabiensis Patton and An. quadriannulatus Theobald, to a man, a calf and different release rates of carbon dioxide (man, calf and cow equivalents) were conducted in north-eastern South Africa. Various combinations of baits were compared in two-choice tests, using two ...
Habedank D - - 1998
The ventilatory equivalent for CO2 defines ventilatory efficiency largely independent of metabolism. An impairment of ventilatory efficiency may be caused by an increase in either anatomical or physiological dead space, the latter being the most important mechanism in the hyperpnoea of heart failure, pulmonary embolism, pulmonary hypertension and the former ...
Loeppky J A - - 1998
BACKGROUND: Measurements of pulmonary gas exchange are especially sensitive to low levels of CO2 in the environment; this is an important consideration in measurements in enclosed spaces. METHODS: In order to determine the responses to these low levels, subjects were exposed in five studies to partial pressures of inspired CO2 ...
Kazama T - - 1998
Tension pneumoperitoneum may force gas into a small injured vessel if the opening is kept patent by surrounding tissues. However, the amount of carbon dioxide (CO2) that penetrates through injured or noninjured peritoneum has not been systematically determined. In 25 patients undergoing elective laparoscopic ultrasonography and cholecystectomy, CO2 output (VCO2) ...
Mucci P - - 1998
Exercise-induced hypoxaemia (EIH) in master athletes may be related to a diminished exercise hyperpnoea. The aim of this study was to determine whether EIH is associated with a change in the sensitivity of the ventilation response to activation of the central chemoreceptors. The ventilation response to CO2 was measured in ...
Nakata Y - - 1998
We have compared the differences between end-tidal PE'CO2 and arterial PaCO2 carbon dioxide partial pressures during general anaesthesia using either a cuffed oropharyngeal airway (COPA) or a tracheal tube (TT) in spontaneously breathing adult patients. After induction of anaesthesia, a COPA was inserted in 20 patients who were allowed to ...
Neven L G - - 1998
Fifth-instar codling moth, Cydia pomonella (L.), larvae were exposed to 10 simulated heat treatments of apples and pears and CO2 levels were monitored as a measure of respiration. Marked increases in respiration rates (microliter CO2/mg/min) were noted during these treatments. Respiration peaked between 3.5 and 4.8 microliters CO2/mg/min; the amount ...
Tansley J G - - 1998
Ventilation (VE) rises throughout 40 min of constant elevated end-tidal PCO2 without reaching steady state (S. Khamnei and P. A. Robbins. Respir. Physiol. 81: 117-134, 1990). The present study investigates 8 h of euoxic hypercapnia to determine whether VE reaches steady state within this time. Two protocols were employed: 1) ...
Schneider D A - - 1998
The purpose of the present study was to determine whether the linear relationship between CO2 output (VCO2) and pulmonary ventilation (VE) is altered during incremental cycling performed after exercise-induced metabolic acidosis. Ten untrained, female subjects performed two incremental cycling tests (15 W x min(-1) up to 165 W) on separate ...
Pérez Fontán J J - - 1998
We analyzed the changes induced by central chemoreceptor stimulation on the lung resistances and phrenic neurogram of anesthetized newborn (3-6 days, n = 9) and 9 week old lambs (n = 3). Starting from hypocapneic apnea, 5% CO2 inhalation evoked a reversible increase in total lung resistance in both newborn ...
Passe D H - - 1997
The effects of carbonated beverages on sensory acceptability and voluntary fluid intake after exercise were examined. The level of carbonation in a 6% carbohydrate (CHO) electrolyte drink was systematically varied (0, 1.1, 2.3, and 3.0 volumes of CO2), and its impact was assessed in 52 adults following 30 min of ...
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