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At least 37 records · Page 2Linked to original sources
PubMed1993

Influence of hydrogen ion concentration versus carbon dioxide tension on pulmonary vascular resistance after cardiac operation.

Disturbances of respiratory acid-base status are common in patients supported with mechanical ventilation of the lungs after cardiac operations. This study was conducted with two protocols. The purpose was to determine whether respiratory acid-base status influences pulmonary vascular resistance in adults after cardiac operations and whether the influence is mediated by hydrogen ion concentration or carbon dioxide tension. Patients were studied while under general anesthesia immediately after aorta-coronary bypass. In the first protocol, with seven patients, arterial carbon dioxide tension was manipulated by the addition of 5% carbon dioxide to the breathing circuit. Pulmonary vascular resistance index was determined as arterial carbon dioxide tension rose from 30 mm Hg to 50 mm Hg and back to 30 mm Hg. In the second protocol, with 10 different patients, hydrogen ion concentration was manipulated by the addition of 0.2N hydrochloric acid, sodium bicarbonate, or both as arterial carbon dioxide tension was held constant. We used analysis of variance for statistical data. The results of the first protocol showed that pulmonary vascular resistance index rose by 44% (p < 0.05) as arterial carbon dioxide tension rose from 30 to 50 mm Hg. The results of the second protocol showed that changes in pulmonary vascular resistance index were parallel to changes in hydrogen ion concentration as arterial carbon dioxide tension was held constant (p < 0.05). These data demonstrate that respiratory acid-base status is an important determinant of pulmonary vascular resistance in the adult after cardiac operations. Furthermore, these data suggest the effect is mediated by hydrogen ion concentration, not carbon dioxide tension.

Acid-Base Equilibrium↗
PubMed1980

General method for calculation of hydrogen-ion concentration in multicomponent acid-base mixtures.

A generalized method for the rapid evaluation of complicated ionic equilibria in terms of the hydrogen-ion concentration was developed. The method was based on the derivation of a single general equation that could be used to evaluate any mixture. A tableau method also was developed which allowed calculation of the numerical solution to the general equation without computer analysis or graphical or intuitive approximations. Examples illustrating the utility of the method are presented. These examples include a mixture of barbital, citric acid, boric acid, monobasic sodium phosphate, and sodium hydroxide. Calculated hydrogen-ion concentrations showed good agreement with experimental values for simple and complex solutions. The major advantages of the method are its simplicity and the obtainment of numerical solutions without initial approximations in the calculations. However, activity corrections are not included in the calculations.

Acids↗
PubMed1987

The influence of blood hydrogen ion concentration on the level of consciousness in diabetic ketoacidosis.

Among 287 cases of diabetic ketoacidosis, 212 patients were alert, 48 drowsy, 10 stuporous and 17 comatose. The mean blood hydrogen ion concentrations in these 4 groups of patients were 50.0; 72.8; 106.8 and 109.9 nmol/l, respectively. Increased blood hydrogen ion concentration seems to be an important factor in lowering the level of consciousness in diabetic ketoacidosis.

Consciousness↗
PubMed2001

Protein binding of glipizide using equilibrium dialysis technique: effects of hydrogen ion concentration, drug concentration and ionic strength.

The objective of this research was to investigate the effects of hydrogen ion concentration, drug concentration and ionic strength on the binding affinity of glipizide to albumin protein. Different buffer solutions of different pH values (pH 6.7, 7.5 and 8.5), different drug concentrations (2.45 mg, 4.82 mg and 9.42 mg), and phosphate buffer solutions pH 7.5 of different ionic strength (0.1, 0.4 and 1.0) were prepared. The effects of pH, drug concentration and ionic strength on the amount of glipizide bounded to 0.25 g bovine albumin was investigated. As the pH of the solution was increased from pH 6.4 to pH 8.5, milligrams drug bounded to gram protein (r value) decreased from 8.2 mg to 3.84 mg/g protein. Also as the ionic strength of the solution was increased from 0.1 to 1.0, the r value decreased from 10.76 mg to 3.96 mg/g protein. However, the r value did not change significantly with increasing of drug from 2.45 mg to 9.42 mg/25 ml. The r value was 7.36 mg/g protein when concentration of the drug was 2.45 mg/25 ml and 7.4 mg/g protein when the concentration of the drug was 9.42 mg/25 ml. This study demonstrated that factors such as high pH and high ionic strength can alter drug-protein binding and consequently increase free drug in plasma and increase bioavailability of slightly water insoluble drug such as antidiabetic drugs.

Dialysis↗
PubMed1990

Paradoxical increase in arterial hydrogen ion concentration in patients with hepatorenal failure given lactate-based fluids.

We have investigated lactate intolerance in nine patients with acute hepatorenal failure during 21 machine haemofiltration treatments using a lactate based replacement solution. In all cases hyperlactataemia occurred, the mean arterial lactate increased from 1 +/- 0.2 mmol/l (mean +/- SEM) prior to treatment to 3.2 +/- 0.3 mmol/l at 1 h (P less than 0.01), 4.2 +/- 0.4 mmol/l at 2 h (P less than 0.01), 4.2 +/- 0.4 mmol/l at 3 h (P less than 0.01) and 3.9 +/- 0.4 mmol/l (P less than 0.01) post-treatment. There were correlations between the maximum increase in blood lactate and both the change in arterial hydrogen ion concentration (r = 0.71, P = 0.001) and the mean arterial blood pressure prior to starting treatment (r = -0.57, P = 0.007). During eight of the treatments (38%), the arterial hydrogen ion concentration increased. This group showed increased lactate intolerance in association with a lesser pretreatment mean arterial pressure. The administration of exogenous lactate to patients with hepatorenal failure who are at, or near to, the threshold of their own endogenous lactate metabolism can result in an increase in hydrogen ion concentration rather than the expected decrease, and therefore lactate-based dialysate solutions are best avoided.

Acid-Base Equilibrium↗
PubMed1974

The dumping syndrome and the hydrogen ion concentration of the gastric contents.

Forty patients after vagotomy (truncal vagotomy 18, selective vagotomy 22) with a drainage procedure were given 200 ml of 50% dextrose by mouth (dumping provocation test), the symptoms induced being noted, and any fall in plasma volume was assessed by serial measurement of the haematocrit. An insulin gastric secretion test was also performed on each patient.TWENTY OF THE PATIENTS HAD DUMPING SYMPTOMS OF VARYING SEVERITY AFTER ORDINARY MEALS: in all 20 patients these symptoms were reproduced by the dumping provocation test, which also produced similar symptoms in a further three patients. The hydrogen ion concentration of the gastric contents was significantly lower in the basal state and after insulin hypoglycaemia in those patients with dumping symptoms than in those without such symptoms. Furthermore there was a significant inverse correlation between the hydrogen ion concentration of the gastric contents in the basal and stimulated state and the rate of plasma volume fall. The results show that the occurrence of the dumping syndrome after vagotomy with a drainage procedure is related to the hydrogen ion concentration of the gastric contents. The possible significance of this finding is discussed.

Adult↗
PubMed1976

Hydrogen ion concentration of human tears: Effects of prolonged eye closure.

Using a closed chamber microelectrode technique, human tear hydrogen ion concentration was measured following periods of eye closure of 6 to 8 hours and then compared with normal open eye findings from the same patients. Closed eye tears were found to be significantly more acid (average age difference = 26 nM/1) and required some 3 to 4 hours to return to average open eye levels. The population rate for this return averaged 6.9 nM/1/hr. This degree of acid shift measured for prolonged eye closure, however, remained, for the average patient, well within comfort limits commonly cited, and appeared insufficient to distrub the water content or optical parameters of hydrophilic polymers in common use today for therapeutic or cosmetic purposes.

Adult↗
PubMed1983

The effects of hydrogen-ion concentration on the respiratory efficiency of human liver mitochondria.

To examine the effects of hydrogen ion concentrations on the coupled respirations of isolated human liver mitochondria, eight patients underwent incidental liver biopsies during the conduct of abdominal surgery. Mitochondria were studied by the polarographic technique at pH of 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0. Results indicated severe inhibition of nicotinamide adenine dinucleotide (NAD)-linked substrates but succinate oxidations were minimally affected. Sodium succinate was then studied as a possible substrate in the resuscitation of hemorrhagic shock. Rats were subjected to bleeding to an arterial blood pressure of 50 mm Hg for 3 hours or until 25 per cent of shed blood had to be reinfused to maintain blood pressure. Resuscitation consisted of reinfusion of all shed blood plus a volume of one of four crystalloid regimens: Ringers lactate; isotonic sodium succinate; hypertonic sodium chloride (190 mEq/l): or twice-normal, hypertonic sodium chloride (308 mEq/l). Results indicated that those rats resuscitated with sodium succinate did poorer than animals receiving alternate regimens. The failure of succinate to diffuse across the plasma membrane may explain these data. Additional studies with succinate or a chemical analogue seem warranted.

Animals↗
PubMed2003

A comparison of hydrogen ion concentration and pH genetic predictions and fixed effect estimations when assessing pork quality.

An evaluation of ultimate pH (pH) and hydrogen ion concentration (H+) was conducted to determine if the mathematical conversion of H+ to pH could affect 1. fixed and random effect inferences and 2. prediction of genetic merit of animals when either pH or H+ is used as an indicator in the assessment of pork quality. Data from 4,262 purebred animals and 577 sires having complete three-generation pedigrees from the 1991 to 2001 National Barrow Show Progeny Tests were utilized in this study. Existing loin muscle pH data were converted to their original H+. Numerical changes in values occurred across all fixed effects and in the case of breed and test, changes in differences among subclasses occurred. These changes may result in differing inferences that can be made depending on whether pH or H+ is used as the dependent variable. Heritability estimates for pH and H+ were 0.52 +/- 0.074 and 0.62 +/- 0.078, respectively. The Pearson correlation between pH and H+ breeding values was -0.92. Spearman Rank correlation of -0.91 between pH and H+ breeding values was calculated and indicates that sires do not rank the same when ordered by breeding values for each trait. When pH is the selection objective, the selection differential reduction in H+ from these data ranges from 3.8 to 9.1%. Additionally, only 77.7% of the estimated genetic progress per generation in H+ is realized when selection (5% selected) is based on pH. The genetic correlation between pH and H+ was -0.96. Changes in the absolute values of the genetic correlations between various pork quality indicator traits and pH or H+ concentration were 0.04 or less. Differences in pH and H+ results could impact decisions made by swine breeders and meat processors who are concerned about pork quality. This, combined with the greater heritability and biochemical reality for H+, indicates that H+ rather than pH is the more appropriate trait breeders and processors should focus on when attempting to improve pork quality.

Animals↗