Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We reported a case of Kearns-Sayre syndrome with impaired respiratory regulation. A 55-year-old male was admitted to our hospital complaining of chronic progressive external ophthalmoplegia, limb muscle weakness and dyspnea. On admission, because arterial blood gas analysis showed marked alveolar hypoventilation, ventilatory response was measured and diminished chemosensitivity to both hypoxia and hypercapnia was found. His vital capacity and forced expiratory volume in 1 second were slightly decreased, and a chest X-ray film revealed a moderate degree of elevation of the bilateral diaphragm. Therefore, we considered that the diminished response to hypoxia and hypercapnia in this case was caused by an impairment of the respiratory center, as well as chemoreceptors and also the presence of respiratory muscular weakness.
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PMID:[A case of Kearns-Sayre syndrome with impaired respiratory regulation]. 175 13

Diffuse panbronchiolitis in two brothers is reported. The elder brother aged 46, was admitted in May 1983 due to severe dyspnea and productive cough, which had gradually worsened over several years. He had severe hypoxemia and hypercapnia. He died at age 47 of respiratory failure due to pseudomonas infection despite antibiotic therapy. The younger brother, at age 41, was admitted in March 1983 due to fever, productive cough, and abnormal shadows on chest X-ray films. He showed mild hypoxemia and his symptoms improved with antibiotic treatment. Since then he has been followed as an outpatient for over 7 years while taking 400 mg of Erythromycin per day, and he has had no exacerbation. These two cases had different clinical courses despite the facts that both had similar conditions of chronic sinusitis and appeared to be exposed to no special environmental or occupational hazards. These facts suggest that not only intrinsic factors, such as defenselessness of airways, but extrinsic factors such as viral, mycoplasmal, or bacterial infection may act together on the mechanisms of the onset and progression of diffuse panbronchiolitis.
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PMID:[Diffuse panbronchiolitis in two brothers with different clinical courses]. 175 47

To determine whether the intensity of dyspnea at a given level of respiratory motor output differs between bronchoconstriction and the presence of an external resistance, we compared the sensation of difficulty in breathing during isocapnic voluntary hyperventilation in six normal subjects. An external resistance of 1.9 cmH2O.1-1.s was applied during both inspiration and expiration. To induce bronchoconstriction, histamine aerosol (5 mg/ml) was inhaled until airway resistance (Raw) increased to a level approximately equal to the subject's control Raw plus the added external resistance. To clarify the role of vagal afferents on the genesis of dyspnea during both forms of obstruction to airflow, the effect of airway anesthesia by lidocaine aerosol inhalation was also examined after histamine and during external resistive loading. The sensation of difficulty in breathing was rated at 30-s intervals on a visual analog scale during isocapnic voluntary hyperpnea, in which the subjects were asked to copy an oscilloscope volume trace obtained previously during progressive hypercapnia. Histamine inhalation significantly increased the intensity of the dyspneic sensation over the equivalent external resistive load at the same levels of ventilation and occlusion pressure during voluntary hyperpnea. Inhaled lidocaine decreased the sensation of dyspnea during bronchoconstriction with no change in Raw, but it did not significantly change the sensation during external resistive loading. These results suggest that afferent vagal activity plays a role in the genesis of dyspnea during bronchoconstriction.
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PMID:Effects of bronchoconstriction and external resistive loading on the sensation of dyspnea. 177 11

1. We recorded phrenic nerve activities and single unit firing of mesencephalic neurones in unanaesthetized supracollicularly decerebrated, paralysed and ventilated cats, in which vagi and carotid sinus nerves had been ablated. We made these measurements first at low levels of respiratory drive associated with normal PCO2 levels, then with increased respiratory drive and levels of phrenic activity produced by hypercapnia or by carotid sinus nerve stimulation. 2. We found that at least a quarter of the neurones in the central tegmental field of the mesencephalon, which were irregularly tonic or silent at low respiratory drives, developed a rhythmic increase of firing associated with each respiration. There appeared to be a threshold at about 50% of maximum respiratory activity, below which the respiratory-associated rhythm did not occur. Above this level, neuronal firing increased in graded fashion with increasing magnitude of respiratory activity. The latency from onset of phrenic activity to onset of increased neuronal firing was quite long (1.0 s) at drives just above the threshold but shortened to as little as 0.3 s as drive increased towards its maximum. 3. Cutting the spinal cord at C1-C2 had no effect on the ability of increased respiratory activity to generate a respiratory-associated rhythm in mesencephalic neurones. 4. Short-lasting anaesthesia with the agent Saffan caused mesencephalic neurones to lose the respiratory-associated rhythm with little change in phrenic activity and no change in respiratory cycle timing. 5. We also found a mesencephalic response to ventilator-induced chest expansion. The latency of the response from onset of expansion, indexed by fall of airway PCO2, to onset of neurone firing was shorter (0.2 s) than that found with the respiratory-associated rhythm. In seventeen neurones we found both the respiratory-associated rhythm and the independent ventilator-associated rhythm. 6. We interpret our findings to show that the respiratory-associated rhythmic firing of midbrain neurones is not primarily involved in generation or modulation of the motor function of the respiratory oscillator. We believe, instead, that these neurones are part of a sensory pathway conveying information about the magnitude of central neural respiratory drive, as well as spinally transmitted information from receptors in the chest wall, to thalamus and cortex. We suggest that the sensation ultimately generated may be that of 'air hunger' or dyspnoea.
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PMID:Respiratory-associated rhythmic firing of midbrain neurones in cats: relation to level of respiratory drive. 189 Jun 37

Intermittent mechanical ventilation via nasal CPAP mask was provided to 13 patients admitted to this institution for exacerbation of chronic respiratory failure. Ten suffered from COPD, two suffered from obesity hypoventilation syndrome (OHS), and one from severe hypothyroidism. All except one presented with dyspnea and hypercapnia due solely to progression of their underlying disease processes. Six of the patients with COPD and the patient with hypothyroidism responded to positive pressure ventilation by mask with improvements in blood gas values and clinical status. The remaining two patients with COPD and the two patients with OHS were unable to use the system. Four of the patients with COPD and chronic respiratory failure have been subsequently maintained on daily volume ventilation via nasal mask for about 20 months with persistent clinical and physiologic improvements. Application of volume ventilation through the nasal CPAP mask is a feasible strategy for providing long-term mechanical ventilation to selected patients with COPD and respiratory failure.
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PMID:Intermittent volume cycled mechanical ventilation via nasal mask in patients with respiratory failure due to COPD. 155 51

This study evaluated the effect of chest wall vibration (115 Hz) on breathlessness. Breathlessness was induced in normal subjects by a combination of hypercapnia and an inspiratory resistive load; both minute ventilation and end-tidal CO2 were kept constant. Cross-modality matching was used to rate breathlessness. Ratings during intercostal vibration were expressed as a percentage of ratings during the control condition (either deltoid vibration or no vibration). To evaluate their potential contribution to any changes in breathlessness, we assessed several aspects of ventilation, including chest wall configuration, functional residual capacity (FRC), and the ventilatory response to steady-state hypercapnia. Intercostal vibration reduced breathlessness ratings by 6.5 +/- 5.7% compared with deltoid vibration (P less than 0.05) and by 7.0 +/- 8.3% compared with no vibration (P less than 0.05). The reduction in breathlessness was accompanied by either no change or negligible change in minute ventilation, tidal volume, frequency, duty cycle, compartmental ventilation, FRC, and the steady-state hypercapnic response. We conclude that chest wall vibration reduces breathlessness and speculate that it may do so through stimulation of receptors in the chest wall.
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PMID:Effect of chest wall vibration on breathlessness in normal subjects. 191 40

We have previously shown that the exercise performance of patients with severe chronic obstructive pulmonary disease (COPD) can be increased with the administration of oral morphine (0.8 mg.kg-1). The purpose of this study was to determine whether the administration of dextromethorphan (DXT), an antitussive structurally similar to codeine, would result in increased exercise performance and decreased dyspnoea in patients with COPD, without the side-effects of opiates. Six eucapnic patients (mean age = 66 +/- 3.8 yrs) with COPD (mean forced expiratory volume in one second (FEV1) = 1.01 +/- 0.07 l) underwent two incremental cycle ergometer tests to exhaustion (Emax) and assessment of their hypercapnic and hypoxic ventilatory responses and mouth occlusion pressure responses following first the oral administration of placebo (P) and then dextromethorphan (60 mg) in a single-blind fashion. There was no statistically significant difference in the maximal exercise performance, perceived dyspnoea (modified Borg scale), breathing pattern or expired gases after the two different treatments. In addition, the ventilatory response to CO2 production during exercise (delta VE/VCO2) and the ventilatory and mouth occlusion pressure responses to hypoxia and hypercapnia did not differ significantly after DXT as compared with after P. Indeed the exercise performance was poorer and the ventilatory responses were brisker after DXT. We conclude from this study that the administration of this opiate analogue does not improve the exercise capacity or decrease the ventilatory response of patients with COPD.
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PMID:Lack of effect of dextromethorphan on breathlessness and exercise performance in patients with chronic obstructive pulmonary disease (COPD). 193 24

The long term outcome for 88 patients with bullous emphysema who had operations was analysed from the clinical, respiratory function and occupational point of view. In order to reduce to the minimum any bias which would be likely to appear as a result of a decrease in the number of patients with time respiratory function parameters were compared to those of a restricted number of patients for whom we knew all the values for each period determined. Before the operation all the patients showed radiological signs of bullous emphysema; the respiratory function measurements in 66 of them showed bronchial obstruction with distension, hypoxaemia at rest without hypercapnia. The clinical follow up and respiratory function was spread over more years. It showed a post operative improvement in dyspnoea which was perceptible in 77% of patients at 2 years, 68% at 3 years, 60% at 4 years, 51% at 5 years, 32% at 10 years. 2/3 of the patients who were working before the operation had taken up their normal work following it. the survival levels were 86% at 1 year, 83% at 2 years, 80% at 3 years, 78% at 4 years, 77% at 5 years, 73% at 6 years, 73% at 6 years, 58% at 10 years. Of 20 patients who died 12 had died of respiratory failure. All the spirographic parameters had improved following the operation but a secondary deterioration was noted around the 5th post operative year for the vital capacity, and at the third year for residual volume, FEV 1, and the FEV 1/VC ratio as well as PAO2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Long-term outcome of surgically treated bullous emphysema]. 210 80

To determine whether the intensity of dyspnea at a given level of respiratory motor output depends on the nature of the stimulus to ventilation, we compared the sensation of difficulty in breathing during progressive hypercapnia (HC) induced by rebreathing, during incremental exercise (E) on a cycle ergometer, and during isocapnic voluntary hyperventilation (IVH) in 16 normal subjects. The sensation of difficulty in breathing was rated at 30-s intervals by use of a visual analog scale. There were no differences in the level of ventilation or the base-line intensity of dyspnea before any of the interventions. The intensity of dyspnea grew linearly with increases in ventilation during HC [r = 0.98 +/- 0.02 (SD)], E (0.95 +/- 0.03), and IVH (0.95 +/- 0.06). The change in intensity of dyspnea produced by a given change in ventilation was significantly greater during HC [0.27 +/- 0.04 (SE)] than during E (0.12 +/- 0.02, P less than 0.01) and during HC (0.30 +/- 0.04) than during IVH (0.16 +/- 0.03, P less than 0.01). The difference in intensity of dyspnea between HC and E or HC and IVH increased as the difference in end-tidal PCO2 widened, even though the time course of the increase in ventilation was similar. No significant differences were measured in the intensity of dyspnea that occurred with changes in ventilation between E and IVH. These results indicate that under nearisocapnic conditions the sensation of dyspnea produced by a given level of ventilation seems not to depend on the method used to produce that level of ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sensation of dyspnea during hypercapnia, exercise, and voluntary hyperventilation. 211 5

The tolerance of totally curarized subjects for prolonged breath hold is viewed by many as evidence that respiratory muscle contraction is essential to generate the sensation of breathlessness. Although conflicting evidence exists, none of it was obtained during total neuromuscular block. We completely paralyzed four normal, unsedated subjects with vecuronium (a non-depolarizing neuromuscular blocker). Subjects were mechanically ventilated with hyperoxic gas mixtures at fixed rate and tidal volume. End-expiratory PCO2 (PETCO2) was varied surreptitiously by changing inspired PCO2. Subjects rated their respiratory discomfort or 'air hunger' every 45 sec. At low PETCO2 (median 35 Torr) they felt little or no air hunger. When PETCO2 was raised (median 44 Torr) all subjects reported severe air hunger. They had reported the same degree of air hunger at essentially the same PETCO2 before paralysis. When questioned afterwards all subjects said the sensation could be described by the terms 'air hunger', 'urge to breathe', and 'shortness of breath', and that is was like breath holding. They reported no fundamental difference in the sensation before and after paralysis. We conclude that respiratory muscle contraction is not important in the genesis of air hunger evoked by hypercapnia.
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PMID:'Air hunger' from increased PCO2 persists after complete neuromuscular block in humans. 212 Jul 57


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