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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have studied arterial PO2, PCO2, and hydrogen ion and electroencephalogram during sleep in 10 patients with stable severe chronic respiratory failure. As a group the patients slept badly. Sleep was associated with a worsening of hypoxia and no significant change in PCO2 and H+. Two patients were restudied, receiving oxygen therapy overnight. Both had improved sleep but one, who had an intact hypoxic drive to breathing, developed marked hypercapnia and acidosis when his PO2 was restored to normal during sleep; the other, who had no hypoxic drive to breathing, developed no more hypercapnia or acidosis during sleep when breathing oxygen than when breathing air. Oxygen therapy may improve sleep disturbance in these patients, but its effect on the drive to breathing during sleep should be considered if severe hypercapnia and acidosis are to be avoided.
Thorax 1976 Dec
PMID:Arterial blood gas tensions, hydrogen ion, and electroencephalogram during sleep in patients with chronic ventilatory failure. 1 11

Sixteen male patients with stable chronic obstructive airways disease were separated into two groups of eight according to arterial carbon dioxide tensions. Hypercapnia was associated with lower arterial oxygen tensions, higher red cell volume, and increased weight, while normocapnic subjects were decidedly thin. The considerable difference in body weight between the two groups could not be explained by variation in caloric intake, and malabsorption was excluded as a cause of weight loss in the underweight subjects. Serum tri-iodothyronine, thyroxine, cortisol, and oestradiol concentrations were similar and normal in each group, but both groups had significantly low testosterone values as compared with controls, values in the hypercapnic being appreciably lower than in the normocapnic group. The adrenal androgen dehydroepiandrosterone was significantly high in the normocapnic group and low in the hypercapnic group compared with controls. Serum pituitary luteinising and follicle stimulating hormones were normal, but three hypercapnic individuals had high serum prolactin values. Early morning urinary aldosterone values were significantly higher in the hypercapnic than in the normocapnic group. Such hormone comparisons have not previously been made in subjects with chronic obstructive airways disease grouped according to arterial blood gas values, and it is concluded that major alterations in adrenal and testicular function may occur, possibly due to pituitary suppression from hypoxia. Such hormonal changes might in part account for the contrasting alterations in body habitus found in this condition.
Thorax 1979 Dec
PMID:Diet, absorption, and hormone studies in relation to body weight in obstructive airways disease. 54 19

In a group of patients with chronic bronchitis, repeated night sedation with 10 mg nitrazepam produced a fall in central respiratory drive and a steady rise in arterial carbon dioxide tension. The changes produced over a five-day period were not clinically important, except in two patients who were already hypercapnic before receiving nitrazepam. The use of this drug in patients with carbon dioxide retention should be avoided.
Thorax 1978 Feb
PMID:Depression of central respiratory drive by nitrazepam. 64 47

A consecutive series of ten patients with chronic bronchitis and hypercapnia were studied. All seven patients with chronic hypercapnia and one patient with intermittent hypercapnia showed evidence on skull radiographs of raised intracranial pressure. In five male and three female chronic bronchitics matched for age and ventilatory impairment, but without hypercapnia, no such radiological abnormalities were shown. The clinical significance and pathophysiology of this hitherto unreported finding is discussed. It would appear that in some cases the chronicity of hypercapnia may be diagnosed from a radiograph of the pituitary fossa.
Thorax 1978 Dec
PMID:Chronic hypercapnia and radiological changes in the pituitary fossa. 74 95

Seventeen male patients with chronic obstructive airways disease in remission were separated into two groups according to arterial carbon dioxide tensions. Hypercapnia was associated significantly with hypoxia and increased red cell volume whereas normocapnia was not. Normocapnic patients were significantly lighter than those with hypercapnia. Total body potassium (TBK) measured by the whole body monitor was significantly low in two of the patients studied (P less than 0.005). The mean value for TBK for the normocapnic group as a whole was significantly low (P less than 0.005), but the mean value for the hypercapnic group was not. Serum potassium and erythrocyte potassium concentrations were normal even when TBK was low, and diuretics had no apparent influence on these potassium values. Of four patients (two in the series and two others) who had TBK measured after a recent episode of cor pulmonale, three had significantly low values. The only previous studies using a whole body monitor to measure TBK in chronic obstructive airways disease found no such low values, though other workers estimating exchangeable potassium by isotope dilution techniques had found evidence of gross potassium depletion. It is concluded that low TBK does indeed occur in patients with chronic obstructive airways disease and that gross depletion is more likely to follow an episode of cor pulmonale.
Thorax 1978 Dec
PMID:Potassium studies in chronic obstructive airways disease. 74 98

The airway pressure 100 msec after the onset of an inspiratory effort against a closed airway (P100, occlusion pressure) is theoretically a more accurate index of respiratory neuron motor output than ventilation. Occlusion pressure and ventilation responses to hypercapnia were compared in repeated trials in 10 normal subjects while in the seated and supine positions. During progressive hypercapnia changes in P100 were also compared to changes in tidal volume and inspiratory airflow. These studies show that occlusion pressure increases linearly with hypercapnia in both sitting and supine subjects. Changing from the seated to the supine position, or vice versa, had no significant effect on either ventilation or occlusion pressure responses to CO2. Correlations between P100 and ventilation or airflow rate were significantly higher than correlations between P100 and tidal volume or breathing frequency. Intermittent random airway occlusion had no effect on either ventilation or pattern of breathing during hypercapnia. Occlusion pressure responses were no less variable than ventilation responses in groups of subjects whether studied seated or supine. However, maintenance of a constant moderate breathing frequency (20 breaths per minute) reduced the interindividual variability in ventilation and occlusion pressure responses to hypercapnia.
Thorax 1977 Apr
PMID:Comparison of occlusion pressure and ventilatory responses. 86 36

Breath holding was used as the basis of a simple test of respiratory chemosensitivity. Breath holding was begun at selected degrees of hypercapnia produced by CO2 rebreathing. In 16 healthy control subjects there was a linear regression of the log of breath-holding time on the PCO2 at the start of breath holding. Breath-holding time (BHT) and the slope of a log BHT/Pco2 plot were closely correlated with the ventilatory response to CO2. In five cases of the idiopathic hypoventilation syndrome, CO2 retention and reduced ventilatory response to CO2 were accompanied by prolonged breath-holding time and the regression of log BHT on Pco2 was abnormally flat. However, in 17 patients with chronic airways obstruction, breath-holding time was never prolonged and the log BHT/Pco2 relationship was normal, even though 13 had a diminished ventilatory response to CO2 and four had chronic CO2 retention. It is concluded that the BHT/Pco2 relationship provides a useful index of respiratory chemosensitivity which is not influenced by airways obstruction. This may be helpful in the detection of impaired chemosensitivity as a cause of CO2 retention even when the ventilation CO2 response is reduced non-specifically by coexisting airways obstruction.
Thorax 1975 Jun
PMID:Evaluation of breath holding in hypercapnia as a simple clinical test of respiratory chemosensitivity. 114 39

430 patients with thoracic cancer were given intensive care after major thoracic surgery. Of those 188 (43.72%) developed cardiac complication during their stay in ICU and 2 (0.46%) died. The results indicated that postoperative cardiac complications were closely related to the patients age, preoperative concomitant cardiovascular diseases, duration of operation, hypoxemia, hypercapnia, and surgical complications. Postoperative cardiac intensive care could reduce the mortality rate.
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PMID:[Postoperative cardiac intensive care for patients with thoracic cancer: analysis of 430 cases]. 130 98

Severe idiopathic scoliosis may lead to respiratory failure, which can be treated by assisted ventilation. Twenty four patients with surgically untreated idiopathic scoliosis who had been examined in 1968 were re-examined in 1988 to assess changes in lung function and risk factors for respiratory failure. The patients were aged 15-67 years in 1968 and had a scoliotic angle of 10-190 degrees and a vital capacity of 1.0-6.0 litres. Spirometric values and scoliotic angles were determined in 1968 and 1988, and arterial blood gas tensions in 1988. The decline in spirometric values over the 20 years was of the same magnitude as the predicted decline due to aging. Arterial blood gas tensions in 1988 were strongly correlated with the scoliotic angles and spirometric indices recorded in 1968. Hypoxaemia and hypercapnia was seen in four patients in 1988 (then aged 43-67 years) and these were the four patients who had a vital capacity below 43% predicted in 1968. The remaining 20 patients had blood gas values within normal limits. Two further patients had died from respiratory failure before 1988, so a total of six patients had developed respiratory failure. In a multiple logistic analysis vital capacity expressed as % predicted in 1968 was the strongest predictor of the development of respiratory failure, followed by the scoliotic angle. Respiratory failure occurred only in patients who had a vital capacity below 45% predicted in 1968 and an angle greater than 110 degrees. Thus respiratory failure develops in adults with scoliosis with a large angle and a low vital capacity when normal aging reduces the ventilatory capacity further. Such individuals merit close follow up.
Thorax 1991 Jul
PMID:Lung function in adult idiopathic scoliosis: a 20 year follow up. 187 34

The effects of hypercapnia and hypocapnia on respiratory resistance were studied in 15 healthy subjects and 30 asthmatic subjects. Respiratory resistance (impedance) was measured with the pseudo-random noise forced oscillation technique while the subjects rebreathed from a wet spirometer in a closed respiratory circuit in which end tidal carbon dioxide tension (PCO2) could be controlled. Hypercapnia was induced by partially short circuiting the carbon dioxide absorber, and hypocapnia by voluntary hyperventilation. The circulating air was saturated with water vapour and kept at body temperature and ambient pressure. A rise of end tidal PCO2 of 1 kPa caused a significant fall in respiratory resistance in both normal and asthmatic subjects (15% and 9% respectively). A fall of PCO2 of 1 kPa did not cause any significant change in impedance in the control group. In the asthmatic patients resistance increased by 13%, reactance fell by 45%, and the frequency dependence of resistance rose 240%. These findings confirm that hypocapnia may contribute to airway obstruction in asthmatic patients, even when water and heat loss are prevented.
Thorax 1991 Jan
PMID:Effects of hypercapnia and hypocapnia on respiratory resistance in normal and asthmatic subjects. 190 37


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