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Query: UMLS:C0001127 (respiratory acidosis)
 1,501 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Upon entering into aestivation, Protopterus aethiopicus develops a respiratory acidosis. A slow compensatory increase in plasma bicarbonate suffices only to partially restore arterial pH toward normal. The cessation of water intake from the start of aestivation results in hemoconcentration and marked oliguria. The concentrations of most plasma constituents continue to increase progressively, and the electrolyte ratios change. The increase in urea concentration is disproportionately high for the degree of dehydration and constitutes an increasing fraction of total plasma osmolality. Acid-base and electrolyte balance do not reach a new equilibrium within 1 yr in the cocoon.
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PMID:Acid-base balance and plasma composition in the aestivating lungfish (Protopterus). 1 65

Crayfish, Astacus leptodactylus, for several hours breathed water equilibrated either with a hypoxic gas mixture, or air, or oxygen. The hydrostatic pressure in the right epibranchial cavity was recorded and the left epibranchial water sempled from time to time. The higher the water oxygenation, the less the duration of ventilation, the frequency of the scaphognathite beats which ensure water convection, the negative of the water hydrostatic pressure relative to ambient water pressure, and the respired water flow. The water convection per unit quantity of oxygen consumed decreased by a factor of about 20 when the animal passed from hypoxic water at PO2 of 72 torr to hyperoxic water at PO2 of 697 torr. Prolonged hyperoxia, up to 100 days, results in a hypercapnic acidosis of the prebranchial blood. pH decreased about 0.2 unit, PCO2 increased from 2.5 torr to a value of 6 torr, and [HCO-3] from 6 to a value of 9 meq-L-1. This hypercapnic acidosis remained uncompensated during several weeks exposure to hyperoxia. Observations on the fresh water crayfish, a marine crab, and several species of fish, suggest that in aquatic animals (1) the ventilatory activity depends greatly on the degree of water oxygenation: the higher the water oxygenation, the lower the ventilation; (2) the change of ventilation may be accompanied by a new equilibrium of the blood acid-base status, quite different from that observed in normoxia.
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PMID:Crayfish respiration as a function of water oxygenation. 1 99

The time course of blood acid-base changes was studied in Carcinus maenas during experimental emersion and reimmersion at 15 degrees C by measuring pH and PCO2 and calculating bicarbonate concentration. During the first 4 hr of the emersion period, a marked rise of PCO2 entails a respiratory acidosis which is progressively compensated by a slow increase of the bicarbonate concentration; this compensation is completed after about 100 hr and the steady state mean pH value approximates that found for the immersed controls. Return to aquatic conditions is characterized by a rapid decrease of both PCO2 and blood bicarbonate concentration. During the first 2 hr of the reimmersion period, the decrease of blood bicarbonate concentration is accompanied by excretion of a significant amount of base in water, thus suggesting that readjustments of acid-base balance take place at least in part by ionic exchanges between the blood and the external milieu. Initial status was restored after 9 hr. These finding agree with the general views concerning the blood acid-base changes which must occur at transition from water-to air-breathing.
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PMID:Blood acid-base changes during experimental emersion and reimmersion of the intertidal crab Carcinus maenas (L.). 23 71

When the crab Carcinus maenas respires in hypercapnic water, a respiratory acidosis occurs, which is progressively compensated by a rise of the blood bicarbonate concentration. The CO2 partial pressure in the blood increases in proportion to the change in ambient CO2 partial pressure. Therefore, the regulation of the acid-base status depends mainly on non-respiratory adjustments of the blood bicarbonate concentrations.
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PMID:[Effect of hypercapnia on the acid base states of the blood in the crab Carcinus maenas (L.) (Crustacea-Decapoda)]. 23 96

Intracranial hypertension and brain hydration were scrutinized during acute ethanolism for consideration in the combined head injury setting. Intraventricular pressures and whole brain water levels rose with moderate or high ethanol dosages. The most prominent alterations were associated with respiratory acidosis and hypoxia; less marked changes were found in their absence and point to a second mechanism. Elevated central venous pressures appeared as well in some instances to constitute a third action. It is accordingly suggested that ethanol may add significantly to the combined pathology with associated acute head injury in several ways. These include: contributions to edema formation, to respiratory depression, and to alterations in local hemodyamics.
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PMID:Changes in intracranial pressure and brain hydration during acute ethanolism. 123 77

Recommendations concerning postoperative extubation after thymectomy for myasthenia gravis are presently based upon retrospective chart reviews. We present the results of a prospective investigation of time to extubation after thymectomy for 14 patients over a 12-month period based upon a protocol that included preoperative immunologic therapy, combined epidural and general anesthesia, postoperative epidural narcotic analgesia, and a standardized approach to discontinuation of ventilatory support. After a neurologist took measures to optimize preoperative neuromuscular function, all 14 patients received agents to produce lumbar epidural anesthesia and light general anesthesia. Muscle relaxants were avoided in all but one patient. Postoperative analgesia was initially maintained with epidural hydromorphone, then therapy was switched to patient-controlled intravenous morphine sulfate. Criteria for weaning from mechanical ventilation, first measured at the end of anesthesia, were partial pressure of oxygen (arterial) greater than or equal to 90 mm Hg (fraction of inspired oxygen = 0.40), partial pressure of carbon dioxide (arterial) less than or equal to 50 mm Hg, pH greater than or equal to 7.30, and respiratory rate less than or equal to 30 breaths/min. If these criteria were not met, ventilatory support was continued postoperatively with intermittent mandatory ventilation, and the patient was weaned gradually from this support. Criteria for extubation included meeting the criteria for weaning, vital capacity greater than or equal to 10 mL/kg, and inspiratory pressure better than -30 cm H2O. Criteria for reintubation included tachypnea (respiratory rate greater than 40 breaths/min), respiratory acidosis not due to narcotics, or vital capacity less than or equal to 8 mL/kg. The mean time to extubation was 9 hours (range, 0.75 to 25 hours). Mean preoperative vital capacity was 2.59 +/- 0.64 L (range, 1.90 to 4.20), which decreased approximately 50% to 1.19 +/- 0.39 L (range, 0.70 to 2.0) at the time of extubation. No patient required reintubation. Half of the patients required postoperative anticholinesterase therapy based upon serial neurologic examinations; there were no instances of cholinergic crisis. Thirteen patients returned to the ward on the first postoperative day, and one on the second day. Thirteen patients preferred epidural analgesia to patient-controlled analgesia. The time to extubation and average length of stay in an intensive care setting were markedly reduced compared to those reported in previous retrospective studies. We conclude that a multidisciplinary approach that optimizes neuromuscular function and decreases poststernotomy pulmonary insult will shorten the time to extubation and decrease the length of stay in the intensive care or recovery room after thymectomy.
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PMID:Extubation after transsternal thymectomy for myasthenia gravis: a prospective analysis. 171 Dec 40

The authors sought to determine how hypoperfusion influences acid-base balance in arterial and mixed venous blood. In anesthetized, ventilated pigs (n = 12), we determined hemodynamics, O2 uptake, CO2 output, dead-space ventilation, arterial and mixed venous blood acid-base balances, and lactate concentrations during graded reductions in cardiac output by incremental positive end-expiratory pressure (PEEP, 0-20 cm H2O). Cardiac output decreased from 3.2 +/- 0.2 (mean +/- SEM) to 1.2 +/- 0.1 L/min at 20 cm H2O PEEP. Oxygen delivery declined more than O2 uptake did by 60% +/- 2% and 27% +/- 2%, respectively. The decrease in CO2 output (by 21% +/- 2%) was less than that in O2 uptake. Fractional dead-space ventilation increased. At a slight increase in carbon dioxide tension (PCO2) of 4 +/- 1 mm Hg, pH decreased in arterial blood from 7.54 +/- 0.01 to 7.47 +/- 0.02 mmol/L, and standard bicarbonate decreased from 30.3 +/- 0.5 to 27.5 +/- 0.6 mmol/L. The decrease in standard bicarbonate exceeded the increase in blood lactate concentrations. At a similar decrease in standard bicarbonate, the decrease in pH was larger (P less than 0.005) in mixed venous blood than in arterial blood owing to a larger increase in PCO2 (from 40 +/- 2 to 50 +/- 2 mm Hg, P less than 0.005). The changes were reversed after discontinuing PEEP. The authors conclude that ischemia after incremental PEEP results in tissue metabolic acidosis with superimposed respiratory acidosis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Arterial and mixed venous blood acid-base balance during hypoperfusion with incremental positive end-expiratory pressure in the pig. 195 38

The effect of 52 h of sleep deprivation (SD) upon blood constituents was studied in 12 young women aged 21.5 +/- 0.4 years. Subjects were individually isolated without time cues, performing a sequence of cognitive tasks. Significant decreases in hematocrit (p less than 0.002) and red cell count (p less than 0.04) developed, mainly over the first 28 h of SD, reaching a subsequent plateau or partial recovery. The calculated plasma volume also increased by 10.7 +/- 3.1% at 52 h, with recovery to a 6.9 +/- 3.2% increase the following day. About 1 L of water was retained over the first 30 h of SD, with a subsequent partial elimination of this excess. Plasma albumin and total protein concentrations were largely sustained in the face of the plasma expansion. The plasma pH showed a progressive fall from a baseline value of 7.381 +/- 0.014 to 7.332 +/- 0.006 at 52 h, while plasma bicarbonate decreased from a baseline figure of 31.2 +/- 0.7 to 26-27 mM/L (p less than 0.05). After 8 weeks, all subjects repeated the experiment, with the introduction of 30 min of exercise in the 40th h of wakefulness. Hematocrit and plasma volume changes were similar to those of the first experiment up to the time of exercise, but hematocrit decreased and plasma volume increased after the exercise bout, rather than reaching a plateau. Plasma pH increased with exercise, but returned to the previous low level at 52 h. Any arousing effect of the exercise bout was transient. The plasma expansion reflects metabolic and/or respiratory acidosis, plus possible effects of a prolonged period without recumbency.
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PMID:Moderate exercise and hemodilution during sleep deprivation. 231 Mar 61

To assess the accuracy of a pneumotachometer (PN) for tidal volume (VT) measurements during high-frequency oscillation (HFO), we determined simultaneously VT using a PN and a full body plethysmograph (PL) in 12 rabbits. HFO was delivered with an oscillator at a frequency of 10 Hz, mean airway pressure of 8 cm H2O, and inspiratory time of 50%. Pressure amplitude (delta P) was varied as follows: 40, 60, 80, 20, 100, 40 cm H2O. Finally, in ten rabbits a spacer equal in deadspace (VD) to that of the PN (15 ml) was left in-line for 5 min. Blood gases were obtained before and after the spacer was added. We found that VT-PN correlates well with VT-PL (r = .92), although the difference between VT-PN and VT-PL is greater at large VT. Significant respiratory acidosis developed with the spacer in-line. PN may be used to trend VT during HFO but PN must not be left in-line, as increased VD seriously affects ventilation.
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PMID:Measurement of tidal volume using a pneumotachometer during high-frequency oscillation. 234 57

Decreases in arterial pH markedly increase sodium, chloride, and water absorption in the normal ileum and can reverse ongoing cholera toxin-induced secretion. In the current study we examined whether these effects of pH are evident in other models of ileal secretion, and in a model of increased absorption. Rats were anesthetized and transport was measured in ileal loops during respiratory acidosis and alkalosis. Decreases in arterial pH increased absorption equally in control loops and in adjacent loops perfused with a Ringer's solution containing ST toxin (cyclic guanosine monophosphate-mediated secretion), hypertonic mannitol (passive, osmotically mediated secretion), or glucose. Decreases in arterial pH increased absorption in a similar way in loops exposed to cholera toxin (cyclic adenosine monophosphate-mediated secretion) that were then perfused with glucose-Ringer's solution. Alterations in arterial and luminal pH did not affect glucose absorption. These results suggest that the effect of arterial pH on ileal absorption occurs by a mechanism that is independent of these various means of altering transport.
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PMID:Effect of systemic pH on models of altered ileal transport in the rat. 249 10


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