Acid-base Variables Research Articles

Cerebrospinal fluid acid-base status and lactate and pyruvate concentrations after short (less than 30 minutes) first febrile convulsions in children.

Twenty-nine infants and children with short (less than 30 minutes) first febrile convulsions were studied between 3 and 22 hours after convulsive episodes. Arterial and CSF acid-base variables, lactate and pyruvate concentrations, and lactate/pyruvate ratios were measured. Biochemical signs of cerebral hypoxia were found in only 2 patients, one of whom had short, repeated convulsions. Our findings indicate that hypoxic damage is unlikely to result from a short-duration febrile convulsion.

The van Slyke equation.

The Henderson-Hasselbalch equation has always occupied a central place in the description of the acid-base status of the blood. An equation of similar importance is the equation for the CO2 equilibration curve of blood in vitro. It is proposed to name this the Van Slyke equation: a - 24.4 = - (2.3 X b + 7.7) X (c - 7.40) + d/(1 - 0.023 X b), where a = bicarbonate concentration in plasma/(mmol/l), b = hemoglobin concentration in blood/(mmol/l), c = pH of plasma at 37 degrees C, d = base excess concentration in blood/(mmol/l). These two equations provide an arithmetic algorithm for calculation of the various acid-base variables of the blood after measuring the pH, the pCO2, and the hemoglobin concentration.

Patterns of total and ionized calcium and other electrolytes in plasma during and after general surgery.

Thirteen patients were studied during two hours of anaesthesia for abdmonial operations and for an hour post-operatively. Serial venous blood samples were taken for determination of plasma total and ionized calcium, acid-base variables, Na, K, Mg, PO4 total proteins and parathyroid hormone. One group of patients received 5 per cent dextrose/water and the other 5 per cent dextrose in Ringer's solution, at 250 ml per hour. Total and ionized calcium levels decreased toward the end of operation and an hour later, associated with respiratory alkalosis. Parathyroid hormone increased at the end of operation, as an effect of the decreased ionized calcium. The general effect was mild haemodilution with all the other electrolytes decreasing, as did total protein concentration.

The effect of hepatectomy on the energy state and on acid-base variables of the rat brain.

The influence of hepatectomy on cerebral energy metabolism was studied in rats in which an end-to-side portacaval anastomosis had been performed one week earlier. The hepatectomy gave rise to an exaggeration of the increase in tissue ammonia content resulting from the shunt. Three hours after the hepatectomy there was a fall in tissue glutamate content but no change in alpha-ketoglutarate. The energy state of the tissue, as evaluated from the concentrations of ATP, ADP, and AMP, was unchanged. There was a significant increase in cerebrospinal fluid pH but no change in intracellular pH.

Influence of the Neuroleptanalgesic Combination of Etorphine and Acepromazine on the Horse: Blood Gases and Acid‐base Balance

Respiratory function and acid-base variables were studied in Welsh Mountain ponies before and at predetermined times after the intravenous injection of Immobilon and Revivon.A marked depression of respiratory rate was accompanied by large reductions in arterial blood oxygen tension and saturation and the development of a mild respiratory acidosis following the injection of Immobilon. It was concluded that at least three factors contributed to the hypoxic hypoxia produced by Immobilon; the posture of lateral recumbency, the decrease in respiratory rate and the laboured character of the respiration. Arterial oxygen and carbon dioxide tensions returned towards control levels soon after administering Revivon. Mixed venous oxygen tensions were little affected by either Immobilon or Revivon, and mixed venous carbon dioxide tensions were increased to smaller degrees that those of arterial blood. Haemoglobin was increased initially by Immobilon, had returned to the control level by 30 min and fell below the control following the administration of Revivon.

A Program for Calculation of Intrapulmonary Shunts, Blood-Gas and Acid-Base Values with a Programmable Calculator

With a desk-top, programmable calculator, it is now possible to do complex, previously time-consuming computations in the blood-gas laboratory. The authors have developed a program with the necessary algorithms for temperature correction of blood gases and calculation of acid-base variables and intrapulmonary shunt. It was necessary to develop formulas for the Po2 temperature-correction coefficient, the oxyhemoglobin-dissociation curve for adults (withe necessary adjustments for fetal blood), and changes in water vapor pressure due to variation in body temperature. Using this program in conjuction with a Monroe 1860-21 statistical programmable calculator, it is possible to temperature-correct pH,Pco2, and Po2. The machine will compute alveolar-arterial oxygen tension gradient, oxygen saturation (So2), oxygen content (Co2), actual HCO minus 3 and a modified base excess. If arterial blood and mixed venous blood are obtained, the calculator will print out intrapulmonary shunt data (Qs/Qt) and arteriovenous oxygen differences (a minus vDo2). There also is a formula to compute P50 if pH,Pco2,Po2, and measured So2 from two samples of tonometered blood (one above 50 per cent and one below 50 per cent saturation) are put into the calculator.

Cerebral energy metabolism, pH, and blood flow during seizures in the cat

Cerebral energy metabolism, pH, and blood flow during seizures in the cat

Cerebral blood flow and metabolism in coma following cardiac arrest

Summary Cerebral blood flow (CBF) and oxygen uptake, and cerebrospinal fluid acid-base variables were studied in 11 comatose patients shortly after resuscitation from cardiac arrest. CBF was above normal in 2 patients, but more or less reduced in the other 9 patients. The cerebral oxygen uptake was reduced to below 2/3 of normal. The cerebrospinal fluid showed a lactacidosis, the degree of which was correlated to the CBF.

Observations on lactate and pyruvate concentrations, lactate/pyruvate ratios, and acid-base variables in simultaneously sampled arterial blood and CSF after presumed acute hypoxia in infants and children

Observations on lactate and pyruvate concentrations, lactate/pyruvate ratios, and acid-base variables in simultaneously sampled arterial blood and CSF after presumed acute hypoxia in infants and children

Some numerical methods of estimating acid-base variables in normal human blood with a haemoglobin concentration of 5g-100 cm3.

Three methods are discussed for calculating pHNR, i.e. pH at PCO2=40 mm Hg, from measurements of arterial pH and PCO2. In method I the manual procedure with the Siggaard-Andersen nomogram is transferred to a computer. In method II pHNR is calculated on a desk calculator and in method III on a computer from analytical expressions derived in this paper. The estimated standard deviations, within the range -20 < BE < 20, between pHNR obtained with method I and the pHNR values obtained with methods II and III are 0.0017 and 0.0006 pH units, respectively. The largest differences are 0.005 and 0.003 pH units, respectively. These figures refer to a blood with a haemoglobin concentration of 5 g/100 cm3. An equation for calculating ‘buffer base’ (BB) from pHNR is also given. Other methods of computing acid-base values are reviewed.

A STUDY OF MATERNAL ACID-BASE STATE DURING LABOUR

SUMMARY Arterialized venous blood was used to investigate maternal acid-base state during the first and second stages of normal labour. During labour the range of values obtained for acid-base variables is wide but patterns are discernible. At the beginning of labour Pco2 was lower than it is in non-pregnant subjects, and the pH was higher despite a substantial base deficit. At the end of the first stage the Pco2 declined, the base deficit increased, and blood pH rose slightly. There were further changes in the second stage but these were quite small. The use of various drugs and of epidural analgesia in the first stage had little effect on Pco2 though the use of premixed nitrous oxide and oxygen in the Entonox apparatus resulted in a slightly increased degree of hyperventilation.

A computer program for the blood pH-log pCO2 nomogram.

Dell, R. B., Engel, K. & Winters, R. W. A Computer Program for the Blood pH-log pCO2 Nomogram. Scand. J. din. Lab. Invest. 19 29-37, 1967. A computer program written in Fortran Iv, Version 13, which calculates all of the acid-base variables derivable from the pH, log pCO2 blood acidbase nomogram, has been developed and validated.

ACID-BASE BALANCE IN CEREBROSPINAL FLUID.

<h3>Introduction</h3> ALTHOUGH delirium, reduced consciousness, and abnormal motor function frequently accompany systemic acid-base disorders, the mechanisms producing these symptoms are unknown. Blood pH and other serum acid-base variables usually correlate poorly with the neurological symptoms. Therefore, several laboratories, including our own, have recently investigated the cerebrospinal fluid (CSF) acidbase balance in systemic disorders. Since these data have not previously been discussed in the neurological literature and since no previous report has attempted to correlate CSF acid-base balance with neurological function, the entire field is reviewed here in some detail. Preliminary reports of some of our material have appeared in abstract form.^1,2 The CSF pH depends almost entirely on its carbon dioxide-bicarbonate ratio (CO₂/HCO-₃) and contains so little protein that its buffering capacity resembles a 20 millimolar (mM) bicarbonate solution. Foa,³in 1906, first measured the CSF pH electrometrically and obtained in dog a value of