The Influence of Alterations in Acid-Base Balance Upon Transfers of Carbon Dioxide and Bicarbonate in Man 1

Abstract

The output of carbon dioxide by the lungs is primarily dependent upon the oxidative metabolism of the organism, and may, indeed, be used as a measure of oxidative processes under appropriate conditions (1 to 3). It is well recognized, however, that augmentation or depletion of the large quantity of CO2 stored within the body, which occurs during alkalosis or acidosis, may produce alterations in respiratory CO2 output, independent of oxidative metabolism (4 to 7). Some attempts have been made to establish quantitative relationships between such changes in the output of CO2 by the lungs and fluctuations of acid-base equilibrium within the organism. Shaw (8) measured the respiratory exchange of cats subjected to artificial ventilation with C02-rich mixtures, and correlated the CO2 exchange of the whole animal with variations in blood CO2 content. From such observations, the amount of CO2 absorbed by the tissues could be estimated. Irving and his coworkers (9, 10) made direct determinations of the CO2 content of various tissues of dogs and cats overventilated with air and with CO2 enriched-mixtures. They attempted to account for the net CO2 exchange of the whole organism in terms of altered CO2 content of blood, muscle, bone, and viscera. Applications of Shaw's technique in an effort to determine the CO2 capacity of the human body has been reported by Adolph, Nance, and Shiling (11). Their results were inconclusive, as were those of similar studies by Brocklehurst and Henderson (12) EXPERIMENTAL PROCEDURES AND METHODSThe experiments involving measurement of respiratory exchange were carried out on normal male adults (the same subject was used in all but 2 experiments). The fasting subject came to the laboratory at about 8 a.m. and rested for one-half hour under basal conditions. The basal respiratory exchange was determined over a 10-minute period by the open circuit method, with the subject breathing through a rubber mouthpiece into a Tissot spirometer. Analyses of the expired air for CO2 and oxygen were carried out in duplicate by means of a modified Haldane apparatus. The usual precautions were taken to avoid leaks and the apparatus was checked from time to time by analyses of atmospheric air.Venous blood samples for determination of serum CO2content were obtained anaerobically, without stasis, immediately before the initiation of the procedure designed to alter acid-base equilibrium. In the overventilation experiments, as soon as the blood was in the syringe, the subject began to breathe into the spirometer at a ventilation rate about twice normal. After 5 to 10 minutes of overbreathing, a second venepuncture was made and the spirometer disconnected as soon as the blood sample had been obtained. CALCULATIONSThe magnitude of change in respiratory C02 output produced by altered acid-base equilibrium was calculated as follows:1. The respiratory quotient of the basal period was calculated from the C02 output and oxygen consumption of that period.2. The oxygen consumed during the period of acid-base change was mult...

Changes in Acid-Base Balance of Uremic Patients During Hemodialysis 1

“…The rapidity of change of the serum bicarbonate concentration during dialysis suggests that the extracellular fluid rather than total body water is equilibrating with the dialysate bath. This is in accord with the observation of Rosenbaum that intravenous bicarbonate appeared to be limited in its distribution to the extraceilular fluid (12). Wallace and Hastings (13) It would seem doubtful in these cases of chronic renal insufficiency that the efficacy of hemodialysis is directly due to the removal of a toxic metabolite which has accumulated primarily in the extracellular fluid or which is easily diffusible between the intracellular and extracellular fluids.…”

Effects in Man of Acute Experimental Respiratory Alkalosis and Acidosis on Ionic Transfers in the Total Body Fluids 1

“…Those Earlier workers had demonstrated experimentally that a major portion of CO2 withdrawn from the body by hyperventilation, or retained in the body by inhalation, came from, or was added to, tissues other than blood (39)(40)(41). On the assumption of an unchanged basal R. Q., Rosenbaum (42) calculated that during hyperventilation 21 to 47 per cent of expired non-metabolic CO2 came from outside the chloride-corrected thiocyanate space; conversely, during CO2 inhalation, 12 to 56 per cent of the CO2 was retained in this space. These studies clearly indicated that the intracellular fluid shared in the buffering of respiratory acidbase disturbances) but there was not sufficient appreciation of the obligatory nature of associated transfers of hydrogen and other cations.…”

Distribution of Sodium Bicarbonate Infused Into Nephrectomized Dogs 1

“…Neutralization as bicarbonate of retained carbon dioxide (5)(6)(7)(8) also indicates the role of intracellular buffers when acid loading overwhelms respiratory and renal regulations of acid-base equilibriumi. While intracellular buffers might be-expected to participate in neutralizing excess alkali, studies of the distribution of administered bicarbonate in cat muscle (9) and in the whole body of man (10) do not allocate to intracellular buffers a significant role in neutralizing administered alkali.…”