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

The physiology of respiratory control of acid-base balance is reviewed. The pathophysiological mechanisms during hypercapnia and hypocapnia are discussed in the light of the causes and clinical manifestations of these disturbances. In addition to the role of the kidney in the compensatory processes of these disturbances, renal functional changes during acute and chronic pulmonary acid-base derangement is discussed. Some of the difficulties encountered in the patient with chronic renal disease in whom respiratory abnormalities may be present are also discussed.
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PMID:Respiratory acidosis and alkalosis. 1 97

1. The regulation of cerebrospinal fluid (c.s.f.) bicarbonate concentration was studied using the cat choroid plexus isolated in a chamber in situ. 2. Decreases in plasma bicarbonate concentration caused relatively small changes in the c.s.f. bicarbonate concentration. 3. Alterations in c.s.f. bicarbonate concentration (c.s.f. HCO3-=9 or 28 m-equiv/l.) were countered by changes in the bicarbonate concentration of the fluid produced by the plexus or in the rate of bicarbonate transport which returned c.s.f. bicarbonate towards normal. 4. There was significant regulation of pH in the choroid plexus fluid during hypocapnia and hypercapnia. 5. Alterations of plasma acid-base status did not significantly alter the potential difference across the choroid plexus. However, the potential difference increased when c.s.f. bicarbonate was increased and decreased when c.s.f. bicarbonate was decreased. 6. The data indicate that the bicarbonate concentration in the c.s.f. is actively regulated by the choroid plexus during acid-base disturbances occurring either systemically or in the c.s.f.
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PMID:Regulation of cerebrospinal fluid bicarbonate by the cat choroid plexus. 1 33

Blood and tissue gas exchange properties of mole rats in normoxic and hypoxic-hypercapnic conditions were compared to the common mammalian pattern. RBC count was 14.0 +/- 1.2-10(6)/microliter. Hb concentration was 15.0 +/- 0.4g/100 ml. P50 (at pH 7.4 and 37 degrees C) was 29.5 +/- 0.5 mm Hg. Oxygen capacity averaged 20.2 +/- 0.4 vol% and the Hill coefficient was 2.9 +/- 0.1. The Bohr effect was -0.53 +/- 0.02 (deltalog P/deltapH). The temperature coefficient was 0.0152 +/- 0.0014 (deltalog P/delta degrees C). The Haldane effect was 4.8 +/- 0.5 (deltaCCO2 vol%)at PCO2 =40 mm Hg. Steady-state partial pressures in gas pockets were PO2 = 15.1 +/- 1.4 mm Hg and PCO2 = 85.8 +/- 3.9 mm Hg in normoxia, and 11.5 +/- 3.0 and 101.8 +/- 3.5 repectively in hypoxia-hypercapnia (PIO2 congruent to 85 mm Hg). Under the same conditions 2,3-DPG dropped from 0.87 and 0.88 to 0.62 and 0.65 (mol/mol Hb) in the rat and in the white rat, respectively. Heart muscle myoglobin concentration of the mole rat (1.44 mg/g) did not differ significantly from that of the white rat (1.96 mg/g), whereas masseter myoglobin was 4.0 mg/g--significantly different from the rat (1.21 mg/g). Results indicate that the strategy used by the mole rat to maintain a normal metabolic rate under variable atmospheric conditions, besides having high oxygen affinity, is to expand the physiological range of the oxygen dissociation curve to very low oxygen tensions, at the expense of its acid-base regulation. The regulation of the shape of the oxygen dissociation curve is discussed.
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PMID:Blood-gas properties and function in the fossorial mole rat under normal and hypoxic-hypercapnic atmospheric conditions. 1 98

In 61 patients with chronic cor pulmonale with compensation and decompensation of circulation, the stroke and minute heart volume were studied as well as the indices, characterizing the blood-gas contents and acid-base blood state. The minute heart volume in the patients examined proved to be with normal values. Stroke heart volume is decreased in all patients examined with chronic cor pulmonale. The acceleration of heart activity enables the maintenance of normal minute volume. Hypoxemia has a cardiac depressive effect as regards minute volume and heart rate. The moderate hypercapnia has a certain stimulating effect on heart. A direct proportional correlation exists between the hypercapnia degree and the tendency of minute volume increase and especially of heart rate. The campaign against hypoxemia is an essential element in the prophylaxis and early treatment of chronic cor pulmonale.
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PMID:[Cardiac output, blood gas analysis and the acid-base state of the blood in chronic cor pulmonale]. 1 45

Standard clearance studies were performed in mechanically ventilated intact and acutely thyroparathyroidectomized (TPTX) rats to document and characterize the effect of hypercapnia (HC) on urinary phosphorus excretion (U(P)V). HC as compared to normocapnia (NC) was associated with an increase in U(P)V in intact (62.5 vs. 7.93 mug/min) and TPTX (30.5 vs. 0.59 mug/min) rats, an increase in filtered load of phosphorus in intact (218 vs. 191 mug/min) and TPTX (243 vs. 146 mug/min) rats, an increase in blood bicarbonate concentration in intact (27.8 vs. 26.0 meq/liter) and TPTX (24.5 vs. 22.3 meq/liter) animals, and a decrease in blood pH in intact (7.15 vs. 7.42) and TPTX (7.07 vs. 7.39) rats. Additional TPTX rats with NC and HC were studied during phosphorus infusion at a comparable filtered load of phosphorus (NC = 307 mug/min and HC = 328 mug/min). U(P)V was 18.5 mug/min in NC and 85.2 mug/min in HC animals. Intact NC animals infused with NaHCO(3) achieved a blood bicarbonate of 45.9 meq/liter compared to 26.0 meq/liter in intact NC NaCl-infused rats. U(P)V was 10.0 mug/min in the NaHCO(3) and 7.93 mug/min in NaCl-infused animals. In intact HC animals infused with NaHCO(3), blood pH was 7.36 compared to 7.42 in NC intact NaCl-infused animals. U(P)V was 83.2 mug/min in the HC bicarbonate-infused and 7.93 mug/min in the NC NaCl-infused rats. These experiments demonstrate that elevated blood carbon dioxide tension per se increases U(P)V. Increases in filtered load of phosphorus and blood bicarbonate which are associated with HC contribute to the phosphaturia as does parathyroid hormone. The phosphaturia is not dependent upon reduction of extracellular pH.
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PMID:Relationship between phosphaluria and acute hypercapnia in the rat. 1 98

1. Blood O2 transport and acid-base balance were studied at 20 degrees C in rainbow trout (Salmo gairdneri) which had been kept in water of high CO2 content (15 mmHg) for at least a week. Also the blood gas chemistry of fish rapidly entering or leaving the hypercapnic environment was studied. 2. Fish entering high CO2 water suffered a sharp decrease in blood pH which significantly reduced O2 transport by the blood, but after a few hours considerable compensation was achieved. 3. After at least a week in high CO2 water, trout showed elevated plasma bicarbonate and PCO2 levels, and a decrease in plasma chloride, while pH was about 0 - 1 pH unit below the level for control fish. Oxygen transport by the blood was marginally reduced. 4. Hypercapnic fish rapidly entering fresh water showed a sharp increase in blood pH and a decrease in blood PO2. These parameters regained normal values after a few hours but plasma bicarbonate and chloride levels took much longer to regain control concentrations. 5. Acid-base balance in hypercapnic fish is discussed with particular reference to the role of the branchial ion exchanges.
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PMID:Blood respiratory properties of rainbow trout (Salmo gairdneri) kept in water of high CO2 tension. 1 48

The cooling of rats under conditions of hypercapnia and hypoxia during the first 15 minutes increases the contents of free fatty acids, acetoacetate and beta-oxybutyrate in the tissues of the brain, myocardium, liver, skeletal muscles and blood and decreases them by the end of the effect (120 min later) down to the initial values, in the liver and skeletal muscles tissues the content of the mentioned intermediates falls lower the initial values. In the carbohydrate metabolism the amount of phosphoenolpyruvate 15 and 120 min after the action beginning and the amount of malate in the myocardium and brain at the end of the experiment increase to a different extent; the content of lactate rises only in the brain 30 and 120 min after the beginning of cooling. In the rat venous blood the value of pCO2 increases up to 71.8+/-6.0 mm Hg, the total content of CO2 rises, the values of the standard bicarbonates decrease and the pH value drops sharply down to 6.98+/-0.03. It is suggested that one of the main reasons of such changes in metabolism is development of hypercapnia state and acidosis and the resulted increase in intensity of the carboxylation processes in the tissues.
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PMID:[Changes in lipid and carbohydrate metabolism in rat tissues under combined effect of hypercapnia, hypoxia and cooling]. 1 64

The acid-base values of 13 patients with stable carbon dioxide tensions under controlled ventilation have been used to define the response to chronic hypocapnia in man. These patients had a respiratory paralysis and no apparent complicating disorders. Over a range of carbon dioxide tensions from 24 to 40 millimetres of mercury, the arterial blood hydrogen ion concentration decreased linearly by 0.32 nanomole per litre per millimetre of mercury decrement in carbon dioxide tension. Of primary interest was the finding that the slope of the regression line in chronic hypocapnia is close to that already reported for chronic hypercapnia. The physiological response to chronic hypocapnia in man is defined by a band that is approximately 10 nanomoles per litre (0.09 pH unit) wide for hydrogen ion concentration and 6 millimoles per litre wide for bicarbonate concentration. These significance bands may be used to differentiate additional acid-base disorders in patients with chronic hypocapnia over a clinically useful range of carbon dioxide tensions.
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PMID:Acid-base response to chronic hypocapnia in man. 2 Jan 87

The renal net acid excretion (NAE), the blood pH (pHe), the total body intracellular pH (pHi) and the urinary pH (pHu) were calculated in 10 patients with chronic obstructive lung disease and hypercapnia and in 5 normocapnic subjects. The mean value of NAE was significantly higher in hypercapnic subjects than in normocapnic ones. pHe was significantly lower in hypercapnic than in normocapnic subjects. The differences of pHi and pHu between normo and hypercapnic subjects were not significant. NAE is significantly correlated with PaCO2, pHe, pHu and pHi in all the subjects considered together. H+-secretion probably depends on the H+-availability and pHi of tubular cells, but from our results it is not possible to confirm this relationship, because the method used for pHi is fundamentally a measure of muscle-pHi.
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PMID:Relationship between urine acidification and intracellular pH in respiratory acidosis. 2 Oct 21

Eleven instances of a mixed acid-base disorder consisting of chronic respiratory acidosis and metabolic alkalosis were recognized in eight patients with chronic obstructive lung disease and carbon dioxide retention. Correction of the metabolic alkalosis led to substantial improvement in blood gas values and clinical symptoms. Patients with mixed chronic respiratory acidosis and metabolic alkalosis constitute a common subgroup of patients with chronic obstructive lung disease and carbon dioxide retention; these patients benefit from correction of the metabolic alkalosis.
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PMID:Effect of metabolic alkalosis on respiratory function in patients with chronic obstructive lung disease. 2 Oct 28


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