Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: HUMANGGP:003739 (CO2)
 48,959 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Death in the late stage of Duchenne muscular dystrophy is most frequently a consequence of respiratory failure. Since muscles of ventilation become weakened the bellows mechanism fails insidiously. Patients exhibit symptoms of ventilatory insufficiency, the first to be noticed are those associated with CO2 retention: dyspnea, nightmares, increased heart rate, and increased blood pressure. Ten patients with late stage Duchenne muscular dystrophy have been supplied with mechanical aid for ventilatory assistance. The age of onset of respiratory distress needing mechanical assistance varied from 10 to 20 years. Meaningful survival after allegedly reaching the end stage has been from 2 to 7.5 years with an average of 3.4 years. With a caring family, these patients can have a meaningful life, even though they require continuous mechanical ventilatory aid.
 ...
PMID:Mechanical ventilation of patients with late stage Duchenne muscular dystrophy: management in the home. 45 24

Transpulmonary pressure, lung volume, and flow rate were recorded in two healthy subjects performing graded exercise between 1 and 10 ATA. At simulated depths greater than 4 ATA, exercise was terminated by severe choking dyspnea at levels of work, oxygen consumption, heart rate, and ventilation significantly lower than during maximum exercise at 1 ATA. Comparison of exercise ventilatory mechanics with corresponding maximum expiratory flow-volume and expiratory isovolume pressure-flow (IVPV) curves demonstrated that the reduced aerobic capacity was associated with expiratory flow limitation. We conclude that dynamic airways compression limited aerobic capacity at these depths by causing a persistent cough making it seem difficult to continue exercise. Analysis of the IVPV curves suggested that maximum expiratory flow was reduced at depth below the rate allowing adequate exercise ventilation because increased gas density raised the resistance downstream from equal pressure points. At each level of sumbaximal exercise, end-expiratory position and alveolar CO2 tension increased with ambient pressure due primarily to the density dependence of airways resistance. In these respects, healthy subjects breathing dense gas resemble patients with obstructive lung disease.
 ...
PMID:Exercise ventilatory mechanics at increased ambient pressure. 63 63

A technique has been developed which enables respiratory motor output to be measured independently of lung mechanics. The maximum rate of change of pressure at the mouth during initial transient occlusion of the airway, (d P/dt) max., represents the rate of isometric force development by the inspiratory muscles. This technique was used to study central CO2 sensitivity in 40 patients with chronic airways obstruction. Subnormal CO2 sensitivity was associated with chronic cough and sputum production, relatively mild dyspnoea, raised arterial CO2 tension, hypoxaemia, polycythaemia and cor pulmonale. Normal CO2 sensitivity was associated with severe dyspnoea, normal blood gas tensions, and allergic features.
 ...
PMID:The relationship between central carbon dioxide sensitivity and clinical features in patients with chronic airways obstruction. 86 74

Seven normal male subjects performed 5-min bicycle exercise ranging from 50-100% maximum oxygen uptake at 4 ATA and three were also studied at 6 ATA. At all pressures, the subjects breathed 0.2 ATA O2 plus nitrogen. All subjects were able to perform maximum work at all pressures. No pressure-dependent variations in heart rate, O2 uptake, or CO2 output were noted. At both 4 and 6 ATA, ventilation was decreased at exercise levels greater than 80% maximum O2 uptake. The magnitude of the decrease was not great, however, and signified only minor CO2 retention. In some instances exercise ventilation closely approached the 15-S maximum breathing capacity and these subjects noted severe dyspnea, possibly due to dynamic compression of large airways. In three subjects, respiratory frequency was measured as well as minute ventilation; this relationship did not change with depth. Subjects performing heavy exercise at 6 ATA noted disturbances of consciousness, presumably due to N2 narcosis.
 ...
PMID:Exercise tolerance at 4 and 6 ATA. 95 29

If diagnosis of chronic thromboses of pulmonary arteries is usually easy at the stage of confirmed chronic pulmonary heart, it is not so when dysponea is the only symptom of the disease. The authors report 30 cases of chronic thrombosis and remark that if respiratory alkalosis is very frequent, hipoxemia is often missing. On the other hand they observe 27 times out of 28 an increase of CO2 alveoloarterial difference; measuring the CO2 difference appears a safe and reliable test for detecting chronic thrombosis. It should take place in every systematic complete examination of unexplained dyspnoea.
 ...
PMID:[Respiratory function in chronic obstructions of the large pulmonary arteries (study of 30 cases]. 100 61

A 38-year-old patient with effort dyspnea, somnolence, cianosis and cor pulmonale is presented. Chest roentgenograms and lung function studies suggested the diagnosis of pulmonary fibrosis. The patient showed also severe hypercapnia with normal resting ventilation and ventilatory response to exercise lower than usual for this condition. Autopsy confirmed the clinical diagnosis. This subject may belong to the growing group of patients where CO2 retention is not explained by their pulmonary pathology.
 ...
PMID:Idiopathic interstitial pulmonary fibrosis with hypercapnia. 117 39

1. The effect of breathing an anaesthetic aerosol of 5% bupivacaine hydrochloride has been assessed in dog and man. 2. In the dog, the cough reflex was abolished and the Hering-Breuer inflation reflex severely impaired or abolished; breathing became slower and deeper; no pathological changes were found in the lungs of these dogs. 3. In man, no untoward effects resulted from a 10 min period of aerosol inhalation; there were no systematic effects on airway resistance or lung volumes and the cough reflex in response to either tactile or chemical (citric acid aerosol) stimulation was invariably abolished. The Hering-Breuer inflation reflex was impaired, but this was not associated with any change in resting ventilation. The Ve/CO2 response was enhanced after aerosol anaesthesia; subjects felt an exaggerated dyspnoea. The aerosol anaesthesia abolished the afferent pathway of a reflexly elicited bronchoconstriction in one subject. There was no effect on the ability to hold the breath, or on the quality of the associated sensation. 4. Control aerosols of sodium chloride solution or phosphate buffer produced no effects. Control experiments with intravenous infusions of bupivacaine proved that none of the effects could have been produced by systemic effects of the absorbed anaesthetic. 5. Plasma concentrations of bupivacaine in man did not exceed a recognized toxic level. The experiments demonstrate a safe reversible anaesthesia of the airways in man lasting for a period of 10-20 min.
 ...
PMID:The effect of anaesthesia of the airway in dog and man: a study of respiratory reflexes, sensations and lung mechanics. 127 53

The aim of the study was to ascertain the reasons which lead to discontinuance of exercise on the bicycle ergometer in healthy untrained subjects and to assess the dependence of dyspnea on breathing pattern and on ventilation. The physical load was progressively increased to the maximum in 11 volunteers at the age of 21 +/- 1 years. During exercise some cardiovascular and respiratory parameters were measured simultaneously with the degree of dyspnea. Breathlessness was rated by means of a scaling according Borg, where 0 indicates no, 10 maximal dyspnea. Dyspnea was not a reason for termination of maximal exercise, its value being 6 +/- 1.9 in men and 4.5 +/- 2.3 in women at the end of exercise. The reasons for termination of exercise were the sensations of general fatigue and pain in lower the extremities. The degree of dyspnea correlated with the minute ventilation, with the decrease of end-tidal CO2 concentration, with the duration of exercise and some other values. The grading varied among subjects. The mathematical dependence of dyspnea was summarised by two regression equations, one without suppression, the other with suppression of interindividual differences in responses.
 ...
PMID:Breathlessness in healthy subjects at physical load. 130 83

To identify the effect of chronotropic responsive cardiac pacing on ventilatory responses to exercise, 9 patients with chronotropic incompetence underwent paired cardiopulmonary exercise tests with fixed demand rates (AAI, VVI) and chronotropic responsive (AAIR, VVIR, DDD) pacing modes. Compared with fixed rate pacing, chronotropic responsive pacing increased peak oxygen uptake and delayed the attainment of the anaerobic threshold (AT) with a higher level of oxygen consumption (p < 0.01). Dyspnea was a major symptom that limited exercise time in 7 patients with fixed rate pacing, which was prominent with chronotropic responsive pacing. Ventilation (VE) and the ratio of ventilation to CO2 production (VE/VCO2) were consistently higher with fixed rate pacing during exercise. To compare the responses between the 2 pacing modes with the same work loads under aerobic conditions, we measured ventilatory variables one min prior to the AT as obtained with fixed rate pacing. When switching the pacing mode from fixed rate pacing to chronotropic responsive pacing, VE and VE/VCO2 decreased significantly from 22.0 +/- 7.8 to 19.8 +/- 6.8 l/min, and from 37.4 +/- 5.4 to 33.6 +/- 5.2, respectively. Tidal volume did not change, but respiratory frequency decreased more with chronotropic responsive pacing (p < 0.05). Although peak VE did not differ between the 2 pacing modes, VE/VCO2 decreased more with chronotropic responsive pacing (p < 0.01). Respiratory frequency decreased and tidal volume increased more with chronotropic responsive pacing (p < 0.05). This study suggests that chronotropic responsive cardiac pacing attenuates exertional dyspnea by improving ventilatory responses to exercise as well as increasing the cardiac output in patients with chronotropic incompetence.
 ...
PMID:[Effects of chronotropic responsive cardiac pacing on ventilatory response to exercise in patients with bradycardia]. 133 9

To identify the effect of chronotropic responsive cardiac pacing on the ventilatory response to exercise, ten selected patients with complete atrioventricular block underwent paired cardiopulmonary exercise tests in fixed rate ventricular (VVI) and dual chamber (DDD) or rate responsive ventricular (VVIR) pacing modes. Compared to VVI pacing, DDD or VVIR pacing increased peak oxygen uptake (P < 0.005) and augmented anaerobic threshold (P < 0.001). In eight patients, dyspnea was the major symptom limiting exercise with VVI pacing and this was markedly attenuated with DDD or VVIR pacing. In all patients, ventilation (VE) and the ratio of ventilation to CO2 production (VE/VCO2) were consistently higher with VVI pacing during exercise. To compare the response of the two pacing modes at the same workloads in an aerobic condition, we measured ventilatory variables 1 minute prior to the anaerobic threshold obtained with VVI pacing. When DDD or VVIR pacing was compared with VVI pacing, VE and VE/VCO2 significantly decreased from 20.5 +/- 5.3 L/min to 18.3 +/- 5.0 L/min (P < 0.005) and from 35.9 +/- 5.8 to 31.9 +/- 5.0 (P < 0.001), respectively. Respiratory frequency rose significantly more with VVI pacing (P < 0.001) despite an unchanged tidal volume. Although peak VE did not differ between the two pacing modes, VE/VCO2 at the peak exercise increased significantly more with VVI pacing (P < 0.005). Respiratory frequency also rose more with VVI pacing (P < 0.005) and tidal volume did not change. This study suggests that chronotropic responsive cardiac pacing attenuates the exertional dyspnea by improving the ventilatory response to exercise as well as increasing the cardiac output in patients with complete atrioventricular block.
 ...
PMID:Effects of chronotropic responsive cardiac pacing on ventilatory response to exercise in patients with complete AV block. 138 60


1 2 3 4 5 6 7 8 9 10 Next >>